Neuromuscular ABPN and HY

Question 1

Sporadic MND types

Answer 1

ALS, PMA, PLS, progressive bulbar palsy

Question 2

Amyotrophic lateral sclerosis (ALS) types

Answer 2

Familial form AD
progressive muscular atrophy (LMN), primary lateral sclerosis (UMN), progressive bulbar palsy (PBP)

Split hand phenomena

Needle EMG two required: evidence of chronic neurogenic change and evidence of acute denervation.

Decreased motor unit recruitment with rapid firing of a reduced number of motor units

-and/or large amplitude, long duration motor unit potential with or without evidence of remodeling
(increased number of phases) in combination with abnormal spontaneous activity including positive sharp waves, fibrillations, and/or fasciculation potentials.

Question 3

Progressive muscular atrophy (PMA)

Answer 3

pure LMN
men aged 64+;
longer survival (48 months) than “usual” ALS

Question 4

Primary lateral sclerosis (PLS)

Answer 4

UMN signs 4 years after onset

usually leg onset (stiffness, falls) with slow progression

Question 5

Progressive bulbar palsy PBP

Answer 5

often menopausal women, very poor prognosis

Question 6

Flail person in a barrel: Bilateral upper extremity wasting (BLUE)

Answer 6

9:1 male: female
longer survival (57 months)

Question 7

Genetic MND: familial ALS, SMA, SBMA, Tay-Sachs, distal hereditary motor neuropathy

Question 8

Familial amyotrophic lateral sclerosis MND
Inheritance

Answer 8

AD (5-10% of cases, most sporadic).

Question 9

Spinal muscular atrophy MND (SMA)
Inheritance and gene

Answer 9

AR, SMN1 gene, childhood and adult forms

Question 10

Spinal and bulbar muscular atrophy (SBMA) MND (Kennedy’s Disease)
Inheritance
Repeat

Answer 10

XLR, CAG repeat in androgen receptor
onset 20-60 yo
slowly progressive
tongue and testicular atrophy

late-onset gynecomastia, defective spermatogenesis, and androgen resistance.

The androgen receptor gene contains an expansion in the number of glutamine repeats.

Question 11

Tay-Sachs disease MND
Inheritance
Gene

Answer 11

• AR
• HEXA gene makes beta-hexosaminidase A enzyme
• GM2 ganglioside
• peripheral neuropathy, dev. delay, cherry-red spot on macula, lysosomes w onion skin

Question 12

Distal hereditary motor neuropathy MND

Answer 12

axonopathy without sensory deficits

Differential Diagnosis
Charcot-Marie-Tooth disease: Distinguished by sensory involvement.

Spinal muscular atrophy: Often involves proximal muscle weakness.

Amyotrophic lateral sclerosis: Progressive, involving upper motor neuron signs.

Metabolic or toxic neuropathies: May mimic distal motor involvement.

Question 13

Focal MND: monomelic amyotrophy (Hirayama disease)

Answer 13

juvenile onset. Patients present with asymmetric weakness and atrophy, typically of the upper extremities, without sensory involvement.

Intermittent compression of the lower cervical spinal cord results in slow deterioration of motor neurons. The dorsal dural sac buckles, and there is intermittent anterior displacement and compression of the cord during neck flexion. Management is controversial at this time.

Question 14

Paraneoplastic MND

Question 15

Toxic MND: Lathyrism

Answer 15

Key Features:
• Neurological Symptoms:
• Gradual onset of spastic paraparesis (bilateral lower limb weakness and stiffness).
• Hyperreflexia and clonus in the legs.
• No significant sensory deficits (pure motor syndrome).
• Onset:
• Symptoms appear after months to years of consuming toxic quantities of grass pea (usually >30% of the diet).
• Epidemiology:
• Endemic in regions of South Asia, Sub-Saharan Africa, and Mediterranean countries, particularly during drought or famine.

Pathophysiology:
• Neurotoxicity:
• ODAP acts as an excitotoxin, overactivating AMPA glutamate receptors, leading to degeneration of upper motor neurons in the spinal cord.
• Selective Vulnerability:
• The corticospinal tracts are predominantly affected, resulting in spasticity and motor dysfunction.

Question 16

Infectious MND: polio, rabies, West Nile virus, tetanus, enterovirus D68

Question 17

Polio MND

Answer 17

Paralytic polio typically affects LMN, causing asymmetric flaccid paralysis with preserved sensation.
Poliomyelitis (~0.1–1% of cases):

•	Initial symptoms: Febrile illness resembling minor polio or nonparalytic polio.
•	Paralysis onset: Acute, flaccid paralysis occurs asymmetrically.
•	Weakness begins distally and progresses proximally.
•	Legs > arms in involvement.
•	Bulbar involvement (in ~10% of cases):
•	Dysphagia, dysarthria, and respiratory failure.
•	Spinal involvement: Damage to anterior horn cells causes LMN paralysis.
•	Reflexes are absent in affected muscles.
•	Sensation remains intact (distinguishing it from other causes of paralysis).
•	Paralysis can be permanent or recover partially over weeks to months.

3. Post-Polio Syndrome (PPS)
   • Onset: Occurs decades after recovery from acute polio (20–40% of survivors).
   • Symptoms:
   • New or worsening muscle weakness, fatigue, and pain.
   • May result from chronic overuse of compensatory muscles and neuronal degeneration.

Question 18

Rabies MND

Answer 18

Rabies is a fatal viral encephalitis caused by the rabies virus, a rhabdovirus of the genus Lyssavirus. It is a critical neurological emergency because of its almost 100% fatality rate once clinical symptoms appear. A neurologist must recognize its key features to aid in early diagnosis, treatment, and prevention.

Key Features of Rabies

1. Epidemiology
   • Transmission:
   • Bite or scratch from an infected animal (commonly dogs, bats, raccoons, foxes, and skunks).
   • Rarely via mucosal exposure or organ transplantation.
   • Global Burden:
   • Over 99% of human rabies deaths occur in Asia and Africa.
   • Bats are the most common source of rabies in the Americas.
2. Pathophysiology
   • Route of infection:
   
   1. Virus enters through saliva via a bite or wound.
   2. Replicates in local muscle tissue.
   3. Travels retrogradely along peripheral nerves to the CNS via the neurotropic route.
   4. Spreads to salivary glands, cornea, and other tissues.
      • Targets:
      • Neurons in the brainstem, hippocampus, thalamus, and hypothalamus.
      • Leads to widespread neuronal dysfunction without significant inflammation.
3. Incubation Period
   • Typically 1–3 months (range: 1 week to several years).
   • Shorter incubation is associated with bites on the head or neck due to proximity to the CNS.
4. Clinical Features

Rabies has two primary clinical forms:

a. Encephalitic (Furious) Rabies (80% of cases):
• Neurological symptoms:
• Hyperactivity, agitation, confusion.
• Hydrophobia: Painful spasms of the throat upon swallowing liquids.
• Aerophobia: Aversion to air movement over the skin.
• Seizures and hallucinations.
• Autonomic dysfunction: Hyperthermia, tachycardia, hypersalivation.
• Rapid progression to coma and death within days.

b. Paralytic (Dumb) Rabies (20% of cases):
• Presentation:
• Flaccid paralysis resembling Guillain-Barré syndrome (ascending paralysis).
• Sensory symptoms and encephalopathy are absent initially.
• Progression to respiratory failure, coma, and death.
• Slower clinical progression compared to furious rabies.

5. Diagnosis

Rabies is a clinical diagnosis, especially in endemic areas or with a history of animal exposure. Laboratory confirmation includes:
• Ante-mortem testing:
• RT-PCR for viral RNA in saliva or CSF.
• Detection of rabies antibodies in serum or CSF (not useful early).
• Skin biopsy from the nape of the neck: Demonstrates viral antigens in nerve endings via immunofluorescence.
• Post-mortem:
• Histopathology showing Negri bodies (intracytoplasmic inclusions) in neurons, especially in the hippocampus and Purkinje cells.

6. Differential Diagnosis
   • Encephalitis causes:
   • Herpes simplex encephalitis.
   • Autoimmune encephalitis (e.g., anti-NMDA receptor).
   • Japanese encephalitis, West Nile virus.
   • Neurological disorders:
   • Tetanus (spasms without hydrophobia).
   • Guillain-Barré syndrome (mimics paralytic rabies).
7. Treatment
   • No effective treatment once clinical symptoms appear (nearly 100% fatal).
   • Experimental protocols (e.g., Milwaukee Protocol) have limited success.
   • Supportive care:
   • Manage seizures, autonomic instability, and respiratory failure.
   • Pain relief and sedation for agitation.
8. Prevention
   • Pre-exposure prophylaxis:
   • Recommended for high-risk individuals (e.g., veterinarians, spelunkers, travelers to endemic areas).
   • Vaccination schedule: 3 doses of rabies vaccine on days 0, 7, and 21/28.
   • Post-exposure prophylaxis (PEP):
   • Urgent and lifesaving.
   • Immediate wound cleaning with soap and water (reduces transmission risk).
   • Rabies immunoglobulin (RIG):
   • Administered around the wound in non-immunized individuals.
   • Rabies vaccine:
   • Four-dose regimen on days 0, 3, 7, and 14 (or 2 doses for previously vaccinated individuals).

Key Teaching Points
1. Rabies is preventable but nearly always fatal once symptoms develop.
2. Clinical diagnosis relies on a history of exposure, hydrophobia, aerophobia, and autonomic signs.
3. Post-exposure prophylaxis is effective if administered before symptom onset.
4. Neurologists should include rabies in the differential for acute encephalitis or ascending paralysis in endemic areas or after potential animal exposure.

Understanding these features allows neurologists to identify rabies early, provide timely prophylaxis, and advocate for global eradication through vaccination programs.

Question 19

West Nile virus MND

Answer 19

Key Teaching Points for Neurologists
1. Neuroinvasive disease presentations (meningitis, encephalitis, AFP) are critical to recognize for early diagnosis and supportive care.
2. Acute flaccid paralysis mimics polio and GBS but is asymmetric and lacks sensory involvement.
3. Diagnosis hinges on CSF WNV IgM serology, particularly in endemic areas.

WNV: Febrile illness with asymmetric LMN paralysis and WNV IgM in CSF.

AIDP: Symmetric ascending weakness, areflexia, albuminocytologic dissociation, and demyelination on NCS.

Polio: Asymmetric paralysis, preserved sensation, and poliovirus detection in stool or CSF, often in unvaccinated patients.

Question 20

Tetanus MND

Answer 20

blocks release of GABA and glycine which increases alpha motor neuron firing causing rigidity

rx human tetanus immune globulin

Question 21

Enterovirus D68 (EV-D68) MND

Answer 21

Key Teaching Points for Neurologists
1. EV-D68 should be suspected in children presenting with acute flaccid paralysis, particularly during late summer or fall.
2. AFM is the most severe neurologic complication, and early recognition is critical for supportive care.
3. MRI findings of spinal cord gray matter lesions and PCR detection of EV-D68 in respiratory secretions help confirm the diagnosis.
4. Polio-like presentation underscores the importance of distinguishing EV-D68 from other causes of paralysis, such as poliovirus, GBS, or transverse myelitis.
5. Supportive care and early rehabilitation are the cornerstones of management due to the lack of specific antiviral or immune-modulating therapies.

Question 22

Cervical Spinal root disorders

Question 23

Thoracic Spinal root disorders

Answer 23

Key Teaching Points for Neurologists
1. Thoracic nerve root disorders often present as unilateral dermatomal pain, with or without sensory deficits.
2. Common causes include herpes zoster, disc herniation, and neoplastic lesions.
3. Always rule out visceral causes of thoracic pain (e.g., cardiac or abdominal pathology).
4. MRI is the diagnostic modality of choice to identify compressive or inflammatory lesions.
5. Early recognition of treatable causes, such as herpes zoster, can prevent complications like post-herpetic neuralgia.
6. Educate patients on the benign course of most thoracic radiculopathies, with reassurance and conservative management often being sufficient.

Question 24

Lumbosacral Spinal root disorders

Answer 24

Lumbosacral spinal root disorders involve pathology affecting the lumbar or sacral nerve roots, causing radiculopathy characterized by pain, weakness, sensory disturbances, and reflex changes in the corresponding dermatomes and myotomes. These disorders are common and clinically important for neurologists due to their high prevalence and diverse etiologies.

1. Anatomy Overview
   • Lumbosacral Nerve Roots:
   • Lumbar roots: L1–L5.
   • Sacral roots: S1–S5.
   • Each nerve root exits below its corresponding vertebra (e.g., L5 root exits below the L5 vertebra).
   • Key Functions:
   • Motor: Innervates muscles of the lower limbs.
   • Sensory: Provides sensation to the lower back, buttocks, and lower limbs.
   • Reflexes:
   • Patellar reflex (L2–L4).
   • Achilles reflex (S1).
2. Common Causes
   • Degenerative:
   • Disc herniation: Most common cause, especially at L4–L5 and L5–S1 levels.
   • Spondylosis: Osteophytes compress nerve roots.
   • Spinal stenosis: Narrowing of the spinal canal or foramina.
   • Trauma:
   • Vertebral fractures or dislocations.
   • Neoplastic:
   • Spinal cord or nerve root tumors (e.g., schwannomas, metastatic lesions).
   • Inflammatory/Infectious:
   • Herpes zoster: Dermatomal pain with or without a rash.
   • Radiculitis: Seen in conditions like Lyme disease.
   • Diabetes:
   • Diabetic radiculopathy (often thoracolumbar but can involve lumbosacral roots).
   • Other:
   • Pregnancy (lumbar lordosis or direct nerve compression).
   • Epidural fibrosis post-surgery.
3. Clinical Features

a. Pain:
• Radicular pain:
• Sharp, burning, or electric-like pain radiating along the nerve root’s dermatome.
• Commonly unilateral but can be bilateral in severe stenosis.
• Provocation:
• Worsened by coughing, sneezing, or Valsalva maneuvers (increased intraspinal pressure).

b. Sensory Symptoms:
• Dermatomal paresthesia (tingling) or hypoesthesia (numbness).
• Specific sensory patterns help localize the affected nerve root.

c. Motor Symptoms:
• Weakness in the myotomal distribution of the affected root:
• L2–L4: Hip flexion, knee extension.
• L5: Ankle dorsiflexion, big toe extension (foot drop).
• S1: Ankle plantarflexion, eversion.
• Muscle atrophy in chronic cases.

d. Reflex Changes:
• L2–L4: Reduced or absent patellar reflex.
• S1: Reduced or absent Achilles reflex.

e. Gait Abnormalities:
• L5 radiculopathy: Foot drop leads to a high-stepping gait.
• S1 radiculopathy: Difficulty with toe walking.

4. Commonly Affected Nerve Roots and Their Syndromes

L4 Radiculopathy:
• Pain: Radiates from lower back to anterior thigh and knee.
• Weakness: Knee extension (quadriceps).
• Reflex: Diminished patellar reflex.

L5 Radiculopathy:
• Pain: Radiates from lower back to lateral thigh, anterior leg, and dorsum of the foot.
• Weakness: Ankle dorsiflexion, toe extension (extensor hallucis longus), foot inversion/eversion.
• Reflex: Typically normal.

S1 Radiculopathy:
• Pain: Radiates from lower back to posterior thigh, calf, and lateral foot.
• Weakness: Ankle plantarflexion (gastrocnemius, soleus), foot eversion.
• Reflex: Diminished or absent Achilles reflex.

Cauda Equina Syndrome (Emergency):
• Bilateral radiculopathy with:
• Severe low back pain.
• Saddle anesthesia (perineal sensory loss).
• Bladder/bowel dysfunction (incontinence or retention).
• Lower extremity weakness (varies by nerve root involvement).

5. Diagnostic Evaluation

Clinical Examination:
• Straight Leg Raise (SLR):
• Positive: Reproduction of radicular pain between 30–70° of hip flexion (indicates L5 or S1 radiculopathy).
• Femoral Stretch Test:
• Positive: Anterior thigh pain (suggests L2–L4 radiculopathy).

Imaging:
• MRI (gold standard):
• Identifies nerve root compression (disc herniation, stenosis, tumors).
• CT scan:
• Useful for bony abnormalities when MRI is contraindicated.
• X-rays:
• Limited utility; may show degenerative changes or alignment issues.

Electrodiagnostic Studies:
• EMG/NCS:
• Confirms radiculopathy and excludes peripheral neuropathy.

Lab Studies (if indicated):
• ESR, CRP, and infectious workup for suspected inflammatory or infectious causes.

6. Differential Diagnosis
   • Peripheral neuropathy (e.g., diabetic neuropathy, mononeuropathies).
   • Myopathy (e.g., polymyositis, muscular dystrophies).
   • Spinal cord lesions (e.g., myelopathy, tumors, syringomyelia).
   • Hip or knee joint pathology (e.g., arthritis, bursitis).
   • Vascular claudication: Distinguished from neurogenic claudication by lack of positional relief.
7. Management

Conservative Treatment:
• Medications:
• NSAIDs, acetaminophen for pain.
• Neuropathic pain agents: Gabapentin, pregabalin, or tricyclic antidepressants.
• Physical Therapy:
• Stretching, strengthening, and postural training.
• Lifestyle Modifications:
• Weight loss, ergonomic adjustments.

Interventional Treatments:
• Epidural Steroid Injections:
• Provide temporary pain relief in radiculopathy caused by inflammation.
• Nerve Root Blocks:
• Diagnostic and therapeutic for radicular pain.

Surgical Treatment:
• Indicated for:
• Persistent or progressive neurological deficits.
• Severe pain refractory to conservative measures.
• Emergencies like cauda equina syndrome or significant spinal instability.

8. Prognosis
   • Most cases resolve with conservative treatment, particularly those caused by disc herniation.
   • Chronic or severe cases (e.g., spinal stenosis) may require long-term management or surgical intervention.

Key Teaching Points for Neurologists
1. Radicular pain following a dermatomal pattern, often provoked by movement, is a hallmark feature of lumbosacral root disorders.
2. Localize the lesion using dermatomal sensory loss, myotomal weakness, and reflex changes.
3. L5 and S1 radiculopathies are the most common, with distinct sensory, motor, and reflex findings.
4. Always evaluate for red flag symptoms like saddle anesthesia or bowel/bladder dysfunction (indicative of cauda equina syndrome).
5. MRI is the gold standard for imaging, and EMG/NCS can help confirm the diagnosis.
6. Most patients improve with conservative management; surgery is reserved for severe or refractory cases.

Question 25

Polyradiculopathy Spinal root disorders

Answer 25

Polyradiculopathy refers to dysfunction of multiple spinal nerve roots, typically involving both motor and sensory symptoms, caused by diverse underlying etiologies. It often presents as a combination of radicular pain, weakness, and sensory disturbances that span multiple adjacent dermatomes or root levels. Here are the key features neurologists should know about polyradiculopathy and spinal root disorders:

1. Etiologies

Polyradiculopathy can result from a variety of causes, including:

a. Inflammatory/Infectious:
• Guillain-Barré Syndrome (GBS):
• Acute inflammatory demyelinating polyradiculoneuropathy (AIDP).
• Symmetric ascending weakness and areflexia.
• Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP):
• Chronic course with progressive or relapsing weakness and sensory loss.
• Lyme Disease:
• Neuroborreliosis causing radicular pain and sensory loss.
• Herpes Zoster (Shingles):
• Dermatomal pain and vesicular rash; can affect multiple roots.
• Cytomegalovirus (CMV):
• Polyradiculopathy in immunocompromised patients, especially in HIV/AIDS.

b. Neoplastic:
• Meningeal carcinomatosis:
• Malignant infiltration of nerve roots; presents with pain and multiple radiculopathies.
• Lymphoma or leukemia:
• Nerve root involvement due to neoplastic infiltration.
• Schwannomas or meningiomas:
• Benign tumors causing polyradicular symptoms.

c. Compressive/Structural:
• Epidural Abscess:
• Infection causing nerve root compression, back pain, and neurological deficits.
• Epidural or subarachnoid metastases:
• Compress multiple nerve roots.
• Degenerative changes:
• Spinal stenosis or spondylosis affecting multiple levels.
• Disc Herniation:
• Large or central herniations compressing multiple adjacent nerve roots (e.g., cauda equina syndrome).

d. Metabolic/Toxic:
• Diabetic Lumbosacral Polyradiculopathy:
• Severe pain and weakness, often involving L2–L4 roots.
• Nutritional Deficiency:
• Vitamin B12 deficiency affecting spinal cord and roots.

2. Clinical Features

a. Pain:
• Radicular Pain:
• Sharp, burning, or stabbing pain in a dermatomal distribution.
• May affect multiple contiguous or non-contiguous dermatomes.

b. Motor Symptoms:
• Weakness:
• Involves multiple myotomes, often asymmetric initially.
• Progressive weakness in inflammatory or infectious causes.
• Areflexia or hyporeflexia:
• Due to root involvement; commonly seen in Guillain-Barré syndrome.

c. Sensory Symptoms:
• Paresthesia (tingling or burning) or hypoesthesia (numbness).
• Follows multiple dermatomal distributions.
• Dysesthesia:
• Painful abnormal sensation, often a feature in diabetic polyradiculopathy.

d. Autonomic Symptoms:
• Bladder or bowel dysfunction, particularly in cauda equina syndrome or meningeal carcinomatosis.
• Orthostatic hypotension in cases with significant autonomic involvement (e.g., GBS).

e. Constitutional Symptoms:
• Fever, night sweats, or weight loss may suggest an infectious, inflammatory, or neoplastic cause.

3. Common Syndromes

a. Cauda Equina Syndrome:
• Key Features:
• Severe back pain, radicular pain in multiple nerve roots.
• Saddle anesthesia, bowel/bladder dysfunction.
• Lower motor neuron (LMN) weakness and hyporeflexia.
• Causes:
• Central disc herniation, tumors, epidural abscess.

b. Diabetic Amyotrophy (Diabetic Lumbosacral Polyradiculoneuropathy):
• Severe unilateral or bilateral thigh pain and weakness.
• Involves L2–L4 roots.
• Gradual resolution over months, often incomplete.

c. Guillain-Barré Syndrome (AIDP):
• Symmetric, ascending weakness with areflexia.
• Autonomic dysfunction (e.g., tachycardia, arrhythmias).

d. Meningeal Carcinomatosis:
• Multiple radicular pain and progressive sensory/motor deficits.
• Associated with malignancy (e.g., lung, breast, melanoma).

4. Diagnosis

Clinical Examination:
• Identify dermatomal and myotomal patterns.
• Assess reflexes and autonomic dysfunction.

Imaging:
• MRI with contrast:
• Detects nerve root compression (disc herniation, tumors, abscesses).
• Enhancing nerve roots suggest inflammation or malignancy.
• CT myelography:
• Useful in patients who cannot undergo MRI.

Electrodiagnostic Testing:
• EMG/NCS:
• Confirms polyradiculopathy and excludes peripheral neuropathy.
• Shows evidence of demyelination (e.g., in GBS or CIDP) or axonal damage (e.g., in diabetes).

Laboratory Studies:
• CSF Analysis:
• Elevated protein with normal WBC count in GBS (albuminocytologic dissociation).
• Pleocytosis suggests infection (e.g., Lyme disease, CMV) or malignancy.
• Serologies:
• Lyme disease, HIV, or syphilis testing as indicated.
• Blood tests:
• Glucose, HbA1c (for diabetes), and markers of systemic inflammation.

5. Management

Underlying Cause:
• Infections:
• Antiviral therapy (e.g., acyclovir for herpes zoster).
• Antibiotics for bacterial infections.
• Autoimmune:
• Immunotherapy for GBS (IVIG or plasmapheresis) or CIDP (IVIG, corticosteroids, or immunosuppressants).
• Neoplastic:
• Radiation or chemotherapy for malignant causes.
• Structural:
• Surgical decompression for abscesses, stenosis, or herniated discs.

Symptomatic Management:
• Pain control:
• Neuropathic pain medications (e.g., gabapentin, pregabalin).
• Rehabilitation:
• Physical therapy for motor recovery.

6. Prognosis
   • Highly variable based on cause:
   • GBS: Often good with treatment but requires monitoring for respiratory failure.
   • Neoplastic: Poor prognosis unless treated early.
   • Diabetic polyradiculopathy: Recovery is gradual but often incomplete.

Key Teaching Points for Neurologists
1. Polyradiculopathy involves multiple nerve roots, presenting with radicular pain, weakness, and sensory deficits in multiple dermatomes/myotomes.
2. Always investigate red flag symptoms (e.g., fever, bladder/bowel dysfunction) that suggest an urgent cause like infection, malignancy, or cauda equina syndrome.
3. MRI with contrast and CSF analysis are key diagnostic tools for distinguishing between inflammatory, infectious, and compressive etiologies.
4. Management focuses on treating the underlying cause and supportive care, including immunotherapy for inflammatory conditions.
5. Close monitoring for complications, such as respiratory failure in GBS or permanent deficits in compressive etiologies, is crucial.

Question 26

Diabetes Spinal root disorders

Answer 26

Diabetic spinal root disorders, also known as diabetic radiculopathies, are a subset of diabetic neuropathies involving one or multiple spinal nerve roots. These disorders are often associated with poorly controlled diabetes and result in significant pain and functional impairment. A key syndrome within this category is diabetic lumbosacral radiculoplexus neuropathy (DLRPN), also known as diabetic amyotrophy.

Key Features of Diabetic Spinal Root Disorders

1. Common Syndromes
   
   1. Diabetic Lumbosacral Radiculoplexus Neuropathy (DLRPN):
      • Presentation:
      • Severe, asymmetric pain in the lower back, hip, or thigh.
      • Weakness and atrophy in the proximal lower limbs.
      • May progress to involve distal lower limb muscles.
      • Pathophysiology:
      • Microvascular ischemia and inflammation affecting the lumbosacral plexus, roots, and peripheral nerves.
      • Often occurs in older patients with type 2 diabetes.
   2. Thoracic Radiculopathy:
      • Presentation:
      • Severe, burning or stabbing pain in a dermatomal distribution along the chest or abdomen.
      • Often mistaken for cardiac, gastrointestinal, or musculoskeletal pain.
      • Pathophysiology:
      • Likely caused by ischemic damage or metabolic dysfunction of thoracic nerve roots.
   3. Cervical or Lumbar Radiculopathy:
      • Less common than lumbosacral or thoracic involvement.
      • Presents with radicular pain, sensory loss, or weakness in the cervical or lumbar regions.
2. Clinical Features
   
   1. Pain:
      • Severe, burning, sharp, or lancinating pain, often worse at night.
      • Pain typically starts unilaterally but may become bilateral.
      • In thoracic radiculopathy, pain follows a dermatomal “band-like” distribution.
   2. Weakness:
      • In DLRPN, weakness affects proximal lower extremity muscles (e.g., hip flexors, quadriceps).
      • Leads to difficulty standing, walking, or climbing stairs.
      • Can progress to involve distal muscles over time.
   3. Sensory Loss:
      • Sensory involvement is variable and may include numbness, tingling, or hypoesthesia in a dermatomal or patchy distribution.
   4. Atrophy:
      • Muscle wasting, particularly in proximal muscles of the thighs or hips, becomes evident as the disease progresses.
   5. Autonomic Dysfunction:
      • May include bowel, bladder, or sexual dysfunction in lumbosacral involvement.
3. Pathophysiology
   • Ischemia and Microvascular Damage:
   • Diabetes-associated small vessel disease leads to ischemia of the nerve roots, plexus, and peripheral nerves.
   • Immune-Mediated Inflammation:
   • Contributing role of inflammatory infiltrates around nerve fibers.
   • Metabolic Dysfunction:
   • Hyperglycemia causes oxidative stress, leading to nerve injury.
4. Differential Diagnosis
   • Other Neuropathies:
   • Idiopathic lumbosacral radiculoplexus neuropathy (non-diabetic).
   • Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).
   • Compressive Radiculopathy:
   • Disc herniation, spinal stenosis.
   • Spinal Cord Disorders:
   • Myelopathy, transverse myelitis.
   • Other Plexopathies:
   • Neoplastic infiltration, radiation-induced plexopathy.
   • Infectious:
   • Lyme disease, herpes zoster radiculopathy.
5. Diagnosis
   
   1. Clinical Features:
      • History of poorly controlled diabetes with characteristic symptoms (e.g., proximal pain and weakness).
   2. Electrodiagnostic Testing:
      • EMG/NCS:
      • Evidence of axonal degeneration (reduced amplitude of compound motor action potentials and sensory nerve action potentials).
      • Localizes involvement to nerve roots, plexus, or peripheral nerves.
   3. Imaging:
      • MRI (with contrast):
      • Excludes compressive causes (e.g., herniated disc, tumor).
      • May show enhancement of nerve roots or plexus in inflammatory radiculoplexus neuropathy.
   4. Blood Tests:
      • Glycemic control (HbA1c, fasting glucose).
      • Rule out other causes of neuropathy (e.g., B12 deficiency, thyroid dysfunction).
6. Management
   
   1. Optimize Glycemic Control:
      • Strict glucose control helps prevent further nerve damage but does not reverse established deficits.
   2. Pain Management:
      • Neuropathic Pain Medications:
      • Gabapentin, pregabalin, or tricyclic antidepressants.
      • Analgesics:
      • NSAIDs or acetaminophen for mild cases.
      • Corticosteroids (in select cases):
      • May benefit patients with significant inflammatory features.
   3. Physical Therapy:
      • Strengthening exercises to prevent contractures and improve mobility.
      • Assistive devices (e.g., walkers, braces) for gait instability.
   4. Symptomatic Management:
      • Address autonomic dysfunction (e.g., bladder, bowel issues).
   5. Rehabilitation:
      • Long-term rehabilitation for muscle atrophy and weakness.
7. Prognosis
   • Diabetic Amyotrophy:
   • Pain often improves within weeks to months.
   • Weakness and atrophy may persist for months to years, with incomplete recovery.
   • Thoracic Radiculopathy:
   • Pain may resolve over months with good glycemic control.
   • Chronic Cases:
   • Can lead to significant functional limitations without intervention.

Key Teaching Points for Neurologists
1. Diabetic radiculopathies often present with severe, asymmetric pain and motor weakness, particularly in proximal lower limbs (DLRPN) or along thoracic dermatomes.
2. Pain precedes weakness and sensory loss in most cases.
3. Differential diagnosis should exclude structural, neoplastic, and infectious causes with appropriate imaging and lab tests.
4. Electrodiagnostic testing is essential to confirm the diagnosis and localize involvement to the roots or plexus.
5. Treatment focuses on glycemic control, pain management, and physical rehabilitation.
6. Despite treatment, recovery is often slow, with persistent weakness in many cases. Early intervention improves outcomes.

Question 27

Segmental herpes zoster and post-herpetic neuralgia Spinal root disorders

Answer 27

Segmental herpes zoster and post-herpetic neuralgia (PHN) are significant spinal root disorders caused by the varicella-zoster virus (VZV) reactivation. These conditions involve the spinal nerve roots and can lead to acute pain, dermatomal rash, and chronic neuropathic pain.

1. Segmental Herpes Zoster

Etiology
• Varicella-zoster virus (VZV):
• After primary infection (chickenpox), the virus becomes latent in dorsal root ganglia.
• Reactivation occurs with waning immunity (e.g., age, immunosuppression).

Clinical Features
1. Dermatomal Pain:
• Severe, burning, stabbing, or tingling pain in a single dermatome.
• May precede the rash by 1–5 days (prodrome).
2. Dermatomal Rash:
• Vesicular eruption along a single dermatome.
• Rash evolves from erythematous macules to vesicles, then crusts over.
• Most commonly affects thoracic dermatomes (T3–T12).
3. Sensory Symptoms:
• Hyperesthesia or hypoesthesia in the affected dermatome.
• Paresthesia and dysesthesia (e.g., itching or electric shocks).
4. Motor Symptoms (Rare):
• Radiculitis causing segmental motor weakness.
• Involvement of thoracic or lumbosacral nerve roots can lead to abdominal wall weakness or foot drop.
5. Autonomic Symptoms:
• Occasional bladder or bowel dysfunction (in lumbosacral involvement).
6. Complications:
• Disseminated zoster in immunocompromised patients.
• Secondary bacterial infection of the rash.

Diagnosis
• Clinical Diagnosis:
• History of dermatomal pain and vesicular rash.
• Confirmatory Tests:
• PCR: Detects VZV DNA from vesicle fluid.
• Direct immunofluorescence: Rapid confirmation of VZV.

Treatment
1. Antiviral Therapy:
• Initiate within 72 hours of rash onset to reduce severity and prevent complications.
• Acyclovir, valacyclovir, or famciclovir.
2. Pain Management:
• NSAIDs or acetaminophen for mild pain.
• Neuropathic agents (e.g., gabapentin, pregabalin) for severe pain.
3. Adjunctive Measures:
• Topical agents (e.g., lidocaine patches).
• Corticosteroids: Sometimes used to reduce acute inflammation in severe cases.

2. Post-Herpetic Neuralgia (PHN)

Definition
• Chronic neuropathic pain persisting >90 days after the resolution of the acute herpes zoster rash.

Epidemiology
• Risk factors:
• Advanced age (especially >60 years).
• Severe acute zoster pain and extensive rash.
• Immunosuppression.

Pathophysiology
• Nerve Damage:
• Inflammation and necrosis of the dorsal root ganglia and nerve fibers.
• Persistent central and peripheral sensitization lead to chronic pain.
• Spinal Cord Involvement:
• Hyperexcitability of spinal neurons and loss of inhibitory modulation.

Clinical Features
1. Pain Characteristics:
• Burning, stabbing, or electric-shock-like pain in the previously affected dermatome.
• Pain is constant or intermittent and exacerbated by light touch (allodynia).
2. Sensory Abnormalities:
• Hyperesthesia, hypoesthesia, or paresthesia.
3. Functional Impact:
• Chronic pain leads to sleep disturbances, anxiety, and depression.

3. Diagnosis
   • Clinical diagnosis based on persistent pain in the dermatome affected by prior herpes zoster.
   • No specific diagnostic tests are necessary.
4. Treatment

Pharmacologic Therapy:
1. First-line:
• Gabapentin or pregabalin (reduces neuropathic pain and central sensitization).
• Tricyclic antidepressants (e.g., amitriptyline, nortriptyline).
2. Topical Agents:
• Lidocaine patches (localized relief for mild pain).
• Capsaicin cream or patches (desensitizes pain receptors with repeated use).
3. Second-line:
• Opioids or tramadol for refractory cases (use with caution due to dependence risk).

Non-Pharmacologic Therapy:
1. Nerve Blocks:
• Epidural or paravertebral blocks during the acute zoster phase may prevent PHN.
2. Neuromodulation:
• Spinal cord stimulation for refractory PHN.

Preventive Measures:
• Vaccination:
• Recombinant zoster vaccine (Shingrix) significantly reduces the incidence of herpes zoster and PHN in older adults.

5. Prognosis
   • Segmental Herpes Zoster:
   • Self-limiting in immunocompetent individuals, resolving in 2–4 weeks.
   • Post-Herpetic Neuralgia:
   • Chronic and debilitating but may improve over months to years.
   • Risk of recurrence or chronicity increases with age.

Key Teaching Points for Neurologists
1. Segmental herpes zoster presents with dermatomal pain and rash that follow spinal root distributions, most commonly thoracic roots.
2. Early treatment with antivirals (e.g., valacyclovir) reduces the risk of complications, including PHN.
3. Post-herpetic neuralgia is the most common complication and requires prompt management with neuropathic pain agents.
4. Always consider herpes zoster as a differential diagnosis in radicular pain, even without a visible rash (zoster sine herpete).
5. Vaccination with the recombinant zoster vaccine is highly effective in preventing both herpes zoster and PHN.

By recognizing these features, neurologists can improve outcomes and provide appropriate treatment for patients with herpes zoster and its complications.

Question 28

Infectious Spinal root disorders

Answer 28

Infectious spinal root disorders are conditions where infectious agents directly or indirectly damage the spinal nerve roots. These disorders often cause radiculopathy, characterized by pain, weakness, and/or sensory disturbances, and may progress to polyradiculopathy if multiple roots are affected. Here’s an overview of the key infectious spinal root disorders:

Key Infectious Spinal Root Disorders

1. Herpes Zoster (Shingles)
   • Cause: Reactivation of the varicella-zoster virus (VZV) from dorsal root ganglia.
   • Clinical Features:
   • Acute dermatomal pain, often burning or stabbing.
   • Vesicular rash along the affected dermatome (thoracic and lumbar roots most common).
   • Motor weakness (zoster paresis) in some cases.
   • Complications:
   • Post-herpetic neuralgia (PHN): Chronic pain persisting >3 months.
   • Rarely, transverse myelitis or radiculomyelitis.
   • Diagnosis:
   • Clinical features, PCR for VZV DNA in vesicular fluid.
   • Treatment:
   • Antivirals (e.g., acyclovir, valacyclovir) and pain management.
2. Cytomegalovirus (CMV) Radiculopathy
   • Cause: CMV infection, typically in immunocompromised patients (e.g., HIV/AIDS).
   • Clinical Features:
   • Severe lower back or sacral radicular pain.
   • Progressive flaccid weakness, sensory loss, and urinary retention.
   • Often involves lumbosacral nerve roots.
   • Diagnosis:
   • CSF analysis: Elevated protein, pleocytosis, CMV DNA by PCR.
   • MRI: Enhancement of lumbosacral nerve roots.
   • Treatment:
   • Antivirals (e.g., ganciclovir, valganciclovir) with immune reconstitution in HIV.
3. Lyme Disease (Neuroborreliosis)
   • Cause: Infection with Borrelia burgdorferi, transmitted by tick bites.
   • Clinical Features:
   • Radicular pain (sharp, burning), often in the thoracic or lumbosacral region.
   • Cranial nerve involvement (e.g., facial palsy) is common.
   • Motor weakness and sensory changes in severe cases.
   • Diagnosis:
   • Serologic testing for Lyme antibodies (ELISA, confirmed by Western blot).
   • CSF: Lymphocytic pleocytosis, elevated protein, and intrathecal antibody production.
   • Treatment:
   • Doxycycline or ceftriaxone for CNS involvement.
4. Tuberculous Radiculomyelitis (Pott’s Spine)
   • Cause: Mycobacterium tuberculosis, usually secondary to spinal tuberculosis.
   • Clinical Features:
   • Back pain and progressive neurological deficits (radiculopathy, myelopathy).
   • Often associated with vertebral body destruction and spinal deformity.
   • Diagnosis:
   • MRI: Vertebral destruction, abscesses, and nerve root compression.
   • CSF: Elevated protein, lymphocytic pleocytosis, low glucose, AFB stain, or PCR.
   • Treatment:
   • Anti-tuberculous therapy (e.g., isoniazid, rifampin, ethambutol, pyrazinamide) with or without surgery.
5. Bacterial Meningitis with Radiculopathy
   • Cause: Spread of infection to spinal nerve roots from bacterial meningitis.
   • Clinical Features:
   • Neck stiffness, fever, headache, and radicular pain.
   • Motor or sensory deficits in severe cases.
   • Common Organisms:
   • Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes.
   • Diagnosis:
   • CSF analysis: Elevated WBC, elevated protein, low glucose, positive cultures.
   • Treatment:
   • Empiric broad-spectrum antibiotics followed by targeted therapy based on cultures.
6. HIV-Associated Polyradiculopathy
   • Cause: HIV infection with or without opportunistic infections (e.g., CMV).
   • Clinical Features:
   • Subacute onset of lower back pain, progressive weakness, sensory loss, and sphincter dysfunction.
   • Affects lumbosacral roots (polyradiculopathy).
   • Diagnosis:
   • CSF: Elevated protein, pleocytosis, HIV RNA.
   • Treatment:
   • Antiretroviral therapy (ART) and management of secondary infections.
7. Neurosyphilis
   • Cause: Chronic infection with Treponema pallidum.
   • Clinical Features:
   • Tabes dorsalis: A form of late neurosyphilis with degeneration of the dorsal columns and nerve roots.
   • Severe lancinating radicular pain.
   • Sensory ataxia, loss of proprioception, and Argyll Robertson pupils.
   • Diagnosis:
   • CSF: Positive VDRL or FTA-ABS, lymphocytic pleocytosis.
   • Treatment:
   • Penicillin G (IV) for neurosyphilis.
8. Epidural Abscess
   • Cause: Bacterial infection (e.g., Staphylococcus aureus).
   • Clinical Features:
   • Severe back pain, fever, radicular pain.
   • Rapid progression to neurological deficits (weakness, sensory loss, incontinence).
   • Diagnosis:
   • MRI with contrast: Epidural collection compressing spinal nerve roots.
   • Treatment:
   • Emergent surgical decompression and antibiotics.
9. Other Viral Infections
   • Epstein-Barr Virus (EBV):
   • Rarely causes radiculopathy, typically in immunocompromised patients.
   • Enteroviruses (e.g., EV-D68):
   • Can cause acute flaccid myelitis with spinal root involvement.

Diagnosis of Infectious Spinal Root Disorders
• Clinical Clues:
• Radicular pain, dermatomal distribution, or motor/sensory deficits.
• History of systemic infection, rash (e.g., herpes zoster), or immunosuppression.
• Imaging:
• MRI with contrast: Nerve root enhancement or compression.
• CSF Analysis:
• Elevated protein, pleocytosis, low glucose (in bacterial or fungal infections).
• PCR for specific pathogens (e.g., CMV, HSV, Lyme disease, VZV).

Management Principles
1. Treat the Underlying Infection:
• Antivirals (e.g., acyclovir for VZV, ganciclovir for CMV).
• Antibiotics or antifungals based on the organism (e.g., ceftriaxone for Lyme, anti-TB drugs for tuberculosis).
2. Symptomatic Management:
• Pain control with NSAIDs, neuropathic pain medications (gabapentin, pregabalin), or corticosteroids if inflammation is prominent.
3. Supportive Care:
• Physical therapy for motor recovery.
• Surgical intervention for abscesses or compressive lesions.

Key Teaching Points for Neurologists
1. Infectious spinal root disorders often present with radicular pain, motor weakness, and/or sensory deficits, with or without systemic symptoms.
2. Herpes zoster is the most common cause of infectious radiculopathy, but other conditions like CMV or Lyme disease should be considered in specific populations.
3. MRI with contrast and CSF analysis are critical for diagnosis, along with pathogen-specific testing (e.g., PCR, serology).
4. Early treatment of the underlying infection improves outcomes and prevents complications like chronic pain (e.g., post-herpetic neuralgia) or permanent deficits.

Question 29

Neoplastic Spinal root disorders

Answer 29

Neoplastic spinal root disorders involve damage or compression of spinal nerve roots by tumors or neoplastic processes, leading to radiculopathy or polyradiculopathy. These can result from primary tumors, metastatic disease, or neoplastic infiltration of the meninges or nerve roots.

Key Features of Neoplastic Spinal Root Disorders

1. Etiology

Neoplastic spinal root disorders can arise from:
1. Primary Spinal Tumors:
• Intramedullary tumors: Ependymomas, astrocytomas.
• Extradural tumors: Schwannomas, neurofibromas, meningiomas.
• Bone tumors: Chordomas, osteosarcomas.
2. Metastatic Disease:
• Common primary sites: Lung, breast, prostate, kidney, and melanoma.
• Frequently involves vertebrae, leading to root compression from vertebral collapse or direct tumor invasion.
3. Meningeal Carcinomatosis (Leptomeningeal Disease):
• Tumor cells infiltrate the meninges and nerve roots.
• Common in hematologic malignancies (e.g., lymphoma, leukemia) and solid tumors (e.g., breast, lung).
4. Paraspinal Tumors:
• May invade the spine and nerve roots from adjacent soft tissues (e.g., psoas tumors).

2. Clinical Features

Neoplastic spinal root disorders present with radiculopathy or polyradiculopathy, and their features depend on the tumor’s location, growth rate, and involvement.
1. Radicular Pain:
• Sharp, burning, or shooting pain in the affected dermatome.
• Exacerbated by movement, coughing, or sneezing (Valsalva maneuver).
2. Sensory Symptoms:
• Dermatomal paresthesia or hypoesthesia.
• Progressive sensory loss if untreated.
3. Motor Symptoms:
• Weakness in the myotomal distribution of the affected root.
• Muscle atrophy with chronic compression.
• Asymmetric or symmetric weakness in polyradiculopathy (e.g., meningeal carcinomatosis).
4. Reflex Changes:
• Reduced or absent reflexes in the corresponding myotome.
• E.g., diminished patellar reflex (L2–L4), Achilles reflex (S1).
5. Autonomic Dysfunction:
• Bowel or bladder incontinence with lumbosacral root involvement.
• May occur in cauda equina syndrome or meningeal carcinomatosis.
6. Constitutional Symptoms:
• Weight loss, fatigue, night sweats, or fever (suggests systemic malignancy).
• Pathologic fractures with vertebral metastases.

3. Common Syndromes
   
   1. Schwannomas/Neurofibromas:
      • Typically benign, slow-growing tumors.
      • Present with radicular pain and focal neurological deficits.
      • Often involve cervical or lumbar roots.
   2. Meningiomas:
      • Commonly extradural, compressing roots and spinal cord.
      • Gradual onset of radicular pain and sensory-motor deficits.
   3. Metastatic Radiculopathy:
      • Most common cause of neoplastic spinal root disorders.
      • Presents with polyradiculopathy (e.g., bilateral leg weakness and numbness in lumbar metastases).
      • Thoracic spine is a common site for vertebral metastases, leading to chest wall pain.
   4. Meningeal Carcinomatosis:
      • Involves multiple spinal roots.
      • Severe polyradicular pain, often associated with progressive weakness and sensory loss.
      • May involve cranial nerves and spinal roots simultaneously.
   5. Cauda Equina Syndrome:
      • Often caused by metastatic or primary tumors compressing the cauda equina.
      • Presents with saddle anesthesia, bladder/bowel dysfunction, and progressive weakness.
4. Diagnostic Workup
   
   1. Clinical Examination:
      • Assess dermatomal and myotomal patterns of deficits.
      • Look for red flags: Progressive pain, weakness, or systemic symptoms.
   2. Imaging:
      • MRI with contrast:
      • Gold standard for identifying nerve root compression, tumors, and leptomeningeal enhancement.
      • Differentiates between intramedullary, intradural extramedullary, and extradural tumors.
      • CT scan:
      • Better for detecting bony involvement or fractures from metastases.
      • PET scan:
      • Identifies primary malignancy or metastatic lesions.
   3. CSF Analysis:
      • Useful in leptomeningeal disease:
      • Elevated protein, lymphocytic pleocytosis, positive cytology for malignant cells.
      • Glucose may be low.
   4. Biopsy:
      • Required for histopathological diagnosis in uncertain cases.
   5. Electrodiagnostic Studies:
      • EMG/NCS to confirm radiculopathy and exclude peripheral nerve involvement.
5. Management
   
   1. Definitive Treatment:
      • Surgery:
      • Indicated for compressive lesions causing progressive neurological deficits.
      • Decompression or tumor resection.
      • Radiotherapy:
      • For inoperable or metastatic tumors.
      • Chemotherapy:
      • Systemic or intrathecal chemotherapy for meningeal carcinomatosis or hematologic malignancies.
   2. Symptomatic Treatment:
      • Pain management:
      • Neuropathic agents (e.g., gabapentin, pregabalin), NSAIDs, or opioids for severe pain.
      • Steroids:
      • High-dose corticosteroids (e.g., dexamethasone) to reduce inflammation and edema.
      • Physical therapy:
      • For rehabilitation and to maintain strength.
   3. Palliative Care:
      • Focus on quality of life in advanced metastatic disease.
6. Prognosis
   • Primary benign tumors (e.g., schwannomas, meningiomas):
   • Excellent prognosis with surgical resection.
   • Malignant metastatic tumors:
   • Poor prognosis, especially with leptomeningeal spread.
   • Early detection and treatment are critical for preventing permanent neurological deficits.

Key Teaching Points for Neurologists
1. Radicular pain, weakness, and sensory deficits following a dermatomal pattern are hallmark features of neoplastic spinal root disorders.
2. MRI with contrast is the imaging modality of choice to identify tumors or meningeal involvement.
3. Always evaluate for red flag symptoms: Progressive deficits, constitutional symptoms, or bladder/bowel dysfunction.
4. Metastatic disease is the most common neoplastic cause, often requiring multimodal therapy (radiation, surgery, and chemotherapy).
5. Early recognition and management of compressive lesions (e.g., cauda equina syndrome) are critical to preventing irreversible damage.

By understanding these features, neurologists can diagnose and manage neoplastic spinal root disorders effectively, improving patient outcomes.

Question 30

Degenerative/trauma Spinal root disorders

Answer 30

Degenerative and traumatic spinal root disorders are among the most common causes of radiculopathy, involving damage or compression of spinal nerve roots due to structural changes or injury. These disorders often present with pain, weakness, and sensory disturbances localized to specific dermatomes and myotomes.

Key Features of Degenerative/Traumatic Spinal Root Disorders

1. Degenerative Spinal Root Disorders

Degenerative conditions affect the spine’s structures over time, leading to nerve root compression or irritation.

a. Common Causes
1. Disc Herniation:
• Protrusion or extrusion of the intervertebral disc material compressing adjacent nerve roots.
• Most common in the cervical and lumbar spine.
• Lumbar: L4–L5 and L5–S1 levels are most affected.
• Cervical: C5–C6 and C6–C7 levels are common.
2. Spinal Stenosis:
• Narrowing of the spinal canal or foramina, leading to nerve root compression.
• Can be central, foraminal, or lateral recess stenosis.
• Often associated with spondylosis (degenerative arthritis of the spine).
3. Spondylolisthesis:
• Slippage of one vertebra over another, causing root compression.
• Commonly affects L4–L5 and L5–S1 levels.
4. Osteophytes:
• Bony spurs forming as a result of degenerative changes.
• Compress adjacent nerve roots in the foramen.
5. Facet Joint Hypertrophy:
• Degeneration of facet joints contributes to stenosis and root compression.

b. Clinical Features
1. Pain:
• Radicular Pain:
• Sharp, burning, or stabbing pain radiating along the affected dermatome.
• Worsened by movement, coughing, or sneezing (Valsalva maneuver).
• Neurogenic Claudication (in stenosis):
• Pain and weakness in the legs during walking or standing, relieved by sitting or lumbar flexion.
2. Sensory Symptoms:
• Dermatomal numbness, tingling, or hypoesthesia.
3. Motor Symptoms:
• Weakness in myotomal distribution.
• Example:
• L5 radiculopathy: Foot drop (weakness in ankle dorsiflexion).
• C7 radiculopathy: Weakness in triceps and wrist extension.
4. Reflex Changes:
• Reduced or absent reflexes corresponding to the affected root:
• Patellar reflex (L2–L4).
• Achilles reflex (S1).
• Biceps reflex (C5–C6) or triceps reflex (C7).
5. Positional Symptoms:
• Pain and weakness worsen with extension in stenosis (e.g., walking downhill).

c. Diagnosis
1. Clinical Examination:
• Dermatomal and myotomal deficits.
• Positive Straight Leg Raise (SLR) test for lumbar radiculopathy.
2. Imaging:
• MRI (gold standard): Visualizes nerve root compression, disc herniation, and stenosis.
• CT: Better for bony changes (e.g., spondylolisthesis, osteophytes).
• X-rays: Assess alignment, degenerative changes, or instability.
3. Electrodiagnostic Studies:
• EMG/NCS: Confirms radiculopathy and distinguishes from peripheral neuropathy.

d. Management
1. Conservative Therapy:
• Medications:
• NSAIDs, muscle relaxants, or neuropathic pain agents (e.g., gabapentin, pregabalin).
• Physical Therapy:
• Core strengthening, stretching, and postural training.
• Lifestyle Modifications:
• Weight loss and ergonomic changes.
2. Interventional Treatments:
• Epidural steroid injections for pain relief.
3. Surgical Treatment:
• Indicated for progressive deficits, intractable pain, or cauda equina syndrome.
• Examples: Discectomy, laminectomy, or spinal fusion.

2. Traumatic Spinal Root Disorders

Trauma to the spine can cause direct injury to the spinal nerve roots, leading to acute radiculopathy or polyradiculopathy.

a. Common Causes
1. Fractures and Dislocations:
• Vertebral fractures (e.g., burst fractures) can compress nerve roots.
• Common at thoracolumbar and cervical junctions.
2. Whiplash Injury:
• Hyperextension and flexion injury of the cervical spine, causing radicular pain and inflammation of nerve roots.
3. Penetrating Trauma:
• Gunshot or stab wounds damaging nerve roots.
4. Post-Surgical Trauma:
• Nerve root damage during spinal surgery or instrumentation.

b. Clinical Features
1. Acute Onset:
• Sudden pain and neurological deficits following trauma.
2. Radicular Pain:
• Severe, sharp pain radiating along the nerve root’s dermatome.
3. Motor and Sensory Deficits:
• Vary depending on the level and severity of the injury.
• E.g., C5–C6 injury: Weakness in shoulder abduction and elbow flexion.
4. Reflex Changes:
• Hyporeflexia or areflexia in the affected limb.

c. Diagnosis
1. Imaging:
• CT: Best for detecting fractures or bony injuries.
• MRI: Essential for soft tissue and nerve root evaluation.
2. Electrodiagnostic Studies:
• EMG/NCS for delayed or chronic radiculopathy assessment.

d. Management
1. Acute Management:
• Immobilization to prevent further injury.
• Surgical decompression for fractures causing root compression.
2. Pain Management:
• Analgesics, NSAIDs, or neuropathic pain medications.
3. Rehabilitation:
• Physical therapy to regain strength and mobility.

Key Syndromes
1. Cauda Equina Syndrome:
• Often caused by trauma, large disc herniation, or stenosis.
• Symptoms: Saddle anesthesia, bowel/bladder dysfunction, and lower limb weakness.
• Emergency requiring surgical decompression.
2. Neurogenic Claudication:
• Seen in lumbar stenosis due to degenerative changes.
• Symptoms worsen with standing or walking and improve with sitting.

Key Teaching Points for Neurologists
1. Degenerative spinal root disorders, such as disc herniation and spinal stenosis, are the most common causes of radiculopathy, especially in the cervical and lumbar spine.
2. Traumatic disorders often present with acute radiculopathy following fractures or dislocations.
3. MRI is the gold standard for identifying nerve root compression and soft tissue injury, while CT is better for bony injuries.
4. Conservative management is effective for most degenerative cases, but surgical intervention is necessary for progressive deficits, cauda equina syndrome, or severe trauma.
5. Always assess for red flag symptoms, such as bladder or bowel dysfunction, that indicate urgent intervention.

Question 31

Myeloneuropathy

Answer 31

Myeloneuropathy refers to a condition where both the spinal cord (myelopathy) and peripheral nerves (neuropathy) are simultaneously affected. It is not a single disease but a clinical syndrome caused by various underlying conditions. Recognizing the key features of myeloneuropathy is crucial for timely diagnosis and management.

Key Features of Myeloneuropathy

1. Definition
   • Myelopathy: Dysfunction or damage of the spinal cord.
   • Neuropathy: Dysfunction or damage of the peripheral nerves.
   • Myeloneuropathy: Combined involvement of the spinal cord and peripheral nerves, presenting with both upper motor neuron (UMN) and lower motor neuron (LMN) signs.
2. Etiologies

a. Nutritional Deficiencies
1. Vitamin B12 Deficiency (Subacute Combined Degeneration):
• Demyelination of the dorsal columns and lateral corticospinal tracts (myelopathy).
• Peripheral neuropathy due to axonal degeneration.
• Cause: Malabsorption (e.g., pernicious anemia), vegan diet.
2. Copper Deficiency:
• Mimics B12 deficiency; causes myelopathy and neuropathy.
• Cause: Gastric surgery, zinc toxicity.
3. Vitamin E Deficiency:
• Ataxia due to dorsal column and spinocerebellar tract involvement.

b. Toxins
1. Nitrous Oxide (N2O) Abuse:
• Inactivates vitamin B12, leading to subacute combined degeneration-like syndrome.
2. Heavy Metals:
• Lead, arsenic, or mercury poisoning can cause neuropathy with possible spinal cord dysfunction.

c. Infectious/Inflammatory
1. HIV-Associated Myelopathy and Neuropathy:
• Vacuolar myelopathy with symmetric posterior column and corticospinal tract involvement.
• Distal symmetric polyneuropathy (DSPN) from direct viral or drug-induced damage.
2. HTLV-1-Associated Myeloneuropathy (HAM/TSP):
• Chronic progressive spastic paraparesis (myelopathy) with sensory loss and peripheral neuropathy.
3. Syphilis (Tabes Dorsalis):
• Dorsal column degeneration (light touch, vibration) and radiculopathy.

d. Hereditary Conditions
1. Friedreich’s Ataxia:
• Degeneration of the spinal cord (dorsal columns, corticospinal, and spinocerebellar tracts) and peripheral nerves.
• Presents with ataxia, weakness, and areflexia.

e. Paraneoplastic Syndromes
• Paraneoplastic myelopathy combined with sensory or motor neuropathy caused by autoimmune reactions to tumors (e.g., lung or breast cancer).

f. Metabolic
1. Diabetic Myeloneuropathy:
• Peripheral neuropathy with rare spinal cord involvement due to ischemic or metabolic damage.
2. Uremic Neuropathy and Myelopathy:
• Associated with chronic kidney disease.

g. Vascular
1. Spinal Cord Ischemia (e.g., due to aortic aneurysm repair):
• Causes myelopathy with peripheral nerve involvement (ischemic radiculopathy).

3. Clinical Features

a. Myelopathy Signs:
1. Upper Motor Neuron (UMN) Features:
• Spasticity, hyperreflexia, clonus.
• Positive Babinski sign.
• Sensory changes in a level-dependent distribution.
2. Posterior Column Dysfunction:
• Loss of proprioception and vibration sense (seen in B12 deficiency and syphilis).
3. Lateral Corticospinal Tract Dysfunction:
• Weakness with increased tone (spastic paraparesis).
4. Bladder/Bowel Dysfunction:
• Common in cervical and thoracic spinal cord involvement.

b. Neuropathy Signs:
1. Lower Motor Neuron (LMN) Features:
• Flaccid paralysis, atrophy, fasciculations.
• Hyporeflexia or areflexia.
2. Peripheral Sensory Loss:
• Stocking-glove distribution of numbness and tingling.
3. Autonomic Neuropathy (in some cases):
• Orthostatic hypotension, erectile dysfunction.

c. Combined Features:
• Coexistence of UMN and LMN signs is a hallmark of myeloneuropathy.
• Gait abnormalities:
• Ataxia from posterior column or spinocerebellar tract dysfunction.
• Sensory ataxia with peripheral neuropathy.

4. Diagnostic Approach

a. Clinical Examination:
• Assess for mixed UMN and LMN signs.
• Evaluate sensory modalities (proprioception, vibration, light touch, pain).

b. Laboratory Tests:
1. Vitamin Levels:
• Serum B12, methylmalonic acid, homocysteine, and copper levels.
2. Toxin Exposure:
• Heavy metal levels (e.g., lead, arsenic).
3. Infectious Workup:
• HIV, HTLV-1, syphilis (RPR, FTA-ABS).
4. Metabolic:
• Blood glucose, HbA1c, renal function tests.

c. Imaging:
1. MRI Spine:
• To evaluate myelopathy (cord compression, signal changes).
• Posterior column hyperintensities in B12 deficiency.
2. CT Myelogram:
• For suspected compressive lesions.

d. Electrodiagnostic Studies:
1. Nerve Conduction Studies (NCS):
• Identifies axonal or demyelinating peripheral neuropathy.
2. Electromyography (EMG):
• Confirms LMN involvement.

5. Management

a. Treat the Underlying Cause:
1. Vitamin Deficiency:
• Replace B12, copper, or vitamin E.
2. Toxins:
• Remove exposure and chelation therapy if indicated.
3. Infections:
• Antiretroviral therapy for HIV; penicillin for syphilis.
4. Metabolic Causes:
• Optimize glucose control for diabetes, dialysis for uremia.

b. Symptomatic Treatment:
1. Spasticity:
• Baclofen, tizanidine.
2. Neuropathic Pain:
• Gabapentin, pregabalin, or TCAs.
3. Rehabilitation:
• Physical and occupational therapy to improve function.

6. Prognosis
   • Reversible in early stages of B12 or copper deficiency if treated promptly.
   • Progressive in hereditary and degenerative conditions (e.g., Friedreich’s ataxia).
   • Prognosis depends on early recognition and addressing the underlying cause.

Key Teaching Points for Neurologists
1. Myeloneuropathy presents with mixed UMN and LMN signs, distinguishing it from pure myelopathy or neuropathy.
2. Nutritional deficiencies (B12, copper) are common and treatable causes.
3. MRI and electrophysiologic studies are crucial for identifying the extent of spinal cord and nerve involvement.
4. Always consider toxic, infectious, and metabolic causes in the differential diagnosis.
5. Early diagnosis and treatment can significantly improve outcomes, particularly in reversible causes like nutritional deficiencies.

Question 32

Brachial plexopathies: traumatic, radiation, neuritis, hereditary, neoplastic, TOS

Answer 32

traumatic lower trunk can involve T1 and therefore Horners syndrome may occur

Question 33

Hereditary brachial plexopathy

Answer 33

Ch 17q25 SEPT gene
AD
Painful brachial plexopathies

Childhood onset of hereditary brachial plexopathy is not unusual.

Many patients exhibit a relapsing-remitting course
characterized by attacks that resolve spontaneously, either completely or incompletely,
leaving additive residual weakness. The disorder can also follow a progressive pattern.
Physical exertion and pregnancy are reported triggering events.

Question 34

Traumatic plexopathies (neonatal, penetrating injury)

Answer 34

Traumatic plexopathies involve injury to the brachial or lumbosacral plexus due to trauma, such as birth-related injuries or penetrating trauma. These conditions result in motor, sensory, and sometimes autonomic dysfunction depending on the level and extent of plexus involvement.

1. Neonatal Plexopathies

Etiology
• Birth-related brachial plexus injuries (BPI) occur due to excessive traction on the infant’s head, neck, or shoulder during delivery.
• Risk factors:
• Shoulder dystocia.
• Large-for-gestational-age infants.
• Instrumental deliveries (e.g., forceps or vacuum extraction).
• Breech presentation.

Clinical Presentations
1. Erb-Duchenne Palsy (C5–C6 Injury):
• Most common type of neonatal brachial plexus injury (~80–90% of cases).
• Key Features:
• Weakness of shoulder abduction, external rotation, and elbow flexion.
• “Waiter’s tip” posture:
• Arm adducted, internally rotated.
• Elbow extended, forearm pronated.
• Wrist flexed.
• Sensory loss over the lateral arm.
• Reflex changes:
• Absent Moro and biceps reflex on the affected side.
2. Klumpke Palsy (C8–T1 Injury):
• Less common.
• Key Features:
• Weakness in intrinsic hand muscles and wrist flexors.
• “Claw hand” deformity: Hyperextension of the metacarpophalangeal joints and flexion of interphalangeal joints.
• Sensory loss over the medial arm and forearm.
• Complications:
• Horner syndrome if T1 sympathetic fibers are involved (ptosis, miosis, anhidrosis).
3. Total Plexus Palsy (C5–T1 Injury):
• Complete paralysis of the arm.
• Flaccid limb with no spontaneous movement.
• Severe sensory loss.

Diagnosis
• Clinical examination:
• Posture of the limb, weakness, reflex changes.
• Electrodiagnostic studies:
• EMG/NCS to assess nerve integrity (often deferred until 4–6 weeks of age to allow for Wallerian degeneration).
• Imaging:
• MRI or ultrasonography may identify nerve root avulsions or pseudomeningoceles.

Management
1. Conservative:
• Physical therapy:
• Gentle range-of-motion exercises to prevent contractures and maintain joint flexibility.
• Observation:
• Many cases of Erb palsy resolve spontaneously within 3–6 months.
2. Surgical:
• Indicated for severe injuries (e.g., nerve root avulsion or no improvement by 3–9 months).
• Techniques: Nerve grafting, nerve transfer, or tendon transfer.

Prognosis
• Erb palsy:
• ~70–90% recover fully with conservative management.
• Severe injuries (e.g., total plexus palsy) have poorer outcomes and often result in permanent deficits.

2. Penetrating Traumatic Plexopathies

Etiology
• Penetrating trauma to the brachial or lumbosacral plexus:
• Gunshot wounds, stab injuries, or shrapnel.
• Secondary damage:
• Hematoma, scar tissue, or ischemia compressing the plexus.

Clinical Presentations
1. Brachial Plexopathy:
• Upper plexus (C5–C6):
• Weakness in shoulder and elbow movements.
• Sensory loss in the lateral arm and forearm.
• Lower plexus (C8–T1):
• Weakness in hand and wrist movements.
• Sensory loss in the medial arm and forearm.
• Possible Horner syndrome.
• Complete plexus:
• Paralysis of the entire arm with sensory loss.
2. Lumbosacral Plexopathy:
• Upper plexus (L1–L4):
• Weakness in hip flexion, knee extension.
• Sensory loss in the anterior thigh and medial leg.
• Lower plexus (L4–S3):
• Weakness in hip extension, knee flexion, ankle plantarflexion, and dorsiflexion.
• Sensory loss in the posterior thigh and lower leg.
• Possible bladder and bowel dysfunction if sacral roots are involved.

Diagnosis
• Clinical examination:
• Localization based on motor, sensory deficits, and reflex changes.
• Electrodiagnostic studies:
• EMG/NCS to evaluate the extent of nerve damage.
• Helps differentiate plexopathy from radiculopathy or peripheral nerve injuries.
• Imaging:
• MRI with contrast to assess hematomas, scarring, or nerve root avulsions.
• CT angiography for vascular injuries compressing the plexus.

Management
1. Acute Phase:
• Surgical exploration:
• Indicated for nerve root avulsions, foreign bodies, or vascular injuries.
• Pain management:
• NSAIDs, neuropathic pain medications (gabapentin, pregabalin).
2. Rehabilitation:
• Physical therapy to maintain joint mobility and prevent atrophy.
• Splints or braces for functional support.
3. Chronic Phase:
• Surgical reconstruction:
• Nerve grafts, tendon transfers for functional restoration.
• Amputation:
• Rare, reserved for cases with irreversible injury and intractable pain.

Prognosis
• Recovery depends on the extent of injury and timing of intervention.
• Complete nerve transections have a poorer prognosis compared to partial injuries.

Key Differentiating Features

Feature Neonatal Plexopathy Penetrating Traumatic Plexopathy
Cause Birth trauma (traction) Gunshot, stab injuries, or shrapnel trauma
Common Plexus Brachial (C5–T1) Brachial (C5–T1) and lumbosacral (L1–S3)
Onset At birth Sudden after trauma
Pain Absent Severe, sharp pain in the affected region
Motor Deficits Upper or lower brachial plexus involvement Variable based on location and extent
Prognosis Excellent for mild injuries (Erb palsy) Depends on the severity and timing of repair

Key Teaching Points for Neurologists
1. Neonatal brachial plexus injuries are often birth-related, with Erb palsy (C5–C6) being the most common and having the best prognosis.
2. Penetrating traumatic plexopathies are frequently associated with pain and require prompt imaging and surgical evaluation to address nerve or vascular injuries.
3. Recovery is highly dependent on early diagnosis and intervention, particularly for severe injuries involving nerve root avulsion or transection.
4. Electrodiagnostic studies and MRI are crucial for evaluating the extent and location of nerve damage in both neonatal and traumatic plexopathies.
5. Multidisciplinary management, including physical therapy, pain management, and surgical repair, is essential for optimizing outcomes.

Question 35

Radiation-induced plexopathies

Answer 35

months to years after radiation treatment,

painless, gradual-onset weakness and sensory loss in the distribution of the affected plexus.

Pain is typically absent or mild, which is a key feature distinguishing it from tumor recurrence.

Imaging, particularly MRI and PET-CT, helps rule out tumor recurrence or infiltrative lesions.

Electrodiagnostic studies (EMG/NCS) reveal diffuse abnormalities, consistent with radiation damage.

Question 36

Neuralgic amyotrophy plexopathies (brachial neuritis) aka Parsonage Turner Syndrome

Answer 36

Immune mediated inflammatory
pain, weakness, sensory loss
can be bilateral
Improvement: 36% at 1 yr, 75% at 2 yrs, 89% at 3 yrs
Hereditary form: AD

Question 37

Hereditary neuralgic amyotrophy plexopathies

Answer 37

Recognizing recurrent, trigger-associated brachial plexopathies as a hallmark.
2. Ordering SEPT9 gene testing in the context of family history.
3. Distinguishing HNA from other causes of neuralgic amyotrophy or plexopathies.

Question 38

Neoplastic Plexopathies

Question 39

Neurogenic thoracic outlet syndrome plexopathy

Question 40

Lumbosacral Plexopathies: traumatic, radiation, diabetic, neoplastic

Question 41

Traumatic Lumbosacral Plexopathies(hematoma, ischemic)

Question 42

Radiation-induced Lumbosacral Plexopathies

Question 43

Diabetic radiculoplexus Lumbosacral Plexopathies neuropathy (DLRPN) aka Diabetic amyotrophy

Answer 43

vasculitic axonal neuropathy
presents with the acute onset of severe unilateral thigh pain, progressive weakness and atrophy, significant weight loss, self limited but deficits often remain

Question 44

Neoplastic Lumbosacral Plexopathies

Question 45

Peripheral nerve disorders: Mononeuropathies, mononeuorpathy multiplex, polyneuropathy

Question 46

Median Mononeuropathies

Answer 46

ANTERIOR FOREARM MUSCLE INNERVATION:
- FLEXOR DIGITORUM SUPERFICIALIS
- PRONATOR QUADRATUS
- FLEXOR DIGITORUM PROFUNDUS
(WITH ULNAR NERVE)

HAND MUSCLE INNERVATION
- THENAR EMINENCE
- LUMBRICAL MUSCLES of INDEX & MIDDLE FINGERS

high median nerve palsy: weakness in forearm pronation and wrist and finger flexion, in addition to lack of thumb opposition.

Hyperextension of the thumb and index finger with thumb adduction at rest (“ape hand
deformity”) may be present. Loss of flexion of the radial half of the digits will result in a
“benediction sign” when the patient tries to make a fist. High median nerve injuries may
occur as a result of trauma (e.g. supracondylar fracture of the humerus, elbow
dislocation with brachial artery injury, direct laceration of the brachial artery by a
projectile or stab wound) or from iatrogenic injury as a result of complications of
brachial artery cannulation (e.g. hemorrhage, aneurysm).

Question 47

Ulnar nerve

Answer 47

C8-T1
muscular branch,

sensory:
palmar cutaneous branch, dorsal cutaneous branch, superficial branch

anterior forearm motor:
flexor Carpi Ulnaris
medial half of flexor digitorum profundus

hand:
hypothenar muscles
medial two lumbricals
Adductor Pollicis
Interossei of hand
Palmaris brevis

Palmar cutaneous branch branches off Ulnar before entering ulnar Guyons canal

Question 48

Flexor Digitorum Superficialis FDS

Answer 48

flexes middle and proximal phalanges of index, middle, ring and little finger (digits 2-5)

median n. (sometimes AIN)

Question 49

Pronator Quadratus

Answer 49

pronation of radio-ulnar joint (with pronator teres)

AIN (C8-T1)

Question 50

Flexor Digitorum Profundus

Answer 50

most powerful forearm muscle, gripping power

medial half (ring and little finger): ulnar nerve

lateral half (middle and index finger): AIN (C8-T1)

Question 51

Anterior Interosseous Nerve

Answer 51

AINS can cause pain in the forearm, wrist, or elbow, and weakness in the thumb and index finger.

A common symptom is difficulty pinching a sheet of paper between the thumb and index finger.

Unable to make OK sign

Decreased pronation strength

The cause of AINS is unknown, but it can be traumatic.

The AIN is a branch of the median nerve that’s important for hand and thumb function. It’s almost entirely a motor nerve, but it does have some sensory branches in the wrist joint and the interosseous membrane between the radius and ulna

Question 52

High median nerve palsy

Answer 52

Entrapment of the median nerve at the ligament of Struthers produces high median
nerve palsy, characterized by weakness in forearm pronation and wrist and finger
flexion, in addition to a lack of thumb opposition. Hyperextension of the thumb and
index finger with thumb adduction at rest (“ape hand deformity”) may be present, and
the loss of flexion of the radial half of the digits will result in a “benediction sign” when
the patient tries to make a fist. Sensory changes are present in the distribution of the
cutaneous branches of the median nerve in the forearm and hand.

Question 53

Pronator Teres Syndrome

Answer 53

occurs when the median nerve is compressed in the upper forearm

Aching discomfort in the forearm, paresthesias in the thumb, pointer, and index finger, weakness in the forearm muscles

Carpenters, mechanics, assembly line workers, tennis players, rowers, weight lifters, people with diabetes, alcoholism, or hypothyroidism

often confused with carpal tunnel syndrome (CTS) because they share some symptoms and can both be made worse by repetitive activity. However, patients with pronator syndrome don’t usually experience pain at night, which is a distinguishing feature.

Question 54

Posterior Interosseous Nerve

Answer 54

branch of radial n
primarily motor
sensory to dorsal wrist capsule
weakness of wrist extension in neutral position, radial deviation with extension in extreme cases

weak finger and thumb extension

originates under Arcade of Frosche, a fibrous arch at top of supinator muscle

Question 55

Ulnar Mononeuropathies: wrist, elbow

Answer 55

Ulnar nerve entrapment at the elbow (Cubital Tunnel Syndrome) and wrist (Guyon’s Canal Syndrome)

Guyon’s canal syndrome: entrapped between the hook of the hamate and the transverse carpal ligament, 2/2 direct pressure on a handlebar (i.e. bicycle handlebar, weight lifting, construction equipment) - weakened finger abduction and adduction (interossei)
weakened thumb adductor (adductor pollicis)
Sensory loss and pain: palmar surface of the fifth digit and medial aspect of the fourth digit & the dorsum of medial aspect of the fourth finger and the dorsum of the fifth finger don’t have sensory loss.

Ulnar Claw may present (sign of Benediction)

Question 56

Radial Mononeuropathies

Answer 56

Radial nerve injury at the spiral groove: weakness of radial-innervated muscles except for arm
extension because the motor branch to the triceps and anconeus splits off before the
midshaft area.

Usually present with wrist and finger drops.

Because the posterior brachial cutaneous nerve also splits off before the midshaft area,
if sensation is lost, it only affects the forearm or hand. The triceps reflex is spared.

Lesions distal to the “spiral groove” above the elbow may spare the brachioradialis or
extensor carpi radialis longus muscles.

Saturday night palsy - from falling asleep with one’s arm hanging over the arm rest of a
chair, compressing the radial nerve at the spiral groove.

Handcuff neuropathy - from tight-fitting handcuffs compressing the superficial branch
of the distal radial nerve; this is also referred to as cheiralgia paresthetica.

Crutch palsy - from poorly fitted axillary crutches.

Squash palsy - from traction forces in a manner usually associated with the sport
squash, can happen to squash players during prolonged periods between matches.

In this patient - A posterior interosseus nerve lesion is unlikely because: There was
involvement of muscles outside posterior interosseous nerve territory (brachioradialis,
extensor carpi radialis longus).

C7 radiculopathy is unlikely because: The triceps was not involved. Brachioradialis (C5, 6)
was involved.

A posterior cord lesion can give a radial palsy but is unlikely because:
triceps was spared (supplied by the proximal radial nerve, branching from the posterior
cord in the lower axilla) and deltoid was spared (supplied by the axillary nerve, the other
branch of the posterior cord).

Question 57

Musculocutaneous Mononeuropathies

Answer 57

C5-6, lateral cord, becomes lateral antebrachial cutaneous nerve at the elbow, motor above elbow, sensor below elbow,

innervates biceps brachii (flex and supinates forearm)

Neuorpathy: weak forearm flexion at elbow, weak supination, absent/hypoactive biceps reflex, sensory loss lateral forearm

Question 58

Axillary Mononeuropathies

Question 59

Spinal accessory Mononeuropathies

Question 60

Suprascapular Mononeuropathies

Question 61

Sciatic Mononeuropathies

Answer 61

• L4, L5, S1, S2, and S3 roots.
• two initial branches: the superior and inferior gluteal
  nerves.
• The superior gluteal nerve innervates the gluteus medius, minimus, and tensor
  fascia latae. (dorsal rami of ventral rami L4,5,S1 of sacral plexus)
• The inferior gluteal nerve innervates the gluteus maximus (dorsal division of ventral rami L5, S1, S2 of sacral plexus)

Question 62

Peroneal (fibular) Mononeuropathies

Question 63

Tibial Mononeuropathies

Question 64

Femoral Mononeuropathies

Question 65

Obturator Mononeuropathies

Question 66

Facial Mononeuropathies

Question 67

Trigeminal Mononeuropathies

Question 68

Lateral femoral cutaneous Mononeuropathies (meralgia paresthetica)

Question 69

Mononeuropathy multiplex: diabetic, vasculitic, inflammatory, genetic, neoplastic, infectious

Question 70

Diabetic Mononeuropathy multiplex

Question 71

Vasculitic Mononeuropathy multiplex

Question 72

Inflammatory Mononeuropathy multiplex

Question 73

Genetic Mononeuropathy multiplex

Question 74

Neoplastic Mononeuropathy multiplex

Question 75

Infectious Mononeuropathy multiplex

Question 76

Polyneuropathy: hereditary, acquired, DRG, small fiber

Question 77

Hereditary Polyneuropathy: demyelinating, axonal, TTR amyloid, porphyria

Question 78

Demyelinating Polyneuropathy: CMT 1, CMTX, HNPP, Refsum, Metachromatic leukodystrophy

Question 79

CMT1a Demyelinating Polyneuropathy

Question 80

CMTX Demyelinating Polyneuropathy

Answer 80

CMT1X, X linked, females mild or asx carriers of GJB1 gene for connexin-32 (Cx32) gap junction protein

CMT1X: Associated with acute episodes of ataxia, dysarthria, and in some cases, asymmetric weakness, with white matter changes particularly within the posterior fossa, during these episodes.

The symptoms resolve in weeks to months, and typically do not recur. They are often triggered by metabolic stressors such as travel to high altitudes, febrile illnesses, hyperventilation, and concussion.

mutations of the GJB1 gene, which encodes the protein connexin-32.

The presence of CNS symptoms does not correlate with the duration or severity of neuropathy. The neuropathy typically presents as distal lower extremity weakness, slowed running and frequent sprained ankles, typically beginning by 10 years of age in affected males. Hands, particularly the thenar muscles, may be affected later in the course.

Distal sensory loss with painful sensory paresthesias may also occur. Heterozygous females may be asymptomatic, but often have mild
manifestations.

Question 81

CMT2D unique feature

Answer 81

hands affected early in course

• presents adolescent or early-adulthood. Mutation of GARS gene. If sensory and motor: CMT2D, if only motor: distal hereditary motor neuropathy (dHMN) type V

Question 82

Which CMT is AR

Answer 82

CMT 4

• mixed group of disorders, demyelinating and axon-loss
• rare w early age of onset.
• significant disability compared to autosomal-dominant forms of CMT.

Clinical features of the CMT4 subtypes include vision loss, severe scoliosis, and hearing loss. The
typical phenotype is characterized by distal muscle weakness and atrophy, sensory loss,
and foot deformities.

Question 83

Hereditary neuropathy with tendencies to pressure palsy (HNPP) Demyelinating Polyneuropathy

Answer 83

AD PMP22 deletion (85%), can also be point mutation of PMP22 w AD or AR

scoliosis

Cranial nerve involvement possible

Distinguish from CMT and Dejeerine-Sottas (DSS): weakness and sensory changes are episodic mononeuropathies, and DSS is severe neuropathy beginning in infancy

Question 84

Refsum disease Demyelinating Polyneuropathy

Question 85

Metachromatic leukodystrophy Demyelinating Polyneuropathy

Question 86

Axon loss Polyneuropathy: CMT 2, Adrenoleukodystrophy

Question 87

CMT2 Axon loss Polynueropathy

Question 88

Adrenoleukodystrophy Axon loss polyneuropathy

Question 89

TTR amyloid polyneuropathy

Answer 89

FAP types 1 and 2: AD, mutation of transthyretin (TTR) gene that accelerates transthyretin formation.

• peripheral and autonomic neuropathy, infiltrative
  cardiomyopathy, or both.

Type 1: onset 3rd and 4th decades of life, peripheral neuropathy and autonomic dysfunction, cardiomyopathy

Type 2: onset 4th and 5th decades of life, no autonomic dysfunction. Age misfolding, No TTR mutation.

RX both: Tafamidis (TTR stabilizer) and RNA Silencers (inhibit TTR production in liver).

Question 90

Porphyric polyneuropathy

Question 91

Acquired Polyneuropathy: immune, metabolic, toxic, infectious

Question 92

Immune mediated Acquired Polyneuropathy: GBS, CIDP, multifocal mononeuropathy w conduction block, DADS, MADSAM, paraneoplastic, amyloidosis, sarcoidosis, paraproteinemic

Question 93

Guillain-Barré syndromes: AIDP, Miller Fisher, AMAN, AMSAN, PCP

Answer 93

C jejuni in AIDP but especially in AMAN

Question 94

Acute inflammatory demyelinating polyneuropathy (AIDP)
Guillain-Barre AIDP GBS

Answer 94

CSF: high protein low wbc
- assoc. w several infections: C jejuni, zika, resp. infxns. )
- molecular mimicry
- autonomic dysfunction: tachycardia
- rx: PLEX or IVIG

EMG/NCS: most pronounced 2 wks after symptom onset

Progressive symmetrical weakness of the legs and eventually arms
(ranging from mild weakness to total paralysis),
areflexia or hyporeflexia in the affected extremities is required for diagnosis.

• cranial nerve involvement, autonomic dysfunction, pain, mild sensory findings,
  absent fever at onset, and elevated protein in CSF without pleocytosis
  (albuminocytologic dissociation).
• Nerve conduction studies and needle EMG can
  distinguish demyelinating forms of GBS from axonal forms.

Demyelinating forms
include acute inflammatory demyelinating polyneuropathy, Miller Fisher syndrome,
facial diplegia and distal limb paresthesia, and acute bulbar palsy with areflexia.

Axonal degeneration is characteristic of acute motor axonal neuropathy and acute motor and
sensory neuropathy.

Findings consistent with the demyelinating forms of GBS include decreased motor conduction velocity, conduction blocks, temporal dispersion,
prolonged distal motor latency, and increased F wave latency.

Axonal forms are
characterized by decreased distal amplitudes in sensory and motor nerves and
reversible conduction failure.

Question 95

Miller Fisher variant (GQ1b antibody)

Answer 95

ataxia, areflexia, ophthalmoplegia

Question 96

Acute motor axonal neuropathy (AMAN)

Question 97

Acute motor and sensory axonal neuropathy (AMSAN)

Question 98

Pharyngeal-cervical-brachial (PCB)

Question 99

Chronic inflammatory demyelinating polyneuropathy (CIDP)

Answer 99

PLEX and IVIG produces more rapid improvement vs steroids but not associated with achieving remission. IVIG less likely to produce remission.

Motor insidiously progressive, may have sensory and autonomic.

o Symmetric proximal and distal weakness with/without sensory loss and hypo/areflexia
o Requires > 8 weeks to make diagnosis (GBS if < 4 weeks)
o CSF cell count < 10, elevated protein
o EMG: peak latency prolonged, decreased conduction velocity, prolonged F-wave latency
o IGG-4 subtype Abs (neurofascin-140/155, contactin-1) respond well to rituximab
o MADSAM: slow progression beginning with upper limbs and later lower limbs
o Distal Acquired Demyelinating Symmetric Neuropathy

Question 100

Multifocal mononeuropathy with conduction block

Question 101

Distal acquired demyelinating symmetric neuropathy (DADS)

Answer 101

distal symmetric sensory loss and weakness

DADS-M (IgM monoclonal abs)

(Anti-MAG is similar but not CIDP variant, test for anti-MAG abs if suspicious)

DADS-I (idiopathic)

older age (usually over 60 yo), slowly progressive, distal sensory predominance, symmetric deficits, and possible monoclonal gammopathy

Question 102

DADS vs anti-MAG neuropathy

Answer 102

DADS (Distal Acquired Demyelinating Symmetry)
Predominantly distal weakness and sensory changes (though motor weakness can be a notable feature).
Can present similarly to a length-dependent polyneuropathy, but with clear evidence of demyelination on electrophysiology.
Some patients respond to immunomodulatory treatments used for CIDP (IVIG, steroids, etc.), though response may be variable.

Anti-MAG Neuropathy (IgM monoclonal gammopathy, often produced by a clonal B cell disorder)
Often presents with sensory ataxia (imbalance and proprioceptive deficits) and distal paresthesias, typically more sensory-dominant.
Tremor (an “action” or postural tremor) is also frequently reported—sometimes referred to as a “tremor of neuropathic origin.”
Progression is typically very slow, and overt weakness can be mild or late, although distal motor deficits can appear over time.

4. Laboratory Findings

DADS:
May be idiopathic or associated with non-specific monoclonal gammopathy (IgG or IgA in some cases).
Anti-MAG antibodies are not typically seen.

Anti-MAG:
Characterized by the presence of IgM monoclonal protein targeting myelin-associated glycoprotein.
Specific testing for anti-MAG antibodies in the serum confirms the diagnosis.

Question 103

Multifocal acquired demyelinating sensory and motor polyneuropathy (MADSAM)

Answer 103

Lewis-Sumner Syndrome

asymmetric, usually UE first
CSF: mildy elevated to no protein, no pleocytosis
slowly progressive, UE first
negative Abs to myelin
multifocal conduction block
RX: IVIG or steroids
can be confused w mononeuropathy multiplex (responds to IVIG only as does motor-predominant CIDP)

Question 104

Paraneoplastic polyneuropathy

Question 105

Amyloidosis polyneuorpathy

Question 106

Sarcoidosis polyneuropathy

Question 107

Paraproteinemic polyneuropathy

Question 108

Metabolic Polyneuropathy: diabetic, nutritional, critical illness

Question 109

Diabetic Polyneuropathy

Answer 109

DSP: Distal symmetric polyneuropathy, small fiber, largely axonal, DM 1 and 2, less 3, pain, loss of sensation

Question 110

Vitamin B6 deficiency Polyneuropathy

Question 111

Vitamin B12 deficiency Polyneuropathy

Answer 111

Subacute combined degeneration of the spinal cord

• limb weakness and ataxia
• degeneration WM in cerebral hemispheres, optic nerves, and spinal cord
• triad: megaloblastic
  anemia, Gl symptoms, and neurological symptoms, including dementia, numbness,
  depression, and muscle weakness.

Chronic Nitrous oxide use cause B12 deficiency

Question 112

Copper deficiency Polyneuropathy

Question 113

Alcohol Polyneuropathy

Question 114

Hypervitaminosis B6 Polyneuropathy

Question 115

Critical illness Polyneuropathy

Answer 115

distal, symmetric, motor and sensory axonal
polyneuropathy.

Sxs: distal loss of pain, temperature, and vibratory
sensation, with flaccid, symmetrical weakness and hyporeflexia.

Involvement of the phrenic nerve may cause difficulty in weaning from mechanical ventilation.

reduced compound muscle action potential (CMAP) and/or sensory nerve action potential (SNAP) amplitudes with preserved conduction velocities

Fibrillation potentials and positive sharp waves may occur after 2-3 weeks.

Treatment is supportive and symptoms typically improve over weeks to months.

Question 116

Toxic Polyneuropathy: arsenic, lead, thallium, n-hexane, organophosphates, drug-induced

Question 117

Arsenic Polyneuropathy

Question 118

lead Polyneuropathy

Question 119

thallium Polyneuropathy

Question 120

n-Hexane Polyneuropathy

Question 121

Organophosphates Polyneuropathy

Question 122

Isoniazid Polyneuropathy

Question 123

Metronidazole Polyneuropathy

Question 124

Nitrofurantoin Polyneuropathy

Question 125

Chloroquine/hydroxychloroquine Polyneuropathy

Question 126

Lithium Polyneuropathy

Question 127

Chemotherapy Polyneuropathy

Question 128

Infectious Polyneuropathy: diphtheria, HIV, leprosy, Lyme, syphillis

Question 129

Diphtheria Polyneuropathy

Question 130

HIV Polyneuropathy

Answer 130

-distal symmetric axonal polyneuropathy
- painful burning and paresthesias
- 1/3 of HIV patients get it

Question 131

Leprosy Polyneuropathy

Answer 131

India, Brazil, Africa, Nepal, Louisiana, FL, TX, exposure to infected armadillos.

Respiratory or broken skin transmission

Multifocal neuropathy with macules and papules on the trunk and abdomen

Enlarged peripheral nerves

Acid-fast bacilli in skin smears or biopsy

Multidrug treatment

Neuropathy may worsen (“leprosy reaction”)

Based on the type of disease (tuberculoid vs. lepromatous), treatment includes different regimens consisting of dapsone, rifampin,
clofazimine, macrolides, minocycline, or fluoroquinolones. Steroids.

Question 132

Lyme disease Polyneuropathy

Question 133

Syphilis Polyneuropathy

Answer 133

E. Tertiary syphilis classically causes tabes dorsalis, resulting from infection of the
posterior columns and dorsal nerve roots.

Tabes dorsalis is characterized by urinary
dysfunction and painful sensory ataxia, predominantly in the legs.

Question 134

Dorsal root ganglion disorders: nutritional/toxic, autoimmune/inflammatory, Freidreich, idiopathic

Question 135

Sensory neuronopathy or ganglionopathy

Answer 135

DRG degeneration
progressive asymmetric, non-length dependent sensory deficits, sensory ataxia, areflexia, dyesthesia.

Paraneoplastic often: SCLC w ant-Hu abs

Sensory neuronopathy or ganglionopathy is characterized by degenerative changes in
the dorsal root ganglia, which result in progressive sensory deficits, sensory ataxia,
areflexia, and dysesthesia in an asymmetric, non-length-dependent pattern. Motor
neurons are rarely affected. It frequently occurs secondary to a primary pathology.
A common paraneoplastic-associated sensory neuronopathy occurs with small cell lung
cancer. Anti-Hu antibodies are typically present. A Guillain-Barre variant characterized
by sensory neuronopathy is associated with HIV infection, HTLV-1, Epstein-Barr virus,
varicella zoster virus, and measles.
Other etiologies include chemotherapeutic agents, nicotinic acid deficiency, pyridine
toxicity, vitamin E deficiency, and riboflavin deficiency. Sjogren’s syndrome, a
rheumatologic condition characterized by inflammation of the exocrine glands leading
to keratoconjunctivitis sicca and xerostomia, has been associated with sensory
neuronopathy, as well as other types of peripheral neuropathy.
Diagnostic workup should include a search for malignancy in older clients. Further
evaluation should include Schirmer’s test, SSA and SSB antibodies, and lip biopsy to
detect inflammatory changes in small salivary glands. Nerve conduction studies reveal
asymmetric, non-length-dependent loss of SNAPs, but electromyography is normal.

Question 136

Nutritional/toxic (including hypervitaminosis B6) DRG disorders

Question 137

Hu antibody syndrome DRG disorders

Question 138

Connective tissue disease (Sjögren syndrome) DRG disorders

Question 139

Friedreich ataxia DRG disorders

Answer 139

• GAA repeats
• X25 gene (frataxin)

AR
Presents in second decade of life with progressive ataxia, weakness, and skeletal abnormalities, such as pes cavus and kyphoscoliosis

Question 140

Idiopathic DRG disorders

Question 141

Small fiber neuropathy

Answer 141

painful sensory polyneuropathy

myelinated A-delta fibers and unmyelinated C fibers

sudomotor function may be affected

skin biopsy has positive and negative predictive values over 90%

symptomatic rx: amitriptyline, gabapentin, pregabalin, carbamazepine

Question 142

Neuromuscular junction transmission disorders: MG, LEMS, botulism, congenital/hereditary MG, medication-induced

Question 143

Myasthenia gravis (MG)

Answer 143

• avoid checkpoint inhibitors
• anti-MuSK: present in female, 30s w ptosis, diplopia, progress to bulbar, pyridostigmine less effective, Rituximab or PLEX helps, anti-MuSK abs impair AChR clustering and membrane stability.

Medial rectus muscle most commonly and severely affected.

Sensory and motor NCS may be normal in MG

RX: symptomatic treatment, rapid immunotherapies, chronic immunotherapies, thymectomy

Steroids: remission and improve symptoms w/in 3 wks, first 10 days can worsen symptoms

Chronic immunotherapeutic agents used in the treatment of MG include azathioprine,
cyclosporine, and (in cases unresponsive to other therapies) rituximab, tacrolimus, and
cyclophosphamide.

Thymectomy: may help w pts with Ach receptor abs

Anti-striated muscle abs marker for thymoma in early onset MG between 20-50 yo (positive in 36% of patients but positive in 80% of those w thymoma)

progresses to other muscles in 75% of patients who present w ocular disease

increased risk of other autoimmune disorders

Question 144

Lambert-Eaton myasthenic syndrome (LEMS)

Answer 144

release of AcH impaired
proximal weakness, hypo-reflexia, dysautonomia (dry mouth), LE > UE, ptosis, opthalmoparesis, milder than MG, Sxs worsen w heat or fever,

abs VGCCs (P/Q calcium channel) on presynaptic motor nerve, anti-Jo-1 associated w antisynthetase syndrome (v high levels of CK, interstitial lung disease)

Cancer 40%, SCLC

autoimmune disorders

RX: prednisone, plex, 4-diaminopyridine, IVIG

Low CMAP and increment w high frequency repetitive stimulation

decrement w low frequency stim (1-5 Hz) hallmark of MG, but also of LEMS BUT incremental response to high frequency (50Hz) is hallmark of LEMS

Question 145

Botulism

Answer 145

• wound botulism at an injecting site from heroin
• differential diagnosis is a variant of GBS
• Wound botulism should be considered in any injecting drug user who presents with descending motor and autonomic signs.
• Clinical symptoms occur within 24 to 72 hours of exposure, can manifest as early as 2 hours or as late as 5 days after exposure.
• symmetrical cranial nerve palsies, followed by a progressive, descending paralysis. Sensation and cognition are spared.
• Anticholinergic symptoms can also occur
• classical diagnostic pentad of dry mouth, nausea or vomiting, dysphagia, diplopia, and fixed dilated pupils
• differential diagnosis of botulism would include myasthenia gravis, Lambert-Eaton
  syndrome, Guillain-Barré Syndrome (GBS) and its variants, tick paralysis, stroke,
  diphtheria, or exposure to other toxins, such as organophosphates or other nerve
  agents, carbon monoxide, or neuromuscular junction blockers.
• The GBS usually present with sensory findings, which are absent in botulism.
• Nerve conduction studies are normal other than for low amplitude CMAP.
• Repetitive stimulation at low frequency (3Hz) produces no decrement suggestive of myasthenia gravis.
• stimulation at 20Hz produces a prominent incremental response consistent with a pre-synaptic neuromuscular transmission defect.

Question 146

Congenital/hereditary myasthenia

Question 147

Medication-induced

Question 148

Muscle disorders: hereditary, acquired, rhabdomyolysis

Question 149

Hereditary Muscle Disorders: Muscular Dystrophies, Congenital myopathies, Metabolic Myopathies, Periodic Paralysis/Channelopathies

Question 150

Muscular dystrophies: Duchenne/Becker, Fascioscapulohumeral, Limb-Girdle, myotonic, oculopharyngeal, myofibrillar, congenital

Answer 150

DMD: sxs before 6 yo boys

Question 151

Duchenne/Becker MD

Answer 151

X linked
toe walking, lumbar lordosis, adhd, dyslexia, cardiomyopathy

Becker MD: DMD mutation short dystrophin protein

Question 152

Facioscapulohumeral MD

Question 153

Limb-girdle type 1 MD

Question 154

Limb-girdle type 2 MD

Question 155

Myotonic dystrophy 1 (including distal presentation)

Answer 155

AD
CTG repeat, DMPK gene (dystrophia myotonic protein), Ch 19
weak: face, SCM, ankle dorsiflexion, hand intrinsic muscles, distal forearms

characteristic look: hallowed cheek, arched palate, sagging jaw, ptosis, SCM wasting

Question 156

Myotonic dystrophy 2

Answer 156

AD
CCTG repeat, ZNF9 gene (aka CNBP), Ch 3
weak: neck flexors, finger flexors, hip girdle, proximal leg, elbow extension,

muscle pain from exercise, temperature change, palpation

Question 157

Oculopharyngeal MD OPMD

Answer 157

AD, GCN repeat, PABPN1 gene (polyadenylate binding protein nuclear 1), French Canadians
late-onset
ocular and phyaryngeal involvement

proximal and distal weakness

Question 158

Myofibrillar (including distal presentation)

Question 159

Congenital muscular dystrophy

Question 160

Congenital myopathies: central core, nemaline, centronuclear/myotubular (including distal presentation)

Answer 160

severe at birth, MR

Differentiate them:
muscle wasting: Nemaline or Centronuclear
extra ocular weakness: Centronuclear
malignant hyperthermia: Central Core
cardiomyopathy: probably Central Core

Question 161

Central core myopathy

Answer 161

severe at birth
no muscle wasting
no extra ocular weakens
YES malignant hyperthermia (caution w general anesthetics)
cardiomyopathy
No Mental retardation

RYR1 gene at chromosome 19q13.1.

Although facial muscles may be affected, there is no ptosis or weakness of extraocular muscles.

Respiratory muscles and bulbar muscles are
also spared.

Kyphosis, scoliosis, foot deformities, contractures, and congenital hip dislocation.

Usually not progressive.

Absence of oxidative mitochondrial activity is demonstrated by histochemical staining with nicotinamide adenine dinucleotide

Question 162

Nemaline myopathy

Answer 162

severe at birth
yes muscle wasting
no extraocular weakenss
no malignant hyperthermia
rare cardiomyopathy
no mental retardation

Gomori Trichrome stain for mitochondrial activity: ragged red fibers in MELAS for example

Question 163

Centronuclear/myotubular (including distal presentation) myopathy

Answer 163

• severe at birth: extra ocular, facial, limb weakness, resp failure, XLR, MTM1 gene
• muscle fibers w central nuclei

severe at birth
yes muscle wasting
yes extra ocular weakness
no malignant hyperthermia
no cardiomyopathy
no mental retardation

Question 164

Metabolic myopathies: mitochondrial, glycogenoses, lipidoses

Question 165

Mitochondrial myopathy: MERRF, MELAS, Kearns-Sayre

Question 166

Myoclonic epilepsy with ragged red fibers (MERRF)

Question 167

Mitochondrial myopathy, lactic acid, and stroke (MELAS)

Question 168

Kearns-SayreKearns-Sayre syndrome mitochondrial myopathy vs Progressive External Opthalmoplegia

Answer 168

progressive external ophthalmoplegia, retinitis pigmentosa, and heart block

onset <20

short stature, sensorineural hearing loss, dementia, ataxia, decreased ventilatory drive, multiple endocrinopathies

Progressive external ophthalmoplegia (PEO): doesn’t have retinitis pigments or cardiac abnormalities, can be confused with MG but no double vision

Question 169

Glycogenoses myopathies: Pompe/Acid maltase deficiency, McArdle disease

Question 170

Pompe disease/Acid maltase deficiency myopathies

Question 171

Myophosphorylase deficiency (McArdle disease) myopathy (aka glycogen storage disorder V)

Answer 171

AR, Ch 11, PYGM mutation
exercise intolerance
childhood onset
increased CK and uric acid
intermittent myopathy
2nd wind phenomenon
emg silent during contracture
forearm ischemia test: no increase in lactate but ammonia is elevated
dark urine (myoglobinuria), can lead to renal failure

Question 172

Lipidoses myopathies: carnitine deficiency, CPT2

Question 173

Carnitine deficiency myopathy

Question 174

Carnitine palmitoyltransferase 2 deficiency (CPT2) myopathy

Question 175

Periodic paralyses/channelopathies

Question 176

Hypokalemic Periodic Paralysis

Answer 176

more severe than Hyper K PP

calcium channelopathy

presents adolescence
hours to days of weakness
progressive weakness into adulthood

Triggers: heavy carb meals, insulin/glucose

no myotonia

Rx low carb diet

Question 177

Hyperkalemic Periodic Paralysis

Answer 177

AD

presents childhood

sodium channelopathy

inactivation of sodium channels leads to weakness, attacks generally mild c/w hypoK PP

triggers: rest after exercise or prolonged sitting, potassium ingestion

Rx: insulin/glucose, high carb diet

myotonia on EMG

Question 178

Andersen-Tawil syndrome

Question 179

Nondystrophic myotonias

Question 180

Acquired Muscle Disorder: inflammatory, critical illness, toxic/drug-induced, metabolic/endocrine, necrotizing autoimmune myopathy

Question 181

Inflammatory myopathies: polio, dermatomyositis, IBM, sarcoidosis, HIV

Question 182

Polymyositis

Question 183

Dermatomyositis

Question 184

Inclusion body myositis (IBM) Sporadic (including distal presentation)

Answer 184

Distinguish from other myositis: IBM has slowly progressive weakness and wasting of both distal and proximal muscles, asymmetric,
Early: finger flexion, proximal limb muscles,
elevated CK

Age >50.
insidious onset, painless weakness, atrophy and wasting predominantly of finger flexors, hip flexors, and
quadriceps.

DTRs are reduced. Esophageal dysmotility and dysphagia due to involvement of striated muscle of pharynx and upper
esophagus in up to 60% cases.

CK - normal to mildly elevated.

EMG - mixed neuropathic and myopathic changes.
Muscle biopsy - “rimmed”
vacuoles within muscle fibers (classic finding) with granular material (contain amyloid, desmin, ubiquitin, tau) and filaments, varying degree
of inflammation around muscle fibers.

Treatment - patients do not respond well to steroids and immunosuppressants.

Question 185

Inclusion body myositis (IBM) Hereditary (including distal presentation)

Question 186

Sarcoidosis

Question 187

HIV

Question 188

Critical illness myopathy

Answer 188

flaccid proximal weakness
b/l UE and LE
No facial involvement
Sensory exam normal
DTR diminished or absent

Question 189

Toxic/drug-induced myopathy

Question 190

HMG-CoA reductase

Question 191

Alcohol myopathy

Question 192

Chloroquine/hydroxychloroquine myopathy

Question 193

Corticosteroids myopathy

Question 194

Colchicine myopathy

Question 195

Antiretroviral medications myopathy

Question 196

Metabolic/endocrine muscle disorders: hypothyroid, hyperthyroid, hypokalemic, Cushing disease

Question 197

Hypothyroid muscle disorder

Question 198

Hyperthyroid muscle disorder

Question 199

Hypokalemic muscle disorder

Question 200

Cushing disease

Question 201

Necrotizing autoimmune myopathy: anti-HMG-CoA, anti-SRP

Question 202

Anti-HMG-CoA reductase myopathy

Answer 202

immune mediated from statins, doesn’t resolve w drug discontinuation

Question 203

Anti-signal recognition particle (anti-SRP)

Answer 203

immune mediated from statins, doesn’t resolve w drug discontinuation

Question 204

Toxic effect on muscle

Answer 204

statins (direct and immune-mediated), glucocorticoids, alcohol, ipecac,

Question 205

Rhabdomyolysis

Question 206

Hyper-excitability disorders: stiff-person syndrome, potassium channelopathies (Isaacs Syndrome)

Question 207

Stiff-person syndromes

Question 208

Potassium channelopathies (Isaacs syndrome)

Question 209

Autonomic dysfunction in neuromuscular diseases: autoimmune, GBS, paraneoplastic, Fabry, due to infectious disease, diabetes, amyloidosis, Addie Syndrome, small fiber, toxic

Question 210

Autoimmune autonomic neuropathy and ganglionopathy (including Sjögren syndrome)

Question 211

Guillain-Barré syndrome

Answer 211

follows infection, often C jejune but others too

Classic GBS presents with numbness & tingling in the feet that ascends (stocking glove)

Pain the back & limbs is common

Sensory level should not occur!

Weakness follows sensory disturbance (arguably motor is worse than sensory)

Areflexia (beware that a minority of pts have retained reflexes, esp AMAN, or delayed hyporeflexia)

Autonomic dysfunction (2/3rds of patients; tachycardia most common)

Bowel & bladder are usually spared
–
Symptoms should not proceed >8 weeks (or even 4)

98% of pts achieve “plateau phase” by 4 weeks that lasts 1-4 weeks

Duration of “plateau” usually 12 days

Question 212

GBS etiology

Answer 212

T-Cell mediated response to myelin
–Mononuclear infiltration into peripheral nerves, T-cell activation, Ab binding to Schwann cells, and macrophages targeting myelin components

F-waves are slowed/absent early in AIDP

Prolonged/abnormal distal latencies, slow conduction velocities, abnormal H-reflex, reduction in CMAP amplitude, conduction block

AMAN (axonal variant): due to C. jejuni and poorer prognosis

Miller Fisher variant: ataxia, ophthalmoplegia, areflexia due to GQ1b antibody

Question 213

GBS abs

Answer 213

GM1 abs - correlates w c. jejuni infection
GQ1b abs - C Miller Fisher (ataxia, areflexia, opthalmoparesis)

Question 214

GBS best predictor of poor outcome

Answer 214

low distal CMAP amplitudes (<20% LLN)

Question 215

Paraneoplastic autonomic neuropathies

Question 216

Fabry disease autonomic neuropathy

Answer 216

x-linked lysosomal storage disorder, GLA gene
deficiency of lysosomal hydrolase alpha-galactosidase A.
Globotriaosylceramide accumulates within lysosomes of different cell types, causing progressive organ damage and dysfunction.

Beginning in childhood, individuals with the classic phenotype experience neuropathic pain or limb pain and develop telangiectasias and angiokeratomas.

Angiokeratomas in the groin, hip, and periumbilical area are typical. Gastrointestinal symptoms, corneal opacities, and proteinuria with progressive renal failure are characteristic.

Affected adults develop cardiac and cerebrovascular manifestations,

The diagnosis in men can be made if alpha-Gal A leukocyte activity is <3%, but if alpha-Gal A
leukocyte activity is between 3% and 35%, this may indicate a heterozygote or an atypical variant, so the patient should undergo genetic testing for a mutation in the GLA gene that is associated with Fabry disease. Women who are thought to be heterozygous for the disease
should undergo genetic testing to make the diagnosis.

Question 217

Autonomic neuropathies due to infectious disease: Chagas, Leprosy, Diphtheria, HIV

Question 218

Chagas disease

Question 219

Leprosy

Question 220

Diphtheria

Question 221

HIV

Question 222

Diabetes (autonomic manifestations)

Question 223

Amyloidosis

Question 224

Adie syndrome

Question 225

Small fiber polyneuropathy (autonomic manifestations)

Question 226

Toxic neuropathies: vapor, hexane, ciguatoxin, vincristine, cisplatin, paclitaxel, heavy metal, POTS

Question 227

Vacor neuropathy

Question 228

Hexane neuropathy

Question 229

Ciguatoxin neuropathy

Question 230

Vincristine neuropathy

Question 231

Cisplatin neuropathy

Question 232

paclitaxel neuropathy

Question 233

Heavy metals: arsenic, mercury, thallium

Question 234

Arsenic neuropathy

Question 235

Mercury neuropathy

Question 236

Thalium neuropathy

Question 237

Postural orthostatic tachycardia syndrome (POTS) neuropathy

Answer 237

exaggerated sympathetic response to
upright posture.

females (5:1) than males.

The typical onset is between the ages of 15 and 45.

Criteria include a heart rate increase of>30
beats/min on standing from a supine position or >40 beats/min increase in 12- to 19-
year-old patients or an absolute heart rate of >120 beats/min within 10 minutes of
standing from a supine position, with the absence of hypotension, arrhythmias,
sympathomimetic drugs, or other causes of tachycardia.

1 in 7 patients have ganglionic acetylcholine
receptor antibodies, which suggests the disorder may have an autoimmune etiology in
some patients.

In addition, the development of POTS may occur in some patients after a viral syndrome, surgery, or pregnancy.

Symptoms may be mild and managed by the
avoidance of precipitants like dehydration and standing. Treatment may include
increased fluid intake, salt intake, and graduated exercise to improve tolerance to
orthostasis. Pharmacologic measures may include fludrocortisone, a mineralocorticoid
that expands plasma volume; beta-blockers to reduce excess sympathetic activity;
ivabradine, a selective If channel blocker at the sinoatrial node; and midodrine, an
alpha-1 agonist.

Associated disorders include chronic fatigue syndrome, mastocytosis, and mitral valve prolapse.

Vital Concept:
POTS syndrome is characterized by exaggerated sympathetic response while in upright
posture. POTS syndrome is 5 times more common in females than males. Typical
symptoms include palpitations while standing.

Question 238

END OF ABPN OUTLINE CARDS

Question 239

SNAP amplitude

Answer 239

of axons

normal in radiculopathy bc recorded distal to lesion

Question 240

Sensory latency

Answer 240

prolongation = demyelination

Question 241

Conduction velocity in sensory NCS
- definition

Answer 241

distance btwn stim and recording site divided by latency (distance/time)

Question 242

CMAP amplitude decrease for conduction block

Answer 242

20% decrease amplitude
conduction block = demyelination

from focal demyelination, such as: MMN or CIDP

Question 243

Sensory latency
prolonged =

Answer 243

prolonged = demyelination

Question 244

Demyelinating neuropathies changes in:
conduction velocity
distal latencies
temporal dispersion
CMAP amplitude

Answer 244

slowed conduction velocity (<70% lower limit normal)

prolonged distal latencies

temporal dispersion (broadening of CMAP >30% duration)

CMAP amplitude decrease (>20% decrease)

Question 245

Motor nerve conduction study: CMAP amplitude based on:

Answer 245

based on action potential transmission, status of NMJ, and muscle fibers

Question 246

F Wave definition and significance

Answer 246

supra maximal stim of motor nerve

impulse travels antidromically (backwards) toward neuron and then orthodromically (forwards) toward muscle

• evaluates the proximal segment of the peripheral nerve and the plexus and anterior horn cells.
• helpful when you suspect radiculopathies or plexopathies, or when investigating Guillain-Barré syndrome, CIDP, or other demyelinating conditions where proximal nerve segments are involved.

Latency & Conduction:
F-wave latency can be prolonged in demyelinating or axonal lesions involving proximal nerve segments.

It is also an indicator of overall nerve conduction speed between the limb and the spinal cord.

Reproducibility:
Unlike the H reflex, F waves can often be recorded from most muscles innervated by a motor nerve, but they tend to vary (or “jitter”) in latency and amplitude from trial to trial.

Question 247

H Reflex definition and significance

Answer 247

= S1 ankle reflex

sub maximal stim of tibial nerve at popliteal fossa while recording soleus muscle

orthodromic travel through sensory nerve afferent, enters spinal cord, to anterior horn cell, then down motor nerve to muscle

-provides direct information on spinal reflex circuitry (the Ia afferent - alpha motor neuron loop).

• used to evaluate S1 radiculopathy (or L5-S1 nerve root issues) in the setting of sciatica or suspected disc herniation.

Prolonged or absent H reflex can suggest a lesion affecting the S1 nerve root, peripheral nerve, or the reflex arc.

Central vs. Peripheral Lesions:
Changes in H reflex amplitude or latency can be seen in various conditions, including polyneuropathies, spinal cord lesions, and nerve root compressions.

Question 248

Needle EMG insertional activity is
increased …..
decreased….

Answer 248

increased in denervated muscle/myotonic disorders

decreased when muscle is replaced by fat/connective tissue during paralysis

Question 249

Needle EMG spontaneous activity (always abnormal)
spontaneous activity types:

Answer 249

fibrillation potentials - denervation individual muscle fibers (2-3 wks post injury)

positive sharp waves - downward (positive) deflection, means same as fibrillation potentials

fasciculation potentials - irregular discharge of motor units (motor unit=1 anterior horn cell and all its muscle fibers, larger than fibrillation potentials)

myotonic discharges - waxing/waning frequency and amplitude w dive bomber sound

myokymic potentials - regularly occurring bursts of motor units firing spontaneously

Question 250

Voluntary Contraction needle EMG

Answer 250

Neurogenic Disorder: fib potential, fasciculation, large motor units, reduced recruitment

Myopathic Disorder: fib potential, no fasciculation, small motor units, rapid recruitment

Question 251

single fiber EMG to dx MG: sensitive, specific, both?

Answer 251

highly sensitive but not specific
It just means a NMJ problem

Question 252

Radiculopathy

Answer 252

Normal SNAPs (recorded distal to lesion, Cell body, dorsal root ganglia, & postgang fibers are unaffected)

Low-amplitude CMAPs
EMG – Fibrillation potentials seen 3 weeks after axon loss

Plexopathy is the same PLUS low-amplitude SNAPs (NCS) & myokymic discharges (EMG)

Question 253

Axon Loss Lesion

Answer 253

NCS: low-amplitude CMAPs, slowing of CV, prolonged DL, low-amplitude SNAPs

Immediate reduced recruitment of MUPs on EMG

Wallerian degeneration from lesion completed in 7-10d; conduction block w/ in 10d

Spontaneous muscle activity (fibrillation potentials) appear 3rd week from injury on EMG

Large polyphasic motor unit potentials (MUPs) seen 3-6mo later

Question 254

Carpal Tunnel Syndrome

Answer 254

classic median nerve sensory disturbances (especially nocturnal), positive provocative tests, and supporting electrodiagnostic findings (prolonged latencies, slowed conduction in the carpal tunnel, or reduced amplitudes in advanced cases)

palm sensation preserved bc cutaneous sensory nerve branches proximal to carpal tunnel

Question 255

Carpal Tunnel contents

Answer 255

Median Nerve
Nine Flexor Tendons
Four tendons of the Flexor Digitorum Superficialis (FDS)
Four tendons of the Flexor Digitorum Profundus (FDP)
One tendon of the Flexor Pollicis Longus (FPL)

Question 256

Anterior Interosseous Nerve and Syndrome
- what muscles?

Answer 256

muscles: FDP to 2nd-3rd digits, FPL, pronator quadratus

• purely motor branch of the median nerve that travels along the interosseous membrane in the forearm. It innervates:

Flexor Pollicis Longus (FPL)
Pronator Quadratus (PQ)
Lateral part (radial half) of the Flexor Digitorum Profundus (FDP) – specifically, the portion responsible for flexing the index and sometimes middle finger.

AIN syndrome: difficulty flexing the interphalangeal joint of the thumb (FPL weakness) and the distal interphalangeal joint of the index finger (FDP to index finger weakness), but without sensory loss.

Question 257

Giant Axonal Neuropathy

Answer 257

AR
Mutation in GAN1 gene (encodes for gigaxonin)
presents early childhood

Progressive sensorimotor neuropathy, UMN signs, optic atrophy and eventual death

Characteristic tightly curled hair & gait of walking on inner edges of feet

Neuropathology: large focal axonal swelling containing disorganized neurofilaments