6 - Polyneuropathy Flashcards
List 3 Inherited Peripheral Neuropathies.
1. Hereditary motor and sensory neuropathies (HMSN)
Charcot–Marie–Tooth disease (CMT)
Duplication mutation of the PMP-22 gene
Hereditary neuropathy with liability to pressure palsy (HNPP)
2. Hereditary sensory and autonomic neuropathies (HSAN)
Sensory: Pain and temperature dysfunction
Autonomic: thermal dysregulation, bladder dysfunction, and cognitive deficits.
3. Hereditary motor neuropathies (HMN)
Affect motor neuron → anterior horn cell
Progressive atrophy and weakness of the upper and lower extremities.
Progress to vocal cord and facial muscle paralysis
Cuccurollo 4th Edition Chapter 5 EDX pg419-420
List 4 Acquired neuropathies 🔑🔑
💡 Acquired polyneuropathies → usually distal onset of symptoms
- Diabetes mellitus (most common)
- Acute inflammatory demyelinating polyradiculopathy (AIDP) / (GBS)
- Chronic inflammatory demyelinating polyradiculopathy (CIDP)
- Vasculitic neuropathies
- Medications
- Thyroid disorders
- Alcohol abuse
- Vitamin B12 deficiency
- Inflammatory neuropathies
Cuccurollo 4th Edition Chapter 5 EDX pg420
52 years old man with bilateral hand numbness and weakness 🔑🔑 MOCK
Past medical history of Rheumatoid Arthritis
Give two DDx and two investigations for your DDx
- Cervical myelopathy (C1-C2 subluxation) → Cervical MRI
- Compression neuropathies—carpal tunnel syndrome → EDX
- Mononeuritis multiplex in rheumatoid vasculitis → EDX
- Mild distal symmetric sensory neuropathy—late complication
Braddom 6th Edition Chapter 41 pg873 Box 41.10
NCS: Inherited vs Acquired polyneuropathies 🔑🔑
ACQUIRED NEUROPATHY
- Focal area is affected
- Increased CV, temporal desperation and leading to conduction block.
HEREDITARY NEUROPATHY
- Diffuse nerve injury, no specific area, diffuse slowing of the nerve impulse
- No temporal dispersion or conduction block.
Cuccurollo 4th Edition Chapter 5 EDX pg419
What is the significance of conduction block in peripheral neuropathy?
Conduction Block
Compound muscle action potential (CMAP) drop of 30% to 50% is recorded between the distal and proximal stimulation sites due to focal disruption of the myelin sheath.
Distal to the block, conduction is preserved.
Clinically important because it implies a potentially reversible defect causing weakness.
- Acute reversible ischemic injury
- Compression-induced demyelination
- Demyelination mononeuropathy (Neuropraxia)
- Acquired demyelinative neuropathies
Hereditary neuropathy
One major exception, hereditary neuropathy with liability to pressure palsy (HNPP).
Patient presenting with hand and leg dysthesia, he is diabetic. List 3 reasons of why would you use EDX in his case? 🔑🔑
-
Type of lesion via NCS
- Demyelination lesion (good recovery) or axonal loss (poor recovery)
-
Chronicity of the disease via EMG
- Acute = De-innervation: Fibrillations and PSWs in predominantly distal muscles
- Chronic = Re-innervation: Large-amplitude, long-duration MUAPs
-
Confirm diagnosis (diabetic neuropathy in this case)
- R/O condition like plexopathy, radiculopathy, anterior horn cell, mononeuritis multiplex
EDX: Demyelination vs Axonal Injury 🔑🔑 EXAM 2019-2022
Demyelination
- Findings NCS: Decreased CV, Increased DL, Temporal Dispersion & Conduction Block
- EMG: Decreased recruitment (clinical weakness)
- Proximal Weakness & no Reflex (F & H Reflex)
Axonal
- NCS: Reduced SNAP/CMAP amplitude
- EMG: Decreased recruitment (clinical weakness)
- Major Findings in EMG (Fibs, PSW, Requirement, LDLA)
- Distal Weakness, atrophy, fasciculation
Cuccurollo 4th Edition Chapter 5 EDX pg421
(A) Normal
(B) Axonal injury
(C) Hereditary (Uniform) Demyelinating
(D) Acquired (Segmental) Demyelinating
F-waves is important in diagnosing polyneuropathies. List 3 conditions. 🔑🔑 Which neuropathies begin proximally rather than distally?
💡 Fake wave for fake sugar dip
- DP: Diabetic polyneuropathy (Sugar)
- AIDP: Acute inflammatory demyelinating polyneuropathy (Hot Red)
- CIDP: Chronic inflammatory demyelinating polyradiculoneuropathy (Cold Blue)
Autonomic Nerve Studies, Mention 4
- Sympathetic skin response
- Anal sphincter activity
- Valsalva ratio
- Norepinephrine synthesis and release
- Sinus arrhythmia
Draw Polyneuropathy Algorithm 🔑🔑
Classical triad of Polyneuropathy? List 3 distinctive features. 🔑
💡 Neuro examination & add the specific fiber affected
Polyneuropathy = LMN Examination
- Sensory → Sensory changes in a stocking/glove distribution
- Motor → Distal (↑ common axonal) > proximal (↑ common demyelination) weakness
- Reflexes → Diminished/absent DTR
Special Fibers Affected
- Inherited polyneuropathies (i.e CMT) → Large (Dorsal Column) → Sensory Ataxia
- Acquired polyneuropathies (i.e. Diabetic) → Large & Small → Burning/Pain/Paresthesias
Cuccurollo 4th Edition Chapter 5 EDX pg420
Multifocal Motor Neuropathy (MMN): Pathology - PEx - EDX - Treatment 🔑🔑
Multifocal Motor Neuropathy (MMN)
Immune-mediated disorder causing inflammatory demyelination and remyelination
Clinical presentation (Motor Neuropathy → LMN)
- Sensory: Sensation is normal (Motor)
- Motor: Progressing focal weakness & atrophy, Fasciculations and cramps (LMN), Myokymia (unilateral and uncontrollable lid twitch or tic)
- Reflexes: Asymmetric reduced MSR (LMN)
Labs
- Nerve Bx: Endoneurial edema, lymphocytic inflammation, reduced myelin density, onion bulb formation.
- Blood: Increased anti-GM1 antibody titers
NCS: Acquired - Demyelinating - Multifocal Motor
💡 More than one site of conduction can occur in a single motor nerve.
- Sensory Study SNAP: Normal (Motor)
- Motor Study CMAP: Prolonged Latencies, Decreased CV, Conduction Block, Reduced Amp
- F-wave: Abnormal
EMG
- Abnormal spontaneous activity of motor neuron: fasciculations, myokymic discharges
Treatment
- like CIDP → High dose IV-Ig (Picture): (A) Severe deformities in the right hand were much improved after treatment (B) with high-dose intravenous immunoglobulin (0.4 g/kg/day) for 5 consecutive days.
Cuccurollo 4th Edition Chapter 5 EDX pg429
Distinguish Multifocal Motor Neuropathy (MMN) from Motor Neuron Disease (MND) 🔑🔑 Hint: Where is the injury? What are the results?
Multifocal Motor Neuropathy (MMN)
- Focal Peripheral n. Injury → Focal Muscle
- Traced back to peripheral nerve territories
- Focal muscle weakness supplied with same periphral n.
Motor Neuron Disease (MND) think ALS
- Anterior Horn Cell Injury → Root Muscle(s)
- Traced back to spinal segmental
- Diffuse muscle weakness supplied by same root.
Cuccurollo 4th Edition Chapter 5 EDX pg429
Hereditary motor sensory neuropathy (HMSN) Charcot-Marie-Tooth Disease (CMT) Gene - Course - Type of Neuropathy - Presentation - EDX
Gene
- Autosomal dominant, PMP Gene 22
Course
- Early childhood in first 2 years
Type of Neuropathy
- Hereditary (Uniformal) Demyelinating Sensorimotor
Neuro Examination (LMN + Fiber Specific)
- Sensory → sensory loss in stocking/Glove pattern
- Motor → Proximal weakness (demyelination), lower limbs > the upper limb (Stork leg/champagne bottle leg appearance), Pes cavus and hammer toes, Bilateral foot drop, Steppage gait
- Reflexes: Abnormal
- Large Fibers (Dorsal Column) → Abnormal vibration and proprioception & Sensory Ataxia
Labs:
Nerve Biopsy: Onion bulb formation from focal demyelination, then remyelination
EDX of Hereditary Motor Sensory Neuropathy
- SNAP: Abnormal (Sensory)
- CMAP: Reduced CV, No temporal dispersion or conduction block (Motor-Hereditary)
- EMG: Normal
Cuccurollo 4th Edition Chapter 5 EDX pg424
Charcot-Marie-Tooth disease (CMT). List 4 findings in foot examination.🔑🔑
Static Inspection: Distal muscle wasting - High Arch - Claw Toe
Dynamic Gait: Foot drop, High steppage gait
Sensory: Neuropathic pain - Paresthesia - Cold extremities
Tone: Hypotonic but superimposed by planterflexion Contracture
Motor: Weakness
Reflex: Decreased DTR (Neuropathy → LMN)
Charcot-Marie-Tooth Disease (CMT). 4 EDX findings 🔑 🔑
NCS of Hereditary demyelinating motor sensory neuropathy
- Reduced conduction velocity (Hereditary)
- Reduced amplitude (SNAP & CMAP) → Clinical weakness
- No temporal dispersion or conduction block (Hereditary)
EMG
- Normal (demyelinating)
Acute inflammatory demyelinating polyneuropathy (AIDP) Guillain-Barré Syndrome (GBS) Etiology - Type - Presentation - 1st EDX finding 🔑🔑
💡 Variants: Miller-Fisher syndrome, pure sensory
Etiology
- 1–4 weeks post illness, vaccination, or surgery
Type
- Segmental Demyelinating Motor > Sensory
Clinical Presentation (Sensory & Motor Neuropathies)
- Classic scenario: Ascending symmetrical weakness & numbness, Bowel & bladder dysfunction, Respiratory dysfunction, Facial Palsy
- Reflexes: Abnormal (Neuropathy → LMN)
Labs
- CSF: Increased Protein ← Losing muscles
NCS (Acquired Demyelinating Sensory & Motor Neuropathies)
- SNAP: Abnormal (Sensory)
- CMAP: Temporal dispersion and conduction block (Demyelinating - Acquired)
- F-wave: Abnormal—first EDX sign
EMG
- Normal (Demyelinating)
Treatment
- Plasmapheresis
- IV immunoglobulins
- Respiratory support
- Steroids are ineffective
Cuccurollo 4th Edition Chapter 5 EDX pg425
How to support diagnosis of AIDP? (Acquired Demyelinating Polyneuropathy) 🔑🔑
NCS of two or more nerves showing abnormalities of demyelinating lesion
- Decreased CV
- Prolonged Latency
- Temporal dispersion (TD)
- Conduction block (CB)
- Late responses (early findings)
Ref: Braddom
List 2 Cranial nerve symptoms in GBS 🔑🔑
💡 CN 1 & 3 are spared
- Facial palsy
- Bulbar: Dysarthria & Dysphagia
60yo male with 5 day history of ascending weakness that eventually involves respiratory muscles and admitted to ICU. CSF shows normal cells, increased protein.
- What is the diagnosis?
- Name 2 electrodiagnostic findings you would expect after 5 days
- What are the predictors of severe disease and poorer outcome in patients with
- List 3 Evidence of poor prognosis for AIDP.? 🔑
ANSWER 1 DIAGNOSIS
Duration < 4 weeks
Acute Inflammatory Demyelinating Polyneuropathy (AIDP)
or Guillain-Barre Syndrome (GBS)
Duration 4-8 Weeks
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
ANSWER 2 EDX FOR DEMYELINATING SENSORY & MOTOR NEUROPATHY
Demyelination Criteria for AIDP in NCS 3 out of 4
- Reduced conduction velocity
- Conduction block or abnormal dispersion
- Prolonged distal latencies
- Prolonged F-waves (1st sign)
EMG
- Normal or decrease motor unit recruitment if severe
ANSWER 3 PREDICTORS
- Old age
- Rapid onset of severe tetraparesis
- Need for early artificial ventilation
- Severely decreased CMAPs (<20% of normal)
- Acute motor-sensory axonal form of the disease
Neurology Secrets 6th Edition Chapter 6 Peripheral Neuropathy pg85
ANSWER 4 EVIDENCE
EDX → Evidence of axonal involvement
- CMAP: Reduced Amplitude <20% of normal, serve axonal loss
- F-wave: Absent (Motor Unit Abnormalities)
- EMG: Abnormal activity
Cuccurollo 4th Edition Chapter 5 EDX pg425 Table 5-36
Clinically → Ascending Pattern
- Areflexia
- Autonomic involvement
- Cranial nerve involvement
Cuccurollo 4th Edition Chapter 5 EDX pg426 Table 5-37
Chronic inflammatory demyelinating polyneuropathy (CIDP)
Course - PEx - Presentation - EDX - Treatment
Course
- Any age, peaks at 50–60 years of age:
- Relapsing and remitting course
- Less cranial nerve involvement
- AIDP but the longer chronicity
Presentation
- Sensory: Abnormal
- Motor: Symmetric weakness: proximal > distal (demyelination)
- Reflexes: Abnormal (Neuropathy → LMN)
Lab
- CSF: Increased protein
EDX of Acquired Demyelinating Sensory & Motor Neuropathy
- SNAP: Abnormal
- CMAP: Abnormal; increased TD
- F-wave: Abnormal
- EMG: Abnormal, if severe (axonal involvement)
Treatment
- Rehabilitation
- IV Ig
- Plasmapheresis
- High-dose steroids
Cuccurollo 4th Edition Chapter 5 EDX pg425
List 4 Features Not Consistent With Guillain-Barré Syndrome
List 4 Diseases Commonly Associated With CIDP
Features Not Consistent With Guillain-Barré Syndrome (Red)
- Severe pulmonary involvement early, without significant weakness
- Bowel or bladder involvement at onset
- Severe sensory symptoms with minimal weakness
- Fever
- Well delineated sensory level
- Slow progression, limited weakness, no respiratory involvement
- Marked asymmetry
Braddom 6th Edition Chapter 41 Neuropathies pg866 Box 41.5
Diseases Commonly Associated With CIDP (Green)
Chronic Inflammatory Demyelinating Polyneuropathy Variants
- Diabetes mellitus
- Systemic lupus erythematosus
- Human immunodeficiency virus infection
- Sarcoidosis
- Thyroid disease
- Chronic active hepatitis
Braddom 6th Edition Chapter 41 Neuropathies pg867 Box 41.7
Mention 6 Medications associated with periphral neuropathy 🔑🔑 EXAM 🟦
- Hydralazine
- Pyridoxine (Vitamin B6)
- Colchicine
- Vincristine (Chemotherapy)
- Amiodarone
- Isoniazid
- Dapsone
- Lithium
Braddom 6th Edition Chapter 41 Neuropathies pg861 Box 41.2
Friedreich’s Ataxia 🔑🔑
Tracts Affected - Inheritance - Type - Presentation.
Friedreich’s Ataxia
- Spinocerebellar
- Lateral Corticospinal (UMN)
- Posterior Column
Inheritance
- Autosomal recessive
- Onset: 2–16 years old
Type
- Axonal Sensory Neuropathy
Presentation
- Sensory: Loss
- Motor: Weakness - Wheelchair use by 16 years of age
- Reflexes: Reduced (Neuropathy → LMN)
- Fiber Specific: Ataxia (Limb and trunk)
- Specific: Kyphoscoliosis - Pes cavus deformity - Cardiomyopathy - Dysarhtria
NCS
- SNAP: Abnormal (Sensory Neuropathy)
- CMAP: Normal
EMG
- Abnormal activity (motor unit remodeling - axonal loss)
Vincristine (chemotherapy) Neuropathy: Presentation - EDX
Presentation
- Sensory (Large & Small Fibers): Lower limb paresthesias
- Motor: Lower limb weakness > upper limb (bed bound receiving Tx)
- Reflexes: Abnormal
NCS for Axonal & Acquired Neuropathy
- SNAP: Abnormal
- CMAP: Abnormal
EMG
- FIBs and PSWs
Pyridoxine (B6) Neuropathy: Type - Presentation 🔑
Type
- Axonal Sensory Neuropathy
Presentation
- Sensory: Paresthesia (Numb)
- Reflexes: Abnormal
- Specific (Large and Small): Positive Lhermitte’s sign - Gait disturbances
NCS
- SNAP: Abnormal (Sensory Neuropathy)
- CMAP: Normal
EMG
- FIBs and PSWs (De-innervation → axonal loss)
ETOH Neuropathy: Presentation - EDX - Treatment
Presentation
- Sensory: Pain, dysesthesias
- Motor: Muscle atrophy - Weakness in the feet and legs - Foot or wrist drop - Muscle spasms
- Specific: ± associated with a myopathy
Complications (Thiamine (vitamin B1) deficiency)
- Wernicke’s encephalopathy
- Korsakoff’s psychosis
Labs
- N Bx: Wallerian degeneration
EDX of Axonal Sensorimotor Neuropathy
- SNAP: Abnormal (Sensory)
- CMAP: Abnormal (Motor)
- EMG: Fibrillations and positive waves (de-innervation from axonal damage + myopathy)
Treatment
- Thiamin Supplement
- Stop alcohol consumption
- Orthotics for wrist and foot drop
Cuccurollo 4th Edition Chapter 5 EDX pg428
Amyloidosis Neuropathy: Etiology - Presentation - EDX
Etiology
- Amyloid deposition in DRG, inside the pocket.
Clinical Presentation
- Sensory abnormalities
- Weight loss
- Ankle edema
- Hepatomegaly (Liver)
- Purpura (Skin)
- Nephrotic syndrome (Kidney)
- Congestive heart failure (Heart)
Labs
- Tissue Bx: (+) birefringence with Congo red staining
EDX of Axonal Sensorimotor Neuropathy
- SNAP: Abnormal (Sensory)
- CMAP: Abnormal (Motor)
- EMG: Abnormal activity (Axonal)
Cuccurollo 4th Edition Chapter 4 EDX pg428
Sarcoidosis Neuropathy: Etiology - Presentation - EDX
Etiology
Granulomatous disorder (grain)
Clinical presentation
- Uveitis (eyes)
- Cranial nerve involvement (CN VII most common)
- Bilateral hilar adenopathy (lunges)
- Fatigue
- Low birth weight
Labs
- Blood: Increased ESR
- N Bx: Sarcoid tubercles (tube containing grains)
EDX
- SNAP: Abnormal
- CMAP: Abnormal
- EMG: Abnormal activity
Uremic Neuropathy: PEx - Labs - EDX
Clinical presentation
- Sensory: Paresthesia, Hypersensitivity to touch
- Motor: Restless legs syndrome (RLS)
Labs
- Blood: Increased nitrogen and urea (Renal Failure)
- N Bx: Paranodal demyelination, axon loss (mix peripheral neuropathy)
EDX of Axonal Sensorimotor Neuropathy
- SNAP: Abnormal (Axonal & Sensory)
- CMAP: Abnormal (Axonal & Motor)
- EMG Abnormal activity (Axonal)
Treatment
- Rehabilitation, Dialysis, kidney transplant
Cuccurollo 4th Edition Chapter 5 EDX pg428
List 5 HIV-Related Neuropathies. 🔑🔑 EXAM 2021
Five Major Categories
- Inflammatory Demyelinating Polyneuropathy (IDP)
- Mononeuropathy Multiplex
- Autonomic Neuropathy
- Progressive Polyradiculopathy
- Distal Symmetric Polyneuropathy (Most Common)
EDX
- NCS: Abnormal SNAPs and CMAPs
- EMG: Abnormal activity
- Commonly presents with demyelination and axonal loss
Cuccurollo 4th Edition Chapter 5 EDX pg429 Table 5-42
List 4 types of neuropathies seen in diabetics 🔑🔑 EXAM 2020-2021
1- Distal Symmetric Sensorimotor Polyneuropathy (Large > Small)
- Motor (Large Fibers)
- Muscle wasting, particularly of the intrinsic foot muscles
- Depressed Achilles reflexe
- Sensation (Large & Small Fibers)
- Dorsal Column: Feelings of walking on cotton, vague unsteadiness, or difficulty manipulating small objects such as buttons, loss of vibratory sensation and position-sense loss
- Spinothalamic: Dull, cramping ache, hyperalgesia, loss of temperature sensation
- NCS: Sural sensory (earliest changes)
- EDX
- Axon loss and demyelination
- Motor nerve conduction occur later in the course of the disease
2- Proximal Neuropathy
Diabetic Amyotrophy (commonly Femoral neuropathy)
- Pain tends to attenuate over weeks to months
- Sensory abnormalities are usually seen in the femoral and occasionally saphenous distribution, thoracic dermatomes can less commonly occur, presenting with severe abdominal or chest pain
- Pain tends to attenuate over weeks to months accompanied by marked atrophy of the thigh muscles (quadriceps, adductors, and iliopsoas, with relative sparing of gluteal and hamstring muscles)
- DDx: spinal stenosis and chronic inflammatory demyelinating polyneuropathy (CIDP).
- Abnormal SNAP in femoral and saphenous distribution
- Reduced CMAP in femoral nerve conductions
- Management : Tight glycemic control & management of neuropathic pain.
- Corticosteroids, plasmapheresis, and intravenous immunoglobulin (IVIG) have not been shown to be efficacious in management of this condition.
3- Focal Mononeuropathies
Spontaneous recovery occurs over 6 to 8 weeks
- Cranial nerves III, VI, and VII
- Median, ulnar
- Peroneal nerves
4- Autonomic neuropathy (BBSSH) → Small unmyelinated C fiber
- Bowel: esophageal dysmotility, gastroparesis, constipation or diarrhea, and bowel incontinence
- Bladder: Neurogenic bladder leads to overflow incontinence, recurrent urinary tract infection, and pyelonephritis
- Sex: Irreversible erectile dysfunction
- Skin: abnormalities in sweating and thermoregulation, lack of sweating can lead to dryness and cracking and fissuring of the feet, increasing susceptibility to foot ulceration and infection.
- Heart: silent ischemia, lethal arrhythmias, or prolongation of QT interval, resting tachycardia greater than 100 beats/min, orthostasis & hypotension
Braddom 6th Edition Chapter 41 Neuropathies pg864
What is small fiber neuropathy? 🔑🔑
Small Fiber Neuropathies
- Affect the small myelinated A δ and unmyelinated C fibers.
Clinical Presentation
- Dysesthesia “abnormal sensation”
- Hypersthesia: Pain, numbness, burning, “pins and needles-like” sensations (spinothalamic), allodynia and hyperalgesia
- Hyposthesia: Decreased pinprick and temperature sensation Allodynia and hyperalgesia
- Autonomic disturbances (c fibers)
List 3 Shoe modification for diabetic foot. 🔑🔑 EXAM
- Extra-depth toe box
- Extra cushioning
- Offload pressure areas
