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Neuro 2 > Motor Neuron Diseases > Flashcards

Motor Neuron Diseases Flashcards

1
Q

What is affected in Motor Neuron Diseases

A

-motor neurons, their motor axons, and secondarily the muscle fibers they innervated (the motor unit)

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2
Q

Werdnig-Hoffman

A 
Infantile Spinal Muscular Atrophy
-autosomal recessive
-hypotonicity, hyporeflexia, fatal
-tongue fasciculations
-poor suck reflex
-abdominal respirations 
Anterior Horn Cell Disease
-difficulty breathing, swallowing , die early from respiratory failure, "frog-leg" posture
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3
Q

Wolfart-Kugelberg-Welander

A

-Juvenile Proximal Chronic Spinal Muscular Atrophy
-Autosomal recessive
-slowly progressive, fasciculations, proximal weakness, resembles myopathy
Anterior Horn Cell Disease
-atrophy of pectoralis & thigh muscles

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4
Q

Adult Onset Spinal Muscular Atrophy

A

-sproadic (some familial)
-Proximal, distal weakness
-hypotonicity, hyporeflexia
Anterior Horn Cell Disease

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5
Q

Werdnig-Hoffman Disease Tests

A
  • EMG: signs of denervation and fasciculations
  • Muscle Biopsy: group fiber atrophy
  • Mutation: ‘survival motor neuron gene’ on chromosome 5q
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6
Q

Wolfart-Kugelberg-Welander Tests

A
  • EMG & Biopsy: denervation changes
  • Serum CK: normal
  • Mutation: ‘survival motor neuron gene’ SNM1 is absent and the size of SMN2 determines if the patients have neonatal or juvenile form
  • SMN2 is larger
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7
Q

Progressive Bulbar Palsy

A

Adult motor neuron disorders

  • sproadic, fasciculations, Bulbar muscles weakness, rapidly progressive, tongue atrophy
  • may develop ALS
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8
Q

Amyotrophic Lateral Sclerosis (ALS)

A

Adult motor neuron disorders

  • mostly sporadic, some familial cases - 10%, hyperreflexia, spasticity
  • muscle atrophy (fasciculations) , fasciculations, tongue atrophy, rapidly progressive (lethal)
  • upper & lower motor neurons, bulbar weakness
  • normal sensation

Presentation: difficulty swallowing & breathing
Late: biateral Babinski signs, hard to close mouth

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9
Q

Progressive Lateral Sclerosis

A
  • sporadic, involves only upper motor neurons, spasticity
  • hyperreflexia, more benign course
  • little atrophy or signs of denervation
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10
Q

Progressive Spinal Muscular Atrophy

A

-mostly sporadic, progressive weakness, muscle atrophy, fasciculations, areflexia

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11
Q

Signs, Symptoms, & Labs of Motor Neuron Diseases

A
  • Symmetrical or asymmetrical weakness
  • Atrophy
  • inc. or dec. reflexes dep. on corticospinal tract involvement (ALS)
  • fasciculations
  • normal sensation
  • normal nerve conduction velocities
  • denervation on EMG
  • dec. # of motor units
  • muscle biopsy shows atrophic fibers & fiber grouping
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12
Q

Cervical Spondylosis

A
  • seen in MRI
  • present: lower motor neuron signs in upper extremities secondary to nerve root compression & upper motor neuron signs in the lower extremities secondary to compression of spinal cord & corticospinal tracts
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13
Q

Kennedy’s Disease

A
  • Bulbo-spinal muscular atrophy
  • more benign than ALS, family history
  • mutations of the androgen receptor on the x chromosome
  • Phenotype: gyneocomastia & testicular atrophy, lower motor neuron syndrome (atrophy, fasciculations, signs of denervation in limbs & tongue, mild neuropathy)
  • serum CPK elevated
  • DNA testing diagnostic
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14
Q

Pathology of ALS

A
  • degeneration of the corticospinal tracts (lack of myelin)

- Bunina body: dense granules inclusion in cell body cytoplasm (ubiquitin accumulations)

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15
Q

Etiology of ALS

A

-unknown, some familial cases (genetic)

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16
Q

Possible etiologies of ALS and other motor neuron diseases

A

Genetic Defects

  • SOD gene mutations in chromosome 21 in AD familial ALS
  • Juvenile ALS: chromosome 2q33 (also 9q34, 15q15, 8q21), and also ALS associated with mutation of 9q21, XP
  • ALS associated with other diseases such as chromosome 17-linked fronto-temporal dementia (FTD)
  • an expanded section of DNA on chromosome 9 in the gene C90RF72 is most common cause of familial ALS with or without FTD
  • Excitotoxicity: evidence suggests an inc. of glutamate mediated excitotoxicity causing neuronal degeneration (secondary)
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17
Q

Treatment of ALS

A
  • Glutamate antagonists (riluzole)
  • Experimental: creatine & antioxidants such as carotene, coenzyme Q10, vitamins C & E could be of benefit, COX 2 inhibitors, nerve growth factors
  • physical therapy
  • symptomatic treatments such as anticholinergics for sialorrhea, stool softeners, antispastic drugs, botulinum toxin
  • antidepressantts
  • bracing
  • gastrostomy
  • respiratory assistance
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18
Q

Brachial plexus

A
  • extends from spinal cord to distal aspect of axilla

- 6 divisions, behind clavicle

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19
Q

Sensory Domain

A
  • the skin region innervated by the sensory nerve fibers contained with a nerve root
  • Dermatome: sensory domain of a root
20
Q

Muscle Domain

A
  • the muscles innervated by the motor nerve fibers contained within a nerve root
  • Myotome: motor domain of a root
21
Q

What are the 2 most common causes of radiculopathies?

A
  1. Disk herniation & degeneration (>C6
    -Spondylosis: C5 & C6> frequent
    by age 60 yrs, 70% W and 85% M
    after age 70 yrs, 93% W and 97% M
  2. Lumbosacral radiculopathies
    - >95% of HNPs affect either L5 or S1
22
Q

Clinical features of Radiculopathies?

A
  • Pain (hallmark): sharp, stabbing, hot; electric, radiating, aggravated by maneuvers that stretch the root (cervical: neck extension, neck rotation, Spurling’s maneuver)
  • lower extremity (SLR used with L5 or S1 nerve root involvement is suspected and reverse SLR w/L4
  • weakness & atrophy (motor nerve fibers, myotomal distrubution (muscle domain of root))
  • Paresthesias & sensory loss: sensory nerve fibers, dermatomal distribution (sensory domain of a root)
  • Muscle stretch reflexes (diminished or absent)

-Irritation = tingling

23
Q

Spondylosis

A

> 50 yrs

  • Cervical spondylosis: myeloradiculopathy (spinal canal stenosis)
  • Lumbosacral spondylosis: neurogenic cladication (ambulation to LE pain & weakness), cauda equina syndrome
24
Q

Radiculopathy: Fracture of Dislocation

A

-Trauma: major cause in young patients
minor cause amoung elderly
-Bone disease: osteoporosis; osteomalacia; Paget disease, Corticosteroid therapy, congenital anomalies

25
Q

Radiculopathy: Infection

A
  • fever
  • immunosuppressed status
  • IVDA
  • Spinal surgery
  • penetrating wound
26
Q

Radiculopathy: Neoplasm

A
  • history of cancer
  • constitutional symptoms (weight loss)
  • pain at rest
  • neurologic deficit (cauda equina localization)
27
Q

Evaluation of Radiculopathy

A

-H&P (most important):
Spinal cord compression: sensory level, anal tone, fecal or urinary incontinence, check cutaneous reflexes (abdominal; bulbocavernousus; anal wink; cremaster)
-Plain radiographs
-CT (+/- myelography)
-MRI: superior to CT for all spine conditions
multiplanar
greater contrast sensitivity (tumor & infection)
Noninvasive
Non-ionizing radiation
Gadolinium contrast (scar tissue vs. recurrent disk protrusion)

28
Q

EDX Testing

A
  • yields physiologic info
  • complements MRI (anatomic changes, high false+)
  • False + studies extremely uncommon
  • assesses sensory & motor nerve fibers
  • assesses muscle fibers
  • identifies demyelination & axon loss
  • localized the disorder
  • generates ddx or the actual diagnosis
  • determines severity
  • determines prognosis
  • dictates management & follow-up
29
Q

Radiculopathy: Conservative Treatment

A
  • most w/acute radiculopathies improve in 6 weeks
  • bed rest 0-2 days
  • physical therapy (heat, cold, ultrasound, massage, stretching, ergonomic education)
  • Meds: NSAIDS, prednisone, benzodiazephines
  • Nerve Block
30
Q

Radiculopathy: Surgical Treatment

A
  • Etiology (neoplastic process)
  • spinal instability
  • severe or progressive weakness
  • spinal cord compression
  • cauda equina syndrome
  • sphincter or sexual dysfunction
  • incapacitating neurogenic claudication
  • intractable pain (ill-advised if isolated pain with negative imaging)
31
Q

Plexopathies

A

-Brachial plexus elements

anterior primary rami, trunks, divisions, cords, terminal nerves

32
Q

Polyneuropathy

A
  • weakness symmetrically, distally
  • stocking & glove pattern
  • dec. reflexes
  • slow nerve conduction velocities
  • denervation & decreased # of motor units on EMG
  • Muscle biopsy: atrophic fibers & fiber type grouping
33
Q

Mononeuritis

A

(one nerve)

  • weakness in nerve distribution
  • slow nerve conduction velocities
  • denervation & decreased # of motor units on EMG
  • Muscle biopsy: atrophic fibers & fiber type grouping
34
Q

Mononeuritis Multiplex

A

-several nerves
weakness in nerve distribution
-slow nerve conduction velocities
-denervation & decreased # of motor units on EMG
-Muscle biopsy: atrophic fibers & fiber type grouping

35
Q

Demyelinating Neuropathy

A
  • weakness: distal & proximal
  • areflexia
  • dec. vibration & position sense with little deficit of pain & temp sensations
  • very slow NCV, conduction block with normal amplitude of nerve action potential
  • prolonged distal latencies, F responses & H reflexes
36
Q

Axonal Neuropathy

A
  • mostly distal weakness with distal areflexia, glove & stocking sensory deficit to all modalities, trophic changes
  • Nerve conduction is almost normal with reduced action potential amplitude, signs of denervation on EMG (uremia, toxins)
37
Q

Wallerian Degeneration

A

-severe acute damaged to myelin & axons

trauma, vasculities

38
Q

Charcot-Marie-Tooth Disease

A
  • hereditary
  • usually autosomal dominant
  • usually demyelinating, rarely axonal
  • high arched feet
  • hammer toes
  • check NCV in relatives
  • some cases appear late
  • Type 1 has deletions on the genes that express meylin protein PMP 22(1A) or protein 0 P0(1B)
39
Q

Diabetic Neuropathies

A
  • diffuse sensory motor neuropathy has metabolic origin (accumulation of sorbitol, deficiency of myoinositol)
  • presens with burning of feet, then numbness & weakness
  • improves with good control of diabetes
  • mononeuritis, mononeuritis mulitplex & diabetic ophthalmoplegia are produced by infarct to nerves or plexus
  • diabetics are more predisposed to entrapment neuropathies
40
Q

Treatment of Diabetic Polyneuropathy

A
  • good control of diabetes
  • nerve growth factor
  • sorbitol antagonist
  • myoinositol & vitamin supplementation
  • be aware of other conditions (CIDP)
41
Q

Treatment of Mononeuropathy, mononeuropathy multiplex

A

-treatment is conservative, consider steroids if the disease is progressive

42
Q

Guillain-Barre syndrome

A

-acute autoimmune, ascending paralysis accompanied by arreflexia & normal or mildly abnormal sensation with albuminocytological disassociation in the spinal fluid

43
Q

Guillain-Barre syndrome: Clinical Findings

A
  • progressive (symmetrical) paralysis over a period of one to three weeks
  • acute inflammatory radiculoneuropathy
  • ascending paralysis, facial weakness, respiratory insufficiency
  • paresthesia but little evidence of sensory deficit
  • areflexia, normal or almost normal sensation
44
Q

Treatment of Guillian Barre Syndrome

A
  • respiratory assistance if necessary
  • includes plasmapheresis or gamma globulin infusions
  • corticosteroids (NO benefit)
  • physical therapy & emotional support
45
Q

Chronic Inflammatory Neuropathy

A
  • autoimmune inflammatory neuropathy that affects myelin sheath
  • subacute to chronic weakness; symmetrical, distal & proximal
  • no cranial nerve involvement
  • areflexia
  • marked deficit of positional & vibratory senses, little pain & temp deficit, elevated spinal fluid protein, slow NCV
  • evidence of conduction block (vasculitic neuropathy sometimes produces conduction block, simulating demyelination)
  • minimal denervation on EMG
  • rarely can have CNS signs (central demyelination)
  • could have relapsing course
  • nerve biopsy: segmental demyelination, rarely, inflammation
  • same patients have MUGS
  • treat with corticosteroids, immunosuppressant, or gamma globulin

Neuro 2 (16 decks)

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