Diseases of the motor unit

Question 1

what are the clinical patterns of neuromuscular disorders?

Answer 1

functional and anatomic

Question 2

what are the different types of functional deficits in neuromuscular disorders?

Answer 2

• motor
• sensory
• autonomic

Question 3

what are the diagnostic tests in “weak” patients?

Answer 3

• electrodiagnostic: NCS, needle exam, repetitive stimulation
• lab: CK, antibodies (serum, CSF), genetic testing
• biopsy: muscle / nerve

Question 4

what are the features of ALS?

Answer 4

• amyotrophic: LMN symptoms of weakness, atrophy, fasciculations
• lateral sclerosis: UMN symptoms of hyperactive DTRs, clonus, Babinski sign
• progressive muscular atrophy / spinomuscular atrophy / progressive bulbar palsy

Question 5

what does bulbar involvement entail in ALS?

Answer 5

• CN nuclei: flaccid dysarthria, dysphagia, tongue atrophy, fasciculations
• corticobulbar: spastic dysarthria, pseudobulbar palsy

Question 6

what are the differentials for ALS?

Answer 6

• myasthenia gravis

- post-polio syndrome

Question 7

how is diagnosis of ALS made?

Answer 7

• UMN and LMN signs (sparing sensory functions) in bulbar region and 2 spinal regions or in three spinal regions

Question 8

what is the treatment for ALS? what is the MOA?

Answer 8

riluzole - glutamate antagonist

Question 9

what is a mononeuropathy? what is a classic example?

Answer 9

• single nerve distribution

- carpal tunnel syndrome

Question 10

what test helps in distinguishing axonal vs demyelinating neuropathies?

Answer 10

EMG

Question 11

what are the clinical features of hereditary motor sensory neuropathy (HMSN)? what is the other name for it?

Answer 11

• slow, progressive, distal weakness, difficulty walking, clumsy, steppage gait
• intrinsic muscle weakness leads to pes cavus
• absent DTRs
• charcot-marie-tooth disease

Question 12

what are the EMG findings in type 1 and type 2 HMSN?

Answer 12

• type 1 (demyelinating): slowed NCV

- type 2 (axonal): normal or mildly slowed NCV

Question 13

what are the features of acute inflammatory demyelinating neuropathy? what is the other name for it?

Answer 13

• motor difficulties
• loss of DTRs with preservation of cutaneous reflexes
• albuminocytological dissociation
• ASCENDING weakness
• guillain-barre syndrome

Question 14

what are the hallmark findings in LP for guillain barre syndrome?

Answer 14

elevated protein with absence of cells / pleocytosis

Question 15

what electromyography finding indicates a prolonged course for guillain barre syndrome?

Answer 15

presence of axon loss (fibrillations)

Question 16

what is the gold standard treatment for guillain barre syndrome? what is a secondary treatment?

Answer 16

• plasmapheresis: 4 exchanges

- IVIG