Motor Neuron Diseases

Question 1

Neuromuscular diseases affect motor units which are made up of

Answer 1

motor neurons, their motor axons, and secondarily the motor fibers they innervate

Question 2

Spinal muscular atrophy presents at 3 stages, they are:

Answer 2

• infantile (Werdnig Hoffman)
• juvenile (Wohlfart- Kugleberg Welander)
• adult (Adult spinal muscular atrophy)

Question 3

The infantile and juvenile forms of Spinal muscular atrophy follow which inheritance pattern

Answer 3

Autosomal Recessive

Question 4

Adult Spinal muscular atrophy inheritance patttern?

Answer 4

sporadic and occasionaly familial

Question 5

Features of infantile SMA

Answer 5

• Auto recessive
• Hypotonicity
• Hyporeflexia
• Fatal
• Tongue fasiculations
• Poor Suck Reflex
• Abdominal Respirations

Question 6

Babies with SMA (Werdnig- Hoffman) generally die young due to what?

Answer 6

Respiratory failure

Question 7

EMG of SMA (WH) will show what

Answer 7

Denervation and fasciculations

Question 8

Muscle biopsy of someone with SMA will show?

Answer 8

group fiber atrophy

Question 9

Mutation in infantile SMA?

Answer 9

survival motor neuron gene on chromosome 5Q

Question 10

Differentiating spinal muscle atrophy from myopathies

Answer 10

EMG and biopsy show denerveation and serum CK is generally normal

Question 11

Mutation in juvenile SMA

Answer 11

survival motor neuron gene on chromosome 5

Question 12

The survival motor neuron gene has two copies, SMN1 and SMN2. SMN1 is absent in spinal muscular atrophy and they size of SMN2 determines if the patient has the neonatal or juvenile form (larger in the juvenile form)

Answer 12

ok

Question 13

Juvenile SMA called

Answer 13

Wohlfart Kugleberg Wolander

Question 14

Progressive Bulbar Palsy

Answer 14

A presentation of ALS which primarily affects muscles innervated by the medulla neurons, causing tongue and palate weakness.

Question 15

ALS

Answer 15

Manifests with upper and lower motor neuron symptoms and findings as well as “bulbar” weakness.

Question 16

Progressive lateral sclerosis

Answer 16

affects primarily the upper motor neurons with little atrophy or signs of denervation

Question 17

Some other things to consider when diagnosing ALS

Answer 17

• Multisystem atrophy: late onset degenerative disease that could affect lower motor neurons, autonomic neurons and cerebellar neurons
• Hereditary cerebellar degeneration: can’t swallow plus ataxia
• Tumors of the craniocervical junction
• Cervical canal disease or cervical spondylosis: Deg disc dz. Arm hand atrophy or weakness, spasticity from compression of the pyramidal tracts.
• post polio syndrome: patients with a history of polio in childhood may later develop progressive lower motor neuron disease. The cause is unclear.
• Polyglucosan body disease: glycogen storage disorder that presents in younger individuals with a lower motor neuron type weakness
• Hyperparathyroidism: elevated serum calcium and parathyroid hormone level are diagnostic
• Kennedy disease: a more benign disorder that may present without a family history…gynecomastia and testicular atrophy

Question 18

Gross pathology of ALS

Answer 18

lack of myelin and loss of anterior horn neurons

Question 19

Microscopic pathology

Answer 19

Eosinophilic inclusion bodies in anterior horn cells. This same change would be expected in the motor nuclei of the brainstem.