Motor Neuron Diseases

Question 1

Possible locations of motor neuron diseases?

Answer 1

Motor neurons, motor axons, and muscle fibers they innervate

Question 2

Spinal muscular atrophy in an infant? a juvenile? Adult?

Answer 2

Werdnig-Hoffman - infantile spinal muscular atrophy
Wolfart-Kugelberg-Welander - Juvenile proximal chronic spinal muscular atrophy
Adult onset spinal muscular atrophy

Question 3

Characteristics of Werdnig-Hoffman (infantile spinal muscular atrophy?

Answer 3

AR
Hypotonicity
Hyporeflexia
Fatal
Tongue fasciculations
Poor suck reflex
Abdominal respirations

Question 4

Characteristics of Wolfart-Kugelberg-Welander (juvenile proximal chronic spinal muscular atrophy)?

Answer 4

AR
Slowly progressive
Fasciculations
Proximal Weakness
Resembles myopathy

Question 5

Characteristics of adult onset spinal muscular atrophy?

Answer 5

Sporadic (some familial)
Proximal, distal weakness
Hypotonicity
Hyporeflexia

Question 6

Mutation in Werdnig-Hoffman?

Answer 6

‘Survival motor neuron gene’ on chromosome 5q

Question 7

When and how do patients with Werdnig-Hoffman die?

Answer 7

Early in life

Respiratory failure

Question 8

Frog leg posture?

Answer 8

Hips abducted due to weakness

Seen in Werdnig-Hoffman

Question 9

When does Juvenile spinal muscular atrophy (Kugelberg-Welander)present? What does it resemble?

Answer 9

Childhood

Muscular dystrophy

Question 10

What does the EMG show in patients with Kugelberg Welander?

Serum CK?

Answer 10

Denervation changes

Normal

Question 11

Mutation in Kugelberg Welander?

Answer 11

‘Survival Motor Neuron gene’ on chromosome 5q

Question 12

What is absent both infantile and juvenile spinal muscular atrophy? What separates the two?

Answer 12

SMN1

SMN2 is longer in juvenile compared to infantile

Question 13

Characteristic of progressive bulbar palsy?

Answer 13

Sporadic
Fasciculations
Bulbar (innervated by neurons of the medulla) muscles weakness
Rapidly progressive  --> classic ALS
Tongue and palate atrophy

Question 14

Characteristics of Amyotrophic Lateral Sclerosis?

Answer 14

Mostly sporadic (some familial)
Hyperreflexia
Spasticity
Muscle atrophy
Fasciculations
Tongue atrophy
Rapidly progressive

Question 15

Characteristics of Progressive Lateral sclerosis?

Answer 15

Sporadic
Involves ONLY the UMNs
Spasticity
Hyperreflexia
Benign course

Question 16

Characteristics of Progressive spinal muscular atrophy?

Answer 16

Mostly sporadic
Progressive weakness 
Muscle atrophy
Fasciculations
Arflexia

Question 17

Signs/Symptoms of motor neuron disease?

Answer 17

Symmetrical or asymmetrical weakness
Atrophy
Increase/decrease reflexes - dependent upon corticospinal tract involvement (ALS)
Fasciculations
Normal sensation
Normal nerve conduction velocities
Denervation on EMG
Increase # of motor units
Muscle biopsy shows atrophic fibers & fiber grouping

Question 18

What is the root cause of ALS?

Answer 18

Degeneration of the upper and lower motor neurons

Question 19

What are bunina bodies?

Answer 19

Eosinophilic inclusions in anterior horn cell neurons. Ubiquitin accumulations

Question 20

Possible genetic defects seen in ALS?

Answer 20

SOD gene mutations in chromosome 21 in AD familial ALS
Juvenile ALS: in chromosome 2q33 (9q34, 15q15, 8q21)
Mutation of 9q21, Xp
Expanded section of DNA on chromosome 9 in the gene C90RF72 is the most common cause of familial ALS with or without FTD

Question 21

Increase in what can cause neuronal degeneration that can possible cause ALS?

Answer 21

Glutamate mediated excitotoxicity

Question 22

In an EMG, what is the F wave? H wave? M wave

Answer 22

Delayed response to stimuli
Muscle stretch reflex to stimuli
Immediate response to stimuli