Neuromuscular

Question 1

1. What nerve is involved?
2. The above nerve is a branch of what nerve?
3. What muscles does the nerve innervate?

Answer 1

1. Anterior Interosseus Nerve
2. Median Nerve
3. Flexor pollicis longus, flexor digitorum profundus 1&2, pronator quadratus

Question 2

The C4 dermatome lies adjacent to which dermatome on the trunk?

Answer 2

T2

Question 3

Damage to long thoracic nerve causes what

Answer 3

scapular winging due to weakness of serratus anterior muscle

Question 4

gene mutation seen in 10-20% AD familial cases of ALS

Answer 4

SOD1 (Superoxide Dismutase)

• chromosome 21q22
• toxic gain of function of affected gene

Question 5

Emery-Dreifus Muscular Dystrophy

Answer 5

-X-linked

Defect in gene encoding for EMERIN protein

• contractures at the elbows, ankles, & neck
• cardiac involvement is prominent & have serious conduction abn often requiring a pacemaker
• muscle weakness in upper arms 1st then later pelvic girdle & distal legs

Question 6

1. What does this picture represent?
2. Name the associated genetic mutation
3. Clinical presentation
4. Patients are at increased risk of what with anesthesia?

Answer 6

1. Central core myopathy
2. Autosomal Dominant
   - mutation in the ryanodine receptor gene RYR1, chromosome 19
3. weakness & hypotonia soon after birth
   - proximal weakness worse in the pelvic girdle (facial, bulbar, ocular usually spared)
4. increased risk malignant hyperthermia w anesthesia

Question 7

This biopsy is consistent with what NM disease?

Genetics of condition?
Typical age of onset?
Clinical Features?

Answer 7

Duchenne Muscular Dystrophy

Genetics: Most common hereditary NM disease
X-linked recessive disorder due to absence of dystrophin
- out-of-frame deletion in the dystrophin gene at Xp21 site
-1/3 of cases result from new mutations

Clinical Features: Prox musc weakness btw 3 & 5 yrs
Waddling gait, toe walking, difficulty arising from floor, frequent falls
Pseudohypertrophy of calves
Increased lumbar lordosis
Hip girdle weakness

(Dystrophic changes on biopsy)

Question 8

What conditions is the following seen in?

Answer 8

Ragged red fibers

Seen in:

Mitochondrial myopathies

AZT induced myopathy

Question 9

This biopsy is consistent with what NM condition?

What are the clinical features?

Answer 9

Kearns-Sayre Syndrome (Mitochondrial Myopathy) :
Biopsy features: Myofiber w red subsarcolemmal staining on the Gomori Trichrome prep - histologic appearance of a “ragged-red fiber” corresponds to abnormal subsarcolemmal mitochondrial accumulations

Clinical Features:
Progressive external ophthalmoplegia
Retinal degeneration
Heart block*
Hearing loss
Ataxia
Dementia
Short stature
Hypoparathyroidism
Hypothyroidism
Peripheral neuropathy

Question 10

Fascioscapulohumeral muscular dystrophy (FSH)

1. Genetics?
2. Clinical Presentation?
3. Pathology?

Answer 10

1. Autosomal Dominant
   chromosome 4q35
2. Onset infancy to adulthood; 3rd most common muscular dystrophy

Present w facial weakness & scapular winging
Tibialis anterior is affected early
Deltoid is spared
Later the biceps & triceps are affected, sparing the forearm muscles, giving arms Popeye appearance

3. Biopsy: necrotic fibers, inflammatory infiltrate, connective tissue proliferation