Neuromuscular Disorders

Question 1

Most common category of polyneuropathy

Answer 1

Distal symmetric sensory

Question 2

A nerve conduction study can differentiate radiculopathy from a plexopathy. How?

Answer 2

Sensory nerve action potentials are preserved in radiculopathy.

Question 3

The most common cervical radiculopathy affects which nerve root

Answer 3

C7

Question 4

Indications for surgical decompression in radiculopathy

Answer 4

1. Moderate to severe weakness
2. Worsening weakness / sensory loss
3. Severe pain unresponsive to conservative measures

Question 5

PE finding that raises suspicion for a brachial plexus lower trunk lesion

Answer 5

Atrophy of thenar eminence with sensory loss in medial hand / fingers

Question 6

PERIPHERAL NERVE INJURIES
Localize the lesion.

1. Scapular winging
2. Weakness in external rotation of the shoulder
3. Sensory disturbance in the lateral upper arm

Answer 6

1. Long thoracic n
2. Axillary n
3. Axillary n

Question 7

Match radial nerve lesion with presentation

1. Sensory loss in posterior hand; elbow extension spared
2. Wrist drop, finger drop, no sensory loss
3. Weakness of all radial muscles, sensory loss in posterior arm/forearm/hand

A. Radial nerve at the axilla
B. Spiral groove of humerus
C. Posterior interosseous nerve entrapment

Answer 7

1. B
2. C
3. A

Question 8

Ulnar nerve lesion signs

1. At rest, the fifth digit is slightly abducted due to weakness of third palmar intraosseous
2. Curled thumb when trying to pinch (thumb adduction and index abduction weakness leads to weak pinch; to compensate, median-innervated FPL causes thumb flexion)

Answer 8

1. Wartenberg’s sign

2. Froment’s sign

Question 9

The only muscle below the knee with a contribution from the L4 root

Answer 9

Tibialis anterior

Question 10

Most common lumbosacral radiculopathy affects which root

Answer 10

L5

Question 11

Which nerve root is involved?

1. Sensory deficit over posterolateral calf and foot (plantar aspect)
2. Perineal and anal sphincter region
3. Numbness over lateral leg and dorsomedial foot

Answer 11

1. S1
2. S2/S3/S4
3. L5

Question 12

Fat boy gained weight a bit too quickly and now started feeling numbness of the lateral thigh. Symptoms may be due to entrapment of which nerve.

Answer 12

Lateral femoral cutaneous nerve

Question 13

Most common neurological cause of acute generalized weakness

Answer 13

Guillain-Barre Syndrome

Question 14

In Guillan Barre syndrome, antibodies against these 4 organisms are seen.

Answer 14

1. Campylobacter jejuni
2. CMV
3. EBV
4. Mycoplasma

Question 15

Ophthalmoplegia +
Gait ataxia +
Areflexia +
Mild limb weakness

Answer 15

Miller-Fisher variant of acute inflammatory demyelinating polyneuropathy

Associated with C. jejuni
IgG against GQ1b gangliosides

Question 16

Classic sign of vasculitic neuropathies

Answer 16

Multiple mononeuropathies 
(mononeuritis multiplex)

Question 17

Which of the following large vessel vasculitides can present with neuropathy:

Giant cell or Takayasu’s arteritis

Answer 17

Giant cell / temporal arteritis

Question 18

What is the most common necrotizing vasculitis?

Answer 18

Polyarteritis nodosa

Question 19

Acute onset of severe neuropathic pain in shoulder, sometimes arm and hand; lasting days to weeks replaced by weakness with little sensory disturbance

Answer 19

Brachial neuritis
aka neuralgic amyotrophy
aka Parsonage-Turner Syndrome

Question 20

Progressive and widespread muscle stiffness.
Muscle twitching and cramps; persisting during sleep.
Associated hyperhidrosis, encephalopathy and insomnia.

Diagnosis?
What is the pathophysiology?

Answer 20

Isaac’s Syndrome

Antibodies against voltage-gated potassium channel; may be spontaneous or paraneoplastic

Question 21

Most common cause of neuropathy in the world

Answer 21

Leprosy

Question 22

Most commonly affected nerve roots in shingles

Answer 22

THORACIC > lumbosacral and cranial

Question 23

Most common form of DM neuropathy

Answer 23

Distal symmetric sensory

Question 24

Mees lines in the fingernails and toenails.
Acute abdominal pain, nausea, vomiting, diarrhea then distal paresthesias.
Axonal sensorimotor neuropathy.
Pancytopenia and basophilic stippling of RBCs.

Diagnosis?

Answer 24

Arsenic poisoning

Question 25

Slow onset of upper -> lower limb weakness; classic is wrist and finger drop.
Motor axonal neuropathy; usually no sensory complaints.
Basophilic stippling of RBCs, microcytosis, and hypochromia.

Diagnosis?

Answer 25

Lead toxicity

Question 26

Macrocytic anemia.
Decreased vibratory and position sense.
Weakness, hyperreflexia, Babinski sign.

Diagnosis?

Answer 26

B12 deficiency

Question 27

Sensory ataxia, gait instability, Romberg sign, pseudoathetosis, sensory drift.
Non-length dependent sensory loss and hyporeflexia

Deficiency in which Vitamin?

Answer 27

Vitamin E

Question 28

This drug is given to patients with amyotrophic lateral sclerosis to increase tracheostomy-free survival but without any effect on overall life expectancy

Answer 28

Riluzole

Question 29

Distal -> proximal weakness. Temporal atrophy and jaw weakness. Delayed muscular relaxation after forceful contraction; improving with repetition.

Associated with mildly reduced intelligence, depression, cataracts, conduction abnormalities or cardiomyopathy, and diabetes.

Diagnosis?

Answer 29

Myotonic dystrophy type 1

Question 30

Chanellopathies. Which channels are affected?

1. Malignant hyperthermia
2. Hypokalemic periodic paralysis
3. Hyperkalemic periodic paralysis

Answer 30

1. Ryanodine receptor
2. Ca channel
3. Na chanel

Question 31

Triad of periodic paralysis, cardiac arrhythmias and skeletal abnormalities. What is the channel involved?

Answer 31

Andersen-Tawil Syndrome

Mutations in KCNJ2 (inwardly rectifying K channel)