Neuromuscular
QUESTIONS
1. A 42-year-old male presents to his neurologist complaining of right arm weakness that has progressed over the past 2 years. He states he occasionally feels some tingling in that same arm. The examination shows atrophy and fasciculations of his arm and weakness. His reflexes are normal, and his sensory examination is normal. What would be the findings on his electrodiagnostic studies, and what would be the treatment of choice?
A. Decrease amplitude of the sensory nerve action potential amplitudes (SNAPs); intravenous immunoglobulin (IVIG)
B. Conduction block; methylprednisolone
C. Fifty percent reduction in compound muscle action potential (CMAP) amplitude and area; IVIG
D. Normal sensory studies; cyclophosphamide
E. Absent H-reflex; steroids
View Answer
1. Answer: C. Multifocal motor neuropathy (MMN) is a rare disorder and is more common in males with a ratio of 2:1. The presenting features are painless, asymmetrical weakness, atrophy, and fasciculations in the arms usually restricted to one or two nerves. Findings on sensory examination are normal, and reflexes are out of proportion to the weakness of the involved muscles. The electrodiagnostic findings are usually conduction block (typically a 50% reduction in CMAP amplitude and area), segmental demyelination, and normal sensory studies.
2. What antibody is found in myasthenia gravis patients with negative AchR antibodies?
A. Anti-GAD antibody
B. MuSK antibody
C. Anti-Hu antibody
D. Anti-GQ1b antibody
View Answer
2. Answer: B. Approximately 30% of AchR-seronegative patients with myasthenia gravis have the MuSK antibody. These patients are phenotypically different in that they have severe ophthalmoparesis, bulbar, facial, and posterior neck symptoms. The other antibodies are related to other neurologic disorders, anti-GAD with stiff-man syndrome, Ant-Hu with paraneoplastic disease, and anti-GQ1b with Guillain-Barré syndrome.
3. A 24-year-old male diagnosed with HIV was found to have increased myalgia in the proximal leg regions bilaterally. He has been taking antiretrovirals for 2 years. A muscle biopsy was performed, and ragged red fibers were seen. It was recommended that the patient discontinue one of his antiretrovirals. What else may be suggested to help improve the proximal leg weakness?
A. Visit a physical therapist to improve his strength in the lower extremities.
B. Stopping the antiretroviral medication will make no difference and should be restarted.
C. Adding corticosteroids has been shown to improve the weakness in some patients.
D. Nothing else can be done, and there has been evidence that his disease process will accelerate.
View Answer
3. Answer: C. Patients with HIV taking zidovudine (AZT) have been found to develop an inflammatory myopathy with mitochondrial involvement. There are no good controlled studies to date that have proven AZT directly causes this. Some patients have shown improvement with the addition of corticosteroids. This treatment produces increased risk of opportunistic infections, however, and there has been no evidence that there is acceleration of the HIV disease.
4. All of these neuromuscular disorders are often preceded by gastrointestinal (GI) symptoms EXCEPT:
A. intermittent porphyria
B. botulinism
C. lead poisoning
D. arsenic intoxication
E. rabies
View Answer
4. Answer: E. Rabies involves the medullary respiratory centers that usually produce disproportionate respiratory weakness and usually have no GI prodrome. The rest of the diseases or toxins listed are preceded either by hours to weeks with nausea, vomiting, and abdominal pain.
5. Duplication of the PMP22 gene on chromosome 17p11 results in:
A. hereditary sensory and autonomic neuropathy (HSAN) type V
B. hereditary neuropathy with liability to pressure palsies (HNPP)
C. Charcot-Marie-Tooth disease type 1A (CMT 1A)
D. Charcot-Marie-Tooth disease type 1B (CMT 1B)
View Answer
5. Answer: B. Eighty-five percent of patients with HNPP have shown a deletion of the PMP22 gene on chromosome 17p11. The duplication of the same gene results in CMT type 1A. HSAN type V is Strümpell’s disease, which is CMT plus spastic paraparesis, and CMT type 1B is a mutation in the P0 gene on chromosome 1q22-23.
6. Which of the following toxins causes hair loss, arthralgias, GI symptoms, and an axonal sensorimotor neuropathy (predominately sensory)?
A. Mercury
B. Lead
C. Thallium
D. Ethylene glycol
E. None of the above
View Answer
6. Answer: C. Thallium has been shown to produce all of the symptoms listed. Lead toxicity predominately causes motor weakness; mercury poisoning may cause mood change along with gingivitis, and ethylene glycol causes renal failure, metabolic acidosis, and a severe axonal neuropathy with cranial mononeuropathy.
7. All of these are typical of amyloid neuropathy, EXCEPT:
A. autosomal dominant inheritance
B. occurs frequently below the age of 40
C. motor findings are usually minimal
D. course is slow and steady
E. forty percent of patients have M-protein in their serum protein electrophoresis (SPEP)
View Answer
7. Answer: B. Amyloidosis rarely occurs below the age of 40, has primarily sensory and autonomic findings, 40% of the patients have M-protein on their SPEP, the course is slow and steady and is inherited in an autosomal dominant fashion.
8. The mechanism of action of nitric oxide damage to the spinal cord is:
A. calcium channel blockade
B. direct toxicity to the spinothalamic tracts
C. prolonged opening of sodium channels
D. cobalamin inactivation
E. None of the above
View Answer
8. Answer: D. The mechanism of action is via inactivation of cobalamin, resulting in myeloneuropathy.
9. All of the following are related to CMT type IV, EXCEPT:
A. autosomal dominant inheritance
B. accumulation of phytanic acid
C. retinitis pigmentosa
D. high consanguinity rate
View Answer
9. Answer: A. Patients with CMT type IV, also known as Refsum’s disease, have autosomal recessive inheritance. It is caused by an accumulation of phytanic acid in many systems, results in night blindness, and is associated with a high consanguinity rate.
10. Which of the following are inherited forms of autonomic neuropathy?
A. Amyloidosis
B. Shy-Drager syndrome
C. Chagas’ disease
D. Bassen-Kornzweig syndrome
E. Diabetes
View Answer
![](https://freepngimg.com/download/social_media/63059-media-icons-telegram-twitter-blog-computer-social.png)
10. Answer: B. Of the diseases listed, only Shy-Drager syndrome and Bassen-Kornzweig syndrome (abetalipoproteinemia) are inherited. Shy-Drager syndrome causes an autonomic neuropathy. Abetalipoproteinemia primarily affects large fiber sensory modalities.
![](https://freepngimg.com/download/social_media/63059-media-icons-telegram-twitter-blog-computer-social.png)
Stay updated, free articles. Join our Telegram channel
![](https://clinicalpub.com/wp-content/uploads/2023/09/256.png)
Full access? Get Clinical Tree
![](https://videdental.com/wp-content/uploads/2023/09/appstore.png)
![](https://videdental.com/wp-content/uploads/2023/09/google-play.png)
![](https://clinicalpub.com/wp-content/uploads/2023/09/banner1.png)