Neuromuscular disorders

Question 1

What patterns are recognised in MND? 4

Answer 1

• ALS (50% of patients) - amyotrophic lateral sclerosis
• Primary lateral sclerosis (UMN only) - progressive spastic paraparesis
• Progressive muscular atrophy (LMN only, distal before proximal, best prognosis),
• Progressive bulbar palsy (palsy of tongue, chewing/swallowing and facial muscles due to loss of function of brainstem nuclei - worst prognosis)

Question 2

Signs on Examination in MND

Answer 2

• May have mixed UMN and LMN signs - e.g. wasting, weakness, extensor plantar, brisk reflexes
• Fasciculations are useful - “rules out” compressive lesion in spinal cord
• NO sensory symptoms
• NO bladder disturbance
• May involve respiratory muscles –> failure

Question 3

What is Myaesthenia Gravis?

How test for it?

Symptoms suggestive of Myaesthenia Gravis?

Associations?

Answer 3

• Autoimmune disease with antibodies directed against components of NMJ - mainly ACh receptor, but also NMJ protein MUSK (minority)
• Edrophonium test - should improve symptoms because inhibits ACH-esterase

1. Symmetrical Prox muscle weakness - fatigues on exertion
2. Eye signs - diplopia, ptosis due to extraocular muscle weakness
3. Bulbar - dysphagia, dysarthria and apsiration risk
4. Symptoms worse towards end of day
5. Crises that may lead to emergency ventilation

Association with thymic hyperplasia, or thymoma - worse prognosis

Question 4

HOw do you treat MG?

Answer 4

• • immunomodulation - steroids, AZT, plasma exchange
• Thymectomy
• Drugs to prolong ACh action e.g.neostigmine = ACH-esterase inhibitor

Question 5

Define myotonic dystrophy

How is it inherited?

Common signs and symptoms/ associations?

Answer 5

• Multisystem disorder of distal muscle weakness and wasting
• AD Triplet repeat disorder, shows genetic anticipation
• Male pattern baldness, cataract, DM, cardiac conduction defects, absent or depressed reflexes; difficulty relaxing grip

Question 6

what are features of acute polio infection?

What is PPS?

Answer 6

• Viral infection with 7 day incubation,
• 48h flu prodrome then a pre-paralytic stage of increased temp, HR, H, V, stiff neck and tremor;
• Asymmetrical motor weakness with bulbar and respiratory compromise
• In 50% progresses to paralytic stage - myalgia, fatigue, LMN signs - flaccid paralysis ± respiratory failure
• Post-polio syndrome - delayed progression following initial infection - may be 15-30 years later
  
  • progressive, so potential for significant loss in function