Station 3.22: Hereditary sensory motor neuropathy

Question 1

Clinical signs

What are the clinical signs of Hereditary sensory motor neuropathy?

Hereditary sensory motor neuropathy

This man complains of progressive weakness and a change in the appearance of his legs. Please examine him neurologically.

Answer 1

• Wasting of distal lower limb muscles with preservation of the thigh muscle bulk (inverted champagne bottle appearance)
• Pes cavus (seen also in Friedreich’s ataxia)
• Weakness of ankle dorsi‐flexion and toe extension
• Variable degree of stocking distribution sensory loss (usually mild)
• Gait is high stepping (due to foot drop) and stamping (absent proprioception)
• Wasting of hand muscles
• Palpable lateral popliteal nerve

Question 2

Discussion

Discussion - Hereditary sensory motor neuropathy?

Hereditary sensory motor neuropathy

This man complains of progressive weakness and a change in the appearance of his legs. Please examine him neurologically.

Answer 2

• The commonest HSMN types are I (demyelinating) and II (axonal).
• Autosomal dominant inheritance (test for PMP22 mutations in HSMN I).
• HSMN is also known as Charcot–Marie–Tooth disease and peroneal muscular atrophy.

Question 3

Discussion - Other causes of peripheral neuropathy

What are Other causes of peripheral neuropathy in Hereditary sensory motor neuropathy?

Hereditary sensory motor neuropathy

This man complains of progressive weakness and a change in the appearance of his legs. Please examine him neurologically.

Answer 3

Predominantly sensory
* Diabetes mellitus
* Alcohol
* Drugs, e.g. isoniazid and vincristine
* Vitamin deficiency, e.g. B12 and B1

Predominantly motor
* Guillain–Barré and botulism present acutely
* Lead toxicity
* Porphyria
* HSMN

Mononeuritis multiplex
* Diabetes mellitus
* Connective tissue disease, e.g. SLE and rheumatoid arthritis
* Vasculitis, e.g. polyarteritis nodosa and Churg–Strauss
* Infection, e.g. HIV
* Malignancy