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Distal hereditary upper limb muscular atrophy
D W Gross1, A H Rajput, M Yeung
1University of Saskatchewan, Saskatoon, Canada.
Journal of Neurology, Neurosurgery, and Psychiatry
|March 7, 1998
Summary
This study identifies a distinct hereditary motor neuron disease characterized by distal upper limb weakness and atrophy. Autosomal dominant inheritance and specific electrophysiological findings define this unique clinical entity.
Area of Science:
- Neurology
- Genetics
- Clinical Electrophysiology
Background:
- Hereditary motor neuron diseases (HMND) encompass a group of progressive neurodegenerative disorders.
- Unusual presentations of HMND necessitate detailed clinical, electrophysiological, and genetic characterization.
Observation:
- A family presented with autosomal dominant inheritance of a motor neuron disease.
- Affected individuals exhibited distal upper limb weakness and atrophy, with minimal lower limb involvement and brisk reflexes.
Findings:
- Electrophysiological studies revealed normal motor conduction velocity but reduced motor amplitudes and prolonged distal latencies.
- Sensory nerve conduction showed prolonged distal latencies with normal amplitudes.
- Needle EMG demonstrated reduced motor unit potentials and increased motor unit potential size, without signs of active denervation.
Implications:
- The findings suggest distal upper limb muscular atrophy is a distinct clinical entity within the spectrum of motor neuron diseases.
- This research aids in the differential diagnosis of inherited neuropathies and motor neuron disorders.
- Further genetic investigation is warranted to identify the specific gene responsible for this unique phenotype.