[Multifocal motor neuropathy with partial block of nerve conduction]

Multifocal motor neuropathy with partial conduction block is characterized by being a chronic, demyelinating, autoimmune severely disabling neuropathy. In Cuba three cases were reported by Dr. Estrada et al in 1999. This neuropathy presents clinically in relatively young persons. The arms are predominantly affected and the typical signs are of severe asymmetrical weakness, with atrophy which is less marked than the weakness, fasciculations, cramps and myokymiae of the affected muscle. Neurophysiological study shows partial block of motor nerve conduction. Clinical interest is due to it being potentially curable. Many cases are wrongly diagnosed as motor neurone disease.

We present five patients aged under 55 years with progressive chronic motor neuropathy mainly affecting their arms. Study of nerve conduction showed partial block of the conduction in motor nerves, in segments with no block of sensory neuroconduction. One patient had been diagnosed as having motor neurone disease; another had slight sensory involvement in the distal territory of the radial nerve; in two patients the symptoms affected all four limbs. In three patients good results were obtained with intacglobin, followed by azothroprine and prednisone. Two patients showed no improvement with this treatment so intravenous cyclophosphamide was given for nine months which stopped progression of the disorder.

Multifocal motor neuropathy is potentially treatable. In some cases intacglobin azathioprine and prednisone may be a useful alternative to cyclophosphamide.