Isaacs's syndrome following paralytic poliomyelitis
Palomeque G, Ibáñez R, Flores JM, Vaamonde J.
Introduction: Myokymia and neuromyotonia are related clinical phenomena that result from hyperexcitability of peripheral nerve motor axons. Both may occur in a generalized or focal fashion.
Methods: A 49 year old woman developed an acute illness at nine years old and she developed severe weakness and wasting of the limbs. Poliomyelitis was the diagnosis. After several months she began to recover and she was able to use her hands. By the age of 49 she was noticing progressive difficulty due to tremor and increase of weakness of both hands. On examination there was wasting and atrophy of the muscles of the upper and lower limbs and the tendon reflexes were absent.
Results: Electromiographic studies demonstrated markedly impaired recruiment in the affected muscles and continuous motor unit activity comprising many spontaneous bursts of doublets, triplets and multiplets. The average frequency within bursts was 50 Hz with frequencies as rapid as 80-180 Hz. Investigations revealed normal blood count and erythrocyte sedimentation rate and normal biochemistry. Magnetic resonance imaging scan of the brain and spine was normal. Patient improved with gabapentine.
Conclusions: The electromiographic features of the patient were similar of the Isaacs ´s syndrome. Poliomyelitis may be related to the developpement of spontaneous repetitive discharges arising from the hyperexcitable axon membrane that reflect the underlying pathophysiology of continuous motor activity.