Nerve conduction and electromyography.

The advent of computer-based methodology in routine electromyography has much improved the analysis of motor unit (MU) decomposition, of interference pattern study, and of MU counting. Measuring minimum motor and sensory conduction velocities is becoming more accessible and is considered an essential procedure in assessing the condition of peripheral nerves. A series of studies has shown that nerve resistance and vulnerability can be modified by a steep temperature gradient, by ciguatera toxin, or by hyperventilation-induced changes in the electrical properties of the axonal membrane. The controversy as to the diagnostic procedures to use in cases of radiculopathy and carpal tunnel syndrome (CTS) shows no sign of abating. There is, however, general consensus that electrophysiologic procedures must play a key diagnostic role in these conditions. Lastly, several interesting articles have been published describing the use of electrophysiologic tests in motor neurone diseases. Moreover, some advances have been made in the diagnostic yield of single-fibre electromyography (SFEMG) with axonal microstimulation in myasthenia gravis and Eaton-Lambert myasthenic syndrome.