[Electrophysiological characteristics of inflammatory demyelinating chronic polyneuropathy]

The electrophysiological studies, specially nerve conduction studies (NCS) constitute one of the basic supports to obtain an early and accurate diagnosis to perform a successful treatment in the chronic inflammatory demyelinating polyneuropathy (CIDP). There is nevertheless, no definite consensus about which would be the most specific and sensitive electric variables in the illness.

To describe the NCS findings in a group of patients with this diagnosis, in order to contribute to its electrophysiological characterization.

We an analyzed the NCS on 37 patients diagnosed with CIDP. The NCS were done using standard techniques. These studies were assessed according to the reference values of a normative study on 90 healthy persons. We performed somatosensory evoked potentials (SSEP), visual (VEP) and brainstem auditory evoked potentials (BAEP) in 8 patients, and motor potentials (MP) by transcranial magnetic stimulation in 3.

The registered values are presented in media comparison tables (cases/controls). The frequency of abnormalities in latencies (L), amplitudes, conduction velocity (CV) and the presence of partial blocks is analyzed. The affectation of the evoked potentials in some patients, demonstrated subclinical concomitant demyelinization of the central nervous system.

The most sensitive electrophysiological parameters are the motor CV, the total duration and distal latencies, that gives these variables a confident value in the initial stages of the illness. The relative normality of conduction through the sural nerve, even in the presence of severe abnormalities of the median nerve constitutes a repetitive and specific pattern to this kind of illness.