Introduction: Chronic inflammatory demyelinating polyneuropathy (CIDP) is a mixed (predominantly motor) neuropathy, with an autoimmune aetiology and different forms of clinical presentation including the idiopathic form and one related to concurrent diseases. Neurophysiological studies play a decisive role in its diagnosis.
Aim: To evaluate the differences in the electrophysiological patterns in the two forms of presentation of the disease, based on the variables that were analysed by studying nerve conduction and the F wave.
Patients and methods: The study involved 27 patients with a diagnosis of probable CIDP, according to American Academy of Neurology criteria from 1991. Of all the patients included in the study group, 17 presented primary CIDP and in 10 cases it was related to other diseases, such as diabetes mellitus, adenocarcinoma, multiple sclerosis and human immunodeficiency virus infection. Motor and sensory nerve conduction studies were performed, as well as F wave studies of the nerves in the four limbs. Statistical methods were applied to compare the neurophysiological variables in the two groups of patients.
Results: Significant differences were found to exist between the two groups. The sensory study was more affected in patients with primary CIDP, whereas the motor and F wave study were affected to a greater extent in patients with secondary CIDP; these cases displayed a predominantly axonomyelinic pattern, with greater involvement of the proximal motor segment.
Conclusion: The different variant forms of presentation of CIDP display distinct electrophysiological behaviours.