To investigate the frequency of CIDP in south-eastern Santiago and to describe the clinical and electrophysiological characteristics of typical CIDP and subtypes in this population.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated neuropathy usually with insidious onset and with progressive symmetric or asymmetric polyneuropathy. CIDP has heterogeneous clinical features, classified as ‘typical’ CIDP or ‘atypical’ subtypes including multifocal acquired demyelinating sensory and motor neuropathy (MADSAM).

The estimated prevalence and incidence of CIDP were 2.3/100.000 and 0.8/100.00 respectively. Fourteen patients (8 men, 6 women) were classified as definitive or possible CIDP, nine of whom had typical CIDP. The age of onset ranged from 16 to 68 years. Three patients also had diabetes mellitus. The average median and peroneal motor nerve conduction velocities were 33.9 m/s and 33.8 m/s respectively. The average number of conduction blocks per patient was 3.7. All patients had conduction blocks in an upper limb. Distal sensory action potentials were reduced or absent in nine patients. All patients were treated with prednisone, six patients with intravenous immunoglobulin. Four patients became worse after prednisone therapy.

The prevalence and incidence rates were similar to those reported in the Caucasian and Japanese populations and the clinical and physiological features seem to be similar across different races and geographic areas.