Electrophysiological entrapment syndromes in chronic inflammatory demyelinating polyneuropathy.

We do not know if peripheral nerves are more susceptible to entrapment syndromes in chronic inflammatory demyelinating polyneuropathy (CIDP). We studied 31 prospectively recruited patients with CIDP. We determined whether entrapment zones were more frequently affected by demyelination than adjacent segments. The median, ulnar, and fibular nerves were studied at the wrist, elbow, and fibular head bilaterally. Motor conduction velocity and motor conduction block were evaluated at entrapment sites and compared with contiguous segments. Demyelination was significantly more frequent for ulnar and fibular nerves away from entrapment sites. No significant difference was observed for median nerves. CIDP is not associated with increased frequency of demyelination at entrapment sites. The presence of diffuse entrapment neuropathies at compression sites does not favor a diagnosis of CIDP. Although electrophysiological study of entrapment sites is not diagnostically useful in CIDP, it may help distinguish it from other neuropathies and confirm clinically relevant, surgically treatable compressions.