Prominent cauda equina involvement in patients with chronic inflammatory demyelinating polyradiculoneuropathy

In chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), it has not been well known which segment of the peripheral nerves, distal or proximal, is more often involved in electrophysiological examination. This study compares nerve conductions at proximal segments with those at distal segments in 11 patients with CIDP. To obtain cauda euqina conduciton time (CECT), compound muscle action potentials (CMAPs) were elicited by magnetic stimulation using a MATS coil from the abductor hallucis muscle. CECT was prolonged in 9 patients (81.8%), whereas the ankle–knee conduction was delayed in 4 (36.4%). The proximal segments are more frequently involved than the distal segments in this disorder.