P55-T Does sensory conduction block work in CIDP?–Based on serial electrophysiological studies

Abstract

Background The presence of sensory nerve conduction block is not routinely assessed in the evaluation of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Whether this can be useful is not well known. Methods We respectively analyze the serial sensory conduction studies of 20 patients with the diagnosis of typical CIDP. Sensory nerve action potential (SNAP) amplitudes and sensory conduction velocities were recorded in the median, ulnar, tibial, peroneal and sural nerves. Follow-up studies were compared with the baseline to evaluate the variation of SNAP amplitudes in serial recordings. Results Four patients were excluded because of clinical aggravation, and the data of sixteen patients were analyzed, including serial sensory conduction studies in 136 nerves. The SNAPs in 82 nerves were absent at baseline, of which the SNAPs in 24 nerves reappeared during follow-up studies, with a mean amplitude of 3.23 ± 3.57 μ V. In the other 54 nerves, 36/54 (66.7%) SNAP amplitudes increased (median increased by 45%) compared to the baseline, and the improvement rates in 15 nerves were greater than 50%. The mean increase in median nerve was the highest (r = 56.64%), followed by tibial nerve (r = 46%), sural nerve (r = 38.75%), ulnar nerve (r = 28.4%), and peroneal nerve (r = 15.75%). Notably, 20/29 (68%) initially normal sensory nerves showed significant increase in SNAP amplitude (median increased by 37.5%), and the improvement rates in 6 nerves were greater than 50%. Conclusions We propose that conduction block may also exist in sensory nerves, segmental sensory conduction and follow-up studies may be of great value in evaluating patients with CIDP.