[Test of sensory nerve in patients with Kennedy disease]

To study the electrophysiological and pathological features of Kennedy disease (KD) and to make sure the functional and anatomical change of the sensory nerve of KD patients.

Electrophysiological and pathological tests were performed in 14 KD patients, including electromyogram, conduction velocities of median, ulnar, peroneal, tibial, and sural nerves, trigemino-cervical reflex (TCR), contact heat evoked potential (CHEP), and biopsy of the sural nerves. During TCR, the patients lay on the back, holding the heads slightly raised to make the sternocleidomastoid muscles contract slightly. Electrical stimuli were applied to the infraorbital nerves and recording electrodes were placed in the sternocleidomastoid muscles. For CHEP, contact heat was delivered via a circular thermode to excite selectively nociceptors with a rapid rising time at 70 degrees C/s to elicit pain and CHEP. Thermal stimuli were sent at 54.5 degrees C to three body sites: skin of back of hand, proximal volar forearm, and C7. The CHEPs were recorded from Cz and Pz.

The sensory conduction velocity and latency were almost normal, while the amplitude of the sensory nerve action potential (SNAP) declined to 0.65 - 2.85 microV. The latency of trigemino-cervical reflex was longer than normal with the onset peak latency of (38.9 +/- 7.0) ms. The configuration was asymmetric. The onset peak latencies when the skin of the back of hand, volar surface of forearm, and C7 were stimulated were (613 +/- 57), (595 +/- 32), and (489 +/- 37) ms respectively. Biopsy of the sural nerves showed that the large myelinated nerve fiber was decreased.

Sensory nerve is involved in the patients with Kennedy disease, including the large and small fibers.