Schwartz-Jampel syndrome: evidence of central nervous system dysfunction.
We report four patients with Schwartz-Jampel syndrome showing evidence of central conduction impairment documented by somatosensory evoked potentials. Median nerve somatosensory evoked potential showed normal latencies to Erb's point and N13 in all patients. Interpeak latencies between N13 and N19 were prolonged in five nerves, with complete block in three nerves. Posterior tibial nerve somatosensory evoked potentials were performed in three patients. Peripheral latencies were normal in all patients. Interpeak latencies between lumbar and cervical potentials were prolonged in two patients, with conduction delay between cervical and cortical potentials in five of the six nerves tested. Visually evoked potentials, brainstem auditory evoked potentials, electromyography, and nerve conduction velocity studies were normal in all patients. Parents' median nerve and posterior tibial nerve somatosensory evoked potentials were normal.