Electrophysiological studies in Tourette's syndrome.

The value of standard electrophysiological studies using electroencephalography and evoked responses was evaluated in patients with Tourette's syndrome. Sixteen-channel electroencephalograms were obtained in 40 patients (36 males, 4 females) awake and asleep, and evoked responses were obtained in a subgroup of 17 patients. Evoked response variables evaluated included latencies and amplitudes of visual evoked responses, brainstem auditory evoked responses, and somatosensory evoked responses to median and peroneal nerve stimulation. Only 5 of the 40 patients (12.5%) demonstrated electroencephalographic abnormalities, which included central spikes, generalized and paroxysmal slow activity, and slowing of the normal basic frequency. Evoked response studies demonstrated no consistent differences between the patients with Tourette's syndrome and age- and sex-matched controls. The data demonstrate no notable diagnostic or therapeutic value for routine electroencephalographic or evoked response studies in Tourette's syndrome.