Hypersensitivity in Tourette Syndrome: An Evaluation of Perceived Intensity Versus Threshold

This study will investigate how the sensitivity to touch and smell in patients with Tourette syndrome (TS) may differ from that of people without TS. TS is a neurological disorder that causes people to have uncontrolled movements called "tics." A tic can also be vocal, like a cough or bark or string of bad words. The tic is preceded by a "premonitory urge" that may feel like an itch or pressure that builds until the tic occurs. To some patients, the tic feels like a response to an involuntary sensation. In patients with TS, sensory information may be processed differently than it is in people without TS. This study will compare how strong a sensation feels in TS patients and healthy volunteers. It will also look for muscle activity that may be responsible for the feelings in the area of the tic.

Healthy normal volunteers and people with Tourette syndrome, 18 to 65 years of age, may be eligible for this study. Candidates are screened with a medical history and brief physical and neurological examinations. TS patients complete a questionnaire about their tics and are interviewed by a psychiatrist. Women who can become pregnant will have a urine pregnancy test prior to any other procedures. Pregnant women cannot participate.

All participants undergo sensory testing for touch and smell. They are asked to distinguish between a scented and scentless object and rate how strongly they feel the scent. Later, with their eyes closed, they are asked to tell whether or not they are being touched, and to rate how intensely they felt the touch.

In addition to the sensory testing, TS patients, but not normal volunteers, undergo electromyography (EMG), a test that measures the electrical activity of muscles. For surface EMG, small metal disks called electrodes are filled with a conductive gel and taped to the skin. Wire EMG involves inserting a wire into a muscle using a needle. All patients have surface EMG and those who consent to it will also have wire EMG.