Hypersensitivity in Tourette Syndrome

Overview

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.

OBJECTIVE: This study will explore sensory phenomena associated with Tourette syndrome (TS). The first part will evaluate threshold levels versus perceived intensity of tactile and olfactory stimuli in areas reported to be hypersensitive in TS patients. The second part will use electromyography (EMG) to seek correlation between muscle activity and the perceived intensity of "urge" in focal areas of premonitory sensations. STUDY POPULATION: Twenty-six patients and 22 control subjects will be studied. Subjects can be of any race, gender, handedness, or age from 18 to 65 years. DESIGN: To determine olfactory and tactile threshold, n-butanol and Von Frey hairs will be presented in forced-choice modified method of limits paradigms. Perceived intensity will be examined using a generalized labeled magnitude scale (gLMS), whose word values are placed on a ruler for numerical reporting. Randomly arranged series of 7 stimuli for olfaction and touch will be presented in 4 sets, and subjects will report a number on the gLMS that corresponds to the intensity of each sensation. Both threshold and intensity will be measured in the peroneal nerve territory in all subjects, and at one other variable place, which will be matched 1:1 between patients and controls. The variable spot will consist of a patient's sensory tic site. Next, EMG activity will be measured from up to 8 muscles in the area of a sensory tic. Patients will report when a sensory tic is occurring, and will be asked to resist the motor tic for at least 12 seconds from that point. Total EMG activity will be measured in muscles surrounding the sensation at 1, 4, and 7 seconds before and after the tic. OUTCOME MEASURES: Outcome measures include the sensory threshold values for olfaction and touch and the reported intensity values. The outcome measures of the EMG study include the power of total EMG activity at time points before and after a tic.