Hypersensitivity in Tourette Syndrome
Condition: Tourette's Syndrome
MeSH terms: Tourette Syndrome; Hypersensitivity; Syndrome
Study type: Observational

Summary: 
      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.
    

Detailed description: 
      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.
    

Keywords: Sensory Processing; Electromyogram; Tic Disorder; Tourette Syndrome; Tourette's Syndrome; Healthy Volunteer; HV