Neurophysiologic Study of Patient With Essential Tremor and Dystonic Tremor
Condition: Essential Tremor; Cervical Dystonia; Focal Dystonia
MeSH terms: Tremor; Dystonia; Dystonic Disorders; Essential Tremor; Torticollis
Study type: Observational

Summary: 
      Background:

      Essential tremor is when a person has tremor, but no other neurological symptoms. Dystonic
      tremor is when a person also has dystonia. Dystonia is a condition in which muscle
      contraction causes changes in posture. Researchers do not fully know what areas of the brain
      cause these tremors, or how the types differ. They also do not know what tests can identify
      the differences.

      Objective:

      To look at differences between essential tremor and dystonic tremor.

      Eligibility:

      People ages 18 and older with or without tremor

      Design:

      Participants will be screened with medical history, physical exam, and urine tests. Those
      with tremor will complete questionnaires about how tremor affects them.

      The screening and study visits can be done on the same day or on separate days.

      Participants will have 1 or 2 study visits. These include magnetic resonance imaging (MRI)
      and tremor testing.

      For MRI, participants will lie on a table that slides in and out of a cylinder that takes
      pictures. Sensors on the skin measure breathing, heart rate, and muscle activity. This takes
      about 2 hours.

      Tremor testing will include transcranial magnetic stimulation (TMS), electrical stimulation
      of the fingers, doing a movement task, and recording of tremor movements. For TMS, two wire
      coils will be held on the scalp and a brief magnetic field will be produced. A brief
      electrical current will pass through the coils. For the other tests, small sticky pad
      electrodes will be put on the skin. Participants will move their hand when they hear a sound.
      They will get weak electrical shocks to their fingers. These tests will take 3-4 hours.

      Participants can take part in either or both parts of the study.
    

Detailed description: 
      Objectives:

      To explore a neurophysiological difference between patients with essential tremor (ET) and
      dystonic tremor (DT).

      Sample Size and Population:

      We plan to recruit 26 healthy volunteers (HVs), 26 patients with ET, 26 patients with
      dystonic tremor from the Movement Disorders and Botulinum Toxin (BoNT) clinics of HMCS. The
      dystonic tremor group will be divided into 2 subgroups: pure dystonic tremor (pDT), patients
      who have dystonia and tremor in the same limb, tremor associated with dystonia (TAWD),
      patients who have isolated tremor with dystonia elsewhere. We plan to enroll 13 patients with
      pDT and 13 with TAWD. We plan to recruit a total of 20 participants including patients with
      ET, DT and HVs if the use of data from protocol 10-N-0009 is permitted. All neurophysiologic
      results will be compared between patients and HVs.

      Design:

      Subjects will come to NIH for at least one study visit. All subjects will undergo a screening
      visit including taking a medical history and physical examination. Then the patients will be
      scored clinically for tremor in both ET and DT and dystonia only for DT. All subjects will
      have a series of transcranial magnetic stimulation (TMS) studies. TMS-induced
      electromyographic (EMG) activity of hand and forearm muscles will be recorded as motor evoked
      potentials (MEPs). Pyramidal threshold will be determined by inion stimulation. Then,
      paired-pulse stimulation at the cerebellum followed by the motor cortex will be performed at
      rest and at tonic activation of the hand muscle. Only patients will have recordings of tremor
      at rest, postural holding, and with action and specific tasks such as writing by using
      accelerometry and EMG. Additionally, a single TMS will be delivered to the motor cortex or
      cerebellum while the patients elicit their tremor in order to explore the effect of TMS on
      tremor. All subjects (both HVs and ET, DT) will be tested for their threshold to discriminate
      somatosensory stimulation and for their performance of quick ballistic movements. All
      subjects will also undergo a magnetic resonance imaging (MRI) study which includes structural
      MRI, resting state functional MRI (rsfMRI), diffusion tensor imaging (DTI), MR spectroscopy.
      The subjects can either undergo the MRI study on the same visit as the other parts of
      experiment or do it separately.

      Outcome measurements:

      The various neurophysiological results include the data from the TMS experiment, tremor
      analysis, threshold of temporal discrimination, ballistic movement and MRI experiment. These
      results will be compared between HVs and patients group.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients will be referred to NIH or may refer themselves from all over the United States.
      
Keywords: Essential Tremor; Cervical Dystonia; Hand Dystonia; Neurophysiology; Dystonic Tremor