This study will use transcranial magnetic stimulation to examine how the brain controls
muscle movement in focal and generalized types of dystonia. Dystonia is a movement disorder
in which involuntary muscle contractions cause uncontrolled twisting or abnormal postures.
Dystonia may be focal, involving just one region of the body, such as the hand, neck or
face. Focal dystonia usually begins in adulthood. Generalized dystonia, on the other hand,
generally begins in childhood or adolescence. Symptoms begin in one area and then become
Healthy normal volunteers and patients with focal or generalized dystonia 8 years of age and
older may be eligible for this study. First-degree relatives of patients will also be
In transcranial magnetic stimulation, an insulated wire coil is placed on the subject's
scalp and brief electrical currents are passed through the coil, creating magnetic pulses
that pass into the brain. These pulses generate very small electrical currents in the
cortex-the outer part of the brain-briefly disrupting the function of the brain cells in the
stimulated area. The stimulation may cause muscle twitching or tingling in the scalp, face
and limbs. During the stimulation, the subject will be asked to either keep the hand
relaxed or to slightly tense certain muscles in the hand or arm. The test will last about
The cause of dystonia is unknown. It is hoped that a comparison of brain activity in normal
volunteers, patients and their relatives not affected by dystonia will help scientists learn
why some people develop dystonic movements.
The objective of this study is to evaluate intracortical inhibition (ICI) in focal dystonia
and in generalized dystonia of known genetic origin (DYT1 dystonia) in order to determine
whether abnormalities of ICI can represent a marker of genetic predisposition for the
development of dystonia. It is unclear why some carriers of the DYT1 dystonia do not
develop dystonic symptoms. One possible explanation is that the development of dystonia is
a two-stage process: first, loss of ICI (which may be genetically determined) and, second,
exposure to an environmental trigger such as excessive repetitive movements. Thus we
hypothesize that impaired ICI may serve as a marker for the DYT1 carrier state. There is
good evidence that focal dystonia is a genetically determined disorder, but the gene
responsible remains undetermined. We hypothesize that, in up to 50% of first degree
relatives of patients with focal dystonia, impaired ICI may be found which would serve as a
gene marker for the abnormality. In those individuals with this genetic marker of impaired
ICI, further linkage analysis studies could be performed to identify the causative gene. In
this study, we propose to measure ICI using transcranial magnetic stimulation in patients
with both focal and generalized forms of dystonia, their first degree relatives and an age
matched control group.
INCLUSION CRITERIA - Healthy Volunteers:
Healthy Volunteers entered into the study must be free of serious somatic disease as
determined by a standard physical and neurological examination.
INCLUSION CRITERIA - Patients:
For patients, the only selection criteria are the presence of primary dystonia, either
focal or generalized (DYT1).
Children aged 8 years or older will be included. Gender, ethnic origin and race will not
be biased for inclusion.
The exclusion criteria for this study include subjects who have a pacemaker, an implanted
medication pump, a metal plate in the skull, metal objects inside the eye or skull (for
example, after brain surgery or a shrapnel wound) or any recent (less than 3 months) brain