Motor-related Cortical Potential in Patients With Essential Tremor
Motor-related Cortical Potential in Patients With Essential Tremor
In this proposal, in addition to the conventional MRCP recording, the dipoles and sources of
 the different subcomponents of MRCP will also be analyzed with the brain electric source
 analysis (BESA) to evaluate the difference in the solutions and source strength underlying
 the MRCP between normal controls and patients with ET.
Essential tremor (ET) is a common disorder with unknown etiology and pathogenesis. Typically
 described as a postural tremor, ET often has a marked kinetic component suggesting cerebellar
 involvement in the pathogenesis of the tremor. The assumption has been illustrated by both
 positron emission tomography and functional magnetic resonance imaging studies, which
 revealed that blood flow and activity of the cerebellum were increased in ET patients as
 compared to the normal controls. In contrast to the cumulative body of imaging evidence, the
 physiological bases to link the ET and cerebellar functional alternation are scarce. Studies
 with tandem gait analysis have revealed 25% abnormality of ET patients and surface
 electromyographic study has found a delay in the second agonist burst during rapid wrist
 movements suggesting the possible role of cerebellar functional alternation in the generation
 of ET. In addition, since the tremor of ET tends to appear in the movement ignition or during
 postural maintenance, it is conceivable that this sort of tremor might exert certain impact
 on the programming and preparation of the limb movement. Thus it would be appropriate to
 adopt a tool, which can concomitantly assess the cerebellar function and movement
 preparation, to investigate the patients with ET. In this proposal, we will record
 movement-related cortical potentials (MRCP) in ET patients. MRCP is a slow negative shift
 starting 1-1.5 sec before volitional movement. It consists of at least 3 subcomponents, the
 Bereitschaftspotential, the negative slope, and the motor potential. The generators crucial
 for the generation of MRCP include cerebellum, motor and motor association cortex. Thus MRCP
 seems to be an appropriate tool to assess the patients with ET, in whom the trivial
 cerebellar functional alternation could be responsible for the tremor generation and motor
 preparation might be hampered concomitantly. In this proposal, in addition to the
 conventional MRCP recording, the dipoles and sources of the different subcomponents of MRCP
 will also be analyzed with the brain electric source analysis (BESA) to evaluate the
 difference in the solutions and source strength underlying the MRCP between normal controls
 and patients with ET.
Inclusion Criteria:

 -  Bilateral postural tremor with or without kinetic tremor involving hands or forearms,
 which is visible and persistent, and long-standing in duration (>5 years). Tremor
 involving body parts other than upper limbs may be present, the tremor may be
 asymmetrical, amplitude may fluctuate, and the tremor may or may not produce
 disability.

 Exclusion Criteria:

 -  Neurological signs, except for Froment's sign

 -  Causes of enhanced physiologic tremor

 -  Concurrent or recent exposure to tremorgenic drugs

 -  Direct or indirect trauma to the central and peripheral nervous system

 -  Historical or clinical evidence of psychogenic origins of tremor

 -  Convincing evidence of sudden onset or evidence of stepwise deterioration