Brain Stimulation to Treat Blepharospasm or Meige Syndrome

Blepharospasm Clinical Trial

Official title: Blepharospasm and the Experimental Modulation of Cortical Excitability in Primary and Secondary Motor Areas. A Pilot Study.

Status Completed

Clinical Trial Summary

This research study will examine whether magnetic or electrical stimulation of the brain can improve the involuntary closure of the eyelids in patients with blepharospasm or Meige syndrome; conditions that belong to a group of neurological disorders called dystonias. Blepharospasm and Meige syndrome cause excessive involuntary closure of the eyelids or blinking. In an earlier study of patients with writer's cramp, which is another form of dystonia, symptoms improved temporarily with brain stimulation.

Interested people 18 years of age or older with blepharospasm or Meige syndrome may be eligible for this study. Candidates are screened with a medical history, physical examination and a blink reflex test.

Participants undergo brain stimulation and evaluations before and after the stimulation to test the response, as follows:

Procedures

• Transcranial magnetic stimulation (TMS): A wire coil is held on the patient's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. The subject hears a click and may feel a pulling sensation on the skin under the coil. There may be a twitch in the muscles of the face, arm or leg. The subject may be asked to tense certain muscles slightly or perform other simple actions. The effect of TMS on the muscles is detected with small metal disk electrodes taped to the skin of the arms or legs. TMS is done on eight of the ten test days.

• Repetitive TMS (rTMS): The same procedure as TMS, except repeated magnetic pulses are delivered in short bursts. RTMS is done on eight of the ten test days.

• Theta burst stimulation (TBS): A form of rTMS that involves short bursts of impulses. TBS is done on four study days.

• Cathodal transcranial DC stimulation (tDCS): Two conductive-rubber electrodes placed in saline-soaked sponges are positioned over two areas of the head. A constant weak electrical current flow is applied for 20 minutes. tDCS is done on two study days.

Evaluations

• Physician observation: The subject's eyes are videotaped for 5 minutes before and after each TMS session. A physician then counts how many times the subject blinked during the 5 minutes.

• Questionnaire: Subjects are asked to rate their symptoms before and after brain stimulation.

• Electrophysiological test of the blink reflex: Wires are taped to the skin on the nose and temple to record the eye movement during blinking. A thin plastic rod is placed on the skin over the right e...

Clinical Trial Description

BACKGROUND: Blepharospasm (BSP) is a common form of focal dystonia, but the etiology and underlying pathophysiological mechanisms are still obscure. BSP is characterized by excessive involuntary closure of the eyelids. Pathological changes in excitability in the primary motor cortex (MC) and secondary motor areas, such as the anterior cingulate (AC), pre-and supplementary cortex (PMC, SMA) are suggested from electrophysiological and brain imaging studies. It is conceivable that modulation of excitability in some of these areas may lead to amelioration of the symptoms of BSP. Cortical excitability can be experimentally changed by various well-established electrophysiological techniques non-invasively.

METHODS: In this pilot protocol, studying 30 patients with BSP, we will use repetitive transcranial magnetic stimulation (rTMS) over the AC, PMC, SMA and MC in two different inhibitory modes: low frequency rTMS ((lf) rTMS) and continuous theta burst stimulation cTBS. Furthermore, we will apply transcranial direct stimulation (tDCS) in an inhibitory mode (cathodal tDCS) over the MC and low intensity high frequency supraorbital electrical stimulation; the latter will be performed in patients and in 7 healthy subjects. The effects on blepharospasm will be objectively measured by electrophysiological measures (blink reflex recovery curve (BRR), blink rate observation by an investigator blinded to the intervention, and a subjective rating by the patient.

OBJECTIVES: We hypothesize that we will find variable amounts of clinical improvement in BSP patients with these different methods. With this study, we aim to get more insight to the underlying pathophysiological mechanisms of BSP and identify which method of non-invasive brain stimulation may be clinically most efficacious. ;

Related Conditions & MeSH terms

• Blepharospasm
• Dystonia
• Dystonic Disorders
• Focal Dystonia

• NCT number: NCT00411255
• Study type: Interventional
• Source: National Institutes of Health Clinical Center (CC)
• Status: Completed
• Phase: Phase 2
• Start date: June 22, 2006
• Completion date: April 7, 2009