Combined electromyography-functional MRI in patients with tremor for improvement of targeting in stereotactic surgery

On a yearly basis, about 50 patients undergo brain surgery for movement
disorders in the AMC, and about 100 patients in The Netherlands. One of the
problems encountered during this procedure is the identification of the
efficacious target structure. Tremor can have several causes, among which the
most common are Essential Tremor (ET) and Parkinson*s disease (PD). Tremor can
also be secondary to brain lesions occurring after head trauma, ischemia or in
the context of Multiple Sclerosis. When medical treatment is unsatisfactory,
stereotactic surgery (ablative or Deep bran stimulation, DBS) is proposed.
Outcome of surgery on tremor is variable: while some patients have satisfying
and long-lasting benefit, others have only partial or temporary benefit after
surgery. This variability in clinical outcome might be due to differences in
the position of the lesion or stimulating electrode or to inter-individual
differences in the position of the *tremor generator* among patients with
different forms of disease. Thus, there is a need to better define the surgical
target for different kinds of tremor and even to tailor the target area for
each individual patient.

Functional MRI (fMRI) combined with electromyography (EMG) is a new technique
that, compared to usual fMRI protocols, allows correlation of involuntary
movements to brain activity. In this study, we will use EMG-fMRI technique to
study tremor in patients suitable for stereotactic surgery. We hypothesize
that, in patients in whom surgery effectively suppresses tremor, the area
defined by EMG-fMRI overlaps with the surgical area.

We aim to investigate the capability of EMG-fMRI to detect brain areas related
to tremor. In addition, we aim to evaluate the role of this technique to define
the stereotactical target for tremor suppression.

This is a pilot, prospective, cohort study.
Patients will undergo one simultaneous EMG-fMRI recording and neurological
evaluation by means of specific clinical scales

Patients will undergo one site visit, during which standardized clinical
evaluations will be performed with the aid of clinical scales and videos.
During the same visit, patient will undergo an fMRI scan and simultaneous
recording of movements, with the help of surface EMG electrodes. Patient data
is blinded. We will then analyse the correlation of tremor and brain activity,
to define tremor related areas within the thalamus and basal ganglia. Patients
participating in part B will undergo an additional standardized clinical
evaluation during their normally scheduled post-operative follow-up evaluation.
The proposed investigation bears virtually no risks and is usually well
tolerated. EMG-fMRI can potentially improve target-identification for DBS, thus
improving surgical outcome. Ultimately, this study could provide a new tool to
predict the best surgical target for each individual patient and improve the
benefit of stereotactic neurosurgery for tremor.