Gamma knife thalamotomy for disabling tremor: a blinded evaluation.

Area of Science:

• Neurosurgery
• Neurology
• Medical Devices

Background:

• Gamma knife thalamotomy (GKT) is a treatment option for medication-refractory disabling tremor.
• Previous reports show impressive tremor improvement, but data reliability is questioned.

Purpose of the Study:

• To prospectively evaluate clinical outcomes after GKT for disabling tremor using blinded assessments.
• To assess the efficacy and safety of GKT in patients with essential tremor and Parkinson disease tremor.

Main Methods:

• Prospective study with blinded, independent neurologic evaluations at a university hospital.
• Unilateral GKT performed on patients unsuitable for deep brain stimulation.
• Outcomes measured by Fahn-Tolosa-Marin Tremor Rating Scale and activities of daily living scores over up to 30 months.

Main Results:

• Significant improvement in Fahn-Tolosa-Marin Tremor Rating Scale activities of daily living scores (P=.03).
• No significant improvement in other tremor ratings (resting, postural, action, head) or specific tasks (drawing, pouring).
• Three patients experienced delayed neurologic adverse events; one patient with marked tremor improvement had a serious adverse event.

Conclusions:

• GKT demonstrated only modest antitremor efficacy in this cohort.
• The risk of adverse events necessitates careful consideration.
• Further prospective studies with rigorous neurologic evaluation are required before routine clinical recommendation.