Impact of discontinuing tremor suppressing medications following thalamic deep brain stimulation

Many essential tremor patients continue to require tremor suppressing medications following deep brain stimulation. The true incidence of medication usage in the years following surgery remains unclear, and the use of medications has not been included in the post-operative analyses of tremor severity and also quality of life.

Among 28 essential tremor patients treated with deep brain stimulation at a single center between January 2002 and April 2010, we analyzed the prevalence and dosage of pre-operative tremor suppressing medications versus post-operative medications at 12 and 36 months following surgery. We also assessed the influence of medication continuation on clinical outcome measures, such as the Fahn-Tolosa-Marin Tremor Rating Scale, and the 36 item short-form health quality of life survey.

Both unilateral and bilateral deep brain stimulation resulted in a decrease in primidone use (p = 0.0082, 0.046, respectively), and bilateral deep brain stimulation patients used less tremor suppressing medications 36 months following surgery (p = 0.02). The decision to discontinue primidone after surgery resulted in a non-significant long-term improvement in tremor motor score (23 points versus 15 points, p = 0.19), and did not significantly influence the physical and mental composite quality of life scores (p = 0.81, 0.23, respectively).

Bilateral deep brain stimulation effectively eliminated the need for tremor suppressing medications, while unilateral stimulation was not as effective in reducing medication usage. Clinicians and patients should be aware that discontinuation of primidone after surgery may worsen tremor in unilateral deep brain stimulation cases, but discontinuation will not likely impact quality of life.