Spasmodic Dysphonia and Thalamic Deep Brain Stimulation: Long-term Observations, Possible Neurophysiologic Mechanism and Comparison of Unilateral Versus Bilateral Stimulation

The association of upper extremity essential tremor and several types of other dystonias, including spasmodic dysphonia, have been reported in the past [1,2]. We previously reported a brief case description of a patient with essential tremor (ET) of the hands and adductor spasmodic dysphonia (SD) with vocal tremor who responded to bilateral thalamic DBS with six month follow up [3]. Our patient is now 44 months postoperatively with sustained improvement in both her essential tremor and spasmodic dysphonia symptoms. There are no other reports of thalamic deep brain stimulation surgery improving spasmodic dysphonia in patients with or without essential tremor. Given the sustained response of our patient’s SD to chronic thalamic stimulation, we discuss the current literature and explore the possible mechanisms of action.