Intraoperative smile in a multiple sclerosis patient with medication-refractory tremor.

Deep brain stimulation has been utilized to improve disease symptoms in patients with Parkinson's disease, dystonia, essential tremor, and other neuropsychiatric syndromes such as depression and obsessive compulsive disorder. Deep brain stimulation has also been observed to improve tremor for select patients with multiple sclerosis. During intraoperative stimulation in these multiple sclerosis patients, researchers have observed a wide spectrum of motor and sensory phenomena, but no stimulation-induced emotional responses have been reported. We detailed intraoperative smiling associated with stimulation of the ventralis oralis anterior/ventralis oralis posterior border region of the left thalamus.  A single patient with medication-resistant multiple sclerosis tremor experienced smiling, laughing, and subjective euphoria during intraoperative stimulation of the left thalamus. Specifically, during intraoperative stimulation of the left thalamic ventralis oralis anterior border, the patient developed a contralateral smile which progressed to a bilateral smile and was accompanied by a feeling of subjective happiness. The smile habituated in approximately 60 seconds and it was reproducible on a repeat stimulation. The patient could subjectively feel the facial movement, and, at higher voltages, the movement was described as a pulling sensation. Stimulation of the anterior ventralis oralis anterior border of the left thalamus in an multiple sclerosis patient produced a unilateral smile that rapidly developed into a bilateral smile accompanied by euphoria. There were presumed capsular side effects at higher voltages. The exact mechanism by which stimulation of the thalamus produced a smile and mood elevation is unknown, but we speculate that the smile could be induced by stimulation of corticobulbar fibers arising from the caudal cingulate motor area connecting the contralateral facial nerve nucleus.

Unilateral thalamic deep brain stimulation in essential tremor demonstrates long-term ipsilateral effects.

INTRODUCTION: Deep Brain Stimulation (DBS) of thalamus in essential tremor (ET) is effective for the treatment of contralateral tremors. Bilateral DBS controls tremors on both sides but is associated with increased morbidity and risks. We evaluated if unilateral surgery had ipsilateral benefits on tremors and thus could be a potentially safer alternative to bilateral DBS. METHODS: Medication refractory ET patients undergoing unilateral thalamic DBS were included and longitudinally followed. Tremor rating scale was used to record total motor, arm tremor and activities of daily living (ADL) scores at baseline, six months and at last visit (three or more years after surgery). Postoperative scores were recorded with DBS turned OFF and ON. RESULTS: Twenty-two patients with a mean follow-up 3.4 ± 0.14 years were enrolled. When baseline scores were compared to scores with the DBS turned ON, significant improvements were noted in total tremor (40%), ADL (67%) and arm tremor scores both on the ipsilateral and the contralateral side at six months and at the last visit of follow-up (all p < 0.05). Ipsilateral arm tremor (∼56%) improvements were milder compared to the contralateral side (∼73%) tremors. CONCLUSION: Unilateral thalamic DBS in ET demonstrates significant long-term benefits for ipsilateral arm tremors and can be offered to higher risk and to select patients.