Objective: Present the results of bilateral dentate nucleus stimulation in a patient with essential tremor.

Background: Cerebellum has emerged as new and interesting target for modulation in movement disorders. Recent findings showed positive results after dentate nucleus stimulation (DN DBS) in patients with cerebellar stroke and degenerative ataxias, such as SCA 3. Here, we describe a man with essential tremor who underwent DN DBS due to refractory symptoms.

Method: A 75-year-old man presented with a 20 years history of tremor in uppers limbs and voice that became incapacitating over the last 5 years. He was diagnosed with essential tremor and had been taken primidone and high doses of propranolol over the last years, with no improvement seen. By the time of his first visit to our center he wasn’t able to write his name, shave or even eat by himself because of the high amplitude tremor in both arms. After a group discussion we decided that the patient was a good candidate for dentate nucleus deep stimulation specially because of his age and higher cerebral bleeding risks. The patient signed an agreement form to undergo experimental surgery.

Results: The surgery was performed in September 2019 in which electrodes were introduced onto dentate cerebellar nuclei bilaterally.  The patient showed immediate improvement of the tremors as a lesion effect that stood over the next weeks. After three months from the insertion the patient still had some improvement of the tremor if compared to baseline even with stimulation off. After this period the device was turned on and the patient had immediate improvement of the tremor. He was able to write his name and was thrilled. He realized that the last time he had written his name was more than fifteen years ago. Five months from surgery the patient is on monopolar stimulation 133hz, 91mS, and asymmetric energy (1,1mA right and 0,8mA left). Tremor scales show improvement of over 60 % in upper limbs. The voice tremor didn’t show any improvement. The patient perception is an improvement of over 80% of the tremor when stimulated but habituation is visible after 3 weeks from the programming.  Dizziness was reported when we increased the stimulation energy, which partially limited our therapy.

Conclusion: Bilateral DN DBS improved tremor in a single case of essential tremor and was safe and well-tolerated procedure.

References: 1. R.G. Cury, M.J. Teixeira, R. Galhardoni, V.R. Barboza, E. Alho, C.M. Seixas, G. Lepski, D. Ciampi de Andrade, Neuronavigation-guided transcranial magnetic stimulation of the dentate nucleus improves cerebellar ataxia: a sham-controlled, double-blind n = 1 study, Park. Relat. Disord. (2015), https://doi.org/10.1016/j.parkreldis.2015.05.010. 2. C. França, D.C. de Andrade, M.J. Teixeira, R. Galhardoni, V. Silva, E.R. Barbosa, R.G. Cury, Effects of cerebellar neuromodulation in movement disorders: a systematic review, Brain Stimulat. 11 (2018) 249–260, https://doi.org/10.1016/j.brs. 2017.11.015

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