Long-term efficacy and cognitive effects of voltage-based deep brain stimulation for drug-resistant essential tremor

To analyze the long-term efficacy and cognitive effects of voltage-based deep brain stimulation (DBS) for drug-resistant essential tremor (ET).

Patients with drug-resistant ET and treated by voltage-based DBS of the ventral intermediate nucleus (VIM-DBS) were continuously enrolled. Seizure outcomes were assessed by blinded observers using the Tremor Rating Scale (TRS). The full-scale intelligence quotient, full-scale memory quotient, Hamilton Depression Scale, Hamilton Anxiety Scale, and Quality of Life in Essential Tremor Questionnaire were assessed as measures of cognitive function.

Eleven patients met the inclusion criteria, and two of them were excluded because of loss to follow-up. The patient follow-up times ranged from 48 to 66 months (median 51 months). TRS scores decreased by 60.4% and 46.0% at the 12- and 48-month follow-ups, respectively. Both changes were highly significant. During the follow-up period, the patients' intelligence and memory had not significantly changed; depression, anxiety, and quality of life significantly improved. After long-term follow-up, the stimulation efficacy and quality of life gradually decreased, and the depression and anxiety levels increased.

For patients with drug-resistant ET, voltage-based DBS can provide acceptable benefits on tremor, cognitive function, and quality of life. However, the efficacy of VIM-DBS decreased over time.