Longevity of Deep Brain Stimulation in Essential Tremor: A Comparison of Omnidirectional and Directional Leads

Patients undergoing thalamic ventral intermediate nucleus stimulation to treat essential tremor (ET) develop tolerance over time, requiring higher stimulation amplitudes that lead to more frequent battery changes and suboptimal tremor control. The study objective is to determine whether amplitude tolerance differs between patients with omnidirectional vs directional leads.

We conducted a retrospective analysis of ET patients with omnidirectional and directional leads implanted between 2005 and 2022. We compared patient demographics, tremor scores, and energy utilization for directional and omnidirectional leads. Contact impedance was used to normalize amplitude values between groups. Analyses were duplicated after reclassifying omnidirectional and directional based on the utilization of directional programming for 2 or more years.

A total of 24 directional leads in 22 patients and 39 omnidirectional leads in 30 patients were followed for a mean of 3.71 and 7.54 years, respectively. There was no significant difference in age or baseline tremor scores between the groups. Both lead types demonstrated increasing amplitudes over time, but directional leads had significantly less change over time, particularly in the first year ( P = .0012). Patients with omnidirectional leads were more likely to experience a pulse width increase of greater than 20 µs over 1 year (41.0% vs 12.5%; P = .035). Although time to first implantable pulse generator replacement was shorter for directional leads, this was not significant ( P = .062).

Both omnidirectional and directional deep brain stimulation reduces tremor severity in ET patients. However, directional leads offer more stable voltage requirements and less year-to-year voltage change, particularly in the first year. The increased likelihood of significant pulse width changes in omnidirectional leads suggests that directional leads may provide more sustainable therapeutic effects through other programming parameters. Ongoing research is needed to optimize deep brain stimulation technology and programming strategies to maximize patient benefit and device longevity.