Long‐term Thalamic Deep Brain Stimulation for Essential Tremor: Clinical Outcome and Stimulation Parameters

Abstract

Background: The reasons underlying the loss of efficacy of deep brain stimulation (DBS) of the thalamic nucleus ventralis intermedius (VIM-DBS) over time in patients with essential tremor are not well understood. Methods: Long-term clinical outcome and stimulation parameters were evaluated in 14 patients with essential tremor who underwent VIM-DBS. The mean AE standard deviation postoperative follow-up was 7.7 AE 3.8 years. At each visit (every 3-6 months), tremor was assessed using the Fahn-Tolosa-Marin tremor rating scale (FTM-TRS) and stimulation parameters were recorded (contacts, voltage, frequency, pulse width, and total electrical energy delivered by the internal generator [TEED 1sec ]). Results: The mean reduction in FTM-TRS score was 73.4% at 6 months after VIM-DBS surgery (P < 0.001) and 50.1% at the last visit (P < 0.001). The gradual worsening of FTM-TRS scores over time fit a linear regression model (coefficient of determination [R 2 ] = 0.887; P < 0.001). Stimulation adjustments to optimize tremor control required a statistically significant increase in voltage (P = 0.01), pulse width (P = 0.01), frequency (P = 0.02), and TEED 1sec (P = 0.008). TEED 1sec fit a third-order polynomial curve model throughout the followup period (R 2 = 0.966; P < 0.001). The initial exponential increase (first 4 years of VIM-DBS) was followed by a plateau and a further increase from the seventh year onward. Conclusions: The current findings suggest that the waning effect of VIM-DBS over time in patients with essential tremor may be the consequence of a combination of factors. Superimposed on the progression of the disease, tolerance can occur during the early years of stimulation.

Outcomes and Adverse Effects of Deep Brain Stimulation on the Ventral Intermediate Nucleus in Patients with Essential Tremor

“…In addition, in most cases of ET, the tremor score worsens over time, and the average tremor severity increases each year [ 10 ]. Previous studies have found that the benefits of DBS are affected by laterality and stimulation parameters [ 11 , 12 ]. Ondo et al concluded that unilateral thalamic DBS is less effective than bilateral DBS in controlling appendicular and midline ET [ 11 ].…”

“…Ondo et al concluded that unilateral thalamic DBS is less effective than bilateral DBS in controlling appendicular and midline ET [ 11 ]. Moreover, a previous study found that to optimize tremor control, the stimulation parameters, including the voltage, frequency, and pulse width, need to be adjusted [ 12 ].…”

Stimulating the nucleus accumbens in obesity: A positron emission tomography study after deep brain stimulation in a rodent model

“…Nevertheless, our animal model is representative of a particularly resistant kind of obesity, which could potentially benefit from NAcc-DBS depending on the genetic background. We selected the DBS parameters for three main reasons: the success obtained in previous approaches using bilateral DBS [ 23 , 24 ] and similar stimulation protocols [ 22 , 27 , 34 , 69 ]; the tolerance associated with continuous DBS treatments [ 70 , 71 ]; and the technical difficulties in obtaining portable rat stimulators in our facilities. Nevertheless, DBS protocols which were closer to the current clinical scenario may reveal larger differences in weight gain [ 22 , 68 ].…”

Deep Brain Stimulation for Essential Tremor and Other Tremor Syndromes: A Narrative Review of Current Targets and Clinical Outcomes

“…Tremor control from Vim stimulation appears to worsen over time [33][34][35][36]. In one series, 73% of patients had experienced waning stimulation benefit within 5 years of implantation [36].…”