Comparing two deep brain stimulation leads to one in refractory tremor

Area of Science:

• Neurosurgery
• Neurology
• Movement Disorders

Background:

• Medication-refractory tremor often requires advanced interventions like deep brain stimulation (DBS).
• The ventralis intermedialis nucleus (Vim) of the thalamus is a common DBS target for tremor.
• Some patients do not achieve satisfactory tremor control with standard Vim DBS, necessitating alternative strategies.

Purpose of the Study:

• To evaluate the efficacy of a second ipsilateral DBS lead in patients with tremor refractory to standard Vim DBS.
• To provide a double-blind assessment of tremor reduction with additional DBS lead placement.

Main Methods:

• A double-blind study involving five patients with refractory tremor.
• Tremor was assessed using a videotaped tremor rating scale (TRS) under four conditions: both leads OFF, Vim ON/2nd lead OFF, Vim OFF/2nd lead ON, and both leads ON.
• Statistical analysis (paired t-test) compared outcomes between stimulation conditions.

Main Results:

• Four out of five patients demonstrated objective tremor improvement (17-60%) with the addition of a second DBS lead compared to Vim stimulation alone.
• While individual improvements were noted, the overall group results did not reach statistical significance.
• Results were consistent across different tremor rating scales and patient subgroups (multiple sclerosis and essential tremor).

Conclusions:

• The addition of a second DBS lead may offer objective tremor improvement in select patients refractory to standard Vim DBS.
• The lack of statistical significance in this small, heterogeneous sample highlights the need for larger studies.
• Further research is warranted to confirm the efficacy and identify optimal targets for a second DBS lead in refractory tremor cases.