Is the target for thalamic deep brain stimulation the same as for thalamotomy?

Area of Science:

• Neurosurgery
• Neurology
• Medical Devices

Background:

• Deep brain stimulation (DBS) is the primary treatment for essential tremor, largely replacing thalamotomy.
• The optimal target site for DBS is presumed to be identical to the ideal thalamotomy lesion site.
• Previous studies have not directly compared these target locations.

Purpose of the Study:

• To investigate whether the anatomical location of thalamic DBS for essential tremor matches the optimal site for thalamotomy.
• To compare the three-dimensional coordinates of chronic DBS stimulation sites with theoretical thalamotomy targets.

Main Methods:

• Analysis of 11 patients who underwent microelectrode recording and DBS for essential tremor.
• An experienced surgeon, blinded to patient outcomes, identified the ideal thalamotomy site using intraoperative maps.
• Comparison of DBS electrode positions and theoretical thalamotomy sites in stereotactic space.

Main Results:

• No significant difference was found in the mediolateral (x-axis) location between DBS and theoretical thalamotomy sites.
• The tip of the DBS electrode also showed no significant difference from the theoretical thalamotomy site.
• However, active DBS stimulation sites were significantly more anterior (P=0.005) and dorsal (P=0.034) than the ideal thalamotomy target.

Conclusions:

• A spatial mismatch exists between chronic DBS stimulation sites and optimal thalamotomy targets in essential tremor treatment.
• This discrepancy may indicate a need for compromise between therapeutic benefits and adverse effects in chronic DBS.
• The findings suggest potentially distinct mechanisms of action for DBS and thalamotomy in essential tremor.