Awake Brain Mapping Refines DBS Lead Placement Beyond Imaging

Awake brain mapping can reveal information that changes deep brain stimulation lead placement beyond what imaging alone would suggest, according to research published in a medRxiv preprint by Klassen et al. (2025) involving patients with essential tremor.

The retrospective Mayo Clinic analysis examined how recordings of brain activity and stimulation testing influenced surgical decisions during deep brain stimulation procedures. DBS uses implanted electrodes to deliver electrical stimulation to selected brain regions. While scans assist surgeons in mapping out the destination and pathway, testing while the patient is awake enables the medical staff to evaluate reactions as the electrodes are inserted.

The researchers reviewed 137 consecutive leads implanted by one surgeon working with one intraoperative neurologist. They noted whether every individual lead adhered to its initial path and depth, needed a depth modification, or shifted to a parallel route.

Of the 137 leads, 116 remained on the planned trajectory. Within this group, 49 were implanted at the original depth and 67 at an adjusted depth. The remaining 21 leads were placed along a parallel trajectory following intraoperative assessment.

Seventeen of the leads moved to parallel trajectories had imaging available for comparison. Out of these, a mere two shifted nearer to the targeted scan coordinates; 13 ended up at a greater distance, and two stayed at the exact same distance from it.

Such a trend indicates that these adjustments typically arose from physiological data gathered during the operation, rather than acting as mere corrections toward the initial structural goal.

In its report accompanying the research, Mayo Clinic described more favourable intraoperative responses after repositioning, including improved tremor suppression, fewer side effects and wider therapeutic windows. A broader margin separates the electrical intensity required to manage symptoms from the threshold where adverse reactions emerge, which may grant greater latitude during later device adjustments.

The results provide a practical reason to retain awake assessment as an option as imaging technology advances. They demonstrate the ways in which a seemingly correct structural strategy can still be optimized by watching how a patient reacts to electrical currents.

However, the analysis was retrospective and reflected the practice of a single surgical team. Because the study omitted a direct long-term comparison between patients who stayed awake versus those who slept through the operation, it cannot prove that either method is universally superior.

Mayo Clinic reports that future work will explore more efficient ways to collect physiological information during surgery. The objective is to maintain the individualized patient insights guiding electrode placement while cutting down the duration needed to gather them.