Awake deep brain stimulation (DBS) surgery can provide information beyond what imaging alone can capture, helping clinicians personalize electrode placement for patients with essential tremor, according to a Mayo Clinic study published in Operative Neurosurgery.
DBS surgery involves implanting thin wires with electrodes, known as leads, into specific areas of the brain. The electrodes deliver electrical impulses that affect brain activity and can be used to treat brain disorders such as essential tremor, Parkinson's disease and dystonia. Imaging helps clinicians plan where to place the leads.
In many patients, following a standard target based on imaging can lead to optimal therapy. But sometimes the best lead location for a patient may be in a slightly different position."
Bryan Klassen, M.D., a Mayo Clinic neurologist and study co-author
During awake DBS surgery, neurosurgeons and neurologists can measure brain activity, test stimulation and receive feedback from the patient. This information can help the surgical team adjust lead placements during the procedure.
"It is an interactive process that gives us the ability to evaluate patient responses during the procedure and immediately adjust lead placement if neurophysiological recordings or stimulation testing reveal suboptimal positioning," says Matthew R. Baker, Ph.D., a neurosurgery scientist at Mayo Clinic and study co-author. In contrast, DBS performed while the patient is asleep relies primarily on imaging to guide lead placement.
In the retrospective study, Mayo Clinic researchers examined 137 DBS leads implanted in patients who were awake during surgery for essential tremor. Researchers evaluated how often information gathered during surgery changed the final lead position and whether those changes could have been achieved using imaging alone.
For each lead, researchers determined whether the final implant followed the planned path, required an adjustment in depth, or was moved to a parallel path based on recordings of brain activity and stimulation testing. They also compared tremor suppression and side effects before and after leads were repositioned.
About 15% of the 137 leads were meaningfully repositioned. Among those adjustments, 88% could not have been achieved through imaging-based corrections alone.
"The awake procedure frequently led to lead adjustments that would not have been made if clinicians had relied solely on imaging during asleep procedures," says Dr. Klassen. "This is evidence that awake surgery enables a more individualized and optimized lead placement strategy for each patient, increasing the likelihood that a patient receives the best possible therapeutic outcome."
During surgery, repositioned leads also produced more favorable responses, including better tremor control, fewer side effects and wider therapeutic windows - the range between the stimulation level needed to control symptoms and the level at which side effects emerge.
"A wide window provides greater flexibility during future programming and improves long-term treatment management," says Dr. Klassen.
The findings suggest that awake testing can provide clinically useful information even as imaging and surgical technologies advance. Researchers note that clinicians cannot reliably determine before surgery which patients will need the additional information provided by awake testing.
"What this study shows is that when we do make those adjustments, they are often based on information that imaging alone could not provide. That gives us another way to personalize treatment for the individual patient," says Kai Miller, M.D., Ph.D., a Mayo Clinic neurosurgeon and study co-author.
The team is studying ways to make awake DBS procedures more efficient while preserving patient-specific information. Future research includes developing technologies that can evaluate multiple measures of brain activity simultaneously, as well as new patient tasks, stimulation approaches and targeting strategies.
"The next step is to find ways to gather this information more efficiently," Dr. Miller says. "Our goal is to shorten the procedure while preserving the information that helps us make better decisions for each patient. As we learn more about neural biomarkers and develop better tools to measure them, we may be able to further refine how we personalize DBS treatment."
The research supports Mayo Clinic's Bioelectronics Neuromodulation Innovation to Cure (BIONIC) initiative, which seeks to develop personalized neuromodulation therapies to prevent, treat and potentially reverse neurological disorders.
For a complete list of authors, disclosures and funding, review the study published in Operative Neurosurgery, an official publication of the Congress of Neurological Surgeons published by Wolters Kluwer Health.
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