For many patients with difficult-to-treat neuropathic pain, such as that associated with diabetes and phantom limb pain, deep brain stimulation (DBS) can lead to long-term improvement in pain scores and other outcomes, according to a study in the February issue of Neurosurgery, the official journal of the Congress of Neurological Surgeons.
DBS is a neurosurgical intervention in which a small electrode is positioned in a targeted location of the brain to deliver low-stimulation electrical amplitude with the goal of interrupting the abnormal activity. According to the study, it is used in movement disorders and to improve symptoms of epilepsy, Tourette syndrome, obsessive-compulsive disorders, depression, and cluster headaches. While DBS has been used to treat various types of chronic pain for about 50 years, the researchers noted that there is relatively little global research to confirm its benefit. They also pointed out that DBS was decreed “off label” for pain by the U.S. Food and Drug Administration.
For this study, a team of researchers from the University of Oxford, England, reviewed their 12-year experience with DBS for neuropathic pain. Patient-reported outcome measures were collated before and after surgery using a visual analog score, short-form 36-question quality of life survey, McGill pain questionnaire, and EuroQol-5D standardized measure-of-health-status questionnaires. The 85-member cohort comprised 60 men and 25 women, with an average age of 62. It included nine individuals with amputations, seven with brachial plexus injuries, 31 after stroke, 13 with spinal pathology, 15 with head and face pain, and ten classified as miscellaneous.
In 74 patients, a trial of DBS produced sufficient pain relief to proceed with implantation of an electrical pulse generator. Of these 74, 15 patients were excluded due to insufficient follow-up data (none of whom were the patients with amputations). Of the remaining 59 patients, 66 percent (39 patients) gained benefit and efficacy varied by etiology, improving outcomes in 89 percent after amputation and 70 percent after stroke compared to 50 percent of those with brachial plexus injury. Further, on average, scores on a ten-point pain scale (with ten indicating the most severe pain) decreased from about eight to four within the first three months, remaining about the same with longer follow-up. Continued follow-up in a small number of patients suggested further improvement in other outcomes, including quality-of-life scores.
While the study concludes that DBS for pain has long-term efficacy for select etiologies, they acknowledge some limitations to their study including the lack of complete patient follow-up. However, they believe their experience is sufficiently encouraging to warrant additional studies, especially with continued advances in stimulation approaches and technology.
Editor’s note: This story was adapted from materials provided by Newswise and Neurosurgery.
