Study Examines the Effectiveness of Deep Brain Stimulation in Treating Patients with Intractable Pain

To better understand the efficacy of DBS, neurosurgeons in Australia recently performed a meta-analysis of DBS for pain relief. The results of this study, Deep Brain Stimulation for Pain:A Meta-analysis was presented by Richard G. Bittar, MD, PhD, FRACS on Tuesday, April 19, 2005, during the 73rd Annual Meeting of the American Association of Neurological Surgeons in New Orleans. Co-authors are Ishani Kar-Purkayastha, MD, Sarah L. Owen, BA, ODP, Renee E. Bear, BAppSc (Psych)(Hons), Alex Green MD, MRCS, ShouYan Wang, PhD, and Tipu Z. Aziz, MD, DMedSc, FRCS.

DBS is a surgical technique which involves the placement of a fine electrode (wire) into specific parts of the brain. Most commonly, DBS is used to treat Parkinson's disease, but it can also be utilized for the alleviation of pain. DBS works by delivering a continuous electrical pulse to regions of the brain involved in the processing of pain signals. The exact mechanism by which this creates pain relief is yet to be fully understood. The advantages of this technique are that it is reversible, non-destructive, and can be modified by adjustment of the stimulator settings after implantation.

At the Australasian Movement Disorder and Pain Surgery (AMPS) Clinic in Melbourne, Australia, DBS represents a "final resort" treatment for pain. Other strategies that are often utilized first include peripheral nerve and spinal cord stimulation. Motor cortex stimulation is another option; however, it can be very difficult to predict which patients may benefit from this. The most commonly treated conditions that cause pain include stroke, failed spinal surgery, phantom limb pain, atypical facial pain, and headache.

Many published studies examining the effectiveness of DBS for the relief of chronic pain have suffered from such shortcomings as a small patient pool, variable and inadequate measurement and documentation of results, and short follow-up periods. "In order to better understand the utility of DBS in the treatment of intractable chronic pain, this study examined the results of previous studies examining DBS for pain," stated Dr. Bittar, AMPS Clinic director.

The rate of long-term pain alleviation was highest in those patients undergoing DBS of the periventricular gray region plus sensory thalamus 87 percent. A long-term success rate of more than 80 percent was attained in patients with intractable low back pain and failed back surgery syndrome that underwent successful trial stimulation and proceeded to permanent implantation. Trial stimulation was successful in approximately 50 percent of patients with post-stroke pain, and 58 percent of patients with permanent implantation achieved ongoing pain relief. Moderately higher rates of success were seen in patients with phantom limb pain and radiculopathies.

"We conclude from this analysis, as well as our own experience, that DBS has an important role to play in the treatment of selected patients with chronic pain syndromes which have not responded to other forms of treatment," concluded Dr. Bittar.

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