Originally developed in the 1970s for the treatment of pain, chronic electrical stimulation of the brain, or deep brain stimulation (DBS), is being applied in a rapidly expanding menu of indications. While the improvement brought to patients by this technique may be profound, economic barriers-insurers refusing to cover it, or low reimbursement for those performing it-may prevent DBS from reaching many whom it could benefit.
DBS involves the placement of a permanent stimulating electrode into one of a variety of subcortical structures to modulate abnormal neuronal activity. It is essentially a brain pacemaker, though the exact mechanism of action at a cellular level is not well understood. In Parkinson’s disease (PD), the discovery that basal ganglia output is excessive and irregularly patterned led directly to trials of DBS of the subthalamic nucleus or globus pallidus internus for PD.1 Many consider this the most important advance in the treatment of PD since the introduction of levodopa in the 1960s.
FDA Approvals Bolster Case for Reimbursement
Widely available for years in Europe, DBS for treatment of movement disorders was approved by the U.S. Food and Drug Administration only recently. Thalamic DBS for Parkinsonian and essential tremors was approved by the FDA in 1997, but pallidal and subthalamic stimulation for treatment of advanced PD was not FDA approved until 2002. In April a third category of movement disorder-dystonia-was added to the list of on-label indications. With these approvals, more consistent coverage by insurers is anticipated.
Other economic barriers remain, however. The work relative value units (RVUs) assigned to DBS have poorly reflected the time, expertise, and equipment required to perform these procedures correctly. Advanced neurophysiological techniques such as single unit microelectrode recording (MER) can enhance the precision of implantation, but add time and intricacy to the procedure. At present, American neurosurgeons who perform DBS do so at an economic loss compared with the reimbursement they would receive spending the same time performing other neurosurgical procedures.
RUC Recommends RVU Increase: 19 to 31
At the April meeting of the American Medical Association’s Relative Value Update Committee, known as the RUC, a recommendation was made to increase the RVU assignment for MER-guided DBS from 19 to 31. If this recommendation is accepted by the Centers for Medicare and Medicaid Services, it should blunt the economic disincentive that is currently in place for performing DBS.
An additional reimbursement barrier also must be addressed: the minimal compensation for long-term postoperative management of DBS devices by movement disorders neurologists. While DBS promises to greatly improve the lives of many persons with moderately advanced PD, it also adds much time and complexity to their management. In our clinic at the University of California, San Francisco, there is a very large volume of referrals of patients who could benefit-yet it is difficult to find neurologists willing to manage the device programming in conjunction with the overall medical management of the patient. Such integrated, longitudinal management by a movement disorders expert, in addition to patient selection and surgical technique, is a critical determinant of outcome in DBS for PD.
Most of the expanding indications for DBS have been prompted by neurophysiological studies of brain disease that pinpoint areas of excessive or irregularly patterned activity. As discreet abnormalities in diseased brain circuitry are identified, the list of disorders treatable by DBS will expand. The finding from functional imaging that orbitofrontal-striatal circuitry is abnormally active in obsessive-compulsive disorder has led to promising trials of DBS to modulate cortical efferent fibers innervating the limbic striatum.4 The finding of increased metabolism in the lateral hypothalamus during cluster headache attacks has encouraged the application of DBSS for this disorder as well.3 Studies of DBS in epilepsy and Tourette’s syndrome are underway.2,5
Advances in neuroscience are rapidly fueling imaginative new indications for DBS in otherwise highly debilitating brain disorders. For many conditions, DBS promises to help patients achieve a degree of normal functionality while sparing them the unwanted effects of systemic medicine on normal brain circuitry. To be able to apply this technique in the real world for our patients, however, economic barriers must continue to yield.
Philip A. Starr MD, PhD, is assistant professor in the Department of Neurological Surgery, University of California, San Francisco.
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