Study examines reasons for unsatisfactory outcomes following deep brain stimulation surgery

A study of follow-up care for patients with unsatisfactory outcomes from deep brain stimulation (DBS) surgery for movement disorders offers insights into reasons for problems and proposes strategies for improved outcomes. The study will appear in the August print issue of Archives of Neurology.

According to background information in the article, since the Food and Drug Administration approved deep brain stimulation for the treatment of Parkinson's disease, essential tremor and dystonia (uncontrolled muscle movement), there has been a surge in the number of centers offering this surgical procedure, which involves implanting a device to deliver mild electrical stimulation to block the brain signals that cause tremor. There is currently no consensus regarding appropriate screening procedures, necessary training of individuals providing the therapy, the need for an interdisciplinary team, or guidelines for the management of complications, the authors report.

Michael S. Okun, M.D., of the University of Florida Movement Disorders Center, Gainesville, Fla., and colleagues evaluated 41 consecutive patients who came to one of two specialty movement disorder centers over a two year period complaining of unsatisfactory results from deep brain stimulation surgery performed elsewhere. Each patient was evaluated by a movement disorders neurologist; the patient's medical record was reviewed; the DBS device was examined and properly programmed; and postoperative imaging studies were evaluated whenever possible.

The researchers found problems with screening for surgery and determination of diagnosis, five patients (12 percent) had disorders that would not be expected to respond to deep brain stimulation therapy. The researchers found that 19 patients (46 percent) had suboptimal placements of electrodes and three patients' devices had failed due to end of battery life (although these findings may be due to selection bias, the authors suggest). There were also problems noted with programming the DBS device and with medication adjustment. "Patients with movement disorders, with or without DBS, require frequent medication adjustments. Thirty (73 percent) of 41 patients in our series required medication changes. Three patients in our series improved markedly from medications alone, one from DBS programming alone, and 17 after a combination of DBS programming and medication changes. As evidenced by the numbers in this series, surgery does not replace appropriate medical management," the authors write.

"Ultimately, with diligent reprogramming, medication adjustments, and in some cases electrode replacement, 21 (51 percent) of the 41 DBS failures in our study were successfully salvaged," the authors conclude. "Many patients, however, had persistently poor outcomes despite our interventions. This case series provides important insight into the common reasons for 'DBS failures' and proposes some effective strategies for their management. ...As the prevalence of DBS therapy increases, implanting centers are becoming more experienced. We are hopeful that this experience, along with ongoing efforts to educate DBS practitioners regarding effective practices, will result in global improvement in the outcomes of DBS surgery."