Deep-brain stimulation for Parkinson's disease: current perspectives on patient selection with an emphasis on neuropsychology

For some persons with Parkinson's disease, deep-brain stimulation (DBS) is an effective treatment that enhances function and quality of life. It is critical that the preoperative evaluation process yields information that allows the treatment team to determine the likelihood that DBS (directed at a specific target) will be an effective and safe treatment for a given person and that the treatment will meet that person's goals and expectations. Such information allows the team and the patient to perform a cost-benefit analysis and the patient and family to make an informed decision about the potential appropriateness of DBS, and ultimately whether or not to undergo DBS or alternative treatments. We review the multidisciplinary DBS evaluation and education process in general (and by exemplar at Barrow Neurological Institute) engaging the patient with neurology, neuropsychology, neurosurgery, neuroscience nursing, and when needed, psychiatry, social work, and additional medical subspecialties. The review first covers screening, including two standardized instruments, and then the more detailed preoperative evaluation that ensues after screening. Neuropsychological issues in patient selection, and especially cognition, are emphasized, because they remain the most controversial and yet often underlie the judgment that DBS is not an appropriate treatment for a given patient. Outcome studies, perhaps via large, multisite patient registries, are needed to identify neuropsychological risks for unsatisfactory outcome and to define better which surgery (e.g., target, side, timing) is best for a given patient. Such studies would ultimately allow one to judge whether current selection criteria are adequate, need to be stricter, or can be relaxed, and, consequently ensure that the therapy is accessible to the maximum number of persons who will benefit from it without significant adverse effects.