Deep brain stimulation (DBS) is an elective neurosurgical treatment for patients with advanced Parkinson's disease (PD) who suffer from symptoms refractory to medication. DBS requires an invasive procedure in which, first, brain electrodes are implanted while the patient is awake and, second, neurostimulators are implanted under general anesthesia. The neurostimulator batteries require monitoring by specialists and replacement up to every 5 years. Sudden battery depletion could be lifethreatening for patients living with chronic DBS. Additional hardware complications that can occur and that require additional surgery include replacing defective wires or revising skin areas that have eroded. These potential long-term complications can involve ethical choices and challenges for the patient, the surrogate, and treating clinicians.

Pre-existing dementia is currently considered an exclusion criterion for DBS surgery. However, patients with PD are at an increased risk of developing dementia over time. Presurgical evaluation is used to screen patients carefully, so that DBS is not offered when the patient's expectations are not consistent with what DBS can offer and so that patients are educated about possible benefits and risks. The surgical risks of DBS include cerebral hemorrhage, hardware infection, suboptimal placement of electrodes, wire fracture, hardware erosion, apathy, suicide, eyelid opening apraxia, and weight gain. The risk-benefit analysis is unclear when considering the above risks in a patient who has dementia or is at high risk of developing it.

Furthermore, many patients with PD and dementia could benefit from DBS. Ethically, the presence of dementia should not disqualify patients from receiving DBS without solid evidence to support withholding a potentially beneficial treatment. We do not yet have follow-up reports for patients living with DBS who also have dementia, however, and candidacy decisions must therefore be made—and discussions with patients and families held—without outcome data. We do know that PD and other chronic progressive disorders associated with dementia require increasing care needs over time and that living with an implanted device can add to already complicated care needs.

Here we review a case that illustrates a difficult ethical issue that arose during the long-term care of a person with PD dementia. We follow up with a discussion that is relevant to DBS when considering patients with chronic progressive disease that affects cognition and behavior and potentially increases care needs over the long term.
CASE Mrs. D. is a 68-year-old woman with PD that began in her 50s. She has been a patient in the family practice clinic for the past 20 years. She has been receiving bilateral subthalamic nucleus DBS, which has alleviated her severe, disabling hand tremor. She has a history of dementia with psychosis, severe paranoia, and hallucinations that continued to worsen after DBS was performed.

Within a year after receiving DBS, Mrs. D. could no longer live at home because of her dementia; however, she was rejected by several nursing homes, which believed that DBS would increase her need for care. Her husband requested removal of the DBS system so that he could place her in a nursing home, even though removal of the DBS would render her less mobile. She was referred back to the neurology clinic for evaluation.

THE ETHICAL QUANDARY

The team at the clinic faced a dilemma. Should they remove the DBS because it was contributing to the difficulties with nursing home placement? Or should they refuse to remove the DBS because it eased Mrs. D.'s symptoms, even though this would increase the burden of care on her family? The team wanted to respect the husband's choice, but they also sought to protect Mrs. D. from losing the valuable control she had gained over her tremor and stiffness. In absence of DBS, medications to control her tremor and stiffness would certainly worsen her psychosis and further increase care needs.

The team suggested inpatient care for aggressive management of the psychosis and a social work liaison to help educate the nursing home about DBS risks and benefits to Mrs. D. and reduced care needs as a result of DBS. Although a nursing home agreed to accept Mrs. D. after gaining a better understanding of DBS, the clinical team was left with unanswered ethical questions about the appropriateness of DBS in patients with dementia, when (or if) it is acceptable to remove a therapeutic hardware device, and who decides.

DISCUSSION

Cognitive decline in PD influences daily function, safety, and long-term management, even though DBS is a successful therapy for motor symptoms. Making decisions about medical management is tough when few functional outcome studies of patients with dementia are available. This case provides an opportunity to review an ethical dilemma that may impact treatment decisions. It also illustrates how the ethical principles of autonomy, nonmaleficence, beneficence, and justice apply in using DBS to treat patients with PD.

In the case of Mrs. D., the patient did not have the decisional capacity to request removal of her DBS, leaving her husband as the legal decision maker (surrogate). The use of surrogates who articulate the decisions and wishes of the patient is based in law, and the surrogate is expected to act out of respect for the patient's autonomy. The surrogate is to consider the patient's well-being and potential benefit (beneficence) and harm (nonmaleficence). DBS offered significant benefit to Mrs. D. by relieving her tremor and stiffness. Mr. D., the surrogate, argued that greater harm would occur if Mrs. D. could not be placed into a nursing home. Ending the use of DBS would restrain her free movement in a manner comparable to physical or medication restraint. Current standard of practice, laws, and regulations minimize to the greatest extent possible the use of restraints.

The nursing home in this case could be considered a third-party influence. Although Mr. D. may have the best interest of Mrs. D. at heart, removing a therapeutic device based on lack of understanding by a third party would restrict Mrs. D.'s liberty in continuing to receive benefit from an effective treatment. In this case, when the surrogate's decision may be influenced by a third party, an alternative surrogate may be required to consider the best interests of the patient.

Effects of dementia Should the riskbenefit ratio be weighted differently in patients who are likely to progress to dementia or who have dementia? The ethical balance needs to be carefully considered as patients with substantial movement disorders can have linked pain and discomfort. Although dementia is currently a contraindication to DBS surgery, this case is pertinent due to the increasing numbers of patients who will age with DBS.

This case underscores the ethical dilemma presented by a patient who achieves motor enhancement with DBS but, because of cognitive and behavioral deterioration, begins to require more supervised care. DBS is beginning to be used for neurobehavioral disorders, and patients like Mrs. D. are particularly likely to be interested in trying it. Dementia or other behavioral problems may increase the risks associated with long-term use of DBS, and the presence of such problems raises questions about the patient's ability to provide informed consent. On the other hand, the issues that arose in this case could realistically be included in a presurgical discussion, thus limiting or avoiding future harm (nonmaleficence).

One final point to consider: advance directives become even more essential as our medical knowledge, equipment, and skills continue to expand. Advance directives can presumably address questions regarding the possible withdrawal or repair of an implanted device when dementia confounds a patient's decisionmaking capacity.

Bioethics evaluation The participation of bioethics consultants is likely to become increasingly important to address the potential for ethical dilemmas when patients with high risk of cognitive decline seek DBS. The impact of cognitive changes over the long-term care of a patient can easily be overshadowed by the quick reversal of disabling motor symptoms. Hopefully in the near future, we will have long-term studies utilizing assessments that look at quality of life, neuropsychological testing to provide missing information, and better risk-benefit considerations for this elective neurosurgical procedure.

A multidisciplinary committee that includes bioethicists can serve an important function in balancing concerns and considering broad issues of justice in access. The complexity of these decisions requires a meticulous approach that can guide the emerging field of deep brain stimulation toward enhanced protection of vulnerable patients, improved informed consent procedures, and superior standard practices for patients at risk of or with dementia. JAAPA

SUGGESTED READING
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Sierra Farris is the neurostimulation program coordinator at Evergreen Neurological Institute and a teaching associate at the University of Washington Department of Neurological Surgery, Seattle. F.J. Gianola is the department editor for PA Quandaries and is on the faculty of the MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine, Seattle. The authors have indicated no relationships to disclose relating to the content of this article.