Deep Brain Stimulation at End of Life: Clinical and Ethical Considerations

Systematic review of rodent studies of deep brain stimulation for the treatment of neurological, developmental and neuropsychiatric disorders

Deep brain stimulation (DBS) modulates local and widespread connectivity in dysfunctional networks. Positive results are observed in several patient populations; however, the precise mechanisms underlying treatment remain unknown. Translational DBS studies aim to answer these questions and provide knowledge for advancing the field. Here, we systematically review the literature on DBS studies involving models of neurological, developmental and neuropsychiatric disorders to provide a synthesis of the current scientific landscape surrounding this topic. A systematic analysis of the literature was performed following PRISMA guidelines. 407 original articles were included. Data extraction focused on study characteristics, including stimulation protocol, behavioural outcomes, and mechanisms of action. The number of articles published increased over the years, including 16 rat models and 13 mouse models of transgenic or healthy animals exposed to external factors to induce symptoms. Most studies targeted telencephalic structures with varying stimulation settings. Positive behavioural outcomes were reported in 85.8% of the included studies. In models of psychiatric and neurodevelopmental disorders, DBS-induced effects were associated with changes in monoamines and neuronal activity along the mesocorticolimbic circuit. For movement disorders, DBS improves symptoms via modulation of the striatal dopaminergic system. In dementia and epilepsy models, changes to cellular and molecular aspects of the hippocampus were shown to underlie symptom improvement. Despite limitations in translating findings from preclinical to clinical settings, rodent studies have contributed substantially to our current knowledge of the pathophysiology of disease and DBS mechanisms. Direct inhibition/excitation of neural activity, whereby DBS modulates pathological oscillatory activity within brain networks, is among the major theories of its mechanism. However, there remain fundamental questions on mechanisms, optimal targets and parameters that need to be better understood to improve this therapy and provide more individualized treatment according to the patient's predominant symptoms.

How to Use the New European Academy of Neurology/Movement Disorder Society European Section Guideline for Invasive Therapies in Parkinson's Disease

BACKGROUND

The decision to choose invasive treatments for Parkinson's disease (PD) is complex and needs careful consideration.

OBJECTIVES

Although the recommendations of the European Academy of Neurology/Movement Disorder Society European Section guideline for invasive therapies of PD are useful, the different clinical profiles of people with PD who seek advice for possible invasive therapy need further attention.

METHODS AND RESULTS

Here we describe 8 clinical standard situations of people with PD unsatisfied with their current oral treatment where invasive therapies may be considered. These are PD patients presenting with the following symptoms: (1) severe motor fluctuations, (2) beginning of levodopa-responsive fluctuations, severe tremor at (3) young or (4) advanced age, (5) impulse control disorders and related behavioral disorders, (6) hallucinations and psychosis, (7) minimal cognitive impairment or mild dementia, and (8) patients in need of palliative care. For some of these conditions, evidence at lower level or simple clinical considerations exist.

CONCLUSIONS

There are no one-fits-all answers, but physician and patient should discuss each option carefully considering symptom profile, psychosocial context, availability of therapy alternatives, and many other factors. The current paper outlines our proposed approach to these circumstances.

Brain-Computer Interfaces, Completely Locked-In State in Neurodegenerative Diseases, and End-of-Life Decisions

In the future, policies surrounding end-of-life decisions will be faced with the question of whether competent people in a completely locked-in state should be enabled to make end-of-life decisions via brain-computer interfaces (BCI). This article raises ethical issues with acting through BCIs in the context of these decisions, specifically self-administration requirements within assisted suicide policies. We argue that enabling patients to end their life even once they have entered completely locked-in state might, paradoxically, prolong and uphold their quality of life.

End of life care of hospitalized patients with Parkinson disease: a retrospective analysis and brief review

Background

Towards the end of life (EOL), persons with parkinsonism (PwP) have complex needs and can present with unique palliative care (PC) challenges. There are no widely accepted guidelines to aid neurologists, hospitalists, or PC clinicians in managing the symptoms of PwP at EOL. We examined a population of PwP at EOL, aiming to describe trends of in-hospital management and utilization of PC services.

Methods

All PwP admitted to two hospitals during 2018 (N = 727) were examined retrospectively, assessing those who died in hospital or were discharged with hospice (EOL group, N = 35) and comparing them to the main cohort. Their demographics, clinical data, engagement of multidisciplinary and palliative services, code status changes, invasive care, frequency of admissions, and medication administration were assessed.

Results

Among the EOL group, 8 expired in hospital, and 27 were discharged to hospice. Forty-six percent of EOL patients received a PC consultation during their admission. The median interval from admission to death was 37 days. Seventy-seven percent had a full code status on admission. Compared to hospice patients, those who expired in hospital had higher rates of invasive procedures and intensive care unit transfers (41% vs. 75%, in both variables), and lower rates of PC involvement (52% vs. 25%). The transition of code status change for the EOL group from Full code to Do Not Resuscitate (DNR) occurred at a median 4-5 days from admission. For patients that passed in the hospital, the median days from transition of code status to death was 0(IQR 0-1). Levodopa dose deviations were frequent in both EOL and non-EOL group, but contraindicated medications were infrequently administered (11% in EOL group vs. 9% in non-EOL group).

Conclusion

Our data suggest a low utilization of PC services and delayed discussions of goals of care. More work is needed to raise awareness of inpatient teams managing PwP regarding the unique but common challenges facing PwP with advanced disease. A brief narrative review summarizing the suggested management of symptoms common to hospitalized PwP near EOL is provided.

Key concepts and opportunities

Neuropalliative care is an emerging field dedicated to applying palliative care approaches to meet the needs of persons living with neurologic illness and their families. The development of this field acknowledges the unique needs of this population, including in terms of neuropsychiatric symptoms, the impact of neurologic illness on personhood, and the logistics of managing neurologic disability. In defining the goals of this field, it is important to distinguish between neuropalliative care as an approach to care, as a skillset, as a medical subspecialty, and as a public health goal as each of these constructs offers their own contributions and opportunities. As a newly emerging field, there are nearly unlimited opportunities to improve care through research, clinical care, education, and advocacy.

Restoring vision using optogenetics without being blind to the risks

Retinit is pigmentosa is an incurable degenerative disease that causes loss of light-sensitive cells in the retina and leads to severe vision impairment. The development of optogenetics has created great hype around its potential to treat retinitis pigmentosa by the introduction of light-sensitive proteins into other neural cells in the retina. The first-in-human studies of optogenetic treatment for this disease have recently been reported (NCT02556736 and NCT03326336). The treatment involves irreversible gene therapy and requires access to specially designed goggles to deliver light to the treated eye. These highly innovative and high-profile clinical trials raise numerous ethical issues that must be addressed during the early phases of research and clinical testing to ensure trial participants are treated fairly and can provide appropriate informed consent.

When Should Neuroendovascular Care for Patients With Acute Stroke Be Palliative?

Noncurative surgeries intended to relieve suffering during serious illness or near end of life have been analyzed across palliative settings. Yet sparse guidance is available to inform clinical management decisions about whether, when, and which interventions should be offered when ischemic stroke and other neurological complications occur in patients whose survival is extended by other novel disease-modifying interventions. This case commentary examines key ethical and clinical considerations in palliative neuroendovascular care of patients with acute stroke.

Incoming ethical issues for deep brain stimulation: when long-term treatment leads to a 'new form of the disease'

Deep brain stimulation (DBS) has been regarded as an efficient and safe treatment for Parkinson's disease (PD) since being approved by the Food and Drug Administration (FDA) in 1997. It is estimated that more than 150 000 patients have been implanted, with a forecasted rapid increase in uptake with population ageing. Recent longitudinal follow-up studies have reported a significant increase in postoperative survival rates of patients with PD implanted with DBS as compared with those not implanted with DBS. Although DBS tends to increase life expectancy for most patients with PD, this medical benefit does not come without attendant negative consequences. For example, emerging forms of iatrogenic harms are sometimes induced-harms which were not initially expected when clinicians proposed neurosurgery and patients or their guardians consented to the treatment. We report and discuss the clinical case of a patient who was implanted with DBS more than 20 years ago (at the time of writing) and is now experiencing unexpected stages of PD. This case illustrates how extending the life span without improving quality of life may introduce a burden of harms for patients and families. As well, this case shows why we should prepare for the expanding numbers of PD-implanted patients experiencing a gain of longevity but with severe stages of disease leading to diminution in quality of life. This newly observed effect of DBS treatment requires us to explore ethical questions related to iatrogenic harms, informed consent, end of life and caregivers' burden.