Ethics of neuromodulation in adults with cognitive impairment and chronic pain

“I am sorry, but treatment options are limited.” These words can be devastating for patients and their loved ones, particularly for those suffering from debilitating symptoms or progressive disease. Chronic pain is one such condition, which is estimated to impact more than 20% of the US adult population.¹ Similarly, cognitive impairment, including mild cognitive impairment and major neurocognitive disorder (ie, dementia), is experienced by one-third of older adults in the United States.² Importantly, chronic pain and cognitive impairment often coexist, yet there are limited data on the safety and efficacy of analgesic treatment options, including neuromodulation (eg, spinal cord stimulation [SCS]).³ Are treatment options for older adults with cognitive impairment and chronic pain truly as limited as we often present them? We highlight challenges and opportunities for pain management in adults with comorbid chronic pain and cognitive impairment, with a focus on neuromodulation.

Stigma

Chronic pain and cognitive impairment are both accompanied by social stigma, with thematic false perceptions that often overlap between the conditions—isolation, societal burden, a difficult patient, unlikely to benefit from treatment (ie, nontreatability), futility—feelings that might be experienced by the patient, within the medical profession, and by society more broadly. In fact, the word dementia is derived from the Latin word demens, which roughly translates to “mad” or “insane,” making its linguistic foundation one of stigma (hence, the recent adoption of the term major neurocognitive disorder). Thus, individuals with both conditions suffer a dual burden, making it no surprise that pain is consistently undertreated in those with cognitive impairment.⁴ Stigma is difficult to overcome, as it affects not just pain specialists, but also those making referrals (eg, primary care clinicians), potentially resulting in decreased access to advanced pain care.

Underrecognition

Globally, major neurocognitive disorder remains underdiagnosed.⁵ Underrecognition results in decreased use of palliative care services and increased risk of using acute care services compared with those without cognitive impairment. Consequently, persons with cognitive impairment often suffer excess burden due to undertreated pain. Although barriers to efficient detection of cognitive impairment exist at several levels, rapid assessment tools such as the Mini-Cog and AD8 have been validated in community-based settings and are appropriate for risk stratification in high-risk populations.⁶ These tools, in conjunction with functional status assessment (eg, activities of daily living, instrumental activities of daily living), provide high-value information to both the primary care and pain clinic team members. In patients undergoing evaluation for implantable neuromodulation devices like SCS, there is likely underrecognition of cognitive impairment, as formal cognitive assessments are not part of routine presurgical evaluations. However, screening assessment of activities of daily living is often performed as part of the initial evaluation for SCS to guide improvements in functional outcomes.⁷ In those unable to independently perform activities of daily living or already suspected to have cognitive impairment, baseline cognitive assessment is advisable, which could be performed with a rapid tool such as the Mini-Cog.

Treatment assessments

Should assessments for treatment outcomes differ between those with and without cognitive impairment? Indications approved by the US Food and Drug Administration for SCS include intractable pain of the trunk or limbs with associated pain diagnoses, with therapy typically reserved for individuals who have failed conservative treatment and who do not have untreated psychological conditions. Individuals should be able to assess the efficacy of the SCS trial preceding implantation and, traditionally, they need to quantify ≥50% improvement in pain or improvement in physical function.⁷ This level of feedback might be difficult in those with cognitive impairment, particularly major neurocognitive disorder. However, should this disqualify them from treatment? Are there other means of evaluating pain and function in those with cognitive impairment? With mild-to-moderate cognitive impairment, standard pain assessment scales such as the numerical rating scale may often still be used for self-reported pain assessment.⁸ For those with more advanced cognitive impairment, additional tools are available, such as the Pain in Advanced Dementia (PAIN-AD) and Doloplus-2, which incorporate behavioral observations, and care partner assessments. The role of care partners in identifying and evaluating pain should not be underestimated, and validated proxy measures may be used for pain assessment and response to therapy.

Decision-making capacity and respect for patient autonomy

Capacity to make decisions about treatment is dynamic and context specific. Accordingly, a diagnosis of cognitive impairment does not render an individual unable to make his or her own care decisions in all cases. Clinicians must be facile with the nuances of capacity assessment, which involves evaluating the patient’s (1) understanding of the proposed intervention, including risks, benefits, and alternatives; (2) appreciation of how the proposed intervention might or might not benefit them; (3) reasoning with regard to how the intervention could impact their daily life; and (4) ability to choose or express a decision about treatment.⁹ In those without capacity, surrogate decision-makers might make treatment decisions on the basis of previously expressed wishes from the patient, or in the absence of such previously expressed wishes, the surrogate decision-maker’s own substituted judgment.¹⁰ As those with cognitive impairment are apt to lose independence in numerous aspects of life, it is important to ensure that analgesic treatment decisions are consistent with their current, or previously expressed, wishes and goals of care. No matter how advanced cognitive decline might be, no patient deserves to suffer with untreated pain. When patients are unable to express their wishes with regard to analgesic treatment decisions such as SCS, care partners and loved ones can serve as surrogate decision-makers.

Neuromodulation expectations and the well-being of care partners

Finally, analgesic treatment decisions in those with advanced cognitive impairment must be made with consideration of the psychological, physical, and financial well-being of care partners. SCS requires longitudinal patient follow-up, especially during the first 3 months after device implantation. Return visits with the pain provider vary from patient to patient but typically occur with any loss of efficacy from the device to assess for reprogramming needs or device malfunction. As the internal pulse generator reaches its end of life around 8–10 years after implantation, a revision surgery might be needed for internal pulse generator exchange. Additionally, there is potential for procedural or device-related complications that could increase downstream health care exposures, financial costs, and loss of time at home. Care partners, in addition to patients, must be fully informed and counseled on this treatment course beyond device implantation. Given that neurodegenerative conditions are progressive over time, device implantation is not simply an agreement between physician and patient but must also include care partners.

Summary

In summary, there is no compelling reason to withhold neuromodulation from those with coexisting chronic pain and cognitive impairment. Key steps include (1) removing the stigma of nontreatability; (2) quantifying the severity of cognitive impairment, with specific attention paid to the ability to consistently communicate pain and manage the device; (3) clearly outlining the details of treatment, including long-term follow-up; and (4) ensuring support and buy-in from care partners. Those with mild-to-moderate cognitive deficits can retain capacity to self-report changes in pain and function, whereas those with advanced impairment are likely to need the full support of care partners to evaluate device efficacy, function, and safety. Further research is needed into neuromodulation outcomes in those with chronic pain and cognitive impairment.

Funding

N.S.W.’s research is supported by grant K23 AG070113 from the National Institute on Aging. The contents of the article are solely the responsibility of the authors and do not represent the official view of the National Institutes of Health.

Conflicts of interest: N.R.K.’s institution received research funding from Nevro Corporation through an investigator-initiated research grant for work unrelated to this manuscript. N.R.K. and N.S.W. serve on the editorial board for Pain Medicine. N.R.K. reports personal fees from UpToDate that are outside the submitted work.

Supplement sponsorship

This article appears as part of the supplement entitled “Clinical Outcomes in Neurological Disorders with Spinal Cord Stimulation” sponsored by Nevro Corp.