Rechargeable Implanted Pulse Generators and Directional Leads for DBS: An Exercise in Ethics

Resident:  Regarding the use of non-rechargeable implanted pulse generators and directionally steerable leads, isn’t the situation one of “penny wise, pound (English equivalent of the dollar) foolish”?

Attending:  That depends on who is spending the penny and who is spending the pound.

Clinicians now have choices in the type of implanted pulse generator (IPG) and directionally specific leads to use in providing patients Deep Brain Stimulation (DBS).  For example, the clinician may implant the rechargeable or a non-rechargeable IPG.  Clinicians can chose  DBS leads with electrode contacts that are segmented, or in pieces, around the lead.  Previous leads had contacts that were continuous around the circumference.  The advantages and disadvantages are reviewed here.    Whether a rechargeable IPG or directional lead is ultimately used, perhaps the more important part of the selection process is how the decision was made.

Shaping and positioning the volume of tissue activation relative to the regional physiological anatomy surrounding the DBS lead’s electrical contacts is critical to successful DBS therapy.  Leads with continuous circumferential contacts can allow for positioning in the long axis of the lead but not in the plane orthogonal to the long axis of the lead.  For example, if the DBS lead in the subthalamic nucleus is too anterior, and therefore is close and parallel to the posterior limb of the internal capsule, positioning the volume of tissue activation in the long axis may not avoid tonic contractions at stimulation currents necessary for symptomatic relief.  For these patients, there may be no other choice but complete surgical replacement of the DBS lead.

With leads whose electrical contacts are segments in the plane orthogonal to the long axis of the DBS lead, it may be possible to stimulate through the posterior projecting segment, thereby avoiding stimulation of the posterior limb of the internal capsule.  This may allow the patient to benefit and avoid a second DBS lead implantation surgery.  However, it is also possible that the patient receiving the DBS lead with continuous circumferential contacts may settle for compromised benefit, a phenomenon this author describes as the tyranny of partial benefit.

The situation of having to undergo a surgical revision of the DBS lead or to compromise on benefit may not occur very frequently.  In advanced centers, the need for DBS lead surgical revision may be on the order of 2%.  At one institution, it was 10%.  Unfortunately, these percentages do not include those who elect compromised benefit.  Even if these occur 10% of the time, the problem is there is no way to predict which individual patient out of 10 will have compromised benefit that could have been prevented by placement of a directional DBS lead.  If the clinician decides that it is of sufficient value to do all that is reasonable to avoid the potential problem, he or she may elect to place the directional DBS lead in every patient.

One significant advantage of the rechargeable IPG is the reduction in the number of surgeries required to replace expended IPGs.  The reduction in the number of surgeries significantly reduces the risk of infections that could require explantation of the entire DBS system, failure of therapy, and surgery to implant a completely new DBS lead.  The increased risk of infection is not simply additive.  Each surgery increases the risk for the subsequent surgery because of the accumulation of relatively avascular scar tissue.

Another significant advantage relates to postoperative DBS programming.  Initially, much of the strategy underlying DBS programming was directed first at maintaining battery life with non-rechargeable IPGs.  Minimum pulse widths, frequencies and stimulation currents (voltages) were recommended (Montgomery Jr., E. B., Deep Brain Stimulation Programming: Principles and Practice, Oxford University Press, 2010).  Those recommendations remain true when non-rechargeable IPGs are used, but they may no longer hold true with the advent of rechargeable IPGs.

In either case, the endpoint was giving the patient satisfactory control of symptoms, signs and disabilities.   Whatever currents (voltages), pulse widths, frequencies, and electrode configurations necessary for sufficient control dictated programming.  However, starting at minimal stimulation parameters and electrode configurations often would require considerable and extended programming efforts.

With the use of rechargeable systems, minimizing current drain from the IPG battery is no longer the first concern.  Thus, decisions about pulse width, for example, can be driven by what is clinically optimal rather than what is minimal in terms of battery depletion.  There is considerable evidence that starting at a pulse width of 120 microseconds may be the most effective when compared to the typical starting pulse width of 60 or 90 microseconds (Montgomery Jr., E. B., Deep Brain Stimulation Programming: Mechanisms, Principles and Practice, 2nd edition, Oxford University Press, 2016).  This alternative approach, which is based on what is electrophysiologically optimal rather than what is electronically optimal,  may greatly simplify post-operative DBS programming.  This could translate into greater efficiency, which translates to earlier and better symptomatic control and less expense.

There are disadvantages to consider, the first of which is the risk of IPG failure due to lack of adequate recharging.  Certainly, there are case reports of catastrophic exacerbations of symptoms, signs and disabilities of the disease being treated.  Further, there have been reports of a neuroleptic-malignant-like syndrome in patients with Parkinson’s disease following IPG failure.  However, this does not appear to be a common problem with the accumulating experience gained from using rechargeable systems.

The second disadvantage is related to the greater costs of the rechargeable IPG, although it is not clear what drives the increased costs.  It is this increase in costs, and who ultimately bears the burden of those costs, that is the source of ethical difficulties.

The ethics of the rechargeable versus non-rechargeable IPG and directional versus non-directional DBS leads

If there were no financial cost issues, it is likely that there would be little opposition to the preferred use of rechargeable IPGs or directional DBS leads.  That patients are not being offered rechargeable IPGs or directional DBS leads suggests other factors are at play, and these are not solely medical or what is in the best interest of the patient.  This is not to suggest that considerations other than the best interest of the patient are not relevant, but rather the issue is how these other interests  are leveraged in the decision-making process.  Thus, the question is one of ethics.

A strategy in resolving ethical questions is to identify the shareholders (those that have the power to shape the decision) and stakeholders (those that are affected by the decision).  Clearly, the surgeon implanting the IPG is a shareholder.  The person paying for the IPGs is a shareholder; typically this is a governmental organization or a commercial insurer.  Indirectly, IPG and DBS lead manufacturers may be shareholders to the extent that they influence cost considerations and market to surgeons, governmental organizations and commercial insurers.

It is not exactly clear how the patient or the patient’s representative acts as a shareholder.  In the negative sense, the patient or representative could deny the use of the IPG or DBS lead offered.  To use the IPG or DBS lead against the consent of the patient or representative could constitute the criminal act of battery.  However, it is not clear how the patient can compel the use of one IPG or DBS lead over others.

Even with the lack of a patient’s or representative’s power to compel the use of a specific IPG or DBS lead, there remains the requirement of the surgeon to obtain informed consent.  This means that, at a minimum, the patient or representative must be informed of all the reasonable alternatives and the implications of the choice.  Note, it is not what the surgeon considers reasonable; rather it is the information a reasonable patient or representative would want to consider in their decision-making.  The advantages and disadvantages described above would be relevant to obtaining informed consent.

What latitude the surgeon should allow the patient or representative in the IPG and DBS lead decision-making is unclear.  Typically, the answer  is linked to what is considered to be the standard of practice.  Do similarly-situated, reasonable surgeons offer the patient or representative the choice?  If so, then every surgeon is bound to offer the patient or representative the same choice.

Surgeons and the patient community (meaning the patient, family members, caregivers and others affected by the health of the patient) are stakeholders.  Also, society at large may be a stakeholder.  There is another very important stakeholder, those responsible for the postoperative management of the patient.  It is critical for all to understand that the benefits of DBS, particularly as these outweigh the risks and costs, only accrue with actual brain stimulation.  Up to that point, including surgery, it is all risk and cost.

Stakeholders who are not direct shareholders, such as neurologists providing the postoperative management, can become shareholders to the degree that direct shareholders, such as surgeons, cede some shareholder status.  For example, surgeons could acquiesce to neurologists responsible for the postoperative management.  It is not clear that this is the usual practice or that neurologists would be expected to share in the IPG or DBS lead decision-making.

Balancing shareholder’s and stakeholder’s interests

The relations between all the shareholders and stakeholders are complex and almost always involve some conflict of interest.  For example, whoever “pays the bill” will be in conflict with the stakeholders if the reasonable choices involve differences in costs.  How then does one resolve the conflicts of interest?

Ethical principles relate to how people treat each other.  At times, these ethical principles are codified in law or legal case precedents.  More commonly, and for a variety of reasons, conflicts between shareholders and stakeholders are “settled out of court.”  In order to apply ethical principles, it is helpful to examine the pair-wise relationships among and between the shareholder and stakeholders.  Once all the relationships are identified, one examines how these relationships relate to the specific ethical principles.  One set of ethical principles includes autonomy, beneficence, justice, and non-malfeasance.  The last term, non-malfeasance, means not causing harm rather than making a medical mistake.

Autonomy, in its most general sense, means respect for the patient as the ultimate stakeholder.  This does not mean that the patient has the final decision.  As noted, the only absolute final decision available to the patent or representative is to forego the medical care offered.  However, the patient or representative must be given a full and complete understanding of what the patient or representative is being asked to decide.  But autonomy is not unidirectional.  The surgeon as an agent may have autonomy, though not in the sense that the surgeon has unconditional decision-making authority.  One notion of autonomy is taken from the work of Immanuel Kant, in which each person is an end unto him or herself first and not a means to someone else’s end.

Beneficence is the motivation to do good.  In biomedical ethics, it is not necessarily an obligation to do good in that the failure to do good is a failure of the ethical principle.  Typically, one is not obligated to enter a burning house to rescue someone.  There may be some obligation if the person is a firefighter.

Non-malfeasance is not to do harm.  However, even this is conditional.  In the course of providing beneficence through DBS lead implantation, the surgeon will create harm if for no other reason than making an incision in the scalp.  Thomas Aquinas in his Summa Theologica (1485 C.E.) provided some guidelines to balancing beneficence and non-malfeasance in his Principle of Double Effect.

Justice is perhaps the most difficult principle to define.  What justice is relates to the prevailing moral theory.  For example, in Utilitarianism, what is just is that which has the greatest benefit, however that is defined.  Most cases of ethical conflict arise when consideration of the principles of beneficence, autonomy, and non-malfeasance fail to create consilience among all the shareholders and stakeholders.  In these situations, the consideration of justice, interpreted in light of the prevailing moral theory, is used to adjudicate the result.

The patient or representative.  On the axis of beneficence, nearly all shareholders want good for the patient.  The sticky question is what is the obligation of shareholders to beneficence.   This can be considered in terms of cost (malfeasance or harm) to the shareholder.  In the absence of any cost, shareholders are expected to provide beneficence.  When there is a cost to the shareholder, then other considerations are required.

Typically, the obligation to beneficence on the part of the governmental organization or commercial insurer to the patient is contractual, thus invoking a Libertarian theory of justice.  The Libertarian moral theory holds the maximum good is the greatest freedom.  What prevents anarchy is the willingness to give up some freedom in exchange for some beneficence, for example a functioning society.  In the case of a commercial insurer, the freedom exchanged is obligation to pay for the beneficence given to the patient in return for something of value, such as wealth in the form of a premium.  The contract that exits between the insurer and the patient is what has been mutually agreed to and includes societal laws which mediate the contracts.  Thus, whether or not a rechargeable or non-rechargeable IPG or a directional DBS lead is implanted may be stipulated in the contract, more or less.

Based on a Libertarian moral theory, the obligation to beneficence on the part of surgeon to the patient is less clear.  The patient or representative lacks knowledge of sufficient detail to be expected to negotiate a contractual agreement to bind the surgeon.  It is the standard of practice in the profession and governmental laws and policies that define the surgeon’s obligations to beneficence.   Within those constraints, the patient has every right to expect beneficence and at the very least to be fully informed of all reasonable alternatives, such a rechargeable IPGs and directional DBS leads.  The problem arises when the surgeon becomes an agent for the governmental organization or commercial insurer and limits or conditions the expected beneficence; unless of course, the patient or representative are in full understanding that the surgeon also is acting as an agent for those other than the patient.  On the axis of autonomy, the patient or representative has the right to be fully informed by all shareholders and surgeons, as well as those paying the bill.

A significant difficulty ensues where explicit laws and contract terms are not available.  Typically, such contracts are not so fine grained.  Often, analogous situations can be sought to gain some notion of precedence, legal or otherwise.

Other moral theories will define justice differently.  For example, an Egalitarian moral theory would suggest that either all or no patients could expect a rechargeable IPG or a directional DBS lead.

The surgeon.  The notion of autonomy extended to the surgeon is complicated.   Again, borrowing from Kant, the surgeon is an end in his or herself and not as a means to others.  The means that the surgeon is subjected to cannot outweigh the surgeon’s own ends.  In other words, the surgeon cannot be expected to sacrifice his or herself where the costs to the surgeon exceed the benefit in return.  In other words, the surgeon cannot be expected to assume harm or malfeasance.

The surgeon’s obligation to benefit the patient is complex.  In part, the obligation is contractual.  The surgeon is granted a privilege that others are not, analogous to a monopoly.  Not just anyone can practice surgery.  That privilege is granted in exchange for an obligation to patients that are citizens to the state or province that grants such privilege.

Another implicit contractual obligation is to the citizens who subsidized the surgeon’s education, allowing the surgeon the privilege of being a doctor.  It is highly unlikely that any physician bore the full cost of his or her education.  Otherwise, becoming a physician is like a lottery prize and a matter of luck.  Just because an applicant to medical school may have the highest grades, there is no obligation for the citizens to award that person what amounts to a lottery prize free of obligation.

A problem arises when the surgeon assumes the limits to obligations from governmental organizations or commercial insurers as an agent prior to and in the absence of consent by the patient or representative.  In other words, the surgeon cannot be the agent for the government or the insurer without prior consent of the patient or representative.  Thus, the surgeon has an obligation to at least offer rechargeable IPGs or directional DBS leads, though the surgeon is not expected to bear the financial consequences.  It is up to the patient or representative to make a decision based on the patient’s situation.

The neurologists and those providing postoperative management.  As stated, the only benefit that is accrued is when the stimulation has been initiated and optimized.  Thus, the surgeon’s responsibility extends beyond the implantation of the DBS systems; he or she must ensure appropriate postoperative management.  The neurologist and others providing the postoperative management are extensions of the surgeon’s obligations to beneficence.  Hence, surgeons have an ethical relation to the neurologist and those providing postoperative management.  These obligations are to beneficence, autonomy, and justice, to the neurologist and others providing postoperative management.

Those providing the postoperative care should be provided the means to do good.  At the first analysis, the question becomes who is best to decide which DBS systems, rechargeable IPGs and directional leads, is most optimal for the patient.  Unless the surgeon is also an expert in postoperative DBS management, then it is the neurologist and those providing the postoperative management who are in the better position to judge.  Hence, the surgeon has the obligation to autonomy that is respecting the judgment of those providing postoperative care.  The best way to fulfill that obligation to autonomy is to preoperatively engage the neurologist and those providing the postoperative management in the decision-making process.

The governmental organization.  Typically, the ethical obligations related to governmental organizations center on the concept of sovereignty as codified in laws and regulations.  However, given the complexity of the human condition, particularly in disease, it is impossible to anticipate every eventuality in a fine-grained manner.  Further, laws that are too vague in order to be all-encompassing generally fail legal challenge.  Laws can be expanded in range by appending concepts such as standards of practice, appeals to what the reasonable person might do, and case precedence that provides context.  Certainly, all other shareholders and stakeholders have obligations of autonomy, non-malfeasance and justice to governmental organizations.  It is not clear whether this extends to an obligation of beneficence to the government that goes beyond the more contract-like obligations to laws and regulations.  Further, one would always hope that the citizens could change the laws and policies through their representatives in government.

Commercial insurers. This term is used in the context of those paying the bill but excludes governmental organizations.  In the United States, private insurance companies, rather than Medicare or Medicaid, would be the subject.  For commercial insurers, issues of obligation center on contracts.  Typically, obligations of beneficence to patients are limited to contract specifics and law, except certain mandates resulting from the Affordable Care Act of 2010.  Notions of obligations to the standards of patient care typical of physicians and healthcare professionals do not figure in relations with commercial insurers.  Indeed, the Employee Retirement Income Security Act of 1974 (ERISA) have written this distinction into law.

For-profit commercial insurers have an obligation of beneficence to their shareholders that clearly risks a conflict of interest with respect to the insurers’ obligations of beneficence to the patients whose healthcare the insurers pay.  How these conflicts in the obligations to beneficence are resolved is unclear.  In societies where the majority of care is covered by commercial insurers, there is a need for stable and successful insurers.  The question that remains is what is the price of stability extracted from patients and the rest of society.

There is a presumption among laissez-faire capitalists that in an open and free market, the “invisible hand” of the market would optimize the relationships between insurers and insured.  However, the healthcare market is anything but open and free, and thus the assurances of laissez-faire capitalism are suspect.  Generally, patients or representatives are not free agents, as they cannot exercise independent judgment based on sufficient understanding.  Depending on anyone else, the patient becomes married to the advisor’s interests and obligations.

At first, it would seem that the contractual nature of the relationships between commercial insurers and the patient, surgeon, neurologist and those providing postoperative management would be straightforward, but this would be naive.  In the 1980s, insurers wielded threats of non-renewal of contracts with healthcare providers to enforce obligations to the insurers beyond those stipulated in contracts, such as gagging physicians from educating patients and representatives about options based solely on medical concerns.

Society.   Clearly, society is a stakeholder in the medical decisions made.  Ultimately, society will pay in one way or another if a rechargeable IPG or a directional DBS lead is not offered.  There will be harm done to the national “pocketbook,” as well as the nation’s reputation, even if the scale of such loss is minuscule by national standards.  But if society holds that healthcare is a right, by whatever justification, analogous to a person’s civil rights, then just as it is hard to accept that only 99% of citizens have their civil rights respected, it would be hard to accept patients not be offered rechargeable IPGs and directional DBS leads.  To think otherwise is to say that some person’s rights are expendable.

The preamble to the Declaration of Independence of the United States holds that a person’s right to life, liberty and the pursuit of happiness is based on Natural Law.  However, the arguably does not to have the force of law.  Rather, the practical operations of government seem to hinge on enlightened self-interest.  Shareholders may force actions on stakeholders when the shareholders see themselves at risk.  In healthcare, there are quarantines, reporting of communicable diseases and gunshot wounds, and forced vaccinations, among other measures.  The notion that healthcare is a right that must be supported by all citizens reflects a deontological or Kantian moral theory.  The alternative that everyone has a right to enter into a contract to obtain healthcare, but not necessarily to be guaranteed healthcare, is in line with a Libertarian moral theory.

Medical care has advanced to a point were risks can be increasingly compartmentalized.  Diseases among certain stakeholders are no longer seen as a risk to the shareholders.  Tuberculosis in a stakeholder may readily constitute a risk to the shareholder and thus invoke public health law measures.  It may well be that a stakeholder’s Parkinson’s disease is not seen as a credible threat to a shareholder.   The risk of Parkinson’s disease for any shareholder is likely small and the means to mitigate any effect should the shareholder develop Parkinson’s disease may not require optimal DBS treatment utilizing rechargeable IPGs and directional DBS leads.  The new Golden Rule may have become, do onto others what you would want done for you, unless you can avoid it.

Risk management

Support of beneficence to patients in the context of health insurance has always been an issue of risk management.  In the Egalitarian moral theory, risk management is the amortization of risk over the entire citizenry.  The healthy pay more in comparison to what is spent on them as a way of paying forward when the healthy later become ill or disabled.  However, this is difficult.  Ask any young healthy person whether they would want a rechargeable IPG or directional DBS lead in the possible (but unlikely) future, they may say yes in the abstract; but test their willingness to pay for even a part of it now.  It is not surprising that the “individual mandate” was seen as critical to the success of the Affordable Care Act and how any insurance program that does not include some aspect of the “individual mandate” is not likely to be successful.

Another approach to risk management is risk avoidance.  There are as many types of risk avoidance as there are obligations to beneficence.  For example, an insurer, either governmental or commercial, has an obligation to beneficence to the patient.  However, constraining the beneficence can mitigate the risk entailed.  This can be seen by the exclusion of coverage for pre-existing medical conditions, caps on benefits, and panels of providers that are insufficient or impractical to meet the patient’s needs.  A simple way to avoid having to provide the beneficence of a rechargeable IPG or directional DBS lead is simply to not have a surgeon in the network of providers willing or able to provide DBS at all.  Managing the beneficence to the surgeon in order to avoid risk can be accomplished by capitation or reimbursements that effectively make provision of a rechargeable IPG or directional DBS lead too costly to the surgeon.

A final answer?

The purpose here is not to demand a specific answer to whether a rechargeable IPG or directional DBS lead should be offered, though the author’s sympathies should be fairly apparent.  In biomedical ethics, context is all-important; and thus, flexibility in the answers likely is necessary.  However, flexibility is not license for any particular shareholder to do as they please.  Rather, whatever decision is reached in any particular situation should be based on a full and disciplined assessment of all the concerns of all those involved.