BoN in DBS postoperative adjustment process

Being an invasive treatment, DBS is often considered as the last option in cases where patients with severe, debilitating and treatment-refractory illness cannot be treated with pharmaceutical drugs. The current generation of DBS treatments have, in the main, been approved to treat Parkinson's disease, essential tremor and dystonia. DBS has also been used in many trials to treat psychiatric conditions such as severe depression, obsessive-compulsive disorder, Tourette's syndrome, obesity, epilepsy, Alzheimer's disease, impulsive and aggressive behaviour, and addiction.14 In terms of clinical ethics, it is worth asking whether the use of DBS may have unanticipated negative effects similar to those associated with other types of psychosurgery.15

As seen in the introduction, clinical studies of epileptic populations who have received ATL identified a range of side effects and complications known as the BoN syndrome. In many cases, patients express difficulty adjusting to their new status as seizure free. A fundamental characteristic of the BoN syndrome is that self-changes are not directly related to clinical side effects of mood disturbance, but rather are independent and associated with the psychological experience of becoming seizure free.9

There is growing evidence of postoperative adjustment issues within populations of patients treated with DBS.2–4 ,16 Although significant in number,2–4 ,16 challenges associated with postoperative DBS outcomes have not been articulated in terms of a syndrome. It is important to consider the difference in treatment of ATL for epileptic patients and DBS for Parkinson's patients (ATL is irreversible, while with DBS the stimulation can be switched on and off) and recognise that epilepsy and Parkinson's patient populations differ significantly in the nature of their disease. However, when comparing the types of change within both populations, many similarities appear. In terms of the BoN syndrome (table 2), the four types of change in patients with epilepsy who have received an ATL align with the major types of change within DBS Parkinson's patients who find it difficult to ‘reintegrate into a normal familial and social life’ despite improvement in motor disability function.3

Table 2 is presented only as a sampling of evidence of adjustment responses within epilepsy and Parkinson's patients; it provides a set of examples and is not meant as an extensive representation of all possible postoperative responses. Table 2 illustrates that postoperative psychosocial adjustments are not unique or specific to epileptic patients; it also captures the difficulties experienced by Parkinson's patients who have undergone a successful DBS treatment; the BoN syndrome is a postoperative response shared by these two different types of patient treated by distinct kinds of psychosurgery. As such, the ‘type of change’ appears mostly independent of the kind of treatment received by patients. Given the similarities in the ‘types of change’, articulating postoperative DBS adjustment responses in terms of the BoN syndrome helps us to see that the changes experienced by different patient populations are compatible.

However, the mere fact that the phenomenon occurs in two types of effective brain surgery treatments for chronic neurological disorders does not at all imply that it is relevant to all types of effective surgical treatment. In other words, it is not only the change from ‘chronically ill’ to ‘symptom free’ that guarantees the BoN phenomenon to occur; otherwise after knee- or hip-surgery the BoN could be observable in a high percentage of patients. In general, the BoN seems to be statistically observable within postoperative intervention related to brain surgery. One way to understand the statistical correlation between brain surgery for neurological disorders and the phenomenon of BoN is to understand that direct interventions in the brain increased probabilities to affect neuronal regions associated with personality and self.2–4 ,16 In contrast, for example, with surgery to the knee or hip, which are mostly motor-articulation parts of the body, the sense of what a patient makes of himself is inseparable from his brain. This connection between the brain and the sense of the self illustrates that psychosurgery, like DBS or ATL, raised higher probabilities of resulting in a phenomenon such as BoN compared to other medical interventions which involve motor-articulation parts of the body, such as such knee or hip surgery.

In terms of DBS, the BoN syndrome does not rule out that brain surgery, electric stimulation, drug reduction or neurodegeneration due to pathology, might influence a patient's perception of himself. Given that epileptic and Parkinson's patients share BoN syndrome features, it seems that ‘type of change’ in table 2 is not strictly a side effect of the DBS or ATL, but rather a response to effective treatment. In other words, it is the reduction of pathological symptoms related to brain surgery in different patient populations—they share the experience of becoming well, which causes similar postoperative responses. The BoN syndrome seems to take its origin in postoperative response improvements of neurological disorders, rather than in the type of brain surgery treatment. The BoN syndrome suggests that postoperative self-changes are a response of being symptom-free of neurological disorders.

Ethical concerns: is the BoN syndrome evidence that DBS poses a threat to patient's identity?

It has been argued that DBS postoperative change in a patient's identity ‘is alarming’ and ‘is one of the most urgent conceptual and ethical problems’.17 As the above table 2 indicates, some patients declare: “I don't feel myself anymore”, “I haven't found myself again after the operation”.4 However, should it be concluded that the BoN syndrome illustrates that DBS may pose a threat to a patient's identity? Following a successful intervention, the reduction in symptoms does not just affect the person's functioning—the ability of the brain to achieve or approximately accomplish what we take to be normal human capacities; it also affects the phenomenology of experience, that is, the individual's subjective conscious experience of himself, his body and the world around him. Radical life change from the instability of being ill to the stability of being better, due to an efficacious treatment, does not necessarily introduce continuity in identity. Self-image narrative extends across time, pre- and -operation. For some, DBS may generate a biographical disruption,18 ,19 or a break in psychological unity which may problematise patient responsibility for action and decision-making competence.20 But to what extent is the BoN syndrome evidence that DBS is a menace to a patient's identity?

The current DBS postoperative adjustment literature represents an eclectic photograph: some patients seem to suffer from BoN syndrome when they experience a loss of their ‘ill-image’ narratives after stimulation, whereas others describe that being symptom free after stimulation helped them to find their ‘true selves’.2–4 ,16 ,21 What is more, some patients experience continuity between themselves after stimulation and the persons they had been before Parkinson's disease.2–4 ,16 ,21 Within these eclectic reports, the BoN syndrome does not illustrate a threat to the identity per se, but rather suggests that chronic symptoms can be integrated components of patient self-image. What is at stake in cases of the BoN syndrome is that the postoperative self-narrative might simply not cope with the psychosocial consequence of emerging from the absence of symptoms.

In reported cases of DBS treatment associated with personality changes, the BoN syndrome might be explained by an abrupt transition in a patient's self-image which is concurrent with the reduction of the symptoms.9 Although the symptoms are fundamental parts of a patient's self-narrative, the relatively sudden alleviation of chronic symptoms in some patients may result in difficulty in discarding the pathology from their self-image. Patient psychosocial difficulties associated with learning to live as free may be correlated with key identity development periods. Wilson et al9 observed that the greater changes in self-image were associated with seizure onset during, or before, adolescence, and lesser changes in self-image were linked with adulthood onset, and that this might reflect an already established sense of self during adulthood.9 In terms of DBS treatment and the potential threat to a patient's identity, this suggests that change in self-image would therefore be proportional to the early onset of the pathology.

Under this description, it is difficult to see the BoN syndrome as an incarnation of an intrinsic threat to patient's identity. For instance, in some cases, although DBS did not successfully treat the symptoms, patients' postoperative perspective is surprisingly positive.22 In others cases, patients are regarded by their doctors and relatives as ill-adapted after successful stimulation; however patients seem to feel subjectively better.2–4 It appears that the BoN syndrome can occur when the doctor's perspectives differ from the patient's subjective experiences. A distinction between an internal perspective (patient's perspective) and the perspective of external, third- or second-person who judges a patient to beill-adapted (doctors, family members) illuminates heterogeneous narratives. From a patient's perspective, after successful stimulation, the BoN syndrome may reflect how one feels after losing the narrative of being chronically ill (loss of coherence of the self)—and maybe the privileges that go along with being recognised as sick by a third-person perspective. While there is no single understanding of how normality is defined from all perspectives, the BoN syndrome seems to emerge when there is an unexpected outcome from the first-person perspective (there is something wrong with me since the intervention, I did not expect this) and third-person perspectives (doctors and family members say the symptoms are gone, therefore the patient should be well). However, perspectives, built on years of chronic sickness cannot disappear as fast as symptoms, especially when symptoms are abruptly stopped by DBS. Consequently, there is a danger of imposing a ‘forced normalisation’: requiring patients to incorporate ‘a change in self-image which is concurrent to the improvement seen in their illness’.5

From the phenomenal experience of being ill to the subjective perspective of being symptom free, a patient needs to exercise an ongoing narrative. A person's capacity to reinvent her self-image does not take place in a series of disconnected experiences. The heterogeneity of her own narratives extends across time but also across all perspectives (doctors, relatives and patient). Interactions between all perspectives reveal that a conception of identity based on relational components might be more adequate to address the ethical issue of the BoN within postoperative DBS patients.23 The notion of relational identity helps to understand that a successful intervention followed by the BoN syndrome does not necessarily threaten all of the patient's narratives.23 While DBS may result in profound changes in characteristics closely linked to personality, it does not necessary imply a challenge to pre-existing narratives since any sudden event or experience integrated into one's identity-constituting narrative could potentially disturb post-adjustment process.23

Rather than being a threat to identity, the BoN syndrome associated with DBS treatment illustrates the idea that a patient's illness is intimately linked with their relational identity, especially when the initial onset of the disease interfered with early juvenile self-image. as statistically observed within epileptic populations.9 The clinical phenomenology of the BoN syndrome appears to be the process of discovering that a patient's identity and social relationships are deeply tied to illness, at least more than the patients themselves, and/or their relations, had expected prior to psychosurgery.9 Instead of being evidence of a threat toa patient's identity, the BoN syndrome demonstrates that the role of illness in a patient's identity is often underestimated: “I don't seem to recognise myself without the problems I had before”.3 Correspondingly, the ability to discard illness from self-image may be overestimated: the BoN syndrome reflects that patients do not necessarily enjoy a life unrestricted by symptoms as demonstrated in cases where patient wanted ‘to be recognised as sick’ despite successful treatment.4 This suggests that eagerness to abandon illness from self-image might be proportional to a patient's well-being.21

Though it can be argued that the BoN does not threaten a patient's identity per se, it does not imply that there are no important ethical concerns left associated with a patient's postoperative sense of his or her self. Any brain intervention introduces risk to a patient's self in general; especially when it is related to treatment of a psychiatric condition. Indeed, treatment of psychiatric conditions (ie, severe depression, OCD, etc) involves surgery which targets neural substrates other than motor control dysfunction tissues (ie, dystonia, severe tremors, etc); to some extent it could be argued that it aims at fixing precisely the self. In these conditions, brain interventions always carry an ethical risk of negatively affecting patients; probabilities of harming, in particular, patients' postoperative sense of their self remain significant. These ethical risks must not be neglected.

Ethical obligations: does BoN call for pre- and postoperative DBS responses?

Some may object that discussing an ethical strategy for potential BoN is premature, given the current evidence and given that the concept of BoN is mostly limited to epileptic patients. However, seminal DBS clinical follow-up studies have already called for the need to tackle postoperative psychosocial maladjustment within DBS's patients.2–4 Agid et al report “64% of patients who were working before surgery wanted to stop their professional activity and 65% of those who were married (or lived with a partner) experienced a conjugal crisis after operation”,3 while Schupbach et al report 70% of patients developed postoperative martial conflicts and only 56% of patients restarted their professional work after surgery.19 Moreover, other clinical follow-up DBS studies have been alarmed by the significant worsened mood in patients—25% of followed patients—and raised the importance of being ‘educated about the potential impact’ of the postoperative life.24 These numbers may not be absolute evidence, but at least they are significant numbers that help to anticipate further postoperative ethical obligation. Given that there are no unified measures within the postoperative DBS psychosocial adjustment process, articulating these measures in terms of the BoN syndrome model could enhance the framework towards better ethical rehabilitation. This observation follows previous studies which have concluded that it is possible to apply the BoN syndrome model to patient populations other than epilepsy—narcolepsy patients being one example.7

The BoN syndrome raises ethical difficulties because it illustrates that DBS treatment may result in unexpected outcomes for patients, although there has been a diminution of symptoms, even after many years of follow-up.2–4 ,16 As a result, the ethical question of benefits and risks associated with DBS treatment is raised by the BoN syndrome. Unfortunately, the current limited numbers of follow-up studies or data available in the literature do not help in weighing the beneficial and harmful effects on patients. A first ethical obligation, given the state of our current understanding of the BoN in DBS patients, is to encourage further research.5 This research should assess whether the BoN syndrome is a temporary phenomenon or whether it lasts over years, and also whether it can be reversed by turning off the stimulation. Even if the BoN syndrome vanishes progressively after a few years, it raises a moral obligation to inform patients about the transient character of the phenomenon.

The potential psychosocial risk demonstrates that access to information with respect to the BoN syndrome is a moral imperative. It should be an ethical priority to properly inform future patients of treatment responses that might not be appropriate to the therapeutic goals of the DBS intervention. Access to information regarding the BoN syndrome should also highlight the limits of the treatment, and its potential long-term psychosocial effects, despite diminution of the illness. Families, relatives and care-givers should be informed of the BoN postoperative risks.

A lack of preparedness to deal with the BoN outcomes could make patients and their families more vulnerable and lead to distress. Clinical preparation should focus on introducing regulatory preoperative psychometric self-image measurements to identify links between patient self-image and illness. These psychometric self-image measures could prepare patients in anticipating radical self-change due to abrupt improvement. Pre- and postoperative follow-up should frame a rehabilitation programme for patients.

Potential adverse -term psychosocial outcomes require care-givers to act upon rehabilitation, but also on preventing unrealistic expectations and to proactively address improbable hopes while preparing patients and families for potential changes in narrative.8 High expectations for postoperative life are often represented, first, by patients expecting that psychosurgery will solve most of their issues, and second, by families anticipating that familial dynamics will be untouched, and third, by medical teams predicting that psychosocial outcomes will be better following a reduction in pathological symptoms. Patients and families who are poorly prepared before surgery are more likely to show adjustment difficulties after surgery.10 The BoN syndrome stresses the moral obligation for care-givers to accompany patients throughout their entire care trajectory (from early enrolment to many years after intervention) leading to a better social reintegration and adjustment process. Engaging interdisciplinary teams in pre- and postoperative follow-ups would enhance the effectiveness of managing optimal solutions in the face of the BoN syndrome.