The new neurosurgery
The transition from the old psychosurgery to the new, more discrete ablative neurosurgery for psychiatric disorders has been documented in several publications.9 At the technical level, one important innovation was the stereotactic approach and the use of implantable electrodes to perform minute ablative procedures on selected targets. At the ethical level was the US National Commission report on the use of psychosurgery in practice and research10 that suggested guidelines and not, as many had expected, abolition or outside consultation.
MGH began psychosurgery early on and played an important role during the transitional era. Dr Thomas Ballantine, a neurosurgeon at MGH who had been an influential member of the National Commission shaping the guidelines, continued over the years to perform bilateral cingulotomies. A retrospective report of the 198 patients who had a variety of psychiatric disorders and on whom he had performed cingulotomies was published in 1987.11
In fact, a target of choice at MGH and elsewhere in the United States was the anterior cingulate gyrus that Ballantine11 had emphasized. The Neurological Service Web site at MGH claims that staff members have performed more than 800 cingulotomies since 1962.1 Cingulotomy is now the primary neurosurgical procedure used in the United States, while anterior capsulotomy and limbic leukotomy are more prevalent in Europe and elsewhere. However, multiple brain sites have been targeted, and Chinese surgeons believe simultaneous microlesions in several locations produce better results.12
The introduction of ablative stereotactic surgery at MGH in the late 1960s as a treatment for patients who were violent made headlines and created much of the controversy that led to the establishment of the National Commission. Three MGH doctors (a neurologist, psychiatrist, and neurosurgeon) had suggested in letters to the New York Times and the Journal of the American Medical Association that in understanding the race riots of that era it was important to consider the causative contributing factor of biological impairment of the brain among its most violent participants.13
Mark and Ervin,14 who were proponents of this philosophy, had little real neuroscientific understanding of the limbic system or the neural substrate of violence. Nonetheless, they suggested that in certain cases, violence was an epileptic equivalent (temporal lobe epilepsy) and that stereotactic microlesioning of the trigger of violence in the amygdala was a viable treatment for those forms of violence. Mark and Ervin's 1970 publication Violence and the Brain14 was unfairly attacked on racial and political grounds; however, in retrospect they demonstrated the same failings as Freeman: their surgical leap into the brain was based on a woefully incomplete understanding of neuroscience, and they shared Freeman's publicity-seeking hubris. Their preliminary research was publicized in Life magazine—the most important weekly of that era. It is now well recognized that patients with temporal lobe epilepsy are characterized by irritability rather than by violence.15 Extraordinary gains have been made in our understanding of the amygdala—all demonstrating how poorly conceived this surgical intervention was, but the stereotactic approach was used for other disorders and for microablations in many other regions of the brain.
Advances in technology and engineering design have led to the gamma knife procedure, which uses a device capable of irradiating small intracranial targets with gamma ray photons. This ablative procedure does not require surgical incision and claims increased accuracy. Instead of burning or freezing brain particles to achieve the desired lesion, gamma radiation deranges molecules in the target cells so that they can no longer survive. This means that the lesions develop over months and must be monitored through the repeated use of MRI. A preliminary study of gamma knife capsulotomy in cases of severe OCD at Brown University School of Medicine found that 40% of patients who had undergone 2 lesioning procedures were significantly improved 2 years postsurgery.16
In patients with severe treatment-refractory OCD, none of these procedures is clearly more beneficial. The gamma knife procedure, however, has the advantage over stereotactic surgery and DBS of not requiring burr holes and of lacking other rare neurosurgical risks involved in implanting electrodes. MGH established the efficacy of the stereotactic ablative procedure as a treatment for refractory OCD in a landmark article published in the American Journal of Psychiatry in 2002; the authors included the then-chairman of the MGH department of psychiatry.17 It can be considered the launching pad of the new era of neurosurgery for mental disorders. This follow-up study reported significant improvement in one-third of patients and modest improvement in others.
Cause for Concern
As one reviews the careful selection criteria and procedures at a center such as MGH, which is considered the model for China, after the recent scandal, important ethical questions remain unanswered. A major concern is that there is still no system of extra- institutional review. MGH was never required to seek the opinion of an expert who was not a member of the hospital's own staff. Despite the interdisciplinary participation of psychiatrists, neurologists, and neurosurgeons, if they function within one hospital, there exist well-known psychological constraints and pressures for conformity. A second concern is whether a patient with intractable OCD can provide his or her informed consent to the procedure. (MGH involves the family in the informed consent process, but it is the patient who must provide the formal written consent.) The UN's convention sees the external review as a check both on the need for this treatment and on the validity of the informed consent.
A third problem is that although doctors who refer to MGH must attest that their patients have been "refractory" both to medication and to cognitive-behavioral therapy (CBT) before they are accepted for surgery, it is difficult to determine without direct supervision whether there was real adherence to these treatments. Even more problematic, MGH's Web site offered the possibility of neurosurgical treatment to patients who are 18 years and older.1 Given what is now known about continuing brain development, this seems inappropriate and unwarranted. Thus, in my opinion, even if one accepts the practices in place at MGH, this should not be considered a model program for centers around the world.
As to the efficacy of the new neurosurgery, perhaps the most carefully studied patients are those who have been treated for intractable OCD with stereotactic cingulotomy. In its recent guidelines for the treatment of OCD, the American Psychiatric Association considered the efficacy of the procedures and of the ongoing changes in technology. "Improvement rates [in intractable cases] have ranged from 35% to 50%. . . . the unblinded nature of these studies and the ongoing treatment [eg, medications and CBT postsurgery] of many patients limit interpretation of these results."18 The guidelines go on to say that the recent development of less invasive DBS makes it harder to consider ablative neurosurgery as an alternative to highly treatment-resistant or intractable OCD. This seems to be a sensible and prudent judgment.
DBS represents a potential advance over traditional lesioning techniques in that neural tissue is not permanently burned or destroyed in the procedure. It involves surgically implanting tiny electrical stimulators on either side of the brain that are connected to a pacemaker-like generator. When turned on, the impulse generator delivers low-voltage electrical pulses to specific targets in the brain. The procedure is both reversible and adjustable. Early studies at MGH and elsewhere have demonstrated that DBS may provide significant relief to those with severe, treatment-refractory OCD, with improvement rates ranging from 25% to 50%.16
A further scientific benefit of DBS research is the possibility of using sham-controlled studies and within-patient designs. DBS for OCD is still in its infancy; neurosurgeons and the medical community are not fully certain about how the stimulation works, but it appears that the electrical stimulation disrupts the abnormal neural firings. During an invited lecture at Harvard University, the well-known neuroscientist Antonio Damasio, in answer to a question, said that in principle he had no objection to psychosurgery. Presumably, he was suggesting that there is no reason to consider the brain as a sacred organ and not as an object of scientific scrutiny. It may not be sacred in principle, but there is still the question of whether we know enough neuroscience to comprehend what we are doing when we produce small ablative lesions in this extraordinarily complex organ.
The overarching ethical question remains: do we know enough neuroscience to know that we are not doing more harm than good in the long run? Indeed, that is what makes the introduction of DBS such an appealing alternative; it promises to increase our scientific understanding while providing comparable benefits without destroying brain cells. Given the historical burden of the old psychosurgery, the new neurosurgeons have a special obligation to proceed with utmost scientific caution.