Surgical treatment of obsessive compulsive disorders: Current status.

Abstract

Byline: Paresh. Doshi Introduction Surgery for intractable neuropsychiatric illness has generated considerable controversy for a variety of scientific, social, and philosophical reasons. Much of the controversy relates to the widespread and indiscriminate use of psychosurgery in the 1940s and 1950s when no effective psychotropic agents were available. With the introduction of chlorpromazine in 1954, effective medical management led to a rapid decline in surgery for mental illness. Despite the vast array of new, selective psychotropic medications available today, however, many neuropsychiatric illnesses remain refractory and, consequently, some patients remain severely disabled. These patients might be considered appropriate candidates for surgery if the overall result and level of functioning could be improved. Obsessive-compulsive disorder (OCD) is a psychiatric disease characterized by anxiety-provoking thoughts (obsessions) leading to repeated, time-consuming behaviors (compulsions) that may or may not provide temporary relief. With an approximate prevalence of 2 to 3% of the general population and 0.6% in Indian population,[sup] [1] OCD is a debilitating disorder that can significantly affect nearly every aspect of a patient's life, and in some cases, lead to suicide.[sup] [2] In a meta-analysis of a database of the Food and Drug Administration, the annual suicide risk rate in OCD patients with minimal and no comorbidity, participating in a trial of selective serotonergic reuptake inhibitiors (SSRI) was 105/10000 and the annual suicide attempt risk was 1468/100000.[sup] [3] Although OCD has been recognized and studied in the psychiatric literature for nearly a century, only relatively recently has the disease been evaluated in a neuroscientific context. The application of functional imaging techniques, such as functional magnetic resonance imaging and positron emission tomography (PET) scans, to this patient population, coupled with advances in the safety and efficacy of functional neurosurgical intervention, has led to a renaissance of research in this area. Neurobiological model of obsessive-compulsive disorder There is a convergence of evidence implicating the corticostriatothalamocortical (CSTC) loop involving orbitofrontal (OFC) cortex, anterior cingulated cortex (ACC) and basal ganglia as central to the pathophysiology of OCD.[sup] [4],[5],[6] Two distinct routes are conceptualized from the striatum to the thalamus; the so-called and pathways. The direct pathway projects from the cortex to the striatum to the internal segment of globus pallidus and substantia nigra to the thalamus and then back to the cortex. The indirect pathway is similar from the cortex to the striatum but then projects to the external segment of the globus pallidus to the subthalamic nucleus, before returning to the internal segment of the the globus pallidus/substantia nigra, there joining the direct pathway to the thalamus and projecting back to the cortex. Impulses transmitted via the direct pathway disinhibit the thalamus, presumably resulting in a release of behaviors as necessary for an adaptive function. Activity in the indirect pathway inhibits the thalamus, resulting in the cessation of ongoing behavioral routine. The prevailing theory on OCD suggests that a hitherto unknown primary striatal pathologic process underlies a relative imbalance favoring striatothalamic inhibition leading to hyperactivity within OFC and ACC, the caudate nucleus (CN) and the thalamus [Figure 1]. Besides this, prefrontal cortex, cingulated cortex, limbic circuit, OFC, hypothalamus and amygdala are the other structures that communicate with this primary circuits through various feedback loops. This forms the basis of various target sites for treating OCD. Guehl et al. , performed neuronal recordings from CN in three patients before Deep Brain stimulation surgery. These patients had very high Yale-Brown Obsessive Compulsive Scale (YBOCS). …