Neurosurgical targets for compulsivity: what can we learn from acquired brain lesions?

Treatment efficacy of deep brain stimulation (DBS) and other neurosurgical techniques in refractory obsessive-compulsive disorder (OCD) is greatly dependent on the targeting of relevant brain regions. Over the years, several case reports have been published on either the emergence or resolution of obsessive-compulsive symptoms due to neurological lesions. These reports can potentially serve as an important source of insight into the neuroanatomy of compulsivity and have implications for targets of DBS. For this purpose, we have reviewed all published case reports of patients with acquired or resolved obsessive-compulsive symptoms after brain lesions. We found a total of 37 case reports describing 71 patients with acquired and 6 with resolved obsessive-compulsive symptoms as a result of hemorrhaging, infarctions or removal of tumors. Behavioral symptoms following brain lesions consisted of typical obsessive-compulsive symptoms, but also symptoms within the compulsivity spectrum. These data suggests that lesions in the cortico-striato-thalamic circuit, parietal and temporal cortex, cerebellum and brainstem may induce compulsivity. Moreover, the resolution of obsessive-compulsive symptoms has been reported following lesions in the putamen, internal capsule and fronto-parietal lobe. These case reports provide strong evidence supporting the rationale for DBS in the ventral striatum and internal capsule for treatment of compulsivity and reveal the putamen and fronto-parietal cortex as promising new targets.