Late local and remote structural changes after capsulotomy for obsessive compulsive disorder.

Stereotactic subcaudate capsulotomy (SC) is used to treat medically intractable obsessive compulsive disorders (OCD). Although clinical improvement has been observed, post-SC structural correlates are lacking in this biological disorder. Our study provides imaging evidence for local and distant alterations in structures which may have an important role in the manifestations of OCD. Five OCD patients treated with SC received MR imaging for pre-SC planning, early (1-7 days) post-SC assessment, and late (5-12 months) follow-up. The volumes of the anterior limb of the internal capsules, caudate heads, third ventricle, mamillary bodies, thalami, and hippocampal formations were digitally computed. Volumes from each of the serial imaging studies were compared. At 5-12 months post-SC, all patients showed reduction in volume of the anterior limbs of the internal capsules, caudate heads, thalami, and increased volume of the third ventricle (reflecting thalamic/caudate atrophy). 2-5 patients showed reduction in hippocampal formation volume. The post-SC reduction in volume of these structures, some far distant to the stereotactic lesion, suggests that the interrelationships of the anterior limb of the internal capsule, the caudate/thalamic nuclei, and possibly the pallidal and limbic systems are necessary for the manifestations of OCD and their variants.