Up to 40 % of Obsessive-Compulsive Disorder (OCD) patients remain refractory to conventional treatments. For them, an improved, Gamma Knife radiosurgery (Gamma ventral capsulotomy - GVC) was recently developed.

     We report the results from a pilot study with this technique, as well as from the first double-blind, randomized controlled trial (DB-RCT) of its kind.

     Twenty one refractory OCD patients were selected. The first five patients were included in a pilot study. The other 16 subjects randomly received either active (8 patients) or “sham” (7 patients) radiosurgery, as a DB-RCT. One patient remains under blind condition.

     Double-shot, 4 mm collimator lesions were produced at the ventral portions of the anterior limb of the internal capsule. Psychopathological, clinical, and neuropsychological assessments and magnetic resonance scans were provided pre and post-operatively.

     One to five years of follow-up assessments are available. Three out of five patients (60%) from the pilot study and three out of eight patients (37.5%) from the blind active group became responders. As a whole, six out of thirteen (46 %) patients who received active radiosurgery responded, while no patients of the sham group responded, for 12 months of blind follow-up. Statistically significant differences between active and sham groups were observed for OCD symptoms scores (non-parametric analysis of variance, QW=6.760, 1 d.f.., p=0.0093). Mania, delirium, episodic headaches, dizziness, nausea were few times observed. One patient presented a cyst and a floating course of cognitive changes. No other adverse neuropsychological or personality changes were observed.

     This is a retrospective study.

     Preliminary findings indicate that GVC for OCD shows some efficacy.

     There were relatively few adverse effects.