IMPORTANCE: Select cases of intractable obsessive-compulsive disorder (OCD) have 
undergone neurosurgical ablation for more than half a century. However, to our 
knowledge, there have been no randomized clinical trials of such procedures for 
the treatment of any psychiatric disorder.
OBJECTIVE: To determine the efficacy and safety of a radiosurgery (gamma ventral 
capsulotomy [GVC]) for intractable OCD.
DESIGN, SETTING, AND PARTICIPANTS: In a double-blind, placebo-controlled, 
randomized clinical trial, 16 patients with intractable OCD were randomized to 
active (n = 8) or sham (n = 8) GVC. Blinding was maintained for 12 months. After 
unblinding, sham-group patients were offered active GVC.
INTERVENTIONS: Patients randomized to active GVC had 2 distinct isocenters on 
each side irradiated at the ventral border of the anterior limb of the internal 
capsule. The patients randomized to sham GVC received simulated radiosurgery 
using the same equipment.
MAIN OUTCOMES AND MEASURES: Scores on the Yale-Brown Obsessive-Compulsive Scale 
(Y-BOCS) and the Clinical Global Impression-Improvement (CGI-I) Scale. Response 
was defined as a 35% or greater reduction in Y-BOCS severity and "improved" or 
"much improved" CGI-I ratings.
RESULTS: Three of 8 patients randomized to active treatment responded at 12 
months, while none of the 8 sham-GVC patients responded (absolute risk 
reduction, 0.375; 95% CI, 0.04-0.71). At 12 months, OCD symptom improvement was 
significantly higher in the active-GVC group than in the sham group (Y-BOCS, 
P = .046; Dimensional Y-BOCS, P = .01). At 54 months, 2 additional patients in 
the active group had become responders. Of the 4 sham-GVC patients who later 
received active GVC, 2 responded by post-GVC month 12. The most serious adverse 
event was an asymptomatic radiation-induced cyst in 1 patient.
CONCLUSIONS AND RELEVANCE: Gamma ventral capsulotomy benefitted patients with 
otherwise intractable OCD and thus appears to be an alternative to deep-brain 
stimulation in selected cases. Given the risks inherent in any psychiatric 
neurosurgery, such procedures should be conducted at specialized centers.
TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01004302.