Hello everyone, I am Dr. Sait Shirin. I am working at Medicana International Ankara Hospital CyberKnife Radiosurgery Center as a neurosurgeon. Today, I would like to share our experience in CyberKnife radiosurgery for interactable obsessive-compulsive disorder. Well, I have nothing to disclose. I would like to start the history of psychosurgery with Egas Moniz, who first introduced prefrontal lobotomy in 1935, and he was awarded with Nobel Prize in Medicine in 1949. Many centers across the world frontal lobotomy was performed, particularly in United States, in very large numbers of patients by Walter Freeman. The rise of neuropharmacology in 1950s and strong opposition against psychosurgery led to fall of psychosurgery. In the last decades, modern psychosurgery tries to get some role in some indications. Those are refractory to all other treatments. One of them is obsessive-compulsive disorder. In modern psychosurgery, there are lesioning procedures and stimulation techniques. Radiosurgery is a lesioning procedure with high dose radiation and it is irreversible. If you look at the history of OCD radiosurgery, Lars Legstad from Karolinska Institute was the first to perform radiosurgery for an OCD patient with X-ray tube in 1953. Then in 1976, he first used GammaKnife to create anterior capsulotomy. There is limited number of centers performing OCD radiosurgery. Some of them are Stockholm, Sao Paulo, Pittsburgh, Charlottesville, Providence, Madrid, and Istanbul. OCD patients may have some of these items as obsessions and compulsions. They are diagnosed using DSM-5. If you look at the indications for OCD radiosurgery, Y-box score should be more than 28. There must be refractoriness more than 5 years to medical and behavior therapy. There are some centers using 65 as the upper limit of age. Of course, there are certain contraindications like comorbid psychiatric disorders that may interfere with treatment. One of the targets to interfere the orbitofrontal striatotalamocortical circuitry is anterior limb of internal capsule. Internal capsule is the right target for radiosurgery. Since the beginning of OCD radiosurgery, there is an evolution in target and dose selection. Coronal plan is better to understand the target selection. At the beginning, bilateral single mid-capsular shot used in Karolinska. Then they used bilateral three shots. Rasmussen and co-workers defined gamma-ventral capsulotomy using bilateral double shots in the ventral part of the capsule. Virginia group simulated gamma-ventral capsulotomy with bilateral single ventral shots. Pre- and post-operative assessment must be done with neurological, radiological, psychometric, and neuropsychological examination. Y-box is the most important test for OCD patients. Scores 24 to 31 are severe, 32 to 40 are extreme. Many centers uses a response criteria defined as a minimum of 35 reduction in Y-box scores. There are limited number of studies and articles on OCD radiosurgery. One of the recent papers is from Madrid by Martinez Alvarez. Gamma Knife experience started in 1976 with Lexel, Beckland, and Reylander. They first used 3x5mm collimator with a maximum dose of 160 to 180 gray. After then, they used three 4mm shots on each side with maximum 200 gray. Brown group first used bilateral single mid-capsule 4mm shot at maximum 180 gray. After observing failure, they repeated radiosurgery by adding another more ventral 4mm shot in 13 of the 15 patients. After this experience, they decided to use bilateral double 4mm shots and named this as gamma-ventral capsulotomy. Very similar to Brown group, Sao Paolo group first did a five-patient pilot prospective study and double shot GVC with 180 gray maximum dose and then a randomized clinical trial including 16 patients. Peaceburg group treated three patients with GVC but lower doses as 140 to 150 gray. Virginia group used moderately low doses in five patients, but they also modified gamma-ventral capsulotomy with bilateral single ventral shots. Madrid group adopted GVC and they decreased maximum dose to 120 gray. In this table, I summarized the recent Gamma Knife experience. Success rate is increasing in the last years around 70%. Centers try to achieve similar results with lower doses. Of course, decreasing dose resulted in less side effects. There is only one paper about Cyberknife experience in OCD patients from Korea. They treated 11 patients using 75 gray first and after having some unexpected complication, they reduced the dose to 50 gray at 80% isodose line. Their success rate was 54.5%. We are using Cyberknife at our center since July 2013. Between 2014 and 2019, we treated 15 OCD patients. Patients had CT, T1, and T2-weighted MR images for planning. Bilateral target volumes were contoured in the anterior limb of internal capsule at mid-peterminal region on axial plane, reaching the base of internal capsule on coronal plane. Target volume delineation simulates double-shot GVC. This is typical Cyberknife planning for OCD at our center. Coronal image shows target coverage very similar to gamma ventral capsulotomy. Dark blue isodose line shows 20% means this is a very conformal plan in terms of midline structures and optic apparatus. Since there was no Cyberknife data when we started our OCD radiosurgery program, in the first five patients, we used 70 gray, in the second five patients, 80 gray, and in the last five patients, 95 gray. We increased our dose to achieve clinical improvement and appropriate lesions on MR images. In 70 gray group, two patients who had no improvement had repeat radiosurgery with 60 gray after 7 and 10 months interval. For the same purpose, one patient in 80 gray group was retreated with 60 gray after 8 months. These images belong to a patient with sufficient response. Axial T2 and T1-weighted images with contrast show typical lesions we expect. Rim-like contrast enhancement with central hypointensity is seen bilaterally in the anterior limb of internal capsule. With a median 28-month follow-up, 9 out of 15 patients had Weibull score reduction more than 35%. Success rate was 60%. One patient in 95 gray group showed radionecrosis larger than expected. Medical and hyperbaric oxygen treatment resolved all the symptoms. If I conclude, ventral capsulotomy with Cyberknife is safe and effective in patients with intractable OCD. There is a trend in using lower doses for capsulotomy, but we need more studies to explore optimal dose, target localization, and target volume. Also, imaging studies may help us to select the patients and to correlate the results. I thank for your kind attention.

CyberKnife radiosurgery

intractable obsessive-compulsive disorder

psychosurgery history

OCD radiosurgery centers

ventral capsulotomy