Gamma knife capsulotomy for intractable OCD: Neuroimage analysis of lesion size, location, and clinical response.

Obsessive-compulsive disorder (OCD) affects 2-3% of the population. One-third of patients are poorly responsive to conventional therapies, and for a subgroup, gamma knife capsulotomy (GKC) is an option. We examined lesion characteristics in patients previously treated with GKC through well-established programs in Providence, RI (Butler Hospital/Rhode Island Hospital/Alpert Medical School of Brown University) and São Paulo, Brazil (University of São Paolo). Lesions were traced on T1 images from 26 patients who had received GKC targeting the ventral half of the anterior limb of the internal capsule (ALIC), and the masks were transformed into MNI space. Voxel-wise lesion-symptom mapping was performed to assess the influence of lesion location on Y-BOCS ratings. General linear models were built to compare the relationship between lesion size/location along different axes of the ALIC and above or below-average change in Y-BOCS ratings. Sixty-nine percent of this sample were full responders (≥35% improvement in OCD). Lesion occurrence anywhere within the targeted region was associated with clinical improvement, but modeling results demonstrated that lesions occurring posteriorly (closer to the anterior commissure) and dorsally (closer to the mid-ALIC) were associated with the greatest Y-BOCS reduction. No association was found between Y-BOCS reduction and overall lesion volume. GKC remains an effective treatment for refractory OCD. Our data suggest that continuing to target the bottom half of the ALIC in the coronal plane is likely to provide the dorsal-ventral height required to achieve optimal outcomes, as it will cover the white matter pathways relevant to change. Further analysis of individual variability will be essential for improving targeting and clinical outcomes, and potentially further reducing the lesion size necessary for beneficial outcomes.

Cusp kernels for velocity-changing collisions.

We introduce an analytical kernel, the "cusp" kernel, to model the effects of velocity-changing collisions on optically pumped atoms in low-pressure buffer gases. Like the widely used Keilson-Storer kernel [J. Keilson and J. E. Storer, Q. Appl. Math. 10, 243 (1952)], cusp kernels are characterized by a single parameter and preserve a Maxwellian velocity distribution. Cusp kernels and their superpositions are more useful than Keilson-Storer kernels, because they are more similar to real kernels inferred from measurements or theory and are easier to invert to find steady-state velocity distributions.

A time-limited behavioral group for treatment of obsessive-compulsive disorder.

In vivo exposure with response prevention is an effective treatment for obsessive-compulsive disorder (OCD) either alone or combined with pharmacotherapy. Widespread application of this technique has been limited by lack of trained therapists and the expense of intensive individual behavioral therapy. This report describes a time-limited 10-session behavioral therapy group for OCD whose key elements are exposure, response prevention, therapist and participant modeling, and cognitive restructuring. In a naturalistic open trial of 90 patients meeting DSM-III-R criteria for OCD who completed the 10-session group, self-administered Yale-Brown Obsessive-Compulsive Scale scores (mean +/- SD) were 21.8 +/- 5.6 at baseline and 16.6 +/- 6.4 after the 10-week treatment, a significant decrease. A descriptive analysis of the therapeutic elements of the group and its advantages over individual behavioral treatment are presented.

Clinical features of obsessive-compulsive disorder in elderly patients.

There has been no systematic study of the clinical features of obsessive-compulsive disorder (OCD) in elderly patients. This study describes the symptoms and characteristics of OCD among 32 outpatients age 60 or older and 601 younger patients meeting DSM-III-R criteria and given the Yale-Brown Obsessive-Compulsive Scale (YBOCS), NIMH scale, and a 41-item symptom questionnaire. Elderly patients had a later age at onset compared with younger patients. No differences were found in severity of symptoms on the YBOCS. Elderly patients had fewer concerns about symmetry, need to know, and counting rituals. Handwashing and fear of having sinned were more common. There were few differences in clinical features of OCD among the elderly patients compared with younger OCD patients.