Article
Graphical analysis of lead position in regard to outcome for Nucleus accumbens/anterior limb of internal capsule (Nacc/ALIC) deep brain stimulation (DBS) in obsessive compulsive disorder (OCD)
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Published: | June 9, 2017 |
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Objective: OCD is a sometimes debilitating psychiatric disease with a 2% lifetime prevalence. Up to 10% of patients do not respond to conservative treatment. For severe cases, DBS targeting the Nacc/ALIC is a viable option, receiving CE-mark in 2009. However, because of variable success rates and side effects, 8 different targets have been proposed for OCD in the last 18 years - the search for a hotspot continues. In this study, using a novel visualization software, we correlated lead position and resulting volume of tissue activated (VTA) with clinical outcome and side effects in order to narrow down the optimal target area.
Methods: We analyzed data for 16 consecutive patients treated at our center over a period of 3 years with DBS of the Nacc/ALIC following a routine targeting procedure. Based on improvement on the Yale-Brown obsessive compulsive scale (YBOCS) and clinical profit at 12 months follow up, four outcome groups were defined. Subgroups were also designated for unexpected side effects. Individual regions of interest (ROI) from all patient hemispheres were stacked to create a median intensity image, and then registered to the resulting intermediate to create a common anatomical space (patient average MRI, PAM). Using the Suretune Expert Tuning Tool software (Medtronic), the location of the individual contacts used and the resulting VTA were aggregated into the PAM and probabilistic stimulation maps (PSM) were calculated. The adapting Yelnik-Bardinet atlas was aligned to the PAM as an anatomical reference.
Results: The graphical analysis indicates anatomical localization to be correlating with both clinical outcome as well as side-effects. PSM of non- and fair responders were revealed to be distinct from - but nearby to - the PSM of good and excellent responders. All patients reporting unwanted weight-gain had their active contacts clustering in a circumscript area, independent of their improvement in OCD. These patients are followed up with a multidisciplinary approach to further elucidate the underlying mechanism.
Conclusion: While data and analysis is preliminary, this novel tool shows promise for correlation of lead location and clinical effect in the way that PSM suggest an area of best benefit. The results also open the way for further research into the insufficiently understood side effect of weight gain through DBS in OCD.