Lateral cerebellothalamic tract activation underlies DBS therapy for Essential Tremor.

BACKGROUND: While deep brain stimulation (DBS) therapy can be effective at suppressing tremor in individuals with medication-refractory Essential Tremor, patient outcome variability remains a significant challenge across centers. Proximity of active electrodes to the cerebellothalamic tract (CTT) is likely important in suppressing tremor, but how tremor control and side effects relate to targeting parcellations within the CTT and other pathways in and around the ventral intermediate (VIM) nucleus of thalamus remain unclear. METHODS: Using ultra-high field (7T) MRI, we developed high-dimensional, subject-specific pathway activation models for 23 directional DBS leads. Modeled pathway activations were compared with post-hoc analysis of clinician-optimized DBS settings, paresthesia thresholds, and dysarthria thresholds. Mixed-effect models were utilized to determine how the six parcellated regions of the CTT and how six other pathways in and around the VIM contributed to tremor suppression and induction of side effects. RESULTS: The lateral portion of the CTT had the highest activation at clinical settings (p < 0.05) and a significant effect on tremor suppression (p < 0.001). Activation of the medial lemniscus and posterior-medial CTT was significantly associated with severity of paresthesias (p < 0.001). Activation of the anterior-medial CTT had a significant association with dysarthria (p < 0.05). CONCLUSIONS: This study provides a detailed understanding of the fiber pathways responsible for therapy and side effects of DBS for Essential Tremor, and suggests a model-based programming approach will enable more selective activation of lateral fibers within the CTT.

Health Care Provider Adherence to Surgical Guidelines for Risk-Reducing Salpingo-Oophorectomy.

OBJECTIVE: To evaluate health care provider adherence to the surgical protocol endorsed by the National Comprehensive Cancer Network and the American College of Obstetricians and Gynecologists at the time of risk-reducing salpingo-oophorectomy and compare adherence between gynecologic oncologists and obstetrician-gynecologists (ob-gyns). METHODS: In this multicenter retrospective cohort study, women were included if they had a pathogenic BRCA mutation and underwent risk-reducing salpingo-oophorectomy between 2011 and 2017. Adherence was defined as completing all of the following: collection of washings, complete resection of the fallopian tube, and performing the Sectioning and Extensively Examining the Fimbriated End (SEE-FIM) pathologic protocol. RESULTS: Of 290 patients who met inclusion criteria, 160 patients were treated by 18 gynecologic oncologists and 130 patients by 75 ob-gyns. Surgery was performed at 10 different hospitals throughout a single metropolitan area. Demographic and clinical characteristics were similar between groups. Overall, 199 cases (69%) were adherent to the surgical protocol. Gynecologic oncologists were more than twice as likely to fully adhere to the full surgical protocol as ob-gyns (91% vs 41%, P<.01). Specifically, gynecologic oncologists were more likely to resect the entire tube (99% vs 95%, P=.03), to have followed the SEE-FIM protocol (98% vs 82%, P<.01), and collect washings (94% vs 49%, P<.01). Complication rates did not differ between groups. Occult neoplasia was diagnosed in 11 patients (3.8%). The incidence of occult neoplasia was 6.3% in gynecologic oncology patients and 0.8% in obstetrics and gynecology patients (P=.03). CONCLUSION: Despite clear surgical guidelines, only two thirds of all health care providers were fully adherent to guidelines. Gynecologic oncologists were more likely to follow surgical guidelines compared with general ob-gyns and more likely to diagnose occult neoplasia despite similar patient populations. Rates of risk-reducing surgery will likely continue to increase as genetic testing becomes more widespread, highlighting the importance of health care provider education for this procedure. Centralized care or referral to subspecialists for risk-reducing salpingo-oophorectomy may be warranted.