Spreading Depolarization After Chronic Subdural Hematoma Evacuation: Associated Clinical Risk Factors and Influence on Clinical Outcome.

BACKGROUND: Chronic subdural hematoma (cSDH) is a common neurosurgical condition responsible for excess morbidity, particularly in the geriatric population. Recovery after evacuation is complicated by fluctuating neurological deficits in a high proportion of patients. We previously demonstrated that spreading depolarizations (SDs) may be responsible for some of these events. In this study, we aim to determine candidate risk factors for probable SD and assess the influence of probable SD on outcome. METHODS: We used two cohorts who underwent surgery for cSDH. The first cohort (n = 40) had electrocorticographic monitoring to detect SD. In the second cohort (n = 345), we retrospectively identified subjects with suspected SD based on the presence of transient neurological symptoms not explained by structural etiology or ictal activity on electroencephalography. We extracted standard demographic and outcome variables for comparisons and modeling. RESULTS: Of 345 subjects, 80 (23%) were identified in the retrospective cohort as having probable SD. Potential risk factors included history of hypertension, worse clinical presentation on the Glasgow Coma Scale, and lower Hounsfield unit density and volume of the preoperative subdural hematoma. Probable SD was associated with multiple worse-outcome measures, including length of stay and clinical outcomes, but not increased mortality. On a multivariable analysis, probable SD was independently associated with worse outcome, determined by the Glasgow Outcome Scale score at the first clinic follow-up (odds ratio 1.793, 95% confidence interval 1.022-3.146) and longer hospital length of stay (odds ratio 7.952, 95% confidence interval 4.062-15.563). CONCLUSIONS: Unexplained neurological deficits after surgery for cSDH occur in nearly a quarter of patients and may be explained by SD. We identified several potential candidate risk factors. Patients with probable SD have worse outcomes, independent of other baseline risk factors. Further data with gold standard monitoring are needed to evaluate for possible predictors of SD to target therapies to a high-risk population.

Quantity yields quality when it comes to creativity: a brain and behavioral test of the equal-odds rule.

The creativity research community is in search of a viable cognitive measure providing support for behavioral observations that higher ideational output is often associated with higher creativity (known as the equal-odds rule). One such measure has included divergent thinking: the production of many examples or uses for a common or single object or image. We sought to test the equal-odds rule using a measure of divergent thinking, and applied the consensual assessment technique to determine creative responses as opposed to merely original responses. We also sought to determine structural brain correlates of both ideational fluency and ideational creativity. Two-hundred forty-six subjects were subjected to a broad battery of behavioral measures, including a core measure of divergent thinking (Foresight), and measures of intelligence, creative achievement, and personality (i.e., Openness to Experience). Cortical thickness and subcortical volumes (e.g., thalamus) were measured using automated techniques (FreeSurfer). We found that higher number of responses on the divergent thinking task was significantly associated with higher creativity (r = 0.73) as independently assessed by three judges. Moreover, we found that creativity was predicted by cortical thickness in regions including the left frontal pole and left parahippocampal gyrus. These results support the equal-odds rule, and provide neuronal evidence implicating brain regions involved with "thinking about the future" and "extracting future prospects."