Valproate Reduces Delayed Brain Injury in a Rat Model of Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: Spreading depolarizations (SDs) may contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). We tested whether SD-inhibitor valproate reduces brain injury in an SAH rat model with and without experimental SD induction. METHODS: Rats were randomized in a 2×2 design and pretreated with valproate (200 mg/kg) or vehicle for 4 weeks. SAH was induced by endovascular puncture of the right internal carotid bifurcation. One day post-SAH, brain tissue damage was measured with T2-weighted magnetic resonance imaging, followed by cortical application of 1 mol/L KCl (to induce SDs) or NaCl (no SDs). Magnetic resonance imaging was repeated on day 3 followed by histology to confirm neuronal death. Neurological function was measured with an inclined slope test. RESULTS: In the groups with KCl application, lesion growth between days 1 and 3 was 57±73 mm3 in the valproate-treated versus 237±232 mm3 in the vehicle-treated group. In the groups without SD induction, lesion growth in the valproate- and vehicle-treated groups was 8±20 mm3 versus 27±52 mm3. On fitting a 2-way analysis of variance model, we found a significant interaction effect between treatment and KCl/NaCl application of 161 mm3 (P=0.04). Number and duration of SDs, mortality, and neurological function were not statistically significantly different between groups. Lesion growth on magnetic resonance imaging correlated to histological infarct volume (Spearman's rho =0.83; P=0.0004), with areas of lesion growth exhibiting reduced neuronal death compared with primary lesions. CONCLUSIONS: In our rat SAH model, valproate treatment significantly reduced brain lesion growth after KCl application. Future studies are needed to confirm that this protective effect is based on SD inhibition.

Measurement of distinctive features of cortical spreading depolarizations with different MRI contrasts.

Growing clinical evidence suggests critical involvement of spreading depolarizations (SDs) in the pathophysiology of neurological disorders such as migraine and stroke. MRI provides powerful tools to detect and assess co-occurring cerebral hemodynamic and cellular changes during SDs. This study reports the feasibility and advantages of two MRI scans, based on balanced steady-state free precession (b-SSFP) and diffusion-weighted multi-spin-echo (DT2), heretofore unexplored for monitoring SDs. These were compared with gradient-echo MRI. SDs were induced by KCl application in rat brain. Known for high SNR, the T2- and T1-based b-SSFP contrast was hypothesized to provide higher spatiotemporal specificity than T2*-based gradient-echo scanning. DT2 scanning was designed to provide simultaneous T2 and apparent diffusion coefficient (ADC) measurements, thus enabling combined quantitative assessment of hemodynamic and cellular changes during SDs. Procedures were developed to automate identification of SD-induced responses in all the scans. These responses were analyzed to determine detection sensitivity and temporal characteristics of signals from each scanning method. Cluster analysis was performed to elucidate unique temporal patterns for each contrast. All scans allowed detection of SD-induced responses. b-SSFP scans showed significantly larger relative intensity changes, narrower peak widths and greater spatial specificity compared with gradient-echo MRI. SD-induced effects on ADC, calculated from DT2 scans, showed the most pronounced signal changes, displaying about 20% decrease, as against 10-15% signal increases observed with b-SSFP and gradient-echo scanning. Cluster analysis revealed additional temporal sub-patterns, such as an initial dip on gradient-echo scans and temporally shifted T2 and proton density changes in DT2 data. To summarize, b-SSFP and DT2 scanning provide distinct information on SDs compared with gradient-echo MRI. DT2 scanning, with its potential to simultaneously provide cellular and hemodynamic information, can offer unique information on the inter-relationship between these processes in pathologic brain, which may improve monitoring of spreading depolarizations in (pre)clinical settings.

Circle of Willis variations in migraine patients with ischemic stroke.

OBJECTIVES: Migraine is a risk factor for stroke, which might be explained by a higher prevalence in anatomical variants in the circle of Willis (CoW). Here, we compared the presence of CoW variants in patients with stroke with and without migraine. MATERIALS AND METHODS: Participants were recruited from the prospective Dutch acute Stroke Study. All participants underwent CT angiography on admission. Lifetime migraine history was assessed with a screening questionnaire and confirmed by an interview based on International Classification of Headache Disorders criteria. The CoW was assessed for incompleteness/hypoplasia (any segment <1 mm), for anterior cerebral artery asymmetry (difference > 1/3), and for posterior communicating artery (Pcom) dominance (Pcom-P1 difference > 1/3). Odds ratios with adjustments for age and sex (aOR) were calculated with logistic regression. RESULTS: We included 646 participants with stroke, of whom 52 had a history of migraine. Of these, 45 (87%) had an incomplete or hypoplastic CoW versus 506 (85%) of the 594 participants without migraine (aOR: 1.47; 95% CI: 0.63-3.44). There were no differences between participants with and without migraine in variations of the anterior or posterior CoW, anterior cerebral artery asymmetry (aOR: 0.86; 95% CI: 0.43-1.74), or Pcom dominance (aOR: 0.64; 95% CI: 0.32-1.30). There were no differences in CoW variations between migraine patients with or without aura. CONCLUSION: We found no significant difference in the completeness of the CoW in acute stroke patients with migraine compared to those without.

Spreading depolarizations increase delayed brain injury in a rat model of subarachnoid hemorrhage.

Spreading depolarizations may contribute to delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage, but the effect of spreading depolarizations on brain lesion progression after subarachnoid hemorrhage has not yet been assessed directly. Therefore, we tested the hypothesis that artificially induced spreading depolarizations increase brain tissue damage in a rat model of subarachnoid hemorrhage. Subarachnoid hemorrhage was induced by endovascular puncture of the right internal carotid bifurcation. After one day, brain tissue damage was measured with T2-weighted MRI, followed by application of 1 M KCl (SD group, N = 16) or saline (no-SD group, N = 16) to the right cortex. Cortical laser-Doppler flowmetry was performed to record spreading depolarizations. MRI was repeated on day 3, after which brains were extracted for assessment of subarachnoid hemorrhage severity and histological damage. 5.0 ± 2.7 spreading depolarizations were recorded in the SD group. Subarachnoid hemorrhage severity and mortality were similar between the SD and no-SD groups. Subarachnoid hemorrhage-induced brain lesions expanded between days 1 and 3. This lesion growth was larger in the SD group (241 ± 233 mm(3)) than in the no-SD group (29 ± 54 mm(3)) (p = 0.001). We conclude that induction of spreading depolarizations significantly advances lesion growth after experimental subarachnoid hemorrhage. Our study underscores the pathophysiological consequence of spreading depolarizations in the development of delayed cerebral tissue injury after subarachnoid hemorrhage.

Spreading depolarization-modulating drugs and delayed cerebral ischemia after subarachnoid hemorrhage: A hypothesis-generating retrospective clinical study.

BACKGROUND: Delayed cerebral ischemia (DCI) occurs in approximately one-third of patients with aneurysmal subarachnoid hemorrhage (aSAH). A proposed underlying mechanism for DCI is spreading depolarization (SD). Our aim was to, retrospectively, investigate the influence of the use of SD-modulating drugs on the occurrence of DCI. METHODS: We, retrospectively, combined data from four cohorts of aSAH patients with data on the use of home medication prior to hospital admission, occurrence of DCI, and clinical outcome. Home medication was classified as "SD-inhibiting", "SD-facilitating", or "SD-neutral based" on a comprehensive literature review. We defined subgroups "likely", "possibly" and "weak" concerning the amount of evidence in literature. We performed Cox and Poisson regression analysis and calculated hazard ratios (HR) and risk ratios (RR) for the influence of "SD-modulating" drugs on primary outcome measure DCI and secondary outcome measure poor clinical outcome (modified Rankin Scale ≥3) three months after aSAH. We adjusted for age, sex and clinical condition on admission (aHR/aRR). RESULTS: DCI occurred in 343 (29%) of 1194 patients. Patients using SD-inhibiting home medication had an aHR for DCI of 0.66 (95% CI: 0.42-1.06) and an aRR for poor outcome of 1.13 (95% CI: 0.90-1.41). Patients using SD-facilitating drugs had an aHR for DCI of 1.24 (95% CI: 0.83-1.87) and an aRR for poor outcome of 1.19 (95% CI: 0.95-1.50). When comparing patients using SD-inhibiting drugs with patients using SD-facilitating drugs, the aHR was 0.54 (95% CI: 0.29-0.99) for DCI and the aRR 0.97 (95% CI: 0.71-1.32) for outcome. CONCLUSIONS: In this exploratory study chronic use of SD-inhibiting drugs tended to reduce DCI but did not result in a better clinical outcome. Additional research is needed to investigate the specific effects of SD-modulation on DCI and outcome and to further explore its effectiveness in preventing DCI after aSAH.