Experimental study of cerebral ischemia Part 2. Relationship between cerebral blood flow and somatosensory evoked potential

Local cerebral blood flow(1-CBF) and somatosensory evoked potentials(SEP's) were measured during focal cerebral ischemia and after restoration of cerebral blood flow in 17 mongrel dogs. The animals were divided into 3 groups in order to examine changes in SEP's following cerebral ischemia of varying duration and degree. The first portion of the middle cerebral artery(M1) and the common trunk of the anterior cerebral artery (A2) were occluded using a transorbital approach with an operating microscope. In group A(n=7), both Ml and A2 were occluded for two hours. In group B(n=6), M1 was occluded for four hours and A2 was occluded for two hours beginning one hour after the M1 occlusion. In group C(n=4), M1 was occluded for two hours and A2 was occluded for one hour beginning 30 minutes after Ml occlusion. SEP's were suppressed following the decrease of 1-CBF and disappeared below 20ml/100g/min. Following restoration of flow, the SEP's of group B (where the longest and most severe degree of ischemia was produced) recovered poorly or not at all. In animals where SEP's failed to recover well, marked hyperemia and brain swelling were frequently found following restoration of flow. In group C where the duration and degree of ischemia were less, the SEP's improved better, and hyperemia and brain swelling were not found.In this study, two major factors may be considered to have influenced the recovery of SEP' s following restoration of flow. The first factor is the duration and the degree of ischemia, and the second is hyperemia and brain swelling. In animals where the degree of ischemia was severe, SEP's failed to recover well, and marked hyperemia was found in spite of graded restoration of flow. It is felt that the restoration of flow may actually be harmful if collateral circulation is poor and/or duration of ischemia is long

Experimental study of cerebral ischemia Part 1. A new model of cerebral ischemia

The author developed an original model of local cerebral ischemia using mongrel dogs. A left transorbital approach was used to occlude both the first segment of the middle cerebral artery(M1) and the common trunk of the anterior cerebral artery(A2). Histopathological examination revealed severe ischemic brain edema coinciding with severe neurological deficits within 3 days of the occlusion. Additionally, large cerebral infarcts involving the sensorimotor cortex were frequently found at 7 days. These infarcts were more extensive than those in cases with M1 occlusion alone.Fluorescein angiography and measurement of the local cerebral blood flow(l-CBF) demonstrated a filling defect of fluorescein in the gyri around the sylvian fissure coinciding with a 54% reduction of 1-CBF in the anterior sylvian gyrus after M1 occlusion. Additional occlusion of the A2 extended the filling defect zone to the coronal and sigmoid gyri, and lowered the 1-CBF further.The author believes that this model of cerebral ischemia is useful because one can alter the extent and duration of cerebral ischemia by the combination of occlusion or release of M1 and/or A2

National trends in the outcomes of subarachnoid haemorrhage and the prognostic influence of stroke centre capability in Japan: retrospective cohort study

Objectives To examine the national, 6-year trends in in-hospital clinical outcomes of patients with subarachnoid haemorrhage (SAH) who underwent clipping or coiling and the prognostic influence of temporal trends in the Comprehensive Stroke Center (CSC) capabilities on patient outcomes in Japan.Design Retrospective study.Setting Six hundred and thirty-one primary care institutions in Japan.Participants Forty-five thousand and eleven patients with SAH who were urgently hospitalised, identified using the J-ASPECT Diagnosis Procedure Combination database.Primary and secondary outcome measures Annual number of patients with SAH who remained untreated, or who received clipping or coiling, in-hospital mortality and poor functional outcomes (modified Rankin Scale: 3–6) at discharge. Each CSC was assessed using a validated scoring system (CSC score: 1–25 points).Results In the overall cohort, in-hospital mortality decreased (year for trend, OR (95% CI): 0.97 (0.96 to 0.99)), while the proportion of poor functional outcomes remained unchanged (1.00 (0.98 to 1.02)). The proportion of patients who underwent clipping gradually decreased from 46.6% to 38.5%, while that of those who received coiling and those left untreated gradually increased from 16.9% to 22.6% and 35.4% to 38%, respectively. In-hospital mortality of coiled (0.94 (0.89 to 0.98)) and untreated (0.93 (0.90 to 0.96)) patients decreased, whereas that of clipped patients remained stable. CSC score improvement was associated with increased use of coiling (per 1-point increase, 1.14 (1.08 to 1.20)) but not with short-term patient outcomes regardless of treatment modality.Conclusions The 6-year trends indicated lower in-hospital mortality for patients with SAH (attributable to better outcomes), increased use of coiling and multidisciplinary care for untreated patients. Further increasing CSC capabilities may improve overall outcomes, mainly by increasing the use of coiling. Additional studies are necessary to determine the effect of confounders such as aneurysm complexity on outcomes of clipped patients in the modern endovascular era