Similarly, early electroencephalograms were not used to determine the frequency of epileptiform activity neither was admission MRI used to explore LOC as a potential risk factor for early ischemic injury. The timing of recovery of consciousness and assessment of LOC at multiple early time points should be more precisely tracked in future studies, said Mayer and colleagues, noting that in this study, the presence of significant cardiac arrhythmia on admission was not recorded. Approximately 70% of patients with SAH presenting with poor clinical grade on admission have evidence of acute ischemic injury on diffusion-weight imaging, they noted. 'Acute physiological derangements, such as extremes of blood pressure, hyperglycemia, hypoxemia and metabolic acidosis have been shown to predict both poor admission grade and long-term outcome and may exacerbate these processes and serve as targets for intervention,' said the investigators. Other factors that may contribute to cerebral blood flow reduction in early brain injury include: In the 40% of patients with LOC who failed to regain consciousness within one hour after SAH, a primary reduction of cerebral perfusion pressure caused by severe intracranial hypertension could be to blame, said the investigators. LOC was also associated with more prehospital tonic-clonic activity (22.7% versus 4.2% P<0.001) and cardiopulmonary arrest (9.7% versus 0.5%, P<0.001) versus patients who did not experience LOC. Loss of consciousness was associated with poor clinical grade, more subarachnoid and intraventricular blood seen on admission CT scan, and a higher frequency of global cerebral edema ( P<0.001). In all, 590 patients (40.4%) reported LOC at onset of SAH. Michael's Hospital and the University of Toronto, said this study 'solidifies the finding that LOC at the time of SAH is an independent predictor of poor outcome.' There was no association between LOC at onset and delayed cerebral ischemia or aneurysm re-bleeding, said Mayer and colleagues. Loss of consciousness was also associated with global cerebral edema, which is thought to be an important marker of early brain injury after SAH.' Patients with LOC had significantly larger SAHs, intraventricular hemorrhages, and parenchymal intracerebral hemorrhages on admission CT scan findings.

'Our findings indicate that LOC at onset of SAH is a simple and robust indicator of a severe bleeding event. Death or severe disability at 12 months was independently associated with LOC after adjusting for established risk factors for poor outcome, including poor admission clinical grade (adjusted odds ratio 1.94 95% CI 1.38-2.72 P<0.001), said the investigators.

Bleeding on the brain