Prognosis and Neurological Outcomes after Aneurysmal Subarachnoid Hemorrhage
Abstract & Commentary
By Matthew E. Fink, MD, Vice Chairman, Professor of Clinical Neurology, Weill Medical College, Chief of Division of Stroke and Critical Care Neurology, NewYork-Presbyterian Hospital. Mr. Fink reports no consultant, stockholder, speaker's bureau, research, or other relationships related to this field of study.
Synopsis: In spite of great advances in neuroimaging, neurocritical care, and neurosurgical interventions for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (SAH), it is uncertain if case morbidity and mortality have significantly declined.
Sources: Rosengart AJ, et. al. Prognostic factors for outcome in patients with aneurysmal subarachnoid hemorrhage. Stroke 2007; 38:2315-2321.
Tanno Y, et al. Rebleeding from Ruptured Intracranial Aneurysms in North Eastern Province of Japan. A cooperative study. J Neurol Sci 2007;258:11-16.
Advances in CT and MRI technology have made the rapid diagnosis of ruptured intracranial aneurysm a routine matter in most hospitals, and the proliferation of advanced neurocritical care units in neurosurgical referral centers across the U.S. have allowed for referral of most patients to specialized centers that have the most advanced knowledge and technology (including endovascular coiling and stenting) to treat virtually every type of patient with a ruptured intracranial aneurysm. It would be expected, therefore, that these dramatic advances in neurosurgical care would be translated into better outcomes for patients admitted with aneurysmal SAH. Two recent studies, however, have looked at the factors that determine prognosis and outcome, and lead us to question how much real progress we have made in improving the clinical outcome of these patients, in spite of great technological advances that have been applied to their care.
Rosengart and colleagues performed an analysis of a large cohort of 3567 patients, who were enrolled in 4 different randomized trials of tirilizad at neurosurgical centers around the world, between 1991 and 1997. Because there was no significant difference in outcomes between the tirilizad and placebo groups, they were combined in order to have the largest possible cohort to perform a Cox proportional hazards regression analysis for variables that would have an impact on outcomes, as measured by the Glasgow Outcomes Scale (GOS) at three months. The GOS was further simplified into a binary dependent variable — good outcome vs poor outcome. Poor outcome was defined as dead, vegetative, or severely disabled. All patients had their aneurysms treated with open surgical clipping; there were no endovascular interventions in this group. The investigators analyzed a comprehensive list of factors, both preoperative as well as in-hospital factors, that might have an impact on outcome, and converted the associations to hazard ratios that would predict "poor" outcome on the GOS. The reference group used for calculation of the odds ratios was male, age 18-29, World Federation of Neurological Surgery grade 1, no or local thin SAH on admission CT scan, and a ruptured aneurysm < 12 mm in size located on the internal carotid artery. The significant variables identified in the multivariable logistic regression model were increasing age, admission neurological grade, posterior circulation aneurysm, larger aneurysm size, thick clot on CT, intracerebral hematoma, intraventricular hematoma, elevated systolic pressure, previous diagnosis of hypertension, myocardial infarction, liver disease, or previous SAH, temperature > 38°C, symptomatic vasospasm, and cerebral infarction. The use of prophylactic or therapeutic hypervolemia or hypertension was associated with a lower risk of unfavorable outcome. Overall, 70% of the entire group was reported as "good" outcome; this compared to an earlier Finnish study from an earlier decade, using similar statistics, that showed an overall "good" outcome of 68% (Niskanen, et. al. Acta Neurochir 1993; 123:25-32).
The Rosengart study did not address the important issue of early aneurysm re-rupture as a prognostic factor, a topic that was specifically studied by Tanno, et al. In a retrospective chart review of 5612 cases of ruptured intracranial aneurysms in Japan, Tanno, et al identified 181 patients with rebleeding after hospitalization, before the aneurysm could be secured. They noted that rebleeding occurred in 65 (35.9%) within 3 hours and 88 (48.6%) within 6 hours of the initial SAH. The level of consciousness abruptly declined at the time of rebleeding and the diagnosis was made by repeat CT scanning. They also noted that rebleeding occurred more frequently during cerebral angiography (29 patients; 20%) and much less frequently during CTA or MRA (a single case). Systolic BP was noted to be 120-140 immediately prior to the re-bleeding episode. Of the patients who suffered early rebleeding, 60% died within 3 months following SAH.
Advanced imaging with CT, MRI and MRA have improved and simplified the early diagnosis of aneurysmal SAH, and computerized navigation and microsurgical techniques, along with endovascular coiling have dramatically altered the neurosurgical approaches to ruptured intracranial aneurysms. Neurocritical care specialists have concentrated their efforts to improve the care of these patients with special attention to issues surrounding vasospasm, cerebral perfusion pressure, intracranial pressure, and neuroprotection. But have these technical advances improved the overall outcome for these patients? At the present time, we are unable to answer that question, but the studies by Rosengart and Tanno suggest that the major factors that determine survival and recovery are present at the time of admission and there seems to be little we can do to modify these factors. Early re-rupture, which carries a high mortality, can be addressed with faster and safer diagnostic techniques using CT angiography, followed by immediate aneurysm obliteration. Early use of antifibrinolytic drugs should be investigated as a possible method to reduce early re-rupture. Aggressive blood pressure lowering, prior to aneurysm obliteration, should also be investigated as a possible therapy. Other risk factors, as outlined by Rosengart et al, should be systematically studied for any innovative treatment approaches that might modify their influence and reduce their impact on outcome. And finally, we need more population-based studies of case morbidity and mortality to assess our overall success, or failure, in the treatment of this devastating disease.