Management of the Quintessential Brain Attack: Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) remains a devastating clinical entity associated with daunting mortality and morbidity rates. The 2012 Guidelines for Management of Aneurysmal Subarachnoid Hemorrhage (aSAH) represent an update to the previous version of this Stroke Council flagship guidelines, last published in 2009. The authors of this new document focus on summarizing the intervening literature since the last publication, but acknowledge the continued relative dearth of high level evidence upon which to base recommendations. Nonetheless they focus upon reviewing and summarizing recent data with the goals of providing clinically useful recommendations; to this end they have updated several prior recommendations in addition to providing a number of new ones.

A number of Class I recommendations (defined as ‘benefits far outweigh the risks’) are made, although the majority are supported by only Level B (single randomized or non-randomized studies) or C (consensus of experts, case studies or standard of care) evidence. To be fair, it is clear that some of these recommendations address topics that are unlikely to ever be subjected (nor should they reasonably be) to the rigors of multicenter randomized studies; it is hard to imagine, for example, that the recommendation for CSF diversion to treat symptomatic acute or chronic hydrocephalus following aSAH will attain better than Level B or C evidence. Others topics, however, related to optimal treatment protocols for vasospasm, prevention of rebleeding, etc are potentially amenable to further, systematic investigations through comparative effectiveness research.

The sections of the manuscript focus on various aspects of aSAH management, including prevention, diagnosis and treatment. Regarding risk factors for aSAH, recent literature on both patient and aneurysm factors related to rupture risk are reviewed, but it is clear that existing data is not adequately refined to allow the prediction of patient-specific risk for hemorrhage. General actionable recommendations focus on treatment of hypertension, avoidance of tobacco and excessive alcohol, and consumption of a diet rich in vegetables. Despite the uncertainties regarding prediction of individual aneurysm rupture risk, screening in high risk populations (such as familial cases) is proposed as reasonable, as is the consideration of aneurysm morphology/size in addition to patient’s age/ health status when assessing risk for rupture. As far as outcome following aSAH, data continues to indicate that the initial clinical severity is a primary indicator of outcome, and that early aneurysmal rebleeding remains a high risk event early after aSAH, thus warranting urgent evaluation and treatment of suspected aSAH patients. A new recommendation highlights the increasing recognition that survivors of aSAH can suffer cognitive and psychosocial sequelae, by proposing comprehensive evaluation of these domains following discharge.

In regards to diagnosis, the document reviews how the proliferation of advanced CT and MR imaging techniques has provided expanded options for evaluation and diagnosis of aSAH and aneurysms, but ultimately indicates that CT combined with LP if needed, and cerebral angiography remain the gold standards. Recommendations for blood pressure control following diagnosis of aSAH, and an updated recommendation to consider administration of anti-fibrinolytics to prevent early rebleeding are made.

In regards to modality of treatment, the guidelines continue to rely on the primary ISAT trial data¹ which supports the use of coiling as preferred in patients with aneurysms amenable to both coiling and clipping. However, the higher risk of rebleeding, and lower obliteration rates evident following coiling have appropriately prompted several recommendations emphasizing the importance of follow-up imaging, and retreatment with either coiling or clipping to definitively address aneurysm remnants. Specific aneurysm/patient features which may favor one treatment approach over another have also been outlined. The need for individualized decision making is still emphasized, with the importance of multidisciplinary input from experienced endovascular specialists and cerebrovascular surgeons highlighted. Furthermore, the need for management of aSAH patients at high volume centers (>35 aSAH patients/yr) is an important updated recommendation which acknowledges the growing literature regarding volume-outcome benefits related to hospitals and practitioner experience with management of aneurysms.

Unfortunately, since the last iteration of the guidelines, there have been no new positive large scale randomized studies for pharmacological treatments to prevent vasospasm and its sequelae. The STASH) trial examining use of simvastatin is still ongoing, whereas, the CONSCIOUS 2 and 3 (examining the endothelin antagonist clazosentan)² and IMASH (examining magnesium infusion)³ showed no benefits. New recommendations focus on transcranial Doppler and perfusion imaging as options to monitor and diagnose vasospasm, and continue to support the use of endovascular treatments for symptomatic vasospasm unresponsive to standard hypertensive therapy. Regarding management of medical complications, seizures or hydrocephalus none of the recommendations generated are supported by underlying level A evidence. However, as far as providing an assessment of available literature and expert opinion, the recommendations are generally in close alignment with the recently published Neurocritical Care Society multidisciplinary consensus document regarding critical care management of aSAH patients.⁴

Overall, the scope of this guidelines is more focused on the broad implications of management, rather than addressing very specific technical or medical management issues; this can certainly be considered appropriate given lack of high quality evidence for more specific recommendations. The lack of discrete evidence tables which would enhance the transparency of the recommendations is a relative weakness of the data presentation. Otherwise, the authors of this document are to be congratulated for generating guidelines which are appropriately broad, given ongoing uncertainties and limitations of existing data, to guide physicians while still allowing us to individualize care.