Loss of consciousness key outcome marker in SAH

By Eleanor McDermid, Senior medwireNews Reporter

A large study of patients with subarachnoid haemorrhage (SAH) confirms loss of consciousness as a clinically important indicator of outcome.

Patients who lost consciousness at SAH onset were twice as likely to be dead or severely disabled 12 months later as those who remained conscious, the findings published in JAMA Neurology show.

“With improvements in therapy for vasospasm and safer surgical techniques for aneurysm repair, early brain injury now poses the most important threat to survival with good recovery after SAH”, say Stephan Mayer (Icahn School of Medicine at Mount Sinai, New York, USA) and study co-authors

Their findings show that loss of consciousness is a “simple and robust indicator” of early brain injury, with “ominous implications”, they say.

The team assessed data on 1460 patients from the Columbia University SAH Outcomes Project (SHOP) with information on level of consciousness, making this analysis markedly larger than previous studies.

In all, 40.4% of the patients lost consciousness within 6 hours of SAH onset. Loss of consciousness was associated with acute tonic–clonic activity and prehospital cardiac arrest, and longer periods of unconsciousness were associated with worse admission Hunt and Hess scale scores.

But even after excluding patients with these characteristics, and those with poor clinical grade (Hunt and Hess 4–5), loss of consciousness was associated with a significant twofold increase in the risk of being dead or disabled (modified Rankin Scale 4–6) 12 months after onset.

This association was independent of age, admission clinical grade, APACHE II physiological subscore and aneurysm size. Among all patients, 51.2% of those who lost consciousness were dead or disabled at 12 months, compared with 17.7% of those who did not.

In a linked editorial, R Loch Macdonald (University of Toronto, Ontario, Canada) notes that, by assessing only patients with Hunt and Hess grade 1–3, the researchers have helped to untangle the individual effects of loss of consciousness and clinical grade, given that the two are very closely linked.

He adds: “Since patients assessed as Hunt and Hess grade 3 are on the verge of unconsciousness and may not be able to remember an episode of [loss of consciousness], it would be interesting to conduct the analysis only on patients assessed as Hunt and Hess grades 1 and 2.”

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