Among patients with subarachnoid hemorrhage, loss of consciousness at symptom onset is independently associated with death and poor functional outcomes at one year, according to data published online ahead of print November 9 in JAMA Neurology. The findings indicate that loss of consciousness, one of the most common presenting symptoms of subarachnoid hemorrhage, “is a simple and robust indicator of a severe bleeding event,” said Sureerat Suwatcharangkoon, MD, of the Neurological Intensive Care Unit at Columbia University Medical Center in New York and Mahidol University’s Ramathibodi Hospital in Bangkok.

Patients who lost consciousness had significantly larger subarachnoid, intraventricular, and parenchymal intracerebral hemorrhages on admission CT scan findings, compared with patients who did not lose consciousness. “Loss of consciousness has important prognostic value, implying a more than 2.8-fold increase in the risk of death or severe disability at one year, even after controlling for age, admission clinical grade, aneurysm size, and admission physiological derangements,” Dr. Suwatcharangkoon and colleagues said.

A Retrospective Analysis

To clarify the association between loss of consciousness at subarachnoid hemorrhage onset and patient outcomes, the researchers conducted a retrospective analysis of 1,460 consecutively treated patients with spontaneous subarachnoid hemorrhage who were part of the Columbia University Subarachnoid Hemorrhage Outcomes Project (SHOP). Patients were enrolled in the prospective observational cohort study between August 6, 1996, and July 23, 2012. Researchers conducted the analysis from December 1, 2013, to February 28, 2015. The mean patient age was 55. One-third of the patients were men.

Subarachnoid hemorrhage was diagnosed using CT scan or xanthochromia in the CSF. The researchers excluded patients with traumatic subarachnoid hemorrhage and arteriovenous malformation, those younger than 18, and those who were hospitalized more than 14 days after the onset of subarachnoid hemorrhage. Loss of consciousness was broadly defined as any sudden, abnormal alteration of alertness, awareness, or responsiveness to sensory stimuli at symptom onset during the prehospital phase of the illness. The researchers conducted structured interviews with the patients and first responders to identify loss of consciousness. The investigators followed patients for as long as one year to assess functional recovery and assigned modified Rankin Scale (mRS) scores based on telephone or in-person interviews with the patients, family members, or caregivers. One-year outcomes were imputed using discharge or three-month data for approximately 20% of patients who were lost to follow-up.

Risk of Poor Outcome

In this cohort, 590 patients (40.4%) reported loss of consciousness at onset of subarachnoid hemorrhage. The investigators found that 51.2% of patients with loss of consciousness were dead or severely disabled at 12 months (ie, mRS score of 4–6), compared with 17.7% of patients who did not lose consciousness. After excluding patients with prehospital cardiac arrest, witnessed tonic-clonic activity at onset, or poor grade on admission (ie, Hunt and Hess score of 4 or 5), loss of consciousness remained significantly related to functional outcome at 12 months (odds ratio, 2.0).

Loss of consciousness was associated with a higher frequency of global cerebral edema as well as more prehospital tonic-clonic activity (22.7% vs 4.2%) and cardiopulmonary arrest (9.7% vs 0.5%) at admission, compared with no loss of consciousness. There were no differences in age, gender, race/ethnicity, or systolic blood pressure between patients with and without loss of consciousness.

Patients with loss of consciousness were more likely to have their aneurysms coiled than clipped. They were treated on average one-half day earlier than patients who did not lose consciousness, the researchers said.

Duration of Loss of Consciousness

Starting in 2002, the researchers recorded duration of loss of consciousness. Among the 443 patients whose duration of loss of consciousness was recorded, 169 (38.1%) lost consciousness for less than 10 minutes, 93 (21%) for 10 to 60 minutes, and 181 (40.9%) for longer than 60 minutes. If loss of consciousness lasted less than 10 minutes, the risk of presenting with a Hunt and Hess scale score of 4 or 5 was 16.0% and 6.5%, respectively. If it lasted more than an hour, the risk was 21.5% and 67.4%, respectively.

Unlike in prior studies, loss of consciousness was not independently associated with subsequent delayed cerebral ischemia or aneurysm rebleeding. The researchers speculated that lower rates of those events in their study due to modernized care may be one reason why the associations seen in prior studies were not replicated. One limitation of the study was that researchers depended on patient histories to identify loss of consciousness.

“Given its strong association with global cerebral edema and poor admission clinical grade, loss of consciousness should be considered a straightforward and clinically important marker of early brain injury after subarachnoid hemorrhage, with ominous implications,” the researchers concluded. “In the future, the presence or absence of loss of consciousness may be useful for risk stratification and targeting therapy designed to minimize the effects of early brain injury after subarachnoid hemorrhage.”

—Jake Remaly

Loss of Consciousness Predicts Worse Outcomes After Subarachnoid Hemorrhage