Predictors of cognitive function in the acute phase after aneurysmal subarachnoid hemorrhage

Cognitive dysfunction is the most common form of neurological impairment after aneurysmal subarachnoid hemorrhage (aSAH) in the chronic phase. Cognitive deficits in the acute phase after aSAH, however, remain scarcely investigated. The aim of the present study was to test cognitive function and to identify medical predictors of cognitive deficits in the acute phase of aSAH.

Prospective study including 51 patients treated for aSAH. Patients were treated in accordance with a standardized institutional protocol and subjected to neuropsychological evaluation around discharge from neurosurgical care. The neuropsychological test results were transformed into a global cognitive impairment index where an index value of 0.00 is considered normal and 1.00 is considered maximally pathological. Patients with an index score of less than 0.75 were considered having good global cognitive function while those with an index score equal to or above 0.75 were considered having poor global cognitive function. Univariate and multiple regression analysis were used to identify medical predictors of cognitive function.

Fifty-seven percent of the patients had poor cognitive function. They showed severe cognitive deficits, with most tests falling well below two standard deviations from the expected normal mean. Poor cognitive function was not reflected in a poor modified Rankin score in almost half of the cases. Patients with good cognitive function showed only mild cognitive deficits with most tests falling only slightly below the normal mean. Delayed memory was the most affected function in both groups. Univariate analysis identified acute hydrocephalus and aSAH-acquired cerebral infarction to be predictors of poor cognitive function. Cerebrospinal fluid drainage in excess of 2000 ml six-folded the risk of poor cognitive function, whereas a new cerebral infarction 11-folded the respective risk of poor cognitive function.

More than half of aSAH patients have severe cognitive deficits in the acute phase. The modified Rankin Score should be combined with neuropsychological screening in the acute phase after aSAH to get a more accurate description of the patients' disabilities. Acute hydrocephalus and aSAH-acquired cerebral infarction are the strongest predictors of poor cognitive function in the acute phase.