Background: Previous studies on spontaneous aneurysmal subarachnoid haemorrhage (SAH) treatment have found the presence of global cerebral oedema on the first CT scan to be a predictor of poor outcome. We have reviewed our own experience with SAH in order to evaluate the relation of global cerebral oedema to clinical parameters at admission and to functional outcome.

Methods: One hundred ninety patients with spontaneous aneurysmal SAH were included in the study. The first CT scan for each patient was evaluated for signs of global cerebral oedema. Clinical status on admission was assessed according to the Hunt & Hess score and the World Federation of Neurosurgical Societies (WFNS) grade and functional outcome using the Glasgow Outcome Scale (GOS). Clinical condition at admission was dichotomised as 'better' (Hunt & Hess 1-2, WFNS 1-2) or 'worse' (Hunt & Hess 3-5, WFNS 3-5) and outcome as 'favourable' (GOS 4-5) or 'poor' (GOS 1-3). The amount of blood on the CT scan was assessed using the Fisher scale. Comparisons were made between patients with and without global cerebral oedema on the first CT regarding clinical condition, age, gender, mode of aneurysm treatment, outcome, 6-month mortality, amount of blood on the CT scan and time lag to the first CT scan.

Results: Global cerebral oedema was observed in 57% of patients admitted with aneurysmal SAH, which is a much higher frequency than has been reported previously. Patients with oedema were admitted in a worse clinical status, but there was no difference between patients with and without oedema regarding other clinical parameters or outcome. The median time between the haemorrhage and the first CT scan was short compared to earlier studies, 2.5 h for those with oedema and 3.4 for those without. This difference was significant, suggesting that global cerebral oedema can be a very early phenomenon after SAH, and may be missed in later CT scans.

Summary: Early global brain oedema, occurring within a few hours of bleeding, may be more common than previously thought. In aneurysmal SAH patients, the presence of global cerebral oedema was associated with a worse clinical condition at admission which in turn could indicate a more severe initial injury. The clinical significance of early oedema may differ from that of late oedema, which may explain the lack of an association between global oedema and poor outcome in this study. However, the nature of the oedema as well as its relation to the clinical course has to be further studied in separate studies.