The notion of "warning leaks" in subarachnoid haemorrhage: are such patients in fact admitted with a rebleed?

Objective: Often patients with subarachnoid haemorrhage (SAH) recall a recent episode of acute severe headache, usually interpreted as a "warning headache" or first SAH. An alternative explanation is recall bias. The clinical and radiological features of patients with SAH were studied in relation to previous headaches or later rebleeding.

Methods: Patients with either a previous headache episode or a subsequent rebleed were selected from the SAH database in Utrecht within 1 month of the index SAH. The clinical condition was graded on the World Federation of Neurological Surgeons (WFNS) scale. The CT was reviewed and the amounts of subarachnoid blood, hydrocephalus, and intraventricular, intracerebral, and subdural blood were rated. Proportions were compared by unpaired or paired t test.

Results: Forty four of 390 patients (11%) had had a severe headache before their index SAH (11 of these had a subsequent rebleed); 31 other patients had a rebleed in hospital but no preceding headache. Patients with and without preceding headache did not differ in level of consciousness (14 of 44 v 11 of 31 were comatose), nor in any of the radiological features. After rebleeding (42 patients), 37 of 42 patients were comatose (v 11 of 42 before), and CT showed higher proportions of intracerebral haemorrhage (17%), intraventricular haemorrhage, (27%), and hydrocephalus (12%) than baseline scans. Intraventricular haemorrhage was twice as frequent after rebleeding than at baseline.

Conclusions: The clinical and radiological features of patients admitted with SAH after a preceding bout of headache did not differ from those without such an episode, and are clearly dissimilar from those after documented rebleeds. The findings challenge the existence of minor "warning headaches".