Patients with subarachnoid haemorrhage (SAH) resulting from aneurysmal bleeding may exhibit serious neuropsychiatric sequelae, often more disabling from the perspective of rehabilitation than any neurological impairment. This notwithstanding, little is known about their nature and mechanisms. Affective symptoms and personality change remain the more frequently reported psychiatric complications but most studies have not used standard diagnostic categories. Neuropsychological deficits are better documented, but there is still no consensus regarding prevalence, and studies are hampered by methodological weakness. 'Off-the-shelf instruments seem to detect less cognitive impairment than ad-hoc psychometry. Few studies have made use of modern imaging techniques. Certain types of surgery, for example trapping, give rise to high rates of amnestic impairment. It is not yet fully determined whether pre-operative vasospasm, high blood pressure on admission, neurological grade, site of aneurysm, laterality, presence of haematoma and hydrocephalus also predict bad neuropsychological outcome. Further evaluation of the predictive power of the variables predicting bad neurobehavioural outcome is urgently needed so that thay can be made to influence pre-operative neurosurgical decisions.
