The diagnostic pitfalls of subarachnoid hemorrhage from intracranial aneurysms.

The subtle manner in which subarachnoid hemorrhage frequently presents may delay appropriate treatment. The patient may deteriorate and die from aneurysmal rebleeding or from cerebral ischemia associated with vasospasm before the true nature of the disease is recognized. Five patients are described in whom subarachnoid hemorrhage was initially not recognized. Pitfalls in diagnosis are discussed, and an outline is presented for the evaluation of patients suspected of harboring ruptured intracranial aneurysms.