Ruptured intracranial aneurysms as a cause of subdural haematoma. Potential diagnostic pitfalls and the surgical management of the acute patient.

Seven cases of aneurysms that ruptured into the subdural space and were treated surgically are reviewed. Six out of the seven presented with signs of uncal herniation, three of them for at least for four hours or more. They all died in spite of urgent decompression and drainage. Three others suffered from uncal herniation for less than four hours and they all did well. The seventh patient had a small subdural haematoma with no signs of compression of the underlying neural structures. This last patient also had a good outcome. The authors point out that the aneurysm causing the haematoma might be overlooked should one utilize CT (computerized tomography) scan alone without contrast. However, in most instances the history gives the aneurysm diagnosis despite the CT scan of haematoma only. Intravenous contrast CT scan may occasionally demonstrate the aneurysm, provided modern CT equipment is adequately utilised. Severe neurological deficit and uncal herniation might still be reversible provided decompression can be carried out in less than four hours. If accessible the aneurysm should also be clipped at the same time.