A p1 aneurysm and diabetes insipidus caused by traumatic brain injury.

We describe a patient with a P1 aneurysm of the posterior cerebral artery (PCA) with diabetes insipidus (DI) caused by traumatic brain injury. A 21-year-old woman presented with epidural hematoma, left temporal contusion and subarachnoid hemorrhage caused by head trauma. DI occurred with normal anterior hypophyseal function on the second day after admission and cerebral angiography demonstrated an aneurysm at the right P1 portion after one month. DI was treated with administration of desmopressin and the aneurysm and P1 portion of the right PCA were occluded completely. After three months, her DI recovered and decompressin was discontinued. The six month follow-up angiogram confirmed cure of the P1 aneurysm. P1 aneurysm and DI can be caused by traumatic brain injury. Cranial DI caused by head injury with perturbations in water balance may be transitory and resolve.