Nonhemorrhagic complications of intracranial aneurysms of the internal carotid artery

SUMMARYNonhemorrhagic complications of intracranial aneurysms of the carotid artery often follow a recognizable neurological pattern. The brunt of the deficit is borne by the anterior cranial nerves, either singly or in combination. Depending on the location of the aneurysm, further trends of selective involvement are evident. Infraclinoid extradural carotid aneurysms classically attack the cranial nerves III, IV, V, and VI but often spare the optic nerve. By contrast, supraclinoid intradural carotid aneurysms typically affect the optic nerve or chiasma or both, leaving the extraocular muscle nerves relatively unaffected and sparing the second and third divisions of the trigeminal nerve. Severe frontal or orbital pain from involvement of the first trigeminal division is the most frequent and, commonly, the earliest symptom, regardless of aneurysmal location. Evolution of symptoms and signs varies. Progressive stepwise deterioration or a course punctuated by exacerbations and remissions prevails. Neurological deficit, although characteristic of aneurysm, is not pathognomonic. Other intracranial lesions with similar manifestations must be considered.