Internal carotid artery aneurysms, cranial nerve dysfunction and headache: the role of deformation and pulsation.

Cranial nerve dysfunction and headache may occur with unruptured aneurysms of the cavernous and supraclinoid portions of the internal carotid artery. Nerve deformation (mass effect) and transmitted pulsations have been suggested as pathogenetic mechanisms. Differentiation may be possible by studying effects of endovascular treatment with Guglielmi detachable coils. Symptoms and signs of cranial neuropathy were retrospectively contrasted with angiographic aneurysm volumes before and after treatment in 10 patients. Mean follow-up was 36 months. Symptoms improved in three of four patients with cranial nerve dysfunction and in all patients with headache. None of the other patients, one with cranial nerve dysfunction, and three who were asymptomatic, developed any new symptoms after treatment. Aneurysm volume ranged from 0.1 to 2.7 cm(3 )before and 0.2 to 5.7 cm(3) after treatment; the size thus increased by 15 to 110%, a change which was statistically significant (P=0.004). The consistent increase in aneurysm volume with treatment is not associated with clinical deterioration, suggesting that deformation and displacement play a minor role in cranial neuropathy and that transmitted pulsations may be more important.