Reticular fiber deficiency in the intracranial arteries of patients with dissecting aneurysm and review of the possible pathogenesis of previously reported cases.

The pattern of reticular fibers in the tunica media of the major intracranial arteries was investigated in two patients with dissecting aneurysm. In numerous circumscribed areas, the reticular fibers were absent close to the internal elastic lamina in all major arteries of each patient. It is suggested that the subintimal deficiency in reticular fibers results in insufficient fixing of the tunica intima to the media contributing to their separation when the internal elastic lamina becomes defective. The presumed etiologies of the previously reported cases are reviewed and the possible origin of the deficiency in reticular fibers is discussed.