KINKING OF THE SUPRACLINOID SEGMENT OF THE INTERNAL CAROTID ARTERY OVER NEIGHBORING ANATOMIC STRUCTURES IN ACUTE AND SUBACUTE INTRACRANIAL MASS LESIONS
The supraclinoid segment of the internal carotid artery is easily displaced by intracranial space-occupying lesions. When the displacement is marked, the artery may become kinked over neighboring anatomic structures. Previous reports have been made of compression against the anterior clinoid process in lateral displacement of the artery, and of kinking over the optic nerve in medial displacement of the artery. The present report, in addition, demonstrates compression of the internal carotid artery against the upper margin of the dorsum sellae occurring when the supraclinoid siphon is medially displaced and depressed. When this kinking occurs in acute hemorrhagic and traumatic intracranial mass lesions, it signifies a severe displacement of intracranial structures, usually with tentorial or marked subfalcial herniation, and with a fatal outcome in a majority of the cases. Rarely, the kinking will produce arterial compression severe enough to cause infarction in the internal carotid artery territory. Kinking of the supraclinoid segment of the internal carotid artery does not seem to be the cause of cerebral circulatory arrest. However, since both of these conditions occur in acute traumatic and hemorrhagic intracranial mass lesions, they may be expected quite often to be present simultaneously. This was noted in 2 of the cases reported here, and may summate to produce the circulatory impairment.