Of 37 patients with 44 intracavernous carotid artery aneurysms (ICCAAns) diagnosed between 1976 and 1988. patients with 20 aneurysms were followed without treatment for 5 months to 13 years (median, 2.4 years). Ten of the 20 ICCAAns were asymptomatic at diagnosis, and 10 were symptomatic. Three of the asymptomatic ICCAAns were symptomatic at follow-up. One of these required clipping because of a progressing cavernous sinus syndrome; the other 2 were minimally symptomatic and have not required treatment. Of the 10 initially symptomatic ICCAAns, 2 had not changed, 4 became more symptomatic, and 4 had symptomatically improved by follow-up. One patient with an ICCAAn that had not changed clinically was lost to follow-up 6 months after diagnosis. Of the 4 ICCAAns that became more symptomatic, 2 continue to be monitored, and 2 required intervention; one with detachable balloon occlusion of the aneurysm with preservation of the internal carotid artery lumen, and the other with gradual cervical internal carotid artery occlusion. The clinical course of this selected group of patients with ICCAAns suggests that the natural history of ICCAAns can be quite variable. Although clinical progression does occur, symptomatic ICCAAns also can improve spontaneously. Therapeutic intervention for asymptomatic ICCAAns should be reserved for patients with aneurysms arising at the anterior genu of the carotid siphon and/or extending into the subarachnoid space, where subarachnoid hemorrhage is most likely. Intervention for symptomatic ICCAAns should be reserved for patients with subarachnoid hemorrhage, epistaxis, severe facial or orbital pain, evidence of radiographic enlargement, progressive ophthalmoplegia, or progressive visual loss.

The magnetic resonance (MR) images from 17 patients with chondrosarcomas of the skull base were retrospectively reviewed to characterize the size, location, signal intensity, and extension of these tumors. Eleven patients with chondrosarcomas received intravenously administered gadopentetate dimeglumine. In 16 patients, computed tomographic (CT) scans were obtained to evaluate intratumorous mineralization and bone erosion. On short repetition time (TR)/echo time (TE) MR images, chondrosarcomas generally had low to intermediate signal intensity; on long TR/TE MR images, they generally had very high signal intensity. Signal heterogeneity on long TR/TE MR images was seen in 10 of 17 tumors (59%) and was caused by matrix mineralization, fibrocartilaginous elements, or both. Matrix mineralization was demonstrated with CT in seven of the 16 chondrosarcomas. Chondrosarcomas showed marked enhancement after administration of gadopentetate dimeglumine in either a heterogeneous (n = 8) or homogeneous (n = 3) pattern. The information about the size and extent of these neoplasms was important in the choice of surgical approaches for gross total resection of tumor.

Perivascular (Virchow-Robin) spaces normally surround perforating arteries that enter the medial temporal lobes, corpus striatum, and thalamus. The high soft-tissue sensitivity of magnetic resonance (MR) imaging allows for the frequent detection of such cerebrospinal fluid (CSF)-filled spaces. Especially on axial images, these CSF-filled perivascular spaces may be confused with pathologic lesions, such a lacunar infarcts. Postmortem brain specimens demonstrate the anatomy of perivascular spaces around perforating arteries. Orthogonal images in the living patient help confirm this anatomic relationship. The characteristic CSF signal patterns from these foci are further evidence of their anatomic identification and true benign nature.

Thirty-seven patients with 44 intracavernous carotid artery aneurysms (ICCAAns) were seen at one institution from 1976 through 1988. Fifteen patients had multiple intracranial aneurysms and 7 had bilateral ICCAAns. Age at diagnosis ranged from 15 to 80 (median 61). Thirty patients were women. Sixteen had a history of hypertension. In 34% of patients the ICCAAns were asymptomatic at diagnosis. 36% were associated with headache, and 57% had associated signs or symptoms of mass effect including sixth nerve paresis (43%). trigeminal pain or sensory loss (32%), third nerve paresis (20%), decreased vision or visual field cut (18%), fourth nerve paresis (16%), and Horner's syndrome (7%). In 4 patients the ICCAAns ruptured, leading to subarachnoid hemorrhage in 3 and epistaxis in 1. Two patients with ICCAAns were seen with spontaneous thrombosis of the ipsilateral internal carotid artery leading to distal ischemic symptoms in 1. More than 90% of the ICCAAns were saccular. Thirty-four percent were small (<1 cm), 48% were large (1 to 2.5 cm), and 16% were giant (>2.5 cm). The majority arose from the anterior genu of the intracavernous internal carotid artery, followed in frequency by the horizontal segment, and then the posterior genu. Magnetic resonance imaging is superior to computed tomography for diagnosing ICCAAns and is the screening procedure of choice. Angiography remains the “gold standard” for diagnosis and determining specific anatomic details necessary to plan therapy. Analyzing the radiographic anatomy of 44 ICCAAns, we conclude that theories attributing the origin of aneurysms to arterial bifurcations may be inadequate to explain the point of origin and direction of take off of up to one-fourth of ICCAAns. (Neurosurgery 26:71-79, 1990)