Multiplanar metrizamide-enhanced CT imaging of the foramen magnum.

Definition of masses and malformations at the foramen magnum has been less than optimal with traditional radiographic techniques. The use of intrathecal metrizamide with computed tomographic (CT) scanning improves contrast resolution and facilitates detection of abnormalities that may not be apparent on Pantopaque cisternography, plain films, or conventional axial CT alone. Fifty patients with clinically suspected foramen-magnum lesions were evaluated with this technique. Forty were abnormal with the following findings: 14 cases of the Chiari malformation (five cases had associated syringomyelia), five meningiomas, three neuromas, a chondrosarcoma, a chordoma, and five cervical and three brainstem gliomas. Six cases of syringomyelia, a large posterior-fossa subarachnoid cyst, and an anomaly of the cisterna magna were also diagnosed. Sagittal and coronal images were beneficial in defining tonsillar position, configuration of the fourth ventricle, and the relations of mass lesions to the spinal canal and subarachnoid space. Metrizamide CT cisternography provides superior spatial and contrast resolution of lesions at the foramen magnum not obtainable with other radiographic techniques. Morbidity is minimal because of the low dose of metrizamide used. Multiplanar reformations are particularly helpful in assessing anatomic detail not readily recognized on axial scans alone.

Metrizamide CT cisternography and perioptic subarachnoid space imaging.

Opacification of the perioptic subarachnoid space (PSAS) is a normal occurrence. Opacification depends on the anatomy of the meningeal layers surrounding the optic nerves. To determine the reliability and the most efficacious technique for opacifying the PSAS, a retrospective study of 200 computed tomographic cisternography studies with water soluble contrast medium (metrizamide or iopamidol) was undertaken. Of these patients, 32.5% had opacification of the PSAS. Opacification was facilitated by examining the patients in the prone position. Demonstration of the PSAS was frequently noted in patients with empty sella and rhinorrhea.

Traumatic aneurysms of cavernous internal carotid artery with secondary epistaxis.

The syndrome of delayed epistaxis and monocular blindness following nonpenetrating head injury is reviewed. Bleeding results from rupture of a traumatic cavernous internal carotid artery aneurysm into the sphenoid sinus. There were 96 patients with this syndrome found in the literature and another four are added in this report. In 73% of the patients, the cause of the epistaxis was not appreciated until 4 months after the initial episode. No antemortem diagnosis was made in 15% of the patients. More frequent use of carotid angiography in patients with posttraumatic mononuclear blindness and delayed epistaxis might help reduce the reported mortality of 30%.

Radiologic characteristics of primary cerebral neuroblastomas.

Primary cerebral neuroblastomas should be considered in the differential diagnoses of calcified, cystic, supratentorial masses in young patients. The authors review radiologic data for 11 patients with such lesions.