Neuroradiological examinations of extracranial extension of brain tumors

Before the application of CT scan, the exact identification of extracranial extension of brain tumors was difficult. In the present paper, neuroradiological findings of eight brain tumors with extracranial extension were reviewed. These eight cases were composed of two sphenoidal meningiomas, one CP angle meningioma, one CP angle neurofibroma, two pituitary adenomas, and two jugular foramen chemodectomas. After the first application of CT scan on May, 1976, 841 cases of primary intracranial tumors have been experienced in our clinic. So the incidence of brain tumors with extracranial extension was about 1%. The mean age of the patients was 51 years and all of the patients were females. In the neuroradiological examinations, plain skull films, tomograms, angiograms and CT scans were reviewed. Plain skull films and tomograms showed indirect signs of extracranial extension, such as destruction or hyperostosis of the skull and enlargement of the foramina. Direct signs of extracranial extension in the plain films were not obtained except in the pituitary adenomas, which extended into the paranasal sinuses and pharynx. Angiograms showed direct signs of extracranial extension, when remarkable tumor stain existed. Occlusion of the internal jugular vein suggested the extension of the tumor through the jugular foramen. In the cases without tumor stains, angiograms were useless to identify the extracranial portion of the tumor. CT scans were useful in all cases to detect extracranial extension. From the findings of CT scan, extracranial extensions of brain tumors were classified into four types. 1. Extracranial extension with destruction of the skull. 2. Extracranial extension with hyperostosis of the skull. 3. Extracranial extension with both hyperostosis and destruction of the skull. 4. Extracranial extension with enlargement of the skull foramina. To detect extracranial extension of brain tumors, enhanced coronal CT scan seemed most useful. (author)