Treatment of the chordoma is surgical excision and radiation (focused radiation). This form of treatment has effected a 5-year survival without recurrence in approximately 80 percent of patients.
Nasopharyngeal Growths That Erode the Base of the Skull (Nasopharyngeal Transitional Cell Carcinoma, Schmincke Tumor)
These are seen regularly in a general hospital; they arise from the mucous membrane of the paranasal sinuses or the nasopharynx near the eustachian tube, that is, the fossa of Rosenmüller. In addition to symptoms of nasopharyngeal or sinus disease, which may not be prominent, facial pain and numbness, abducens, and other cranial nerve palsies may occur. Diagnosis depends on inspection and biopsy of a nasopharyngeal mass or an involved cervical lymph node and radiologic evidence of erosion of the base of the skull. Bone scans and CT are helpful in diagnosis (see Fig. 44-5). The treatment is surgical resection and radiation but chemotherapy is increasingly being included. Carcinoma of the ethmoid or sphenoid sinuses and postradiation neuropathy, coming on years after the treatment of a nasopharyngeal tumor, may produce similar clinical pictures and are difficult to differentiate. The syndromes resulting from nasopharyngeal tumors are discussed in Chap. 47, under “Diseases of the Cranial Nerves.”
Other Tumors of the Base of the Skull
In addition to meningioma, nasopharyngeal tumors, and the other tumors enumerated earlier, there are a large variety of tumors, rare to be sure, that derive from tissues at the base of the skull and paranasal sinuses, ears, and other structures and give rise to distinctive syndromes. Included in this category are osteomas, chondromas, ossifying fibromas, giant cell tumors of bone, lipomas, epidermoids, teratomas, mixed tumors of the parotid gland, and hemangiomas and cylindromas (adenoid cystic carcinomas of salivary gland origin) of the sinuses and orbit; sarcoid granulomas may produce the same effect. Most of these tumors are benign, but some have a potential for malignant change. To the group must be added the esthesioneuroblastoma (of the nasal cavity) with anterior fossa extension and, perhaps most common of all of these, the systemic malignant tumors that metastasize to basal skull bones (prostate, lung, and breast being the most common sources), or involve them as part of a multicentric neoplastic process, for example, primary lymphoma, multiple myeloma, plasmacytoma, and lymphocytic leukemia.
Suprasellar arachnoid cysts also occur in this region. CSF flows upward from the interpeduncular cistern but is trapped above the sella by thickened arachnoid (membrane of Liliequist). As the CSF accumulates, it forms a cyst that invaginates the third ventricle; the dome of the cyst may intermittently block the foramina of Monro and cause hydrocephalus (see Fox and Al-Mefty). Children with this condition exhibit a curious to-and-fro bobbing and nodding of the head, like a doll with a weighted head resting on a coiled spring. This has been referred to as the “bobble-head doll syndrome” by Benton and colleagues; it can be cured by emptying the cyst. Seesaw and other pendular and jerk types of nystagmus may also result from these suprasellar lesions.
Tables 30-5 and 44-1, adapted from Bingas’ large neurosurgical service in Berlin, summarize the facts about the focal syndromes of the skull base; his authoritative article and the more recent one by Morita and Piepgras, both in the Handbook of Clinical Neurology, are recommended references.