This tumor, like the brainstem glioma, occurs most frequently during childhood and adolescence. In 85 percent of cases, it appears before the age of 15 years (average 3.5 years), and it is twice as frequent in girls as in boys (Cogan). The initial symptoms are dimness of vision with constricted fields, followed by bilateral field defects of homonymous, heteronymous, and sometimes bitemporal type and progressing to blindness and optic atrophy with or without papilledema. Ocular proptosis from the orbital mass is the other main feature. Hypothalamic signs (adiposity, polyuria, somnolence, and genital atrophy) occur occasionally as a result of proximal tumor extension. CT, MRI, and ultrasonography will usually reveal the tumor, and radiographs will show an enlargement of the optic foramen (greater than 7.0 mm). This finding and the lack of ballooning of the sella or of suprasellar calcification will exclude pituitary adenoma, craniopharyngioma, Hand-Schüller-Christian disease, and sarcoidosis. In adolescents and young adults, the medial sphenoid, olfactory groove, and intraorbital meningiomas (optic nerve sheath meningioma) are other tumors that cause monocular blindness and proptosis. If the entire tumor is prechiasmatic (the less-common configuration), surgical extirpation can be curative. For tumors that have infiltrated the chiasm or are causing regional symptoms and hydrocephalus, partial excision followed by radiation is all that can be offered. Both gliomas and nontumorous gliotic (hamartomatous) lesions of the optic nerves may occur in von Recklinghausen disease; the latter are sometimes impossible to distinguish from optic nerve gliomas and should be followed closely.
This is a soft, jelly-like, gray-pink growth that arises from remnants of the primitive notochord. It is located most often within the clivus (from dorsum sellae to foramen magnum) and in the sacrococcygeal region. It affects males more than females, usually in early or middle adult years and is one of the rare causes of syndromes involving multiple cranial nerves or the cauda equina. Approximately 40 percent of chordomas occur at each of these two ends of the neuraxis; the rest are found at any point in the vertebral bodies in between. The tumor is made up of cords or masses of large cells with granules of glycogen in their cytoplasm and often with multiple nuclei and intracellular mucoid material. Chordomas are locally invasive, especially of surrounding bone, but they do not metastasize.
The cranial neurologic syndrome caused by this tumor is remarkable in that all or any combination of cranial nerves from the 2nd to 12th on one or both sides may be involved. Associated signs in the series of Kendall and Lee were facial pain, conductive deafness, and cerebellar ataxia, the result of pontomedullary and cerebellar compression. A characteristic feature is neck pain radiating to the vertex of the skull on neck flexion. The tumors at the base of the skull may destroy the clivus and bulge into the nasopharynx, causing nasal obstruction and discharge and sometimes dysphagia. Extension to the cervical epidural space may result in cord compression. Thus, chordoma is one of the lesions that may present both as an intracranial and extracranial mass, the others being meningioma, neurofibroma, glomus jugulare tumor, and carcinoma of the sinuses or pharynx. CT of the skull base is useful for defining the bony margins of the tumor, and MRI can identify involved and adjacent neural and vascular structures. Midline (Wegener) granulomas, histiocytosis, Erdheim-Chester disease, and sarcoidosis also figure in the differential diagnosis. Chondrosarcoma of the clivus produces a similar syndrome.