Review of the clinical features of 48 patients with chordoma and 49 patients with low-grade chondrosarcoma of the skull base disclosed overlapping clinical profiles but distinctive features. Both tumors occurred at all ages but chondrosarcoma tended to occur in the third and fourth decades. Twenty-five (52%) of the patients with chordoma and 24 (49%) of the patients with chondrosarcoma had ocular symptoms (diplopia or visual impairment) as the initial manifestation of the disease. Of the 59 patients (both groups) with diplopia, the diplopia was initially intermittent in 25 (42%). Headache and diplopia from an insidious abducens nerve palsy was most common in both groups. Abducens nerve palsy occurred in 22 (46%) of the patients with chordoma and 23 (47%) of the patients with chondrosarcoma. Normal examination results were more common in patients with chordoma, whereas visual loss, facial numbness, and multiple cranial neuropathies were more common in patients with chondrosarcoma. The similarities in the clinical features of these tumors reflect their common origin at the central skull base and the vulnerability of the abducens nerves at that site. The differences reflect the tendency of chordomas to originate from the clivus and chondrosarcomas to originate from the temporal bone.
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