Syringomyelia as a postoperative sequela of the resection of a chordoma of the clivus: case report. Syringomyelia has been described frequently in association with various abnormalities of the skull base but rarely with tumors of the skull base. Syringomyelia as a postoperative sequela of surgery of the skull base has not been reported. The authors describe a case of cervical syringomyelia developing after the partial resection of a chordoma and combined conventional and proton beam irradiation. The possible mechanisms causing this abnormality are discussed. 