Endoscopic view of a clival skull base tumor invading the sphenoid space.

A 59-year-old man was referred to us for evaluation of headaches, double vision, and findings of a skull base tumor on computed tomography (CT). His ophthalmologist had detected a right VIth nerve palsy underlying the double vision. CT of the sinuses revealed that a soft-tissue mass in the base of the skull had eroded the clivus and the posterior wall of the sphenoid sinus and extended into the sphenoid sinus. Endoscopic examination of the nose and nasopharynx detected no gross lesions. The patient's neurosurgeon asked for assistance in obtaining a transnasal and transsphenoid biopsy, which we performed as an outpatient procedure.

The patient then underwent a right transnasal sphenoidostomy. Because the superior nasal cavity was narrow, the inferior half of the superior turbinate was resected (figure 1, A), and the sphenoid sinus was entered via a natural sphenoid sinus ostium (figure 1, B). A soft-tissue mass that had originated in the area of the clivus was found in the right sphenoid sinus (figure 1, C). StealthStation CT (Medtronic; Minneapolis) of the sinus confirmed the preoperative diagnosis of a tumor of the clivus and sphenoid sinus (figure 2). Biopsy analysis identified the lesion as an invasive, well-differentiated squamous cell carcinoma.

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The patient was treated with radiation and chemotherapy. Two years postoperatively, CT demonstrated that most of the preoperative erosive changes of the clivus and sphenoid sinus had disappeared. The appearance of the posterior wall of the sphenoid sinus appeared to be normal. The patient's headaches resolved and his double vision cleared. Five years postoperatively, he remained symptom-free, his CT findings were normal, and the endoscopic examination of the sphenoid sinus was clear (figure 1, D).

The clivus, the central part of the floor of the posterior fossa, is made up of the sphenoid and occipital bones. It slopes backward and downward from the dorsum sellae to the foramen magnum in the occipital bone. (1) Clival lesions often invade the sphenoid sinus.

Several strategies and surgical techniques have been used to approach tumors of the anterior skull base. Surgery carries an inherent risk of complications secondary to retraction injuries of the nerves or the brain. The endoscopic endonasal approach is useful in both diagnostic and therapeutic procedures. (2-4) Advances in endoscopic instrumentation, including the development of powered instrumentation and high-speed drills, coupled with the development of computer-aided image guidance systems have allowed us to achieve exposure of anterior skull base lesions transsphenoidally. This minimally invasive method obviates the need for a craniostomy and spares retraction trauma to the brain. The endonasal approach also allows us to identify the optic nerve and preserve its blood supply.

In the case described here, we were able to perform a safe transsphenoid biopsy as an outpatient procedure to identify a squamous cell carcinoma of the sphenoid sinus. The transsphenoid approach to the skull base is a useful modality both for diagnostic purposes (as with our patient) and for the excision of anterior skull base lesions.

References

(1.) Hollinshead WH. Anatomy for Surgeons. Vol. 1. The Head and Neck. 2nd ed. New York: Harper & Row, 1968.

(2.) Gibbons MD, Sillers MJ. Minimally invasive approaches to the sphenoid sinus. Otolaryngol Head Neck Surg 2002; 126:635-41.

(3.) Kingdom TT, Delgaudio JM. Endoscopic approach to lesions of the sphenoid sinus, orbit apex, and clivus. Am J Otolaryngol 2003; 24:317-22.

(4.) Jho HD, Ha HG. Endoscopic endonasal skull base surgery: Part 3-the clivus and posterior fossa. Minim Invasive Neurosurg 2004;47:16-23.

From the Department of Otolaryngology, University of South Florida College of Medicine, Tampa, and the Halifax Medical Center, Daytona Beach, Fla. (Dr. Christmas and Dr. Mirante), and the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group; the Section of Otolaryngology, Hospital of St. Raphael; and the Section of Otolaryngology, Yale University School of Medicine, New Haven, Conn. (Dr. Yanagisawa).