[Trans-extradural approach to resect trigeminal schwannomas involving the cavernous sinus region].

OBJECTIVE: To investigate the techniques and effect of extradural approach for the resection of trigeminal schwannomas involving the cavernous sinus. METHODS: Twenty-three patients (range 26-63 years, mean age 46.2 years) with trigeminal schwannomas involving the cavernous sinus treated by middle fossa extradural approach were retrospectively analyzed. Frontotemporal orbitozygomatic extradural approach was performed in 2 patients. Frontotemporal zygomatic extradural approach was carried out in 21 patients. The first follow-up visit was on the 3rd month after surgery, and if residual was observed on enhanced MRI, then the patient was followed up every 6 months; otherwise, the patient was followed up every 8-12 months. RESULTS: The length of hospital stay after surgery was 7-13 days (mean 8.5 days). Two tumors originated from the ophthalmic branch, 2 from the maxillary branch, 5 from the mandibular branch and 14 from the gasserian ganglion. Total resection was achieved in 21 of the 23 patients (91.3%) and subtotal resection in the other 2 patients. All the patients were followed up from 3 months to 4 years. Median follow-up time was 19 months. The most common symptom was facial hypoesthesia, occurring in 18 patients. This symptom improved in 10 patients and worsened in 8 patients after surgery. New postoperative facial hypoesthesia was observed in 2 patients. Facial pain was observed in 3 patients and subsided after surgery. Two patients had loss of hearing, this symptom improved in 1 patient and worsened in 1 patient after surgery. Diplopia was observed in 6 patients. In 1 of these 6 patients, diplopia resulted from palsy of the oculomotor nerve. In the other 5 patients, diplopia resulted from palsy of the abducens nerve. This symptom improved postoperatively in all these 6 patients. New postoperative atrophy of the temporalis muscle was observed in 3 patients. There was no operation-related mortality. Tumor recurrence was only found in 1 patient after 24 months and was treated by Gamma knife. CONCLUSIONS: The middle fossa extradural approach may be an ideal option for the resection of trigeminal schwannomas involving the cavernous sinus. This approach produces no further impairment, less complication, and is less likely to injured the trigeminal nerve, abducens nerve, trochlear nerve and internal carotid artery.