Background: Dumbbell-shaped trigeminal neurinomas are rare benign tumors with a controversy regarding their treatment and surgical approaches. We conducted an investigation on elucidating a strategy for the treatment of DSTNs.
Methods: One hundred thirty-seven patients with trigeminal neurinomas, accounting for 0.6% of all intracranial tumors and 3.8% of intracranial neurinomas, were screened out from the data bank on brain tumors in Hua Shan Hospital (Shanghai, China) from 1978 to 2003. Among them, 57 patients with DSTNs were found without Recklinghausen disease and analyzed retrospectively. Patients were divided into 2 groups. In the early group (1978-1984), a series of conventional intradural approaches were used, and in the latter group (1985-2003), an extradurotransdurotranstrigeminal pore approach with orbitozygomatic craniotomy was applied. After the tumor in the middle cranial fossa was resected, the tumor in the posterior fossa was resected via a suboccipital approach in the early group and through enlarged porus trigeminus without resection of the petrous apex in the latter group.
Results: There were 12 patients in the early group and 45 patients (including 6 patients with recurrent tumors) in the latter group. The mean age was 37 years (range, 14-56 years) and 39 years (range, 12-72 years), respectively, in the early and latter groups. There was no predominance in sex in the 2 groups. The mean duration of clinical manifestations before admission were 2.2 and 2 years, respectively, in the early and latter groups. Tumor size measured on MRI and/or CT were 30 to 40 mm in 4 (33%) cases from the early group and 14 (31%) cases from the latter group, 41 to 50 mm in 8 (67%) cases from the early group and 25 (56%) cases from the latter group, and more than 50 mm in 6 (13%) cases from the latter group. There were 3 patients in the latter group with a tumor extending into the infratemporal fossa and pterygopalatine fossa. Total tumor resection was achieved in 42% (5/12) of the early group and 87% (39/45) of the latter group (chi(2) = 10.897, P < .001); incomplete tumor removal was done in 58% (7/12) of the early group and 13% (6/45) of the latter group. One patient in the early group died of brainstem injury postoperatively. There was no surgical mortality in the latter group. Cranial nerve morbidities were seen in 80% of the early group and 41% of the latter group (chi(2) = 12.052, P < .01), when patients were discharged. Six months after operation, however, cranial nerve morbidities were seen in 55% of the early group and 18.6% of the latter group (chi(2) = 8.585, P < .01). A long-term follow-up study was available in 41 (75%) patients, with a period of 2 to 20 years (mean, 10 years). Karnofsky prognosis scale scores were at least 90 in 60% of the early group and 77% of the latter group and 70 to 80 in 40% of the early group and 23% of the latter group. Recurrent tumors occurred in 3 patients from the early group and were reoperated on. One patient with a recurrent tumor from the latter group underwent radiosurgery 5 years after the operation.
Conclusion: The best treatment for large or giant DSTNs is microsurgery with extradurotransdurotranstrigeminal pore approach via single-stage skull-base craniotomy. It is not necessary to resect the petrous apex for removal of the tumor in the posterior fossa. Radiosurgery can be used for the residual or recurrent tumors.