Experimental study and clinical application of extended middle fossa epidural approach

Objective To study the microanatomy of middle cranial fossa and report the operative effect and experience in treating trigeminal neurinomas(TN) via extended middle fossa epidural approach. Methods A microanatomical study was conducted in 50 sides specimens for designing and using middle fossa epidural approach.A retrospective contract review of 98 patients with TN treated via intradural or epidural approach (1978～1997)was undertaken. Results 56 patients(57%) had tumor limited to the middle cranial fossa,42 patients(43%) had both supra and infratentorial components of their tumors. The intradural approach was used only for all tumor removal before 1984 and achieved total tumor removal in 68%(19/28),subtotal in 32%. Since 1985, an epidural approach has been used for all operations and total tumor removal was achieved in 71% (27/38), 91%(29/32)in the early group(1985～1992)and late groups (1993～1997) respectively. During a long term follow up study, 6(21%) patients died and 8(29%) patients suffered recurrence of their tumors in intradural group, while 1 patient died and 3 patients suffered recurrence of their tumors in the early epidural group. Cranial nerves morbidity was 70%, 34%, 19%in intradural group and the early and late epidural groups respectively.Conclusion The extended middle fossa epidural approach is the most effective method to resect the TN involving middle fossa, cavernous sinus or/and upper and middle petroclival region.