gms | German Medical Science

Objective: Microvascular decompression of the trigeminal root (MVD) has become the most appropriate operation for the treatment of trigeminal neuralgia. In spite of the concept of neurovascular conflict, the exploration of the trigeminal root results as negative in a variable percentage of the cases, also in whom diagnosed with the more accurate MRI sequences. In case of negative cranial fossa exploration (CFE), the literature does not show any consensus about the way to follow: to close the operation, to make an arachnoidal dissection, to manipulate the root, or to proceed to a root lesion. The surgical procedure proposed by the authors as a "rescue technique" for negative CFE consists in a knife incision (cold lesion) of 3 mm length and 3 mm deep lesion of the trigeminal entry zone (TREZL) at the dorsal aspect of the pars mayor as near as possible to the pons. The authors present their experience, using such a procedure either as a converted operation in cases of negative exploration, or as a primary operation in cases of trigeminal neuropatic pain. Between 1990 and 2013, 215 patients suffering from typical trigeminal neuralgia underwent to posterior fossa exploration at the Department of Neurosurgery of the "Ospedale San Camillo" in Rome. In 187 (87% - group A) a significant arterial confict was found and released; a doubtable conflict or a vein adhesion were considered as negative exploration (13% - group B) and converted into TREZL procedure.

Results:In the group A (187 cases) an excellent outcome (BNI gr.I) was achieved in 93,5% of the cases. In the group B (22 cases) an excellent result (BNI I) was obtained in 23%, BNI II in 59% and failure (no result) in 18%. Out of the unsuccesfull cases at follow-up, from the group A (12 cases of recurrences or failure) 2 underwent successive percutaneous microcompression and 10 posterior fossa re-exploration for TREZ lesion; in 1 case with a Teflon conflict the nerve was released. None of the REZL cases experienced incapacitating face numbness. 6 cases suffering from trigeminal neuropatic disease underwent directly to the TREZL operation and are not included in this series.

Conclusions:MVD is an effective procedure, in our series burdened in the follow-up period by 7% failure/recurrences only, the majority occurring within two years from surgery. We believe that careful intraoperative evaluation of the conflict entity could be the key to achieve a significant improve of the results: over evaluation of a simple vascular contact of doubtful pathogenic relevance, may lead to ineffective decompression and unsatisfactory results. In our opinion trigeminal REZL performed during the trigeminal nerve exploration should be a reasonable and effective solution in the negative findings.