Posterior Fossa Microsurgical Approach to the Trigeminal Nerve for Tic Douloureux: An Operative Technique and Immediate Results

Background: There are several methods for treating tic douloureux including Gamma Knife stereotactic radiosurgery (GKSR), gasserian ganglion percutaneous technique and microvascular decompression (MVD). MVD via the posterior fossa has become the standard treatment for trigeminal neuralgia (TN). This microsurgical procedure has been proven safe in experienced hands and its effectiveness rate is as high as 98%. The aim of this paper is to share the authors' personal experience, from the standpoint of operative technique, with those who are contemplating performing or who are already performing this kind of surgery. Materials and Methods: Over the past two decades, among 349 patients (including three with failed GKSR) with typical TN, 288 received MVD, 39 received partial sensory rhizotomy and 22 received MVD combined with partial sensory rhizotomy. With the patient in a lateral position, a small retrosigmoid craniectomy was used to approach the cerebellopontine angle (CPA) via the lateral supracerebellar route. Exploration and identification of the offending artery (arteries) in contact with the whole nerve, at any point, not merely the root entry zone (REZ), were carefully carried out. Transposition of the offending vessel (vessels) away from the nerve was the main decompression method, followed by Teflon felts interpositioned between the two structures. Results: All patients were evaluated within 1 week of operation. Excellent (90.9%) and good (4.6%) clinical outcomes were achieved in 333 patients; partial pain relief was achieved in 10 patients; and little or no pain relief was achieved in 6 patients. All 6 patients who failed to respond positively to the initial surgery underwent partial sensory rhizotomy within 1 week of evaluation to relieve the pain. Conclusion: MVD is generally accepted as the gold standard for first line treatment of TN, especially in younger patients who are refractory to medication. The anatomical approach that we have adopted is described in detail.