[Microsurgical vascular decompression in trigeminal neuralgia. Comparison of 2 technical modalities and physiopathologic deductions. A study of 120 cases].

Since 1972, 1,000 patients were operated upon for trigeminal neuralgia, 816 percutaneously using thermocoagulation and 184 through a direct approach at the cerebello-pontive angle. This article deals with the microvascular decompression (MVD) procedure, stressing on the influence (on morbidity and results) of different technical modalities. This work compares: 1. a series of 60 patients operated upon in the sitting position, with a wide opening of the cerebellopontine-angle, and using an interposed foreign body to protect the nerve from the conflicting artery (Group I, 1984-1986) and 2. a series of 60 other patients who underwent MVD in the lateral position, with a restricted approach and transposition of the conflicting artery without interposition of synthetic material (Group II, 1986-1988). Both series were fortuitously comparable concerning sex, age and clinical features. Comparison of results in the two series shows that: 1. Duration of the anesthetic induction, surgery and awakening, were all shorter (70 mm, 2 h 47 mn, 1 h 38 mn, respectively) in group II than in group I (110 mn, 3 h 12 mn, 2 h 38 mn). 2. Complications related both to anesthesia and surgery were significantly less frequent in group II than in group I, excepted for rhinorrhea due to C.S.F. leak through the mastoid cells. 3. Trigeminal neuralgia was completely relieved--without any hypoesthesia and/or dysesthesias--in 75% of group I patients (mean follow-up: 41 months) and in 83.3% of group II (mean follow-up: 16 months). Evaluation of results on pain, after one year, in both series shows that the technique used in the second series: transposition of the conflicting vessel without foreign body touching the nerve was not followed by a higher rate of recurrences than in the first series, on the contrary: 4.5% versus 10%. This indicates that MDV would not act by creating a neocompression of the nerve, but in fact by a real decompression mechanism.