Neurovascular compression in trigeminal neuralgia: a clinical and anatomical study.

Neurovascular decompression is a widely practiced technique for the treatment of trigeminal neuralgia, and yet there is still debate as to whether the beneficial effect results from relieving the nerve of compression by an anatomically abnormal vessel or from the manipulation and trauma the nerve undergoes during the procedure. The development of this operation has been hampered by the lack of adequate anatomical studies in normal controls. The authors present a combined study of clinical and anatomical material employing standardized definitions of the neurovascular relationships in both groups. Detailed simulations of the operative procedure were carried out on fresh cadavers matched for age, sex, and side, and a technique of in situ blood vessel perfusion was developed that enabled the normal neurovascular arrangement to be observed post mortem at physiological pressures. Neurovascular compression, typified by a large vessel distorting and creating a groove in the fifth cranial nerve, was found in 37 of the 41 cases of trigeminal neuralgia; recurrence of pain did not relate to the site of compression. A follow-up study was carried out for a median of 53 months (range 12 to 103 months). No distortion was found in a total of 50 normal cadaveric dissections; however, on perfusion to physiological pressures, the percentage of nerves with vessels adjacent or in simple contact increased from 16% to 40%. This study using this new technique confirms that vascular compression of the fifth cranial nerve is an anatomical abnormality specific to trigeminal neuralgia.