NEUROVASCULAR RELATIONSHIPS IN THE POSTERIOR CRANIAL FOSSA, WITH SPECIAL REFERENCE TO TRIGEMINAL NEURALGIA .2. NEUROVASCULAR COMPRESSION OFTHE TRIGEMINAL NERVE IN CADAVERIC CONTROLS AND PATIENTS WITH TRIGEMINAL NEURALGIA - QUANTIFICATION AND INFLUENCE OF METHOD

The theory of neurovascular compression has been tested by comparing t he neurovascular relationships of the trigeminal nerve in a series of operative observations in patients affected by trigeminal neuralgia wi th those of a control series of cadavers, matched for age, sex and sid e, in which operative conditions were simulated during simultaneous ar terial and venous injection-filling to physiological pressures, as des cribed in Part 1 of this article. A rigorous system of classification of neurovascular relations is defined. In 46 patients with trigeminal neuralgia, 91% had a vessel in contact with the trigeminal nerve adjac ent to the brain stem and in all but one a groove was created. Multipl e vessels were found in 17% and in two both the root entry zone and la teral portions of the nerve were compressed. However, in 35 randomly s elected fresh cadavers, not known to have suffered neurological diseas e, 14% had neurovascular contact and a further 26% had vessels ''near' ' to the nerve. No vessel was associated with a groove and no multiple vessels, or sites of contact, were encountered. The difference betwee n the control cadavers and the operative findings in patients related to an increase in the number of arteries. Injection-filling of the cad averic vessels doubled the numbers of vessels in contact with, and nea r to, the nerve. The technique used and system of classification appli ed showed an association between arterial contact and trigeminal neura lgia. The technique may provide a suitable method for the testing of t he neurovascular compression theory in other conditions. (C) 1997 Wile y-Liss, Inc.