Radiological Characteristics of the Affected Trigeminal Nerve in Cases of Trigeminal Neuralgia Caused by Pure Venous Conflict.

Abstract

To assess radiological characteristics that may support the clinical diagnosis of trigeminal neuralgia caused by pure venous conflict. Preoperative constructive interference in steady state images were analyzed retrospectively in 30 patients with trigeminal neuralgia caused by pure venous conflict, which was confirmed during microvascular decompression. Length, width, T2 hyperintensity, and shape of the cisternal segment of trigeminal nerve (CN V), as well as sizes of the trigeminal-pontine angle, trigeminal-petrous angle, and cerebellopontine cistern were evaluated on both sides. On the affected side, the length of CN V was significantly shorter (mean 7.9 mm vs. 9.0 mm, P = 0.0249), whereas its width in midportion (mean 4.0 mm vs. 3.5 mm, P = 0.0022) and the size of the trigeminal-pontine angle (mean 55.3° vs. 48.8°, P = 0.0052) were significantly larger. Other evaluated characteristics did not differ significantly between affected and nonaffected sides. Statistically significant odds ratio (OR) for the association with affected side was revealed for shorter length (OR 10.5, P = 0.0319) and larger width (OR 8.8, P = 0.0487) of CN V; the presence of either of these parameters (i.e., shorter and/or thicker CN V) provided the highest discriminative value (OR 19.3, P = 0.0063). Identification of shorter and/or thicker CN V on the affected side in patients with trigeminal neuralgia without an obvious offending vessel on magnetic resonance imaging may suggest the presence of pure venous conflict and help with decision making about microvascular decompression.