Magnetic resonance imaging contribution for diagnosing symptomatic neurovascular contact in classical trigeminal neuralgia: A blinded case-control study and meta-analysis

Abstract

Although classical trigeminal neuralgia (CTN) is frequently caused by neurovascular contact (NVC) at the trigeminal root entry zone (REZ), both anatomical and MRI studies have shown that NVC of the trigeminal nerve frequently occurs in individuals without CTN. To assess the accuracy of MRI in distinguishing symptomatic from asymptomatic trigeminal NVC, we submitted to high-definition MRI the series of CTN patients referred to our outpatient service between June 2011 and January 2013 (n=24), and a similar number of age-matched healthy controls. Two neuroradiologists, blinded to the clinical data, evaluated whether the trigeminal nerve displayed NVC in the REZ or non-REZ, whether it was dislocated by the vessel or displayed atrophy at the contact site, and whether the offending vessel was an artery or a vein. Our data were meta-analyzed with those of all similar studies published from January 1970 to June 2013. In our sample, REZ contact, nerve dislocation and nerve atrophy were independently associated with CTN (P=.027; P=.005; P=.035 respectively). Compared to a rather low sensitivity of each of these items (alone or in combination), their specificity was high. When REZ contact and nerve atrophy coexisted, both specificity and positive predictive value rose to 100%. Meta-analysis showed that REZ NVC was detected in 76% of symptomatic and 17% of asymptomatic nerves (P<.0001), whereas anatomical changes were detected in 52% of symptomatic and 9% of asymptomatic nerves (P<.0001). In conclusion, trigeminal REZ NVC, as detected by MRI, is highly likely to be symptomatic when it is associated with anatomical nerve changes.

Degree of distal trigeminal nerve atrophy predicts outcome after microvascular decompression for Type 1a trigeminal neuralgia

“…Previous studies using MRI have demonstrated that neurovascular compression without atrophy is common even in asymptomatic individuals, but the presence of atrophy is much more likely to be associated with symptoms. 1,15,18 Pathological analysis of nerve specimens obtained at surgery have demonstrated clear histological and ultrastructural changes in the symptomatic trigeminal nerve, including focal demyelination and axonal loss, which seem to be correlated with the severity of vascular compression. 3,6,12 These changes might lead to alterations in conduction that lead to the development and progression of TN symptoms.…”

“…8,10,13,21 Structural changes in the trigeminal nerve, leading to volume loss, have been well documented, 3,6,12 and a number of studies have demonstrated that nerve atrophy ipsilateral to the symptomatic side is visible on preoperative MRI. 1,4,5,7,9,15,17 Recently, Leal et al demonstrated that atrophy in the midcisternal region of the nerve is associated with more severe vascular compression, and these patients tend to exhibit greater clinical improvement following surgical decompression of the nerve. 10 However, it is unclear whether the nerve atrophy is entirely due to physical compaction by the compressing vessel or whether it is due, in part, to irreversible structural changes.…”

Association between neurovascular contact and clinical characteristics in classical trigeminal neuralgia: A prospective clinical study using 3.0 Tesla MRI

“…This is of major importance to TN etiology and pathophysiology, and possibly also for selection of patients for microvascular decompression (MVD). However, approximately half of TN patients do not have a severe NVC on the symptomatic side (2)(3)(4)(5)(6). Furthermore, a simple NVC, i.e.…”

A Gain-of-Function Mutation in Nav1.6 in a Case of Trigeminal Neuralgia

“…Intraoperative microneurographic recordings in trigeminal nerve fibers after stimulation of the known trigger zone in a TN patient demonstrated afterdischarges that were absent when unaffected facial areas were stimulated (13), loss, demyelination and dysmyelination consistent with NVC of the trigeminal nerve (2). However, recent studies have suggested that only severe neurovascular contact, causing displacement or atrophy of the nerve, is associated with pain in classical TN (3,4), and some studies have questioned whether NVC is necessary and sufficient for TN, since pain can occur and recur in the absence of nerve compression (5,6). A recent study reported…”