Elsevier

World Neurosurgery

Volume 92, August 2016, Pages 189-196
World Neurosurgery

Original Article
New Clinical and Morphologic Aspects in Trigeminal Neuralgia

https://doi.org/10.1016/j.wneu.2016.04.119Get rights and content

Objective

High-resolution magnetic resonance imaging can be used to delineate the morphology of neurovascular compression (NVC) in detail. This study focuses on essential morphologic parameters in relation to the clinical appearance of patients with trigeminal neuralgia (TN).

Methods

A total of 180 patients with TN underwent magnetic resonance-constructive interference in steady state/time of flight. Parameters of the affected nerves (length) and causative vessels were examined: (1) the relationship between the NVC site (caudal/cranial/laterocaudal/mediocranial) and affected area (V1, V2, V3); (2) nerve deformity; (3) vascular loop; (4) existence of a “cerebrospinal fluid (CSF) sign” by a separation of trigeminal fascicles by a vessel; and (5) localization of the causative vessel.

Results

A total of 10 patients with V1 affection showed 6 caudal, 0 cranial and laterocaudal, and 4 mediocranial NVC; 26 patients with V2 affection showed 17 caudal, 0 cranial, 1 laterocaudal, and 8 mediocranial NVC; 29 patients with V3 affection showed 23 caudal, 1 cranial, 3 laterocaudal, and 2 mediocranial NVC; 25 patients with V1 and V2 affection showed 17 caudal, 1 cranial, 0 laterocaudal, and 7 mediocranial NVC; 36 patients with V2 and V3 affection showed 30 caudal, 3 cranial, 1 laterocaudal, and 2 mediocranial NVC; and 6 patients with V1, V2, and V3 affection showed 4 caudal, 1 cranial, 0 laterocaudal, and 1 mediocranial NVC. A total of 63 patients (35%) showed nerval deformity by distorsion of the trigeminal fascicles from compressing vessel; 37 of 39 patients (95%) with right-sided deformity showed right-sided TN; and 21 of 22 patients (95%) with left-sided TN showed left-sided nerve deformation. Two patients with bilateral nerve deformity showed bilateral TN. Rostral superior cerebellar artery (SCA) loop compression was seen in 24 patients (17%), caudal SCA loop compression was seen in 10 patients (7%), and double SCA loop compression was seen in 33 patients (23%). Sandwich compression was seen in 18 (12%), and a CSF sign was seen in 24 patients. All 24 patients (100%) with a CSF sign had V1 affection.

Conclusions

The CSF sign is pathognomonic for V1 affection. Vascular loops from cranial on the nerve were the most frequent types of compression in all areas of pain, followed by mediocranial loops. This evaluation is reproducible and contributes to the role of magnetic resonance imaging and a classification of findings in the preoperative evaluation of NVC.

Introduction

Trigeminal neuralgia (TN) often is caused by distinct vascular compression of the root entry zone of the trigeminal nerve (cranial nerve [CN] V) at the lateral pontine aspect of the brainstem.1, 2, 3 The vascular compression caused by an arterial or venous loop might induce focal demyelinization at the junction between central and peripheral myelin sheath,4 which can lead to ectopic impulses and ephaptic transmission, so that a so-called “cross-talk” between sensible-epicritic and protopathic-nociceptive afferences are explained for the triggered facial pain attacks.5 The exact etiology still is unclear; as a result, idiopathic TN is accepted to be caused by neurovascular compression (NVC).6 The causal treatment of TN is microvascular decompression (MVD), as described by Jannetta to maintain functional nerve integrity.5, 7, 8, 9, 10

Diagnosis is obtained by clinical history and symptoms. Magnetic resonance imaging (MRI) is performed to rule out symptomatic reasons for TN, such as tumors or primary demyelinizing conditions. The MRI-based analysis of NVC shows a relatively low specifity of approximately 40%.11, 12 High-resolution MRI shows asymptomatic NVC of the trigeminal nerve in 40% of healthy persons. This study examines more specific imaging parameters for a better evaluation of the underlying pathologic neurovascular patterns. This study aims to present a detailed analysis of high-resolution MRI data of patients with classical TN to enable a comparative categorization of the morphology and the localization of the underlying NVC with the clinical manifestation and the postoperative outcome.

Section snippets

Clinical Data

A total of 211 patients were admitted from 2001 to 2008 to the neurosurgical outpatient clinics for NVC syndromes at the University Hospital of Erlangen. A total of 31 of 211 patients were excluded from the study because of movemental artifacts on the MRI (n = 7) or patients who had a previous history of MVD (n = 24). The resulting 180 patients with classical TN were included to this study (for demographics and clinical parameters of the examined patients, see Table 2).

Detailed MRI

All 180 patients

Patient Demographics and Clinical Parameters

A total of 180 patients were analyzed. The following chart shows demographic and clinical parameters. A total of 147 patients (81.7%) underwent MVD (Table 2).

Prevalence of TN with Correlation to Innervation Areas

Innervation areas V2 and V3 were affected in 57 of 180 patients (31.7%). Area V1 was affected seldom in 10 of 180 patients (5.6%), and the combination of all 3 areas was seen in 10 of 180 patients (5.6%). In 81 patients (45%), 1 innervation branch was affected in the clinical manifestation and in 89 patients (49.5%), 2 innervations

Discussion

This study shows a systematic analysis of the morphology of affecting vessels in symptomatic patients with TN. The group with a CSF sign significantly differed particularly from all other patients in regard to the distribution of sexes, the amount of nerval deformities, and the involvement of clinical affected trigeminal division: the ophthalmic nerve V1. Patients with a caudal SCA loop axilla were seldom pain-free after 1 year in the postoperative period.

As described in former studies, the SCA

Conclusions

In this study, high-resolution MRI contributed to the clinical valency and potential pathogenity of TN. A total of 76% of the examined patients were integrated to the presented classification. This evaluation is reproducible and standardized, so that the clinical and anatomical details of NVC in the diagnostics of TN could be applied to the described classification in addition to the simultaneous, intraoperative application of 3-dimensional visualization. This study shows that the CSF sign is

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Conflict of interest statement: The authors declare that the content of this article was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Levent Tanrikulu and Peter Hastreiter are co−first authors.

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