The CSF sign - A potential biomarker in ophthalmic neuralgia?

Specific magnetic resonance imaging sequences are utilized in the visualization of the detailed morphology of neurovascular compression (NVC) in classic trigeminal neuralgia (TN). This study focuses on essential morphological parameters especially in the clinical involvement of the ophthalmic branch (V1) of the trigeminal nerve with examination of the cerebrospinal fluid "CSF" sign, which is a separation of trigeminal fascicles by a vessel.

A total of 102 patients (mean age 65.5 ± 11.3 years; f/m: 72/30, 52 left-sided/ 50 right-sided symptoms) with TN were included into this analysis. Complete clinical and radiological data were available for all patients. The patient population was divided into two groups: patients with and without clinical V1 involvement. The occurrence of the CSF sign was analyzed in the high resolution T2 weighted imaging data. A chi²-test was applied for statistical evaluation of the correlation between the existence of a CSF sign and V1-involvement.

There was a statistical significant correlation between the involvement of the V1-branch in TN and the existence of a CSF sign (p = 0.00043; chi²-test). There was a statistical significance for the occurence of TN in females (p = 0.0001; chi²-test). There was no statistical significance in the lateralization of neuralgic symptoms (p = 0.78; chi²-test). A 4.4 fold higher probability of a positive CSF sign was found in patients with V1-symptoms (odds ratio 4.36 for V1 and positive CSF sign). The Cramer V-test showed a medium effect size for the association of V1 positive symptoms and existent CSF sign with a value of 0,349 (∼0.1 weak, ∼0.3 medium, ∼0.5 strong).

Our study demonstrates that there is a statistical significant correlation between the existence of a CSF sign and clinical involvement of ophthalmic branch of the trigeminal nerve in TN. We could herein show, that the CSF sign may act as a potential biomarker in V1 affection in TN.