Diffusion Tensor Magnetic Resonance Imaging and Fiber Tracking of Trigeminal Nerves in Relapsing Herpetic Keratouveitis

Abstract

Purpose: : To study the trigeminal fibres (TGFs) using diffusion tensor magnetic resonance imaging (DTMRI) in relapsing herpetic kerato-uveitis.

Methods: : The TGFs of 7 patients (average age: 61+/-13 years), addressed for relapsing unilateral kerato-uveitis related to Herpes simplex virus (HSV) or varicelle-zoster virus (VZV), were tested using DTMRI. The diagnosis of HSV- or VZV-related disease was based on PCR or specific antibodies production within the aqueous humor, or on medical history (zoster). At the time of DTMRI, the kerato-uveitis was in a quiescent period (no recent increase of inflammation). Data were retrospectively assessed by a blinded examiner to compare the affected-side with the non-affected one and with data from sex- and age-matched normal subjects.

Results: : The DTRMI processing showed a significant difference in the mean isotropic fraction within trigeminal fibres innervating the affected side, compared to the non-affected side (0.41 versus 0.48, p = 0,01). There also was a significant difference between results of the affected side of patients and those of control subjects (0.41 versus 0.46, p =0,049), whereas it was not the case for DTRMI results of non-affected sides (p=0.23).

Conclusions: : DTMRI is an emerging technique that allows an accurate analysis of neuronal networks in patients. Our results suggest that multiple HSV or VZV reactivation episodes induce persistent trigeminal fibres injuries (as shown by reduction of the mean isotropic fraction), that probably reflects a significant decrease in the amount of nerve endings.

Keywords: cornea: clinical science • herpes simplex virus • imaging/image analysis: clinical