Visualisation of the medial longitudinal fasciculus using fibre tractography in multiple sclerosis patients with internuclear ophthalmoplegia

Background: This study investigates the use of fibre tractography to facilitate visualisation of the medial longitudinal fasciculus (MLF) and the impact of internuclear ophthalmoplegia (INO) causing lesions on these reconstructions of the tract. Improved visualisation of such tracts may improve knowledge, understanding and confidence related to neurological conditions. Aims: To explore the use of fibre tractography for the visualisation of the MLF in patients with INO. Methods: Twelve MS subjects with clinical evidence of INO and 12 matched controls underwent magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI), of the brain. Fibre tractography reconstructions were then evaluated and validated by an experienced neuroanatomist. Results: The evaluating neuroanatomist confirmed that the MLF had been reproduced in all of the reconstructed cases (fibre tractography was unsuccessful in five cases). The sensitivity of fibre tractography to MLF pathology was 58.3 % while the specificity was much higher at 85.7 % with a positive predictive value of 87.5 % and a negative predictive value of 54.6 %, with excellent intra-reader reliability. Conclusion: This study demonstrates that fibre tractography of the MLF can potentially be performed with a view to facilitating improved visualisation of the tract and associated pathology in cases of INO. This may help explain the association between lesion type and location with clinical symptomatology and may assist in monitoring disease progression. These reconstructions may provide a valuable addition to the teaching and understanding of clinical signs related to subtle pathology.