MRI characteristics of the MLF in MS patients with chronic internuclear ophthalmoparesis

Objective: The authors imaged the medial longitudinal fasciculus (MLF) in 5 8 patients with MS and chronic internuclear ophthalmoparesis (INO) to deter mine which MRI technique best shows the characteristic lesion associated wi th this ocular motor syndrome. Methods: Using quantitative infrared oculogr aphy, the authors determined the ratios of abduction to adduction for veloc ity and acceleration, to confirm the presence of INO and to determine the s everity of MLF dysfunction in 58 patients with MS and INO. Conventional MRI techniques, including proton density imaging (PDI), T2-weighted imaging, a nd fluid-attenuated inversion recovery (FLAIR) imaging, were used to ascert ain which technique best shows MLF lesions within the brainstem tegmentum. T1-weighted imaging was performed to determine the frequency of brainstem t egmentum hypointensities. Results: All patients studied had evidence of an MLF lesion hyperintensity on PDI, whereas T2-weighted imaging and FLAIR ima ging showed these lesions in 88% and 48% of patients, respectively. With PD I, dorsomedial tegmentum lesions were seen in the pons in 93% of patients a nd in the midbrain of 66% of patients. Lesions were observed at both locati ons in 59% of patients. One patient had an MLF lesion with a corresponding T1 hypointensity. Conclusions: PDI best shows the MLF lesion in patients wi th MS and INO.