Evaluation of early visual recovery in pituitary macroadenomas after endoscopic endonasal transphenoidal surgery: Quantitative assessment with diffusion tensor imaging (DTI)

Background Visual field analyses reflect the degree of the compression to the optic nerve that results the structural damage of the nerve. These structural damages can be evaluated by diffusion tensor imaging (DTI), which assesses the structural integrity of white matter tracts. Thus, we evaluated the quantitative assessment of early visual recovery in patients with pituitary macroadenomas, corresponding DTI with visual field analyses. Methods Seventy-two patients who had pituitary macroadenomas with visual field defects were included in the study retrospectively. All patients were operated on by pure endoscopic transphenoidal approach. Visual field assessment using Humphrey field analyzer and DTI with 3T magnet were performed in the preoperative and postoperative second day and sixth month. Findings Mean symptom duration was 14.7±10.5 weeks in the full recovery group patients, 50.1±29.1 weeks in partial recovery patients, and 92.4±15.4 weeks in the ones with no recovery. There was a significant difference at p<0.001 among the groups. On visual field analysis, the visual lost was mostly recognized at upper temporal levels preoperatively. Visual field findings of both eyes were improved in 80% of the patients. Among these, 25% revealed full recovery, 55.6% partial recovery, and 19.4% did not demonstrate significant changes. DTI assessments of affected sides revealed preoperative fractional anisotropy (FA) values below 0.400 and mean diffusivity (MD) values over 1,400×10-6 mm2 s-1 were related with no visual improvement in the postoperative 6 months period. The percentage increase of mean FA values of the affected areas postoperatively were found to be 21.9% in totally responded patients, 20.6% in partial responded patients, and 9.8% in patients that did not respond. Conclusions There is a correlation between DTI-derived FA values of the optic nerves and visual parameters. DTI assessments of the affected sides with FA and MD values may help to estimate the response of visual improvement to the surgical therapy in the early postoperative period