Visual Outcome of an Endoscopic Endonasal Transsphenoidal Approach in Pituitary Macroadenomas: Quantitative Assessment with Diffusion Tensor Imaging Early and Long-Term Results.

BACKGROUND: Postoperative visual recovery in patients with pituitary adenoma can be influenced by the duration of symptoms, age, and tumor volume. Diffusion tensor imaging (DTI) allows visualization of white matter structure along with quantitative information. The aims of our study were to predict the visual recovery process in the early and long-term periods and to define the parameters affecting the recovery course.

METHODS: A total of 200 patients with pituitary macroadenomas underwent endoscopic transsphenoidal surgery between January 2009 and July 2016. DTI and visual analysis including visual acuity and visual field analyses were performed for these patients at 5 periods, which included 3 years of follow-up. The effects of age, duration of symptoms, and tumor volume on visual recovery were evaluated.

RESULTS: Mean tumor volume was calculated as 8871 ± 2758 mm3 and mean symptom duration was 23.41 ± 3.72 weeks. Mean age of the patients was 43.8 ± 8.9 years in the full recovery group and 48.7 ± 15.1 years in the nonrecovery group. Visual field analysis results on a Humphrey visual chart showed a significant linear strong correlation with fractional anisotropy (FA) values and a reverse strong correlation with mean diffusivity (MD) values on DTI magnetic resonance. DTI FA and MD cutoff values for each group were respectively determined as 0.373 and 1386 (×10-6 mm2 /second) for the preoperative period, 0.423 and 1383 (×10-6 mm2 /second) for the initial period, 0.428 and 1265 (×10-6 mm2 /second) for the early period, 0.432 and 1238 (×10-6 mm2 /second) for the intermediate period, and 0.437 and 1198 (×10-6 mm2 /second) for the late period.

CONCLUSIONS: DTI can assess and predict visual recovery after endoscopic transsphenoidal surgery of patients with pituitary macroadenomas causing chiasmal compression. FA values lower than or MD values greater than the cutoff values of the specific period reflect poor prognosis. Tumor volume was found to be the featured parameter that affects visual recovery. The postoperative first year is the most prominent interval evaluating the prognosis of visual recovery.