The Effect of ETSS Surgery on the Degree of Visual Pathway Disorder in Patients with Pituitary Macroadenoma

Pituitary adenomas account for 12-15 % of intracranial neoplasms. Visual impairment is usually the most common objective symptom in these tumors. Diffusion Tensor Imaging (DTI) is a non– invasive MRI that illustrates the white matter pathways. In the current study, our goal was to use DTI to quantitatively assessthe visual impairment and to predict visual improvement.

In this before and after treatment study, the total of 20 patients with pituitary macroadenoma who complained of visual impairment underwent ETSS surgery between 2018 and2021. Conventional MRI, DTI and Neuroophthalmological examination were performed for 20 patients intwo periods: preoperative and 3 months after surgery. We evaluated the effects of tumor size, duration of symptoms, and age on visual improvement.

The total of 20 patients including nine (45%) women and eleven (55%) men. The meanean age of the patients was 39 ± 13 yearsrangingranged from 16 to 60 years. The mean tumor size was 9.24 ±4.59 mm3 ranging from 4.02 to 21.03 mm3. The mean symptoms duration was 18.6 ± 12.9 weeks. All patients with visual field analysis by mean deviation (MD) on Humphrey visual chart showed visual recovery.
The FA and MD parameters in DTI showed both improvement and reduction of myelin axon damages. The degree of mean deviation was significantly correlated with the Fractional anisotropy (FA) (P-value<0.05) but not with mean diffusivity in DTI analysis.

The present study showed that DTI could be implicated as a tool for quantitative assessment of visual impairment and invisual field defects, in particular. According to the findings, between two parameters of fractional anisotropy and mean diffusivity, FA is most closely related to tumor size and visual field defects. FA before surgery could be used as a measure to predict the extent of visual improvement after ETSS surgery.