Abstract
Purpose: :
The aim of this study was to determine if the MR imaging appearances of optic pathway observed on T2-weighted were correlated with visual field defects in cases of sellar and parasellar tumors that can induce anterior visual pathway compression. Evaluation and comparison was determined in pre and postoperatively time.
Methods: :
Prospectively 30 patients (19 females and 11 males, with age range of 26 to 78 years) operated on for sellar tumors with visual pathway compression were examined. All patients presented a perimetric abnormality secondary to anterior visual pathway by a benign tumour (20 pituitary adenomas, 3 craniopharyngiomas, 3 rathke’s cleft cysts, and one arachnoid cyst). The patients had undergone surgery by a trans-sphenoidal way or sub-frontal way. They were prospectively studied in a pre-operative time, early post-operative (1 to 4 days), at 3 months and 6 months. Optic pathway was evaluated on coronal T2-weighted images with a 3T MR unit. Visual field abnormalities were assessed by a 30-2 Humphrey type perimetry with a SITA standard protocol. Correlations of signal intensity abnormality with the perimetric defects, the size of the tumor, and preoperative pallor of the optic disc were statistically analyzed. Correlations between recovery of imaging appearances of optic pathway after treatment and the above-mentioned factors were also determined.
Results: :
Preoperative hyperintensity on T2 WI on the optic pathway was observed in 12 patients. Hyperintensy was located on the optic nerve in 8 cases, on the chiasma in 10 cases and on the optic tractus in 2 cases.The preoperative hyperintensity was statistically correlated with the perimetric defects and the size of the tumor (p=0.03). The preoperative chiasmatic hyperintensity was correlated with the preoperative pallor of the optic disc. Persistence of hyperintensity at 6 months was significantly correlated with a poor visual field recovery (p<0.001), a low visual acuity (p<0.001) and the preoperative pallor of the optic disc (p=0.003).
Conclusions: :
Preoperative hyperintensity on T2 WI of the anterior visual pathway is associated with the effect of the sellar tumor compression. Their persistence at 6 months is correlated with a poor visual prognosis.
Keywords: visual impairment: neuro-ophthalmological disease • imaging/image analysis: clinical • perimetry