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Naomi E. Tan, Alex J. Shortt, Indran Davagnanam, Gordon Plant; Optic Chiasm Prolapse: Correlation Of Clinical And Radiological Findings. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2980.
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Chiasmal prolapse refers to herniation of the optic chiasm into the empty sella following pituitary apoplexy, surgical or medical treatment of pituitary disease. Visual function can be affected in a variety of ways but there is controversy regarding the pathophysiology of these changes. This work attempts to correlate clinical features with radiological findings in a cohort of patients with chiasmal prolapse and reports their management and clinical course.
The database of the neuro-ophthamology unit was searched for patients with chiasmal prolapse. A retrospective review of case notes was performed and data on visual acuity, color vision and visual fields were extracted. The presence and progression of visual loss over time were evaluated. The extent of chiasmal prolapse was quantified on coronal MRI images by measuring the distance from the midpoint of the displaced chiasm to the point where it would typically be located. Traction and/or deviation of the chiasm from the midline were also evaluated.
Seven patients with chiasmal prolapse were managed over a ten year period from 1999 to 2009, six following treatment for macroadenoma and one a Rathke’s pouch cyst. Following surgery, six of the seven patients experienced an initial improvement in visual function but all patients had a subsequent deterioration, presumed to be due to chiasmal prolapse. Three cases manifested within 12 months and the remaining four cases at three or more years post surgery. Six of the seven patients were managed conservatively and have either remained stable or had a very gradual deterioration in visual function. One patient required chiasmopexy with fat packing of the sella. The severity and pattern of visual loss did not correlate with the degree of chiasmal prolapse. Tethering of the chiasm and/or deviation of the chiasm from the midline were noted in five out of seven cases but there was no consistent association between these and the pattern of visual loss.
Chiasmal prolapse following trans-sphenoidal hypophysectomy is rare but may result in significant visual loss. The degree and pattern of visual loss do not correlate with radiological findings. In the majority of cases the visual loss either remains stable or progresses slowly and therefore can be managed conservatively.
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