Abstract
PurposeTo evaluate whether the occurrence of chiasmal herniation coincides with visual field (VF) deterioration and to compare the course of VF defects in patients with and without radiological chiasmal herniation following treatment of pituitary adenoma.MethodsThis retrospective cohort study included 48 pituitary macroadenoma patients with chiasm compression, divided into three groups: Group 1 (N = 12), downward displaced optic chiasm and deteriorated VFs; Group 2 (N = 16), downward displaced optic chiasm; Group 3 (N = 20), control-group matched for tumour size and follow-up VFs, in mean deviation (dB). VFs were compared over time and a severity index, Chiasm Herniation Scale (CHS), for herniation based on radiological parameters was designed.ResultsAfter treatment, all groups showed improvement of VFs (Gr1: 2.97 dB p = 0.097, Gr2: 4.52 dB p = 0.001 and Gr3: 5.16 dB p = 0.000), followed by long-term gradual deterioration. The course of VFs between patients with and without herniation was not significantly different (p = 0.143), neither was there a difference in the course before and after herniation (p = 0.297). The median time till onset of herniation was 40 months (IQR 6 month-10 years) and did not significantly differ (p = 0.172) between the groups. There was no relation between VFs and the degree of herniation (p = 0.729).ConclusionHerniation does not appear to have clinical relevance with respect to VF outcome. The newly designed CHS is the first scoring system to quantify the severity of herniation and, in the absence of alternatives, may be useful to describe MRI findings to serve future added value in larger sized outcome studies.
Highlights
Patients with pituitary macroadenomas typically present with bitemporal hemianopsia, a partial blindness where vision is missing in the outer half of the visual field (VF), as a result of an elevated and compressed optic chiasm [1,2,3]
The most accepted hypotheses regarding the pathophysiological mechanism of the secondary downward displacement of the optic chiasm and its relation with deteriorating VF and visual acuity (VA) is based on tethering of scar tissue, enlargement of the sella turcica and a deficient sellar diaphragm, the roof of the sella turcica or a combination
When intraocular pressure (IOP) was under control and VF was atypical for glaucoma during the follow-up period, patients were included for the study
Summary
Patients with pituitary macroadenomas typically present with bitemporal hemianopsia, a partial blindness where vision is missing in the outer half of the visual field (VF), as a result of an elevated and compressed optic chiasm [1,2,3]. In the clinical work-up of this deterioration, a Magnetic Resonance Imaging (MRI) scan is performed to exclude new chiasmal compression caused by a recurrent tumour or growth of a remnant Several of these patients showed a radiological herniation, i.e. a (new) downward displacement of the optic chiasm into a Pituitary (2021) 24:68–78 secondary enlarged sella, raising the question whether this is (one of) the reasons for deterioration of VF [2, 9, 10]. The most accepted hypotheses regarding the pathophysiological mechanism of the secondary downward displacement of the optic chiasm and its relation with deteriorating VF and VA is based on tethering of scar tissue, enlargement of the sella turcica and a deficient sellar diaphragm, the roof of the sella turcica or a combination. This results in downward displacement of the optic chiasm, stretching the optic nerves and causing deterioration of the VF [10,11,12]
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