Multi-scale image analysis and prediction of visual field defects after selective amygdalohippocampectomy

Bastian David,Alexander Radbruch,Jasmine Eberle,Jennifer Gaubatz,Bettina Wabbels,Bernd Weber,Jan-Christoph Schoene-Bake,Guido Luechters,Christian E Elger,Jan Wagner,Rainer Surges,Conrad C Prillwitz,Johannes Schramm,Daniel Delev,Theodor Rüber

doi:10.1038/s41598-020-80751-x

Abstract

Selective amygdalohippocampectomy is an effective treatment for patients with therapy-refractory temporal lobe epilepsy but may cause visual field defect (VFD). Here, we aimed to describe tissue-specific pre- and postoperative imaging correlates of the VFD severity using whole-brain analyses from voxel- to network-level. Twenty-eight patients with temporal lobe epilepsy underwent pre- and postoperative MRI (T1-MPRAGE and Diffusion Tensor Imaging) as well as kinetic perimetry according to Goldmann standard. We probed for whole-brain gray matter (GM) and white matter (WM) correlates of VFD using voxel-based morphometry and tract-based spatial statistics, respectively. We furthermore reconstructed individual structural connectomes and conducted local and global network analyses. Two clusters in the bihemispheric middle temporal gyri indicated a postsurgical GM volume decrease with increasing VFD severity (FWE-corrected p < 0.05). A single WM cluster showed a fractional anisotropy decrease with increasing severity of VFD in the ipsilesional optic radiation (FWE-corrected p < 0.05). Furthermore, patients with (vs. without) VFD showed a higher number of postoperative local connectivity changes. Neither in the GM, WM, nor in network metrics we found preoperative correlates of VFD severity. Still, in an explorative analysis, an artificial neural network meta-classifier could predict the occurrence of VFD based on presurgical connectomes above chance level.

Highlights

Selective amygdalohippocampectomy is an effective treatment for patients with therapy-refractory temporal lobe epilepsy but may cause visual field defect (VFD)
Beside its relevance on clinical grounds, the observation of structural changes following neurosurgery is of interest in the context of neurodegeneration and n europlasticity[16] and has been aspired by the authors of several studies: while it has been generally asserted, that VFDs are more likely after epilepsy surgery in the left temporal lobe due to hemispherical asymmetry of the M L12, various studies have employed Diffusion Tensor Imaging and tractography to delineate the Meyer’s loop (ML) and anatomically relate it to either anatomical landmarks or to the resection cavity[17,18,19,20,21,22]
Of the 28 patients included in the study, 21 showed postsurgical VFD (11 incomplete homonymous quadrantopia, 6 complete homonymous quadrantopia, 4 incomplete homonymous hemianopia) while the other 7 showed no VFD in the automated Goldmann perimetry

Summary

Introduction

Selective amygdalohippocampectomy is an effective treatment for patients with therapy-refractory temporal lobe epilepsy but may cause visual field defect (VFD). We aimed to describe tissuespecific pre- and postoperative imaging correlates of the VFD severity using whole-brain analyses from voxel- to network-level. Have been reported to postoperatively occur in 15% to 100% of patients undergoing resective surgery in the temporal lobe[11,12,13], precluding the ability to drive a car even in patients who are permanently seizure-free These VFD, which usually manifest as contralateral homonymous upper quadrant anopia, often referred to as ‘pie in the sky’[14], result from the spatial proximity of the Meyer’s loop (ML) to the resection cavity in the temporal lobe. We apply several whole-brain analyses to imaging and perimetry data of patients undergoing sAH to probe for presurgical gray (GM) and white matter (WM) predictors of postoperative VFD. We further aim to preoperatively predict postoperative VFD using a combination of structural connectomics and supervised machine learning algorithms

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Conclusion