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Homonymous Superior Quadrantic Visual Field Defects after Epilepsy Neurosurgery (Fundus Photography, ww-Perimetry, FDT, OCT, MRI)BrainPatient: Female, 65 years of age, BCVA 1.0 at OD, 0.9 at OS;
Ocular medical history: antiepileptical surgery (Taylor-resection).
General medical history: empty
Main complaint: homonymous peripherial visual defect
Purpose: to present homonymous superior quadrantic visual field defects, due to a defect im Meyer‘s loop after antiepileptical neurosurgery.
Method: patient undergone examination of visual field( w-w-perimetry, FDT), retinal nerve fiber thickness (Spectralis-OCT HE), fundus photography (Kowa-Non-myd camera), and MRI (3-Tesla, Siemens)
Findings:
Visual field (w-w-perimetry): homonymous superior quadrantic visual field defects
Frquency Doubling Technique FDT: homonymous superior quadrantic visual field defects
Retinal nerve fiber thickness:regular thickness with 82 µm at OD, and 81 µm at OS
Fundus photography: regular optic nerve head, no temporal paleness
MRI: FLAIR sequences on the level of the midbrain / LGN demonstrating the gliotic defect (arrow) after partial temporal lobe resection (Taylor-resection), (*) extending into the very ventral part of the optic radiation (Meyer´s loop)
Discussion
Meyer's loop, the most vulnerable part of the optic radiations during approaches to the temporomedial region, extends to the tip of the temporal horn and is often encountered in epilepsy surgery. The risk of damaging Meyer's loop during transsylvian selective amygdalohippocampectomy peaks while accessing the temporal horn through its roof by opening the inferior limiting sulcus of the insula (1). Selective amygdalohippocampectomy (SelAH) is increasingly performed in patients with mesial temporal lobe epilepsy. It was reported (2) that most of the patients who had undergone SelAH had homonymous superior quadrantic visual field defects contralateral to the side of the surgery.
Literature:
(1) Yeni SN, Tanriover N, Uyanik O, Ulu MO, Ozkara C, Karaağaç N, Ozyurt E, Uzan M. Visual field defects in selective amygdalohippocampectomy for hippocampal sclerosis: the fate of Meyer's loop during the transsylvian approach to the temporal horn. Neurosurgery. 2008 Sep;63(3):507-13
(2) Mengesha T, Abu-Ata M, Haas KF, Lavin PJ, Sun DA, Konrad PE, Pearson M, Wang L, Song Y, Abou-Khalil BW. Visual field defects after selective amygdalohippocampectomy and standard temporal lobectomy. J Neuroophthalmol. 2009 Sep;29(3):208-13. -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- -------------------------- |