Awake Surgery With Visual Pathway Mapping in Low Grade Glioma Surgery

Santiago Núñez-Velasco,Juan C Balcázar-Padrón,Sergio Díaz-Bello,Marcos V Sangrador-Deitos,Rodrigo Uribe-Pacheco

doi:10.7759/cureus.22135

Abstract

The visual pathway and its defects have been thoroughly studied in clinical correlation to temporal lobe lesions related to epilepsy and traumatic lesions. Nevertheless, its clinical correlation and other decision-making have not been addressed regarding neoplastic lesions. We present a case report of a 28-year-old man with a one-year history of generalized seizures and left superior homonymous quadrantanopia, with no other neurological disturbance on physical examination. According to diffusion tensor imaging tractography, MRI demonstrated a non-enhancing, right temporal lesion disrupting the visual pathway. An awake surgery with direct cortical electrostimulation of visual pathways was performed with subtotal resection of the tumor to preserve visual function, confirmed with postoperative MRI. Histopathological studies revealed a fibrillary astrocytoma.Surgical technique aided with intraoperative cortical and subcortical stimulation involving low-grade gliomas in eloquent areas is an exceptionally suitable procedure for complex cases where the visual pathway is compromised. Our objective is to describe how intraoperative mapping of visual function is performed in our institution and to comment on the relevant technical nuances, which can serve as a practical guideline for young neurosurgeons, as no previous cases have been reported in our country.

Highlights

In 1907, Dr Adolf Meyer, a Swiss psychiatrist, first described “the peculiar detour of the ventral portion of the geniculocalcarine pathway.” He concluded that a portion of the optic radiation, after leaving the geniculate body, plunged anteriorly into the temporal lobe through the tip of the horn of the ventricle before turning back towards the calcarine cortex [1]
Dr Harvey Cushing recalls, in his paper about field defects after temporal lobe lesions, about a patient with epilepsy resulting from a gunshot injury, in which the bullet was lodged in the right temporal lobe and was diagnosed with no visual field defect
A lot has been studied about visual defects following temporal lobe epilepsy surgery that produce “markedly incongruous superior quadrantanopia” [3], but not much concerning the field of neoplastic lesions

Summary

Introduction

In 1907, Dr Adolf Meyer, a Swiss psychiatrist, first described “the peculiar detour of the ventral portion of the geniculocalcarine pathway.” He concluded that a portion of the optic radiation, after leaving the geniculate body, plunged anteriorly into the temporal lobe through the tip of the horn of the ventricle before turning back towards the calcarine cortex [1]. Low-grade gliomas include grade I tumors, which lack any prior features, and grade II tumors characterized only by atypia Lesions included in this category encompass diffuse astrocytoma, pilomyxoid astrocytoma, pleomorphic xanthoastrocytoma, oligodendrogliomas (WHO grade II), and subependymal giant cell astrocytoma (SEGA), typical from tuberous sclerosis; pilocytic astrocytoma, ganglioglioma, dysembryoplastic neuroepithelial tumor, among others [6]. These tumors are most common in young adults from the second to the fourth decades of life, being the clinical signs and symptoms attributed to the mass effect. Seizures are the debuting symptom in up to 80% of cases [7]

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