An investigation of somatosensory evoked potential responses during brain tumour surgery

Abstract

Introduction: Intra-operative neurophysiological monitoring (IONM) is the use of electrophysiological tools to evaluate and monitor the functional status of the nervous system during surgery. The main aim of IONM is to mitigate the risk of damage to nervous tissue during neurological surgery, such as brain tumour resection surgery, and to reduce the incidence of postoperative neurological complications. The IONM techniques commonly employed include somatosensory evoked potentials (SSEPs). The main use of SSEPs is the indirect warning of possible sensory nervous pathway injury. Intraoperative SSEP monitoring requires adroit coordination by healthcare professionals. Despite progression in this field, there is rather limited research comparing responses in the cortical, sub-cortical contralateral, and ipsilateral SSEP responses. Aim: This study aimed to evaluate the use of continuous SSEP monitoring during resection of intracranial brain tumours to provide an ongoing functional assessment of the somatosensory pathway. Methods: This retrospective study was conducted using data from patients who underwent continuous somatosensory evoked potential (SSEP)monitoring during brain tumour reresection surgery between January 2019 and December 2021 at Steve Biko Academic Hospital (SBAH). The data was compiled electronically and then subjected to statistical analysis as per the study the objectives. Results: Contralateral latencies showed consistently higher values than ipsilateral readings across all the cortical measurements. In addition, the cortical latencies consistently exceeded the subcortical latencies. Particularly, the latencies prior to brain tumour resection tended to exhibit greater values than those recorded during and after the resection process. Conclusion: The data suggests that latency tends to decrease over the course of surgery, reflecting improvements in sensory pathways following tumour removal. This pattern suggests a dynamic relationship between the timing of the surgical intervention and the somatosensory evoked potential latencies.