Neurosurgical Spreading Depolarization Monitoring: Why, How, and What to Do About It

Monitoring of electrocorticography for the purpose of detecting spreading depolarization (SD) events is becoming increasingly used both for research and clinical applications. Although such monitoring bears many similarities to standard long-term epilepsy monitoring, there are a number of differences that neurosurgeons need to be aware of when initiating such a program. In addition, most of the focus in SD monitoring has been on traumatic and vascular conditions, where invasive monitoring is used commonly, but electrocorticography is not commonly used. In this brief review, a clinically focused approach is presented to support successful monitoring. This is not intended to be a comprehensive or systematic description of the neuroscience of SD and its clinical relevance, as many such previous reviews exist. It is also recognized that this is a rapidly evolving field and that new advances may disrupt these approaches and that there is a diversity of opinion on these topics, even among SD experts. Nonetheless, the general approach to SD monitoring has now been in use for >15 years and is the basis for several active and proposed clinical trials (NCT05337618, NCT04966546), so an understanding from a neurosurgical perspective of the rationale and approach to monitoring is warranted. In this review, we will consider the potential indications for SD monitoring in clinical trials or clinical care, the methodology for recording and interpreting, and finally some potential therapeutic approaches that are being considered in patients with clinically detected SD.