Severity Grading, Risk Factors and Prediction Model of Complications After Epilepsy Surgery: a Single-center, Large-scale and Retrospective Study

Epilepsy, involving a persistent predisposition to seizure, is one of the most common chronic neurological disorders, affecting more than 65million people worldwide. Epilepsy not only negatively impacts patients'education, employment, and social contact, but also imposes a serious burden on patients'families and on society. Notably, epilepsy is the second most burdensome neurological disorder, accounting for 0.7% of disability-adjusted life years worldwide, according to the World Health Organization's 2010 Global Burden of Disease study, making it a global public health issue.

Furthermore, about 40% of patients respond poorly to the first 2 antiepileptic drugs and have medically refractory epilepsy. Epilepsy surgery is effective for refractory epilepsy, particularly focal epilepsy, but is still underutilized worldwide. In the United States, the annual percentage of surgical procedures for refractory epilepsy was low (range: 0.35%-0.63%) from 2003 to 2012. Moreover, the number of surgical procedures for mesial temporal sclerosis (the most common type of refractory epilepsy) declined by more than half from 2006 to 2010. Fear associated with the risks of invasive procedures may be the reason for the cautious attitude towards epilepsy surgery. Therefore, the risks of epilepsy surgery in the modern age need to be evaluated thoroughly and precisely to improve epilepsy surgery outcomes.

The safety of epilepsy surgery has been confirmed in several studies. From 1980 to 2012, neurological deficits following epilepsy surgery decreased with time, from 41.8% to 5.2% in temporal resections and from 30.2% to 19.5% in extratemporal resections. However, studies on this topic with large sample sizes (> 500 patients) were either multicenter or covered a long study period. In addition, high-resolution magnetic resonance imaging (MRI) was not used in the early stage in these studies. Differences in medical environment among epilepsy centers and advancements in presurgical evaluations and surgical techniques over time may have caused heterogeneity and biases, thereby limiting the quality of these studies. Over the past two decades, there was no large-scale studies on post-epilepsy surgery complications performed at a single center. Moreover, surgery-related complications are seldom graded according to severity. Especially, the risk factors for these complications remain unclear.

Understanding the incidence and severity of complications after epilepsy surgery and the associated risk factors is beneficial, allowing physicians to provide patients with adequate surgical advice, and allowing patients to make rational decisions regarding epilepsy surgery. Furthermore, this information may help in the prevention of postoperative complications and improve our understanding of the procedures. Therefore, we reported the incidence of complications occurring in a three-month period after epilepsy surgery performed by the single neurosurgeon at the single center, identified the associated risk factors, and developed a nomogram for individually predicting the probability of complications.