Abstracts

Rationale: A wide range of complications have been reported with epilepsy surgery. However, the majority of studies are retrospective case series and reflect the experience of a single surgeon, although multiple surgeon large unselected series have been published. A variety of definitions of whether a complication is minor or major, transient or permanent adds to confusion of interpretation of different studies. Our goal was to systematically review the literature on complications of epilepsy surgery. Methods: A literature search was conducted as part of a larger project on the development of an appropriateness and necessity rating tool to identify patients who should be referred for evaluation for epilepsy surgery. Using an extensive list of terms, we searched PubMed, EmBase and Cochrane databases. 5061 abstracts related to epilepsy surgery were screened. 763 articles were reviewed in full-text. Inclusion criteria were: epilepsy surgery, invasive or resective, n ≥ 20, most surgeries done in MRI era, clearly described complications and English only. 76 articles met eligibility criteria. Minor complications included those which completely resolved within 3 months of surgery while major complications persisted beyond that time frame. Pooled estimates or weighted averages of total series using an inverse variance of the sample size was determined. Results: Invasive monitoring: Minor medical complications were reported in 4.7% (95% CI 2.7-6.6%) most common being CSF leak, aseptic meningitis, bacterial infection and intracranial hematomas. Major medical complications were identified in 1.3%. Resective surgery: Location of resection did not significantly alter risk of most complications. Overall minor neurological complications occurred in 11.3% (95% CI 9.4-13.3%). Visual field defects were most common (15.2%, 95% CI 10.8-19.7%), greater after temporal (TL) than extra-temporal (ET) resections (16.5% vs. 7.3%). Major neurological complications were noted in 4.7% (95% CI 2.7-6.6%) with major field defects in 2.4% (95% CI 0.1-4.8%), greater in ET resection (5 vs. 2.3%). Minor and major cranial nerve defects occurred almost exclusively after TL resection. Minor/temporary dysphasia was seen in 4.4% (95% CI 2.2-6.6%) and major/permanent dysphasia in 0.6% (95% CI -0.02-0.03%). Temporary hemiparesis was seen in 3.6% (95% CI 1.6-5.5%) commonly associated with ET resection (14.6% vs. 1.8%). Permanent hemiparesis was seen in 1.7% (95% CI 0.0-3.5%) more commonly associated with ET resection (3.2% vs. 1.7%). Perioperative mortality was uncommon after epilepsy surgery, occurring in only 0.4% of TL patients (1.24% ET) Conclusions: A variety of complications may occur after epilepsy surgery. The majority of these complications are considered minor or temporary as they tend to completely resolve. Major permanent neurological complications however, may occur in up to 5% of patients and the most common are contralateral hemiparesis and major visual deficits, occurring in up to 2% of patients of patients undergoing TL resections. Mortality as a result of epilepsy surgery in the modern era is rare however.