Abstracts

Rationale: When epileptogenic foci can't be determined noninvasively in epilepsy surgery candidates, intracranial EEG recording is considered as the next presurgical evaluation. Such invasive recording provides invaluable information about accurate epileptogenic foci and eloquent cortices and it also carries the risk of several complications. We aimed at evaluating the infective complications with intracranial EEG recording in order to lessen them. Methods: We retrospectively reviewed our database of epilepsy surgery cases between May 1992 and March 2012. We have 53 cases who underwent intracranial electrode implantation. All of the patients needed intracranial monitoring because they were candidates for epilepsy surgery and noninvasive results didn't reveal localizing information enough in detail to delineate a resection procedure. The number and location of the subdural electrodes to be implanted was carefully individualized based on the noninvasive evaluation. The following clinical information were analyzed: onset age of seizures, age at surgery, gender, the time interval between disease onset and surgery, duration of invasive monitoring, season of monitoring, side of electrode implantation, the number of electrodes (excluding depth and cavernous sinus electrodes), pathological diagnosis, state of associated infections and seizure outcome. Univariate analysis was conducted. Chi-squared test was used to test for association between the categorical variables and the presence of infective complications. T-test was used to assess associations between the continuous variables and the presence of them. Statistical significance was adopted as P value < 0.01. Results: Infective complications related to intracranial electrode implantation occurred in 4 cases. Causative agents were identified as Staphylococcus aureus in 3 cases and Staphylococcus epidermidis in 1. On univariate analysis, the significant risk factor was only season of monitoring. Monitoring performed in the fall was significantly associated with infective complications. Complication occurred associated with a larger number of electrodes, longer duration of monitoring, older age of patient, and the location of implanted electrode in the past report (Neurology 2002;58(1):97-103). In our study, age, gender, duration of monitoring, location and the number of electrodes and pathological diagnosis didn't seem to be an increased risk for infective complications. Infective complications had no significant influence on seizure outcome. Conclusions: Invasive monitor in the fall was a risk factor for infective complications. S. aureus was a common pathogen. Nasal carriers of S. aureus was reportedly an risk of infection with this pathogen(Lancet Infect Dis 2005;5(12):751-62). Previous study of the nasopharyngeal bacterial flora in infancy suggested that S. aureus was more common in the fall and winter months(FEMS Immunol Med Microbiol 1999;25(1-2):19-28). Decolonization of the nose before surgery may decrease the occurrence of infection especially during this season.