Interictal Ionized Magnesium/ Total Serum Magnesium Ratio in Serbian Population with Drug Resistant Epilepsy- Whether is Severe Epilepsy in Fact Brain Injury?

Introduction: We hypothesized that our patients with drug resistant epilepsy have low interictal ionized magnesium/ total serum magnesium ratio to indicate on the protracted brain injury. Objective: The aim of this study was to examine Interictal ionized magnesium/total serum magnesium ratio in patients with drug resistant epilepsy and to consider illness and AEDs related predictors of the possible brain injury. Methods: Patients with drug resistant epilepsy of unknown cause were tested for interictal total serum magnesium concentrations and serum ionized magnesium concentrations at the endpoint visit 14 years later. Ionized magnesium/total serum magnesium ratio cut off point was 0. 60. Groups were monitored in relation to the: seizures types, seizures frequency, duration of epilepsy, appearance of status epilepticus (SE), and longest used first line antiepileptic drugs (AEDs). Results: According to our results, 60, 6% (N= 63) of the patients with drug resistant epilepsy of unknown cause had lower interictal ionized magnesium/total serum magnesium ratio (mean ratio 0.53 ± 0.05). Odds Ratio was 29.19 (95% CI 10.94 to 77.90%. In addition we have found significant differences among groups in: age (p=0.001), the length of suffering from epilepsy (p=0.017), the seizure frequency (p=0.000), the experiencing of the SE (p=0.000), and the longest used first line AEDs (p=0.012) with 54% of the phenobarbital in the study group. Conclusion: Patients with drug resistant epilepsy of unknown cause have low interictal ionized magnesium/ total serum magnesium ratio which can indicate on the protracted brain injury. More evidence is necessary to proclaim ionized magnesium as marker of the protracted brain injury induced by drug resistant epilepsy. Predictors for the low interictal ionized magnesium/total serum magnesium ratio in this group of patients are: status epilepticus, older age in relation with longer suffering from epilepsy, more frequent seizures, and longest total intake of the phenobarbital.