Anales RANF

P.67 BLOOD PURINE CONCENTRATION AS A NOVEL DIAGNOSTIC FOR SEIZURES AND EPILEPSY Edward Beamer 1 , Mariana Alves 1 , Hany El-Naggar 2 , Norman Delanty 2 , Austin Lacey 2 , David Hemshall 1 , Tobias Engel 1 1 Royal College of Surgeons in Ireland, Dublin; 2 Beaumont Hospital, Dublin. A simple method for diagnosing seizures and epilepsy using the detection of biomarkers from blood offers advantages over currently available methods. Principally: lower cost, less necessary expertise, potential for detecting seizures retrospectively, and fast results. Criteria for a clinically useful biomarker include sensitivity, specificity, minimal invasiveness, ease of analysis and robustness to artefacts. We used an enzyme-based detection system, which can reliably measure concentrations of adenosine in the blood. This method involves the immediate analysis of a small amount of fresh blood (finger prick), with results obtained within 5 minutes. In an intra-amygdala kainic acid mouse model of status epilepticus, blood adenosine concentrations increased, 40 minutes following kainic acid injection and remained elevated for 4 hours following seizure termination with lorazepam. Concentrations of adenosine in the blood correlated with the severity of seizures, as indicated by the total power of EEG (R 2 = 0.4892, p < 0.0001) and with markers of neuronal death in the CA3 region of the hippocampus three days following injection (R 2 = 0.2805, p = 0.0006). Data obtained from the epilepsy monitoring unit, Beaumont Hospital, indicate that baseline (>24h seizure free) blood adenosine concentrations are elevated in epilepsy patients compared with controls (t 34 = 2.907, p = 0.0064) and that blood adenosine increases sharply immediately following generalized tonic-clonic seizures. Further, patients with non-epileptic attack disorder showed blood adenosine concentrations no different from controls. These results indicate that blood adenosine concentrations are elevated following seizures in both mice and patients, and that in epilepsy patients; blood adenosine is both chronically elevated and acutely elevated following seizures.