Re-interpreting the results of “controversial” electroencephalogram (EEG) results leads to a different opinion in more than half of the cases, according to a new study published in the journal Clinical Neurophysiology.The study also found that re-interpreting existing EEG results is less time consuming and more cost effective than obtaining a new EEG.The diagnosis of epilepsy often relies on a combination of clinical information and findings from EEGs and brain scans. When these investigations are inadequate or where there are inconsistencies, there is a risk of mis-diagnosing the epilepsy.In order to assess the diagnostic value and effectiveness of re-interpreting EEG results, researchers led by Dr Machiel Zwartsa at Kempenhaeghe Epilepsy Centre in The Netherlands, re-classified the EEGs of 100 people with epilepsy, the results of which were considered to be inconsistent with the clinical diagnosis of the patients.To evaluate the effectiveness of the re-interpretation process, the researchers included a matched control group of patients in whom a new EEG was performed but no re-interpretation of the earlier EEGs was undertaken. They assessed the diagnostic value of the re-interpretation using questionnaires, and the costs by calculating the number of technician hours required.The clinical conclusions reached from previous EEGs were known for 85 patients and for 43 of these (50.6%), the re-interpretation led to a change in those conclusions.In 23 cases, the presence of epileptic activity in the brain changed from positive to negative (17 cases) or from negative to positive (six cases). In 15 cases, the site of origin of the epilepsy was revised and in five cases the epilepsy syndrome changed altogether.Fifty-seven percent of the patients whose EEGs were re-interpreted did not need new EEGs. Almost all re-interpretations (96%) were considered useful by the neurologists who had initially requested a second EEG and 72% of them were also considered useful by other neurologists not directly involved in the study.The average time spent by a technician interpreting new EEG results was almost nine hours per patient. This was reduced to five and a half hours when the technician was re-interpreting existing EEG data.The researchers concluded that re-interpreting “controversial” EEGs is worthwhile. They advise that in cases where there is conflict between clinical information and EEG findings, it is more cost-effective and less time-consuming to re-evaluate existing results than to request a new EEG.Author: Dr Özge ÖzkayaClick here for more epilepsy research news.