This is a common problem among people with epilepsy; a definitive diagnosis may take months or even years. On the other hand, among the population of people diagnosed with epilepsy, about a quarter may have an incorrect diagnosis and are in fact experiencing “non-epileptic episodes” that have a psychogenic or cardiac cause. The misdiagnosis results in unnecessary treatment, interventions and possible complications.
The most reliable diagnostic tool for epilepsy is video-EEG, but this is not readily available in the emergency setting. Additionally, if it is not used shortly after a seizure has taken place the EEG is poor at distinguishing the classic epileptic signature of the brain from those without this condition. Blood or urine biomarkers can also be used for the diagnosis of epilepsy but so far have yet to show good reliability with the present technology. It is evident that patients and doctors are in need of a fast, reliable and easy-to-use test for helping frontline diagnosis of epilepsy.
Recent studies and observations from the friends and families of patients revealed the extraordinary ability of trained dogs to reliably distinguish the odours of patients having a seizure, from those of physical activity and at rest. This opens up the possibility that scent-related molecules might be used as markers for the diagnosis of epileptic seizures.
One approach to this clinical challenge is the non-invasive analysis of organic compounds naturally present in the exhaled breath. For this study, we set up a collaboration between the neurology team at the Jules Thorn centre at the National Hospital for Neurology and Neurosurgery in Queen Square under the supervision of Professor Matthew Walker (Department of Clinical and Experimental Epilepsy, UCL) and worldwide experts in the field of breath analysis lead by Professor George Hanna, alongside Dr Ilaria Belluomo and Dr Piers Boshier at Imperial College London. This partnership is of pivotal importance to help us shed light on the behaviour of volatile organic compounds in the different types of epilepsy and generally after the occurrence of a seizure.
By analysing the type of molecules present in the breath after the occurrence of an epileptic seizure, including their concentrations and combinations, we hope to build a ‘breathalyser test’ to help prevent misdiagnosis. Although the analysis will initially involve complex machinery, this could later be converted into a fast and non-invasive procedure. Similar tests are already in clinical trials for early diagnosis of cancers, and simply involve breathing into a tube and reading the results within seconds.
This study has the potential to predict the likelihood of the occurrence of a seizure many minutes before the clinical signs begin to show, bringing invaluable advantage to the quality of life of those affected by this condition. The ‘breathalyser test’ could then be used by an ambulance crew and emergency staff to distinguish loss of consciousness due to an epileptic seizure from those due to different causes (i.e. psychogenic, cardiac problems, narcolepsy). Such a test could transform clinical practice and make the diagnosis of epilepsy fast and simple.
-Dr Eleonora Lugarà