WASHINGTON, DC — An electronic “nose” that measures various compounds in exhaled breath reliably distinguishes patients with epilepsy from controls, new research shows.
The noninvasive diagnostic tool is faster, less costly, and less invasive than electroencephalography (EEG) — the standard technique to diagnose epilepsy. Patients simply insert a small hand-held device into their mouth and breath into it for 5 minutes.
“It’s super quick, it’s super cheap, and it’s super easy to use,” Cecile C. de Vos, PhD, Montreal Neurological Institute, McGill University, Quebec, Canada, and Department of Neurology and Neurosurgery, Medisch Spectrum Twente, Enschede, The Netherlands, told Medscape Medical News.
Although the technology has been used in other fields, this is the first application in a neurologic disorder, Dr de Vos added.
The findings were presented here at the American Epilepsy Society (AES) 71st Annual Meeting 2017.
The Aeonose (eNose Company) uses sensor arrays and learning algorithms to recognize complex exhaled breath mixtures from patients with epilepsy.
Such patients have a unique “breath print,” said Dr de Vos. Research shows, for example, that they release inflammatory cytokines, as well as certain molecules that emit what could be “danger signals.”
Pattern-recognition software was used to find the best model to distinguish between the breath prints of patients with epilepsy and healthy persons. This model was then used to evaluate sensitivity, specificity, and negative and positive predictive values.
The new study included 62 patients with epilepsy (mean age, about 47 years) who had had epilepsy for an average of 26 years and 44 healthy controls (mean age, about 43 years), all in the Netherlands.
The study also included 6 patients with epilepsy in whom, as part of a video/EEG epilepsy surgery protocol, antiepileptic drugs (AEDs) were temporarily tapered, and 4 patients using AEDs but without a diagnosis of epilepsy. However, these groups were too small to be included in the current analysis.
To use Aeonose, patients simply breathe in and out through the device for 5 minutes. A disposable mouthpiece connected to the measuring instrument is placed in the patient’s mouth and the nose is clipped to avoid entry of nonfiltered air.
“The computer detects all these different compounds and to what extent they are in the breath,” said Dr de Vos, adding that different compounds have different “amplitudes.”
“You get this really complicated pattern of all these spikes for all the different compounds,” she said.
Breathing for 5 minutes through the device was generally well tolerated, although about 5% of study participants reported discomfort or shortness of breath. For that reason, 11 patients with epilepsy and 2 controls were excluded.
Initial analyses showed that Aeonose can distinguish between patients with epilepsy and controls with 84% sensitivity and 76% specificity. The device had a positive predictive value of 81% and a negative predictive value of 80%.
Dr de Vos believes these results are likely similar to test characteristics of standard EEG, but this technique is much cheaper and faster.
“When people arrive at the emergency department or at the monitoring unit, you often don’t know what’s wrong with them. If you could just have them breathe for 5 minutes using this tool, you would know if it is a seizure or whether it’s something psychogenic.”
Having established the diagnosis, “you can then counsel the patient and can start treatment much more quickly.”
Researchers are recruiting more patients with different types of epilepsy to add information and parameters on, for example, time of last seizure.
“Now we can just distinguish epilepsy from non-epilepsy, but when we have enough data, enough subjects, we can fine-tune the diagnosis,” said Dr de Vos. “This is work in progress.” She hopes to eventually gather data from 200 participants.
Breath print technology is being used to help detect lung and colorectal cancers, asthma, and tuberculosis, but so far, epilepsy is the only neurologic disorder for which it’s being tested, said lead study author, Dieuwke van Dartel, Medisch Spectrum Twente.
Dr de Vos predicts that “optimistically” the device could be available within 3 years.
Commenting on the study for Medscape Medical News, Eli M. Mizrahi, MD, AES president and chair, Department of Neurology, and professor of neurology and pediatrics, Baylor College of Medicine, Houston, Texas, said that “for a long time, people have wondered whether olfaction, the sense of smell, is a window into different kinds of brain disorders and whether it can be used to detect, for example, early dementias, changes in Parkinson’s disease, and epilepsy.”
This is a “worthwhile area” to investigate. When you think about it, it’s one of the few direct extensions from the brain out to an area that can be accessed,” he said.
Other researchers are investigating different means of detecting epilepsy. For example, some have developed a panel of inflammatory biomarkers from blood samples that can identify patients who have had recent seizures.