Wearable seizure detectors could influence epilepsy therapy

Many of the devices use accelerometers to detect movement that could result from a seizure. Other devices rely on electromyography or measurements of heart rate or skin conductance. The technology continues to evolve, and future devices could include eyeglasses that incorporate EEG sensors or track eye movements, according to Jacqueline A. French, MD, professor of neurology at New York University.

Devices that monitor more than one biological signal concurrently would provide richer data sets. These multimodal sensors could shed light on patterns of seizure onset and suggest potential seizure triggers, said Sonya B. Dumanis, PhD, senior director of innovation at the Epilepsy Foundation in Landover, Maryland.

In one survey, about two-thirds of patients with epilepsy said that they would use these wearable devices constantly. In practice, individuals use them to varying extents. In general, the rate of participation with medical apps is about 50%, said Dr. Krauss. The degree of acceptance and usage that wearable seizure detectors will gain among patients with epilepsy remains to be seen. Patients with uncontrolled seizures and difficulty managing their epilepsy may become the most consistent users of these devices, said Dr. Krauss. These patients, who represent about 40% of all people with epilepsy, may have the most to gain from these devices.

Compared with traditional scalp EEG, wearable devices have several diagnostic advantages. The wearable detectors do not require a lot of time to set up, nor do they restrict the user’s mobility. They can track information outside of a hospital setting.

Patients and their families are in favor of wearable seizure detectors because the devices have the potential to improve patient safety, prevent injuries, and enhance independence, said Dr. Krauss. Approximately 40% of patients are not aware of their seizures, and wearable devices could help identify problems for these patients, he added. Furthermore, the devices could detect nocturnal seizures that otherwise would be unwitnessed.

What do patients prefer?

In a series of semistructured interviews, patients with epilepsy described their preferences for automated seizure registration devices to Hoppe and colleagues. They wanted devices that were convenient, inconspicuous, and that registered seizures automatically.

“The ideal [device] is something that you wear anyway. If you have a watch and you’re also using it as a seizure detector, that’s the best of all possible [solutions],” said Dr. French.

Although patients expressed interest in devices that made emergency calls to family or caregivers. Nevertheless, “in one survey, patients said that they wanted to be in control of their data and did not want doctors to be directly notified of their seizures,” said Dr. Krauss.

Patients prefer devices that detect all seizures that occur and that have low rates of false positives (e.g., below 25%). For now, the available devices don’t satisfy these criteria, “but we’re working on it,” said Dr. French. Researchers are trying to increase the sensitivity and specificity of wearable seizure detectors.

A survey of patients and caregivers published in Epilepsy & Behavior suggests that caregivers were more likely than patients were to support the marketing of a given hypothetical seizure forecasting device, said Dr. Dumanis. Yet caregivers were less likely than patients were to accept the risk of suboptimal accuracy.

Affordability is a priority for patients, as well. The seizure detector apps with the most features often entail a monthly cost, and this expense could be an obstacle for some patients. Many patients would prefer that a wearable device and its associated expenses be covered by insurance.

 The risk of SUDEP

The potential benefit of wearable seizure detectors that perhaps inspires the most hope among patients and caregivers is the promise of reducing the risk of sudden unexpected death in epilepsy (SUDEP). The risk of SUDEP in patients with uncontrolled tonic-clonic seizures is about 1 in 100 per year. SUDEP is strongly associated with convulsive seizures and nocturnal seizures. “Patients with those seizure types are at highest risk, and I think these devices might be helpful for them,” said Dr. Krauss.

In the postictal phase, which is when SUDEP most often occurs, patients become hypoxemic, hypercapnic, and acidotic. One goal of wearable seizure detectors is to alert caregivers when they detect tonic-clonic seizures. If caregivers are notified and can arrive quickly enough, they can stimulate the patient and turn him or her onto a side position to prevent suffocation. Patients also may need respiratory compensation.

No research has shown that a wearable seizure detector can reduce the risk of SUDEP. “There are studies showing, though, that listening devices reduce risk of SUDEP,” said Dr. Krauss. “There are studies showing that the proximity of a caregiver reduces risk of SUDEP. This [i.e., a wearable seizure detector] is just the next step.”

But for a wearable seizure detector to reduce the risk of SUDEP, a caregiver must be close enough to the patient to intervene quickly. The literature includes a report of a device that accurately detected a patient’s seizure and alerted the caregiver. The caregiver was in a different part of town, however, and arrived too late to prevent the patient’s death.

The very fact that wearable seizure detectors have the potential to reduce the risk of SUDEP could present an opportunity for improved communication between patients, caregivers, and neurologists. “SUDEP is scary,” said Dr. Dumanis. “Doctors don’t want to talk about it, and patients don’t want to dwell on it. Devices can be used as that door opener to start that conversation and to get past that stigma.”

Treatment adjustment and telemedicine

By collecting data, wearable seizure detectors could provide several other clinical benefits, as well. For example, it is necessary to count seizures to gauge how well a patient is responding to therapy or how effective that therapy is. Data suggest that patients’ seizure diaries are unreliable, perhaps partly because of the retrograde amnesia that patients sometimes have after seizures. A wearable seizure detector could provide a more reliable, objective method of counting seizures.

Knowing the number and time of seizures that a patient has had in a given period could reveal patterns that enable seizures to be predicted. “The better people can keep track of their seizures, the better information they can provide, the more predictive we can be,” said Dr. French. For example, a device might eventually be able to determine that a patient’s seizures happen in clusters every 3 weeks and that, given that the patient has just had a cluster of seizures, the current likelihood of a seizure is low.

“If you look at a pattern over a period of time, maybe your medications are not covering you at that time period, and maybe you need to have an adjustment,” said Dr. French. “Maybe the seizures are all at night, and you need a bigger dose at night. The more we know about when seizures are happening, the more refined our intervention can be.”

If a wearable device calculates that the likelihood of a seizure is high today, that warning could prompt the patient to carry rescue medication, said Dr. Dumanis. Rescue medications have been the subject of much recent research, and many new rescue medications may soon be available.

Wearable seizure detectors eventually could be an important adjunct to telemedicine, said Dr. Krauss. “You could have a portal system with a nurse practitioner or medical expert who can help patients monitor for problems in their care. Patients, for example, with uncontrolled seizures could have detectors, fill out comorbidity surveys, and have portals where their data are tabulated and monitored. If they are, say, reporting nonadherence or having recurring seizures, they can be asked through a message to call in [to their clinician’s office]. Then you could adjust their treatment … I think that’s one of the most important things that will evolve here.”

And in addition to the clinical utility that wearable seizure detectors have, they also have personal utility, “in terms of empowerment and enhancing independence and quality of life,” said Dr. Dumanis.