I am an engineer. I build robots. When you want a robot to detect more information about its world and be able to react to it, you add sensors.
Once I started coming to grips with M’s diagnosis - and more specifically the risk of SUDEP - I immediately started researching what things happen to a body before, during, and after a seizure that might be detectable, and how I could detect it. I needed to know more about M’s body. I needed sensors.
There are no shortage of devices out there, some remote, some wearable, that purport to detect and alert to seizure activity. Many of them are pricey - hundreds of dollars, or even $1k or more. We are lucky to be in a position where we would happily write a check for a device we knew would keep M safe, but buying one of everything on the market just to try it is not feasible.
The thing about Dravet spectrum epilepsy is that it’s unpredictable all kinds of ways, but especially in seizure presentation. You can run the gamut of seizure types - generalized tonic-clonics (what they used to call grand mal - what you probably think of when you think of seizures) that involve the whole body, to those that only involve one or two limbs, to those that are clusters of irregular one-off muscle twitches similar to the hypnic jerks you get falling asleep, to absence and “drop” seizures where there’s no shaking at all. This means devices that rely on movement often aren’t a great match for Dravet patients - the accelerometer on a wearable on your left arm won’t detect a hemiclonic seizure on your right side.
The other thing is that Dravet seizures tend to evolve. They often start with the generalized tonic-clonics with fevers in infancy, but become decoupled from fevers as the kid grows, and the different seizure types present unpredictably. What works for detection now may not be reliable in another two years.
So what did this engineer do? Well, first I started advocating for our local Children’s Hospital's epilepsy ward to build a library of popular detection and alert devices that families could check out and try free of cost to help with their decision making. But that wasn’t going to address my immediate need.
So far, all of M’s seizures have been with fevers. That is likely to change, but it’s the one correlation we’ve got going for us right now. So I started looking for wearable body temperature sensors.
Unlike most epilepsy-specific sensors, wearable thermometers are a lot cheaper than most of the seizure alert gadgets out there. Like $60. So I bought two of them: the FeverScout (which I've also seen listed as the FeverSense) and the SmartTemp. Both are adhesive and both transmit readings and alerts to smartphone apps via Bluetooth. You place them under the kid’s armpit for an axillary temp reading (keeping in mind those readings are usually lower than actual body temp).
The SmartTemp sensor was a nice package, but the connectivity wasn’t great and we never really got readings we believed. I gave up after a few days.
The FeverScout had more parts and the packaging gave M calluses in his armpits where the more defined edges rubbed at night, but the connectivity was better (thanks to its charger which doubles as a Bluetooth signal relay, giving the parents monitoring temps greater connectivity range). But the steady-state readings were so low, I didn’t think they were useful, since the lowest alert temp you could set was 98.6 deg F - normal body temperature. When it kept saying M was normally at 96.1, I had a hard time believing it would ever detect a fever that might cause a seizure.
Until it did.
It was actually the last night I was giving it before giving up and trying something else. The alert on my phone went off at 6 AM. I assumed it was a false alarm but I went in to check on M anyway. His eyes were open but unfocused, he wouldn’t respond to me, and when I picked him up I could feel him stiffen and twitch occasionally. A quick read with our forehead thermometer confirmed he was running a fever. We quickly administered Diastat and it was over in a few minutes.
I allowed myself a nerdy pat on the back that morning and immediately went off to buy more adhesive backings.
With his recent bout of pneumonia, the sensor has alerted us to two more seizure events that have happened while he was sleeping. Since it plots the temperature readings against time we can see how quickly his temp spikes - we’d known anecdotally before that he could go from a normal forehead reading to a fever of 101 in just minutes, but it was nice to have the data to back it up. And even if the magnitude of his temperature was off - the fever was obviously not at 98.6 but at a higher actual body temp - this sensor accurately recorded the trends and was consistent enough in its offsets to let us know his temperature was rising.
So we are really big fans. Some day his seizures won’t be marked by fevers and this won’t do everything we need, but for now it’s an inexpensive bit of insurance that helps us sleep easier while we explore other options that might work longer-term.
We have made a few tweaks to how we use it. We don’t have it on him all the time - only when he’s sleeping, and only if we have reason to believe he might be susceptible to fever. Times that someone else in the family is sick, for example, or when he’s teething. This is somewhat pragmatic - the battery is recharageble but not replaceable, so we don’t want to run it 24/7 - but also the calluses I mentioned under his armpits kind of suck, as does the reaction his sensitive skin sometimes has to prolonged use of adhesives to keep the sensor in place.
We also use backup adhesive. We do buy the FeverSense ones to make sure the sensor maintains good contact with his skin, but on their own we found a squirmy toddler made for a migrating sensor that would stop reading reliably. We’ve used both tape and giant band-aids as secondary adhesive. The tape is easy and cheap, and I like the surgical tape versus the bandaging tape since it doesn’t leave as much residue. But the giant bandages do a nicer job of smoothing the edge of the sensor unit to reduce the rubbing on his armpit. (I'm inclined to try something like this in the future to avoid this problem).
And to be clear, this doesn’t stand alone - we are extremely vigilant about fever management when he’s sick or we think he’s at risk, we have both audio and video monitors in his room so we can hear his respiration and check on his movements, and we use a one or two day dose of clomazepam (a sedative used as an anti-seizure drug) as a protective bridge when he’s really sick. But a wearable thermometer has been a really valuable tool in our kit and we’re grateful for it - and I’m still patting myself on the back.
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