NeuroSigma made a splash by announcing that the FDA has granted medical device approval for its external Monarch Trigeminal Nerve Stimulation (eTNS) System for treating kids with ADHD ages 7–12 who are not currently taking medications.

What does medical device approval mean?
The FDA reviewed the Monarch eTNS System through the de novo ­pre-market review pathway, a less rigorous process than the usual pre-marketing approval process. This is a regulatory pathway for low- to moderate-risk devices of a new type, which asserts that the device is safe to use. The process does not affirm effectiveness of the device for the intended use. This level of approval means that subsequent devices of the same type with the same intended use may go through a process that allows the manufacturer to market its device just by demonstrating equivalence to this first (de novo) device.

How does it work?
The cellphone-sized device is meant to be used at home, under a caregiver’s supervision, for 8 hours while the child sleeps. The device has a thin wire that connects to a small adhesive electrode patch, which is placed on the child’s forehead just above the eyebrows. It provides a low-level electrical pulse (120 Hz frequency and cycles of 30 seconds on/off with 2–4 milli-amperes of current), causing mild stimulation to branches of the trigeminal nerve.

Is it effective?
A small 4-week study of kids with moderate to severe ADHD compared treatment with eTNS (n = 32) to a sham placebo device (n = 30). The primary outcome measured was the clinician-administered ADHD Rating Scale ­(ADHD-RS) total score. Although only slightly more than half of eTNS kids had clinically meaningful improvement, a statistically significant reduction was seen compared to placebo (eTNS score 34.1 at baseline to 23.4 at 4 weeks vs placebo device score 33.7 at baseline to 27.5 at 4 weeks), though improvement was seen in both groups. The estimated effect size of 0.5 is similar to the effect sizes seen with non-stimulant medications used to treat ADHD (a medium effect). The number-needed-to-treat (NNT) based on Clinical Global Impression—Improvement (CGI-I) scores at week 4 was 3. This means 3 people would need to be treated to find one who responds (in other words, for every patient who does better than placebo, 2 would have done just as well on ­placebo).

Is it safe?
Most kids will feel a tingling sensation on the skin. Drowsiness, increased appetite, trouble sleeping, teeth clenching, headache, and fatigue were the side effects most commonly reported in the study. A statistically significant increase in heart rate was seen, but pulse rates were still in the normal range and kids were not symptomatic. Weight gain was also statistically significantly greater in the eTNS group. Skin whitening or discoloration under the patch was seen in both groups, particularly in darker-skinned kids. This was attributed to loss of superficial skin layers when the patch was removed, and the discoloration resolved over time and with sun exposure.

How much will it cost?
The prescription-only device will be available from NeuroSigma “in the coming months,” and pricing information is not yet available, although some accounts have priced starter kits at $900.

CCPR’s Take
This is an interesting “gee whiz” device that will no doubt capture the imagination of families looking for a simple approach who don’t want their kids treated with medications, cognitive behavioral therapy (CBT), or parent training, even though these have a proven track record of safety and efficacy. We’re going to need more data than 62 kids in a 4-week manufacturer-run study to understand eTNS’ place in therapy for kids with ADHD. Moreover, the weight gain seen in this study begs for more investigation, perhaps having to do with changes in sleep and cortisol.