3 days ago
A Review of Transnasal Cooling for Migraine Relief
Transnasal evaporative cooling as an acute treatment for migraine has been tested in two randomized clinical trials showing some level of efficacy and tolerability as well as safety.
CALM1 Accrual Issues
The first, CALM 1, was presented as a virtual poster at the 2023 American Headache Society meeting. Although this study enrolled 87 patients with migraine with or without aura, only 24 were randomized to the CoolStat Transnasal Thermal Regulating Device (CoolTech LLC). This comprised 15 minutes of air flow as soon as they arrived at their local testing center during an attack.
CoolStat device in use
The primary endpoint was pain relief at 2 hours; pain freedom, relief of most bothersome symptom, and tolerability were also measured at 2 and 24 hours. Three air flow rates were tested: 24, 18, and 6 liters per minute (LPM). It was originally assumed that the 6 LPM flow rate would act as the sham, but it turned out to be the most effective rate.
In this group, 8 of 9 patients reported pain relief at 2 hours with 4 of them being pain free. Patients treated with the other doses reported a similar rate of pain relief, but none were fully free of pain at 2 hours.
There were no adverse events in the lowest flow rate group and only mild events in the other groups.
The study was terminated due to insufficient accrual rates. The company decided to do a second study with a smaller portable device which patients could use at home earlier in the course of their migraine attack.
CALM 2 At Home Treatment
The CALM 2 study used a 2 LPM dose as the sham: This used an inactive drying agent and patients experienced the sensation of treatment including saline mist. This small, phase 2, dose range-finding trial tested active doses of 4, 6, and 10 LPM. Patients treated their migraine for 15 minutes within 1 hour of pain onset using the Mi-Helper, an investigational device similar in size to a sleep apnea machine.
The Mi-Helper
The Mi-Helper
No other treatment was allowed for 2 hours.
Of the 172 adults randomized, 128 used the device and were included in the modified intention-to-treat analysis. Only 74 were included in the efficacy analysis because the others did not fully follow the protocol for a variety of reasons.
In this study, the 10 LPM air flow rate was the most effective, producing pain freedom at 2 hours in 8 of 17 patients, vs 4 of 25 sham-treated patients. This difference was statistically significant. Two-hour pain relief was seen in 70.6% of this group vs 56% of the sham group, a difference that did not reach statistical significance.
Sustained pain freedom from 2 to 24 hours with no rescue treatment was numerically but not significantly higher than sham with the 10 LPM dose. Results for the other air flow rates (4 and 6 LPM) were not statistically significant.
The most common adverse events, scattered across the three active-treatment groups, were rhinorrhea, nasal irritation, ear pressure, nasal congestion, sore throat, and jaw pain. More events occurred in the 10 LPM group (with none in the sham group), but no patient discontinued the trial because of side effects.
How Does it Work?
The proposed mechanism of action for Mi-Helper, according to Steve Schaefer, the CEO of Cooltech, is that it 'noninvasively cools and inhibits structures of the pterygopalatine fossa, including the sphenopalatine ganglion (SPG) and the maxillary division of the trigeminal nerve.'
The device delivers dry room-temperature air into one nostril with a nebulized saline mist for comfort and to facilitate evaporation. The evaporation from liquid to gas requires energy drawn from the surrounding tissues, particularly the vascularized membranes of the nasal turbinates. This purportedly results in a localized cooling effect targeting the structures of the pterygopalatine fossa, including the SPG and maxillary division of the trigeminal nerve (V2), both areas integrally involved with migraine and cluster headache.
This hypothesis has yet to be corroborated; no preclinical trials have shown any electrical effect on the SPG.
The Mi-Helper is not the same as remote electrical neuromodulation (REN) or other electrical stimulation devices that are already cleared by the FDA for the acute care and/or prevention of migraine attacks. REN uses electrical stimulators and works on various combinations of peripheral nerves involved with migraine. [By way of disclosure, I recently authored a poster on REN.]
What Next
CALM 3, a third, larger, phase 3 trial of the Mi-Helper is underway. It will test a 10 LPM dose of dehumidified air against a 2 LPM sham.
According to CEO Steve Schaefer, it should be completed in September, 2025.
I believe that we need to see data from at least two carefully done phase 3 trials at the correct flow rate (10 LPM), in an appropriate number of patients, before we will know if this device can successfully treat migraine, but the results so far are very promising.
