The mQST was conducted using a protocol similar to previous investigations [32 (link), 33 (link)]. We collected a 30-second baseline video recording of the child in the examination chair for the child to acclimate to the environment and for behavioral coders to identify baseline behaviors not related to stimulus application. The stimuli consisted of six calibrated stimuli and two sham trials in the same order, except for the randomized sham. An initial sham trial was conducted for every mQST, where a von Frey monofilament with the fiber closed was held approximately two inches away from the calf, consistent with all other applications except for the actual touch. Light touch was applied once per second for 5 s by hand with a von Frey monofilament (2.0 g) pressed against the skin until the filament bent at a 45° angle. A light pin prick was applied for less than one second with a plastic neurological exam pin (Medipin; US Neurologicals). Cold touch was applied lightly for five seconds using a room temperature metal thermal probe (approximately 22 °C; Tip Therm, US Neurologicals). Deep pressure was applied by hand using an algometer (Wagner Instruments) pressed into the calf at a consistent 4 lbs of pressure for 5 s. A repeated von Frey monofilament (60 g) was applied by hand at approximately 1 Hz for 30 s. Heat was applied for five seconds using a 3-mm electronic thermal heat probe (WR Medical Electronics) at a temperature of 50 C. The randomized sham was conducted in the same way as the initial sham but was randomized into the sequence.
Stimuli were applied to the back of the child’s bare left and then the right calf. Each stimulus approach and removal were audibly signaled and accompanied by a 5-second lag between signal and application. Timing was guided by an in-ear digital timer. At least a ten-second return to baseline for child behavior separated the application of each stimuli type. If a participant had tears or other signs of distress, the stimulus application was terminated. If distress was ongoing after stopping the application, the entire mQST was terminated at the lead examiner and/or caregiver’s discretion.
Stimuli were applied to the back of the child’s bare left and then the right calf. Each stimulus approach and removal were audibly signaled and accompanied by a 5-second lag between signal and application. Timing was guided by an in-ear digital timer. At least a ten-second return to baseline for child behavior separated the application of each stimuli type. If a participant had tears or other signs of distress, the stimulus application was terminated. If distress was ongoing after stopping the application, the entire mQST was terminated at the lead examiner and/or caregiver’s discretion.
