Assessment of Prolonged Pain in Infants With Excessive Crying: Contribution of Infrared Thermal Imaging - The NEOTHERM Pilot Study (NEOTHERM)

Infants aged 2 to 6 weeks post-term (corrected age) at the first assessment, with crying lasting more than 3 hours per day on at least 3 consecutive days during the 7 days preceding the assessment (modified Wessel criteria). Infants must also meet at least two of the following three protocol-specified Rome IV-related features: crying without an apparent cause, inconsolable crying, and associated signs including agitation, facial flushing, clenched fists, and/or flexed legs.

No intervention will be assigned. Participants will undergo the observational assessments specified in the study protocol.

Infants aged 2 to 6 weeks post-term (corrected age) at the first assessment, with crying lasting less than 2 hours per day during the 7 days preceding the assessment.

Participants in the TC cohort will be matched to participants in the EC cohort according to corrected age at assessment (±1 week), sex where possible, gestational age at birth (±1 week), feeding modality, and maternal parity.

No intervention will be assigned. Participants will undergo the observational assessments specified in the study protocol.

Mean skin temperatures will be extracted from predefined body and facial regions of interest. Infrared thermal imaging indices will include absolute bilateral body temperature differences, central-to-peripheral temperature gradients, and intra-facial temperature gradients calculated relative to the forehead. An absolute temperature difference greater than 0.5°C will be considered an abnormal thermal asymmetry.

The EDIN is a behavioral scale assessing facial expression, body movements, sleep, interaction, and consolability. Each item is scored from 0 to 3. Higher scores indicate greater pain- or discomfort-related behaviors; a total score of 5 or higher indicates probable prolonged pain.

Concordance between infrared thermal imaging indices and EDIN total scores will be quantified using Spearman rank correlation coefficients at each assessment. Thermal images will be analyzed by an external assessor blinded to the EDIN score and cohort classification.

Hair cortisol concentration will be measured in pg/mg of hair from a small sample collected from the occipital region. Cortisol will be quantified using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS).

Hair cortisol concentration will be investigated as a biomarker of prolonged stress. Spearman correlation coefficients will be calculated between hair cortisol concentration, infrared thermal imaging indices, and EDIN total scores

Spontaneous general movements will be recorded with the infant lying supine, wearing only a diaper or onesie, during 2 to 5 minutes of active wakefulness without crying, interaction, a pacifier, or hiccups. Recordings will be independently evaluated by two assessors trained in General Movements Assessment and blinded to cohort classification, EDIN scores, and infrared thermal imaging results.

The General Movement Optimality Score-Revised (GMOS-R; maximum score 38) will be used at Visit 1. The Motor Optimality Score- Revised (MOS-R) will be used at Visit 2; scores of 25 to 28 are considered optimal, whereas lower scores indicate less optimal motor organization. Qualitative motor characteristics, including movement quality, variability, fluency, symmetry, posture, and atypical movement patterns, will also be described and compared between cohorts.

Psychomotor development will be assessed using the Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4). Five subtests will be administered: cognitive development, receptive communication, expressive communication, fine motor development, and gross motor development.

Raw subtest scores will be converted to scalar and composite scores using the normative tables of the Bayley-4. Higher scores indicate better performance in the assessed developmental domain. Scores will be compared between the EC and TC cohorts. Scoring will be performed by an assessor blinded to cohort classification.