Early pain findings in infants with brachial plexus birth injury: Relationship with function and comorbidities, and cut-off point for fractures

Background

Infants with birth brachial plexus injury (BPBI) may have various comorbidities such as fractures, torticollis, plagiocephaly, central nervous system disorders. In infants with BPBI, it is important to identify fractures, which are common among comorbidities, objectively assess pain, and investigate factors that may be associated with pain.

Aim

The aim of this study is to determine the pain level, comorbidities, and motor function in infants with BPBI and to examine the relationship between these parameters. The second aim is to determine the cut-off value of the pain score that may be a sign of fracture in patients with BPBI, in order to suspect and predict a fracture in the shoulder region and to request additional examinations.

Subjects and measurements

59 infants with BPBI aged 15–90 days were included in the study. Comorbidities, active joint movements, and total upper extremity function assessed with the Active Movement Scale and pain scores measured with the FLACC Pain Scale were retrospectively analyzed. In addition, pain, comorbidities and motor function were investigated according to types of Narakas, which indicates the degree of nerve injury.

Results

Of the 59 participants, 18 (30.5 %) had at least one comorbidity and 12 (20.3 %) had fractures. The number of comorbidities (p = 0.41), the number of fractures (p = 0.84), and the level of pain (p = 0.71) did not differ by types of Narakas. There was a moderate negative correlation between pain level and upper extremity motor function in upper trunk injuries (p < 0.5, −0.67 < r < −0.46). There was a difference in pain level measured by palpation (p < 0.01) and passive joint movement (p < 0.01) in infants with and without comorbidities. To suspect a fracture in the shoulder region and to request further evaluation, the cut-off value of the Flacc pain level, which may predict a fracture, was 3.5 points for palpation and passive shoulder abduction and 4.5 points for passive external rotation.

Conclusion

This is the first study in the BPBI to measure pain in infants using a quantifiable and widely used assessment. Pain level was ranked from high to low as infants with fractures, infants with comorbidities other than fractures and infants without comorbidities. Increased pain adversely affects motor function and pain above the cut-off values is a predictor of fracture.