Early MRI Can Predict the Indication for Surgery in Brachial Plexus Birth Injury: Results of the NAPTIME Study.

Abstract

BACKGROUND Magnetic resonance imaging (MRI) has not been routinely used for infants with brachial plexus birth injury (BPBI); instead, the decision to operate is based on the trajectory of clinical recovery by 6 months of age. The aim of this study was to develop an MRI protocol that can be performed without sedation or contrast in order to identify infants who would benefit from surgery at an earlier age than the age at which that decision could be made clinically. METHODS This prospective multicenter NAPTIME (Non-Anesthetized Plexus Technique for Infant MRI Evaluation) study included infants aged 28 to 120 days with BPBI from 3 tertiary care centers. Subjects had nonsedated non-contrast rapid volumetric proton density MRI on 3-T scanners. Neuroradiologists at each site calculated the NAPTIME nerve root injury score for subjects at their site. Interrater reliability was performed on a subset of subjects. All of the subjects were evaluated with routine clinical examinations up to 6 months of age, by which time the treating surgeon determined whether to offer nerve surgery. Surgeons were blinded to the MRI results. The ability of the NAPTIME score to discriminate surgeon indication for surgery was evaluated using the receiver operating characteristic (ROC) curve, by estimating the area under the curve (AUC) across the range of NAPTIME scores. RESULTS Sixty-five infants successfully completed the NAPTIME MRI; 18 (28%) ultimately met the clinical criteria for nerve surgery. The interrater reliability for the NAPTIME score was moderate at 0.703 (95% confidence interval [CI], 0.582 to 0.818). The median NAPTIME score for subjects who met the criteria for nerve surgery was 16.2 (interquartile range [IQR], 9.9 to 18.9), while the median score for those who did not was 7.0 (IQR, 5.0 to10.5). The NAPTIME score predicted meeting the criteria for surgery with an AUC of 0.812 (95% CI, 0.688 to 0.936). A score of >13 offered a specificity of 0.94 and a sensitivity of 0.61 for surgical indication. CONCLUSIONS Non-contrast MRI without sedation is a useful tool in determining the severity of injury in BPBI. The NAPTIME score might distinguish which infants will meet the criteria for reconstructive nerve surgery earlier than when the decision can be made clinically. LEVEL OF EVIDENCE Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.