Clinical Classification Versus MRI Patterns of Injury in Brachial Plexus Birth Injury

Caroline H Hu; Ann E Van Heest; Michelle A James; M Claire Manske; Peter Y Shen; Andrea S Bauer

doi:10.1016/j.jhsa.2025.06.015

Clinical Classification Versus MRI Patterns of Injury in Brachial Plexus Birth Injury

J Hand Surg Am. 2025 Oct;50(10):1183-1189. doi: 10.1016/j.jhsa.2025.06.015. Epub 2025 Aug 19.

Authors

Caroline H Hu¹, Ann E Van Heest², Michelle A James³, M Claire Manske³, Peter Y Shen³, Andrea S Bauer⁴

Affiliations

¹ Department of Orthopedic Surgery, Boston Children's Hospital, Boston, MA; Department of Orthopaedic Surgery, Brigham and Women's Hospital, Boston, MA; Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN; Department of Orthopedic Surgery, Gillette Children's Specialty Healthcare, St. Paul, MN. Electronic address: chhu@umn.edu.
² Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN; Department of Orthopedic Surgery, Gillette Children's Specialty Healthcare, St. Paul, MN.
³ Department of Orthopaedic Surgery, Shriners Hospital for Children-Northern California, Sacramento, CA; Division of Neuroradiology, University of California Davis Medical Center, Sacramento, CA.
⁴ Department of Orthopedic Surgery, Boston Children's Hospital, Boston, MA.

PMID: 40828115
DOI: 10.1016/j.jhsa.2025.06.015

Abstract

Purpose: The Narakas classification describes brachial plexus birth injury (BPBI) according to nerve root injury by the pattern of motor weakness on clinical examination. However, it is unknown whether the classification truly corresponds to the described nerve roots. The distribution of nerve root injuries on magnetic resonance imaging (MRI) in infants with BPBI was compared with the clinical classification.

Methods: Infants with BPBI were prospectively enrolled at three children's hospitals, and the Narakas group was determined by physical examination. Infants underwent MRI prior to age 16 weeks. Neuroradiologists determined the injury severity (intact, rupture, avulsion) at each nerve root on MRI. The nerve root findings on MRI were compared with the expected nerve root injuries, based on the clinical Narakas classification.

Results: Sixty-eight infants completed the MRI revealing 19 distinct patterns of nerve injury. The nerve root injury findings on MRI did not always correspond with the nerve roots involvement expected based on the Narakas classification. In Narakas 1 patients, 23% had injury to C5-C6 only, and 55% had additional injuries to C7, C8, and/or T1. In Narakas 2 patients, only 26% had an injury specifically to C5-C7 only. In the Narakas 3 and 4 groups, 43% had a C5-T1 global injury as expected by the Narakas classification. The mean number of nerve roots affected, and mean avulsions increased with higher Narakas grades. The most commonly injured and avulsed nerve roots were C6 (n = 60) and C8 (n = 15), respectively.

Conclusions: In 68 infants, 19 different patterns of injury were identified, suggesting that the pathoanatomy of BPBI is more nuanced than classically described. For Narakas 1 and 2 infants, the nerve root injury on MRI was often more extensive than expected based on clinical examination. Our results suggest the Narakas classification may not precisely correspond with the injury at the root level, as seen on MRI.

Type of study/level of evidence: Diagnostic II.

Keywords: Brachial plexus birth injury; MRI; Narakas classification; heatmaps.

Publication types

Comparative Study
Multicenter Study

MeSH terms

Birth Injuries* / classification
Birth Injuries* / diagnostic imaging
Brachial Plexus Neuropathies* / classification
Brachial Plexus Neuropathies* / diagnostic imaging
Brachial Plexus* / diagnostic imaging
Brachial Plexus* / injuries
Female
Humans
Infant
Infant, Newborn
Magnetic Resonance Imaging*
Male
Prospective Studies
Spinal Nerve Roots* / diagnostic imaging
Spinal Nerve Roots* / injuries