Pathway for the Differential Diagnosis of Obstetrical Brachial Plexus Palsy.

Abstract

Background: Obstetrical brachial plexus palsy (OBPP) is a common birth injury, generally presenting as upper limb paralysis at birth. While diagnosis is straightforward when associated with known risk factors, misdiagnoses can nevertheless occur. This study aimed to elucidate the process of differential diagnosis for OBPP by analyzing cases of suspected OBPP, ultimately diagnosed with other conditions.

Methods: We reviewed the electronic medical records of patients under 1 year of age presenting with suspected or previously diagnosed OBPP at 2 tertiary childrens' centers in Osaka between 1994 and 2021. Cases were divided into the OBPP and non-OBPP groups, according to the final diagnosis, for comparison of demographic data and physical findings, to determine the clinical course that could be used to differentiate non-OBPP from OBPP.

Results: Of the 414 enrolled cases, 387 (93%) were confirmed as OBPP, while 27 (7%) were diagnosed with other conditions. Statistically significant differences were found in gestational age, birth weight, and age of first visit, between the 2 groups, although these were not clinically meaningful for differential diagnosis. Shoulder dystocia was observed in 54% of OBPP cases, but not in non-OBPP cases. The key characteristics of OBPP included paralysis from birth, paralysis following an anatomic distribution, and paralysis that gradually improved without worsening. Conversely, joint contracture immediately after birth was a key indicator for ruling out OBPP. Using these criteria, 24 of 27 suspected cases were excluded from OBPP diagnosis. Of the remaining 3 cases, spinal cord infarction was detected on MRI in 1 case. In the remaining 2 cases, although normal MRI and surgical findings could rule out OBPP, a definite diagnosis could not be made.

Conclusions: This study highlights that accurate OBPP diagnosis requires careful verification of specific characteristics. If these characteristics are not met, OBPP becomes less likely, and diagnostic uncertainty persists. An MRI of the brachial plexus is needed in such cases.

Level of evidence: Level III-retrospective cohort study.