Predicting The Need for Primary Nerve Surgery in Infants with Brachial Plexus Birth Injury

Hospital for Sick Children, Toronto, Canada

Ibrahim Natalwala, Howard Clarke

AIMS: 1) To re-assess the predictive ability of the Toronto Test Score (TTS) within a large cohort of infants with brachial plexus birth injury (BPBI); and 2) to determine what additional factors help discriminate those infants with an intermediate TTS (TTS-I) [3.5-5.5] that will need primary nerve surgery (PNS).

METHODS: A retrospective cohort study (1991-2023) was performed of all infants with BPBI having a 3-month TTS. Infants having early primary nerve surgery (<3 months) and those undergoing isolated nerve transfers for external rotation were excluded. The ability of the TTS to discriminate those requiring PNS was evaluated using the receiver operating characteristic area under the curve (AUC). In the TTS-I subgroup, we evaluated 6-month Active Movement Scale (AMS) scores and change in scores between 3-6 months as discriminative factors.

RESULTS: 738 patients (53% female; 742 limbs) were included. Median TTS was 7.9 (IQR 5.5-9.3). Surgery was required in 204 patients (28%) at median age of 7.4 months (IQR 4.8-10.1). The TTS was highly predictive of the need for PNS with an AUC of 0.92 (95% CI 0.90-0.94). Infants with a TTS < 5.0 were at highest risk for surgery. 79 of 115 infants with TTS-I had AMS scores at 6 months. Combining all AMS scores at 6 months into a total score (t-AMS) highly correlated with need for surgery (AUC 0.89; 95% CI 0.82-0.96). All patients with TTS-I and t-AMS score <70 at 6-months required surgery, versus 33% for t-AMS >80. T-AMS scores at 6 months were more discriminative than change in elbow flexion scores alone.

SUMMARY: The TTS is a validated tool which has an excellent ability to discriminate patients that are likely to need primary nerve surgery. In the TTS-I subgroup, total AMS scores >80 and elbow flexion >5/7 at 6-months were significantly less likely to require surgery.