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Updated: May 16, 2026
Development of a Neonatal Rat Model for Brachial Plexus Birth Injury
Published on: March 27, 2026
Newborn brachial plexus palsy: evaluation of severity using quantitative ultrasound of muscle
Craig M Zaidman1, Mark R Holland, Michael J Noetzel
1Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri 63110, USA. zaidmanc@neuro.wustl.edu
Introduction:
We studied ultrasound features of muscle after nerve injury.
Methods:
We evaluated ultrasound measurements of muscle thickness and backscatter in injured and contralateral uninjured elbow flexors of 51 children with newborn brachial plexus palsy (NBPP) and compared the results to elbow flexor function (Active Movement Scale), defined as normal, moderate, or severe.
Results:
Compared with uninjured limbs, muscle in injured arms was 15% thinner with severe impairment, 17% thicker with moderate impairment, and no different with normal function. Relative to uninjured limbs, moderately impaired muscle was thicker than both severely impaired and normal strength muscle. Backscatter was higher in injured than in uninjured limbs regardless of function. In 17 patients with sequential measures, muscle thickness, but not backscatter, increased with function over time.
Conclusions:
Muscle thickness differentiates moderate from severe impairment after NBPP and increases with recovery over time. Muscle backscatter identifies prior injury regardless of function.
