Ultrasound Evaluation of Upper Limb Sublesional Muscle Morphology in Cervical Spinal Cord Injury

Muscle & Nerve, 2025 · DOI: 10.1002/mus.28358 · Published: January 12, 2025

Spinal Cord Injury Physiology Medical Imaging

Simple Explanation

This study investigates how muscles in the arms and hands change after a cervical spinal cord injury (cSCI) using ultrasound. The researchers looked at muscle size and echo intensity to see if there were differences between people with cSCI and healthy individuals. The study also examined whether damage to lower motor neurons (LMNs), which connect the spinal cord to the muscles, influences these muscle changes. They used electromyography (EMG) to assess LMN health and compared it with ultrasound findings. The findings showed that muscles in the forearm and hand of people with cSCI were smaller and had higher echo intensity compared to healthy controls. Additionally, muscles with LMN damage showed reduced size and elevated echo intensity.

Study Duration

2-6 months post-injury

Participants

17 individuals with cSCI (3 females, 14 males) and 17 sex-matched healthy controls

Evidence Level

Cross-sectional cohort study

Key Findings

1
Forearm and hand muscle size were significantly lower (15%-41%) in individuals with cSCI compared to healthy controls.
2
Echo intensity (EI) was significantly higher (21%-40%) in forearm and hand muscles of individuals with cSCI compared to healthy controls.
3
Muscles demonstrating abnormal LMN health displayed reduced biceps brachii muscle thickness (MT) and elevated flexor pollicis longus EI.

Research Summary

This study evaluated muscle morphology changes in upper limb muscles of individuals with cervical spinal cord injury (cSCI) using ultrasound and compared them to healthy controls (HC). The results showed significant reductions in muscle size and increased echo intensity (EI) in forearm and hand muscles of cSCI patients compared to HC. The presence of lower motor neuron (LMN) abnormalities, assessed via EMG, was associated with decreased biceps brachii (BB) muscle thickness and increased flexor pollicis longus (FPL) EI, suggesting that LMN damage contributes to muscle degeneration after cSCI.

Practical Implications

Early Intervention

The rapid muscle degeneration observed after cSCI highlights the need for early interventions, such as nerve transfer surgery, to maximize the effectiveness of restorative therapies.

Surgical Timing Optimization

Concordant information from ultrasound and EMG can help optimize the timing of surgical intervention for each patient based on the severity and rate of neuromuscular degeneration.

Clinical Decision-Making

Evidence of rapid morphologic degeneration in upper limb muscles has implications for clinical decision-making following cSCI.

Study Limitations

1
The study did not measure electrodiagnostic parameters a priori.
2
Reliable segmentation of forearm muscles with US is challenging, especially in muscles exhibiting severe degeneration.
3
The relatively small sample size of BB analyses and cross-sectional study design limit the interpretations of our data.

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