Quantitative ultrasound imaging of intrinsic hand muscles after traumatic cervical spinal cord injury

This is a cross-sectional descriptive study.

To quantify differences in hand muscle morphology between persons with cervical spinal cord injury (SCI) and uninjured adults.

The study was performed at the Guangdong Work Injury Rehabilitation Hospital.

We quantified hand muscle cross-sectional area (CSA), thickness, and echo intensity (EI) in 18 persons with subacute to chronic SCI and 23 controls using ultrasound imaging.

Mean SCI abductor pollicis brevis (APB), abductor digiti minimi (ADM), and first dorsal interosseous (FDI) CSA were ~26%, 43%, and 37% smaller than the control means, the deficit in the APB being less than the ADM (P < 0.05). Muscle thickness was also smaller after SCI, but deficits in ADM (31%) and FDI (20%) thickness were less than the CSA deficits (P < 0.05). In five SCI persons, APB CSA and/or opponens pollicis (OP) thickness were normal despite complete motor paralysis. Mean longitudinal image EI was 40% higher in the OP and 15% higher in the flexor pollicis brevis (FPB) after SCI (P < 0.05), suggesting denervation-induced infiltration of fat and fibrous tissues. OP EI was related to OP thickness (r = -0.6, P = 0.007, n = 18). Mean axial image EI was 10% higher in the APB and ADM after SCI (P < 0.05). There were no significant correlations between muscle morphological properties and clinical features in the SCI participants.

Our results indicate significant SCI atrophy and elevated EI that are muscle dependent.