Disclosures: Matthew Tay, FRCP: No financial relationships or conflicts of interest

Objective: Motor weakness of the upper limb is a major complication of stroke. This study aims to investigate changes in ultrasound-derived muscle architecture parameters of the brachialis and correlations in patients with subacute stroke.

Design: Prospective longitudinal observational study.

Setting: Tertiary inpatient rehabilitation center.

Participants: The study recruited 50 adult patients. Inclusion criteria were age between 21 and 80 years old, a first ever clinical unilateral stroke (ischemic or hemorrhagic), duration of < 1 month post-stroke, premorbid modified Rankin scale10 of 0, and presence of elbow flexion weakness in the hemiparetic upper limb of Medical Research Council (MRC) grade 4 or less. Exclusion criteria were limitation of full elbow extension.

Interventions: NA.

Main Outcome Measures: Ultrasound of the intact and hemiparetic brachialis was performed at 3 time intervals: within 1 month of stroke onset and at 1 and 6 months after first assessment. Clinical variables captured included upper limb motor power and elbow flexor spasticity.

Results: The patients had a mean age of 57.2 years with 68.0% being male. Compared to the intact brachialis, there were reduced muscle thickness (1.93cm vs 2.07cm, 1.86cm vs 2.08cm, 1.85cm vs 2.05cm; p=0.022) and increased echo intensity (63.3AU vs 56.8AU, 69.4AU vs 56.6AU, 77.4AU vs 58.2AU; p < 0.001) in the hemiparetic brachialis at all assessment intervals (baseline, 1 month, 6 months). Reduction in muscle mass was greater in older patients, with the correlation coefficient ranging from -0.3 (p=0.03) at baseline to -0.50 (p < 0.001) at 6 months. Presence of elbow flexor spasticity at 1-month assessment interval was associated with lower muscle mass reduction (1.93cm vs 1.74cm; p=0.017), lower echo intensity (65.1AU vs 75.1AU; p=0.023) and longer fascicle lengths (12.92cm vs 9.83cm; p=0.002).

Conclusions: Changes of decreased muscle thickness and increased echo intensity of the hemiparetic brachialis were noted over time. Elbow flexor spasticity at 1-month assessment interval appears to mitigate against these changes.

Level of Evidence: Level I

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/assessment-of-upper-limb-muscle-architecture-changes-on-ultrasound-in-patients-with-stroke/