Reduced trunk muscle mass in patients with stroke is associated with reduced balance function recovery

Skeletal muscles are essential for postural retention and balance function. However, the relationship between trunk muscle mass (TMM) and balance function has not yet been clarified. This study aimed to examine the impact of TMM on the change in balance function in patients with stroke from admission to a rehabilitation hospital to discharge.

This retrospective observational study included patients aged ≥65 years with cerebral infarction admitted to our rehabilitation hospital from May 2018 to July 2022. The trunk muscle mass index (TMI) was calculated at admission and discharge using bioelectrical impedance analysis. Patients were divided into low and high TMI groups according to the median TMI at admission. The primary outcome was the change in the Berg Balance Scale (BBS) score (BBS score at discharge - BBS score at admission).

A total of 315 patients (mean age, 78.9 ± 8.0 years; 172 men and 143 women) were included. The median TMI was 7.31 kg/m² in men and 6.30 kg/m² in women. Among male patients, the high TMI group had higher BBS scores at admission (31.2 ± 18.2 vs. 23.4 ± 17.7, P = 0.005) and discharge (43.0 ± 15.3 vs. 33.4 ± 19.0, P < 0.001) than those in the low TMI group. After adjusting for confounding factors, TMI at admission was independently associated with the change in BBS score (β = 0.587, P = 0.002).

Reduced TMM negatively influences balance function recovery in patients after stroke. A strategy aimed at increasing TMM could have beneficial effects on balance function.