Righting Reaction in Hemiplegic Stroke Survivors: Impact of Lower Limb Motor Paralysis Severity

Background and objective The righting reaction (RR) from a laterally tilted sitting position is influenced by trunk function and walking ability; however, its relationship with the severity of lower limb motor paralysis in persons with stroke remains unclear. If the characteristics of RR response patterns are clearly identified, they may aid in determining individualized physical therapy approaches. This study aimed to clarify RR patterns according to the severity of lower limb motor paralysis and to explore their potential implications for developing individualized rehabilitation strategies. Methods This cross-sectional study included 51 participants with stroke requiring significant assistance in activities of daily living at a Japanese convalescent hospital. Participants were categorized into Mild (n = 16), Moderate (n = 19), and Severe (n = 16) groups based on the severity of lower limb motor paralysis. Neck, trunk, and leg angles during RR were measured. One-way ANOVA with post-hoc tests was used for intergroup comparisons. Results Significant differences were found in the non-paralyzed leg angle during RR toward the paralyzed side (p = 0.0003) and neck angles in both directions (paralyzed side: p = 0.0164; non-paralyzed side: p = 0.0367). The non-paralyzed leg angle was larger in the Moderate group (Mild: -3.6±6.0°, Moderate: 5.5±8.5°, Severe: -2.9±5.2°; Mild-Moderate: 95% CI: 2.6-14.1, p = 0.0011; Moderate-Severe: 95% CI: 3.1-14.7, p = 0.0022). Neck angles were larger in the Severe group than those in the Mild group (non-paralyzed side: 95% CI: 0.6-11.8, p = 0.0241; paralyzed side: 95% CI: 0.3-10.7, p = 0.0333). Conclusions This study demonstrated that the severity of lower limb motor paralysis significantly influences RR movement patterns in stroke survivors. Understanding RR movement patterns based on paralysis severity may aid in developing targeted rehabilitation strategies to improve postural control and functional recovery.