Tsubasa Mitsutake

The Control of Postural Stability during Standing is Decreased in Stroke Patients during Active Head Rotation

[Purpose] The aim of this study was to evaluate the effect of active head rotation on postural control in stroke patients during standing as compared with age-matched healthy subjects. [Subjects and Methods] In total, 46 stroke patients and 37 age-matched healthy subjects were recruited for the study. A stabilometer was used to assess postural stability in participants during standing, with or without active head rotation, and with their eyes open or closed. Subjects were asked to stand on a force plate while rotating their head in the yaw plane at a frequency of 1.0 Hz. A metronome was used to maintain the head rotation frequency, and the head rotation range was maintained at a total of 70° during the postural stability examinations. [Results] The control of postural stability during standing with active head rotation was significantly decreased in the stroke group as compared with the healthy group with both the eyes open and closed. No significant differences in relation to standing without head motion were observed between groups. [Conclusion] The findings suggest that postural instability is increased in stroke patients during active head rotation, and therefore, vestibular function in relation to head rotation might be reduced in stroke patients.

Greater Cervical Muscle Fat Infiltration Evaluated by Magnetic Resonance Imaging is Associated With Poor Postural Stability in Patients With Cervical Spondylotic Radiculopathy.

Study Design. A population-based, cross-sectional study. Objective. The aim of this study was to quantitatively evaluate the relationship between static postural stability and fat infiltration within cervical multifidus muscle in patients with cervical spondylotic radiculopathy (CSR). Summary of Background Data. CSR causes denervation by compression of nerve roots. This denervation is detected by fatty infiltration or results in fatty infiltration within muscles. Proprioceptive information in cervical multifidus muscle plays an important role in coordinated movement of postural stability; however, there have been few studies evaluating the relationship between postural stability and fat infiltration within cervical multifidus muscle among CSR patients. Methods. Sixteen CSR patients with C6 injuries and 25 age-matched healthy controls underwent magnetic resonance images to examine bilateral cervical multifidus muscle. For evaluation of fat within muscle, a muscle fat index (MFI) was calculated by using both measurement of cervical multifidus muscle and intermuscular fat. Participants’ postural stability at upright position with eyes-opened and eyes-closed for 60 seconds was examined by a platform. Two parameters, the total length and the area of the center of pressure (COP), were used for evaluation. Results. The CSR group showed significantly poorer postural stability than the control group (eyes-opened the total length; P < 0.05, eyes-closed the total length; P < 0.05, eyes-closed the area; P < 0.05). There were significant group differences at C4, C5, and C6 MFI (P < 0.05). In the CSR group, a correlation analysis demonstrated that the age, C4, C5, and C6 MFI values were significantly associated with the eyes-closed the total length of the COP (P < 0.05). Conclusions. Fat infiltration within muscle could lead to inhibition of normal activity of musculature. The present study suggests that fat within cervical multifidus muscle could directly cause postural instability in static standing, even though the proprioceptive information has normal lower limbs. Level of Evidence: 3

Factors influencing executive function by physical activity level among young adults: a near-infrared spectroscopy study

[Purpose] Prevention of dementia requires early intervention against it. To ensure that early interventions are effective it is crucial to study the cognitive functions related to dementia in young adulthood. Moreover, it is needed not only to verify the cognitive function test but also to elucidate the actual brain activity and the influence of related factors on the brain activity. To investigate the factors influencing cognitive function among young adults and examine the differences in executive function by physical activity level. [Subjects and Methods] Forty healthy university students (mean age, 20.4 years) were classified into two groups by cognitive function score (HIGH and LOW), determined according to Trail Making Test performance and Stroop task processing time. We then assessed what factors were related to cognitive function by logistic regression analysis. Executive function was determined by brain blood flow using near-infrared spectroscopy during the Stroop task, and was then compared by physical activity levels (determined according to number of steps per hour). [Results] Full-scale Intelligence Quotient according to the 3rd Wechsler Adult Intelligent Scale and number of steps per hour influenced cognitive function score, with odds ratios of 1.104 and 1.012, respectively. Oxy-hemoglobin concentrations in areas related to executive function during the Stroop task were significantly higher among those in the high physical activity group than among those in the low physical activity group. [Conclusion] The study revealed that Full-scale Intelligence Quotient and a number of steps per hour are factors associated with the cognitive functions in young adulthood. In addition, activity in execution function related area was found to be significantly higher in the high physical activity group than in the low physical activity group, suggesting the importance of physical activity for enhancing young adulthood cognitive functions.

Effects of vestibular rehabilitation on gait performance in poststroke patients: a pilot randomized controlled trial

The effects of vestibular rehabilitation on poststroke patients are unknown. This study aimed to investigate whether or not vestibular rehabilitation would improve both the vestibulo–ocular reflex and gait performance of patients with poststroke hemiparesis. Twenty-eight patients with stroke were assigned randomly to either an experimental group (N=14) or a control group (N=14). The experimental group performed the conventional physical therapy for 40 min and vestibular rehabilitation for 20 min, as a 60 min session, during the first 3 weeks and then completed only the conventional intervention for 60 min for the following 3 weeks. The control group performed only the 60 min conventional physical therapy for 6 weeks. Both groups were measured using the gaze stabilization test, the 10 m walking test, the timed up and go test, and the dynamic gait index. Patients were assessed at baseline, and at 3 and 6 weeks. Although the control group showed no significant difference in any outcome measures, the experimental group showed an improvement in gaze stabilization test scoring, which increased significantly after 3 weeks compared with the baseline (P=0.030). The dynamic gait index was also significantly increased after 3 and 6 weeks compared with the baseline (P=0.049 and 0.024, respectively). This study indicated that vestibular rehabilitation might improve poststroke patients’ vestibulo–ocular reflex. Moreover, patients might show improved gait performance at least up to 3 weeks after the vestibular intervention by the sensory reweight to coordinate vestibular input.

Poor gait performance is influenced with decreased vestibulo-ocular reflex in poststroke patients

The vestibulo-ocular reflex (VOR) exerts a significant influence on gait performance. Therefore, a decrease in VOR function could worsen gait impairments in patients with poststroke hemiparesis. The effects of decreased VOR function on gait performance could be further exacerbated by aging-related physical weakness and impaired motor function of the hemiparetic lower limb. The aim of our study was to evaluate the possible synergistic effect of aging and impairment in lower extremity function and the VOR on walking ability of poststroke hemiplegic patients. The VOR was evaluated, using the gaze-stabilization test (GST), in 75 patients with a poststroke hemiplegia. Lower extremity function was assessed using the Fugl-Meyer assessment (FMA-LE). Gait performance was evaluated using the 10-m walking test, the timed up-and-go, and the dynamic gait index (DGI). The relationships between gait performance and age, FMA-LE and GST, as well as whether age, FMA-LE, and/or GST were significant predictors of gait performance were evaluated. The 10-m walking test, timed up-and-go and DGI were significantly correlated to the FMA-LE and GST (P<0.05). On stepwise multiple regression analysis, the GST remained a significant predictor of the DGI (P<0.001). The present study indicates that decreased VOR function after stroke contributes to impairments in gait both in simple and in dual-task walking tests.