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.