Body Sway Velocity Research Articles

Clinical Significance of the Velocity of Bodily Sway of the Center of Gravity

An attempt was made to evaluate the compensation process in patients with vestibular lesions by studying the velocity of bodily sway of the center of gravity.Patients with vestibular neuronitis, Meniere's disease and bilateral vestibular hypofunction were teasted. The data of the body sway test were analyed by micro-computer to obtain the velocity of body sway. The analysis time was 60sec and the sampling time 0.1sec.1) In patients with acute vestibular lesions whose vergigo had persisted for a relatively long time, the velocity difference between swaying to the right and to the left disappeared earlier than did nystagmus under non-gaze conditions.2) The velocity difference or the abnormal high velocity of the center of body sway recovered relatively early when tested with the eyes open in patients with bilateral vestibular lesions. However, abnormal high velocity persisted longer in the non-gaze state, which seems to reflect delayed compensation of the posture.

小児の発育に伴う重心動揺の定量的変動 身体動揺の研究 第２１報

The equilibrium function of children develops with their physical growth, and its estimation must be performed by appropriate examinations. This study deals with the changes in body sway strating at 4 years of age.1. The area and locus length traced by the body's center of gravity decreased with age, and children 12 to 15 years of age showed nearly the same values as adult subjects Changes in the velocity of body sway paralleled those of the area and locus length.3. In right-handed children, the moving area of the center of gravity was mostly to the left of the center line in the standing horizontal plane.

Analysis of Deviation Reaction after Vestibular Stimulation

In order to analyze the deviation reaction while standing using posturography, the author measured the deviation of the center of body sway and the velocity of body sway. Normal subjects after caloric vestibular stimulation and patients with equilibrium disturbance were examined. For the purpose of studying the influence of the vestibular system on leg extensor muscle tone, the H-reflex was investigated in normal subjects in the supine position after caloric vestibular stimulation.1) In normal subjects, when their eyes were closed, the center of body sway tended to shift to the front and the velocity of body sway to the back was faster than to the front.2) After unilateral caloric vestibular stimulation, normal subjects shifted to the stimulated side when cold air (24°C) was used and to the opposite side when warm air (50°C). was employed. The velocity was faster on the opposite side than the stimulated side with cold air and faster on the stimulated side with the warm air.3) In most of the patients with peripheral labyrinthine disorder who had nystagmus, the center of body sway shifted in the same direction as that of the slow phase of nystagmus and the velocity of body sway was high i n the direction of quick phase of nystagmus.4) After unilateral caloric vestibular stimulation, the frequency depression curve of the H-reflex showed the spastic type in both legs. With cold water (5°C), the contralateral leg was predominant, whereas with warm water (44°C), the ipsilatcral leg was predominant.

Observation of the Velocity of Body Sway Ménière's Disease

Vestibulo-spinal reflexes in Ménière's disease were analyzed using gravigrams and velocitygrams.Studies of vestibular disturbance have so far been centered around nystagmus. With the development of the gravicorder, however, a new approach to the testing of vestibulospinal reflexes began to be tried, which is based on the analysis of the center of gravity.A characteristic of gravigrams is that they are positional graphs and provide no information about time-course changes in the velocity with which the center of gravity moves. To clarify time-course changes in the velocity of the sway of the center of gravity while recording its movement, we processed data of the change in the time-course velocity, a component of dynamic control system, with a computer and obtained velocity-grams.On gravigrams, body movements differing in frequency are represented by the same area change as long as their amplitudes are the same. These same body movements, however, produce completely different velocitygrams, which are constructed on the basis of differentials of the above recordings.Eleven patients with Ménière's disease were then tested during a non-attack period with their eyes open and closed. It became clear from the above test that, even among patients who exhibited the same pattern of area change on gravigrams, velocitygrams were different from each other. This means that the velocity is controlled by a different recovery conditions.That the velocitygrams of patients in a non-attack period varied greatly suggests that each patient responded differently to treatment.The above findings indicate that the velocity of body sway, which is a parameter of the dynamic control functions, plays an important role in the clinical diagnosis of equilibrium disturbance.

Significance of Body Sway Velocity-Power-Spectrum Analysis in Postural Equilibrium Dysfunction

The method and objective of the analysis of equilibrium dysfunction based on the indices of gravitudinal fluctuations as well as the expression of the body sway in mathematical values have contributed in the diagnosis of the location of disturbance and the classification of diseases.The power spectrum analysis of deviation is one of the analytical methods which have gained much popularity in practice in recent years.We have recently conducted a power spectrum analysis of body sway velocity. It was not possible to analyze the directional component of a body sway by this method, but observation of sways in terms of velocity was possible. Formerly, it was difficult to analyse the high frequency of the body sway in terms of the power spectrum : however, by converting the body sway into the velocity power spectrum, the analysis of the high frequency body sway could be easily be performed.We used this method for the analysis of 19 cases of spinocerebellar degeneration, seven cases of Parkinson's disease, 22 cases of hemiplegia, and eight cases of Meniere's disease.For basic data, tetanic stimulation of lower limb muscles was given by connecting plate electrodes to the tibial nerves bilaterally below the knees to induce body movements.In this experiment, a peak was observed which coincided with the loaded frequency in the sway velocity power spectrum. It was discovered also in this experiment that the velocity component of body sway in the normal person was a noise which was inversely proportional to the Feurier's frequency, which is said to be Schottky effect (by Johnson 1925, 1/f noise).When various neurological diseases was analysed using this method, a distinct finding was observed at higher frequencies, i.e. a deviation in the slope of the spectrum from that of the 1/f noise.How a method like this can be utilized for the analysis of body movements was discussed.