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PubMed2002

Dynamic posturography using a new movable multidirectional platform driven by gravity.

Human upright balance control can be quantified using movable platforms driven by servo-controlled torque motors (dynamic posturography). We introduce a new movable platform driven by the force of gravity acting upon the platform and the subject standing on it. The platform consists of a 1 m2 metal plate, supported at each of its four corners by a cable and two magnets. Sudden release of the magnets on three sides of the platform (leaving one side attached) induces rotational perturbations in either the pitch or roll plane. Release of all magnets causes a purely vertical displacement. By varying the slack in the supporting cables, the platform can generate small (0.5 degrees ) to very destabilising (19 degrees ) rotations. Experiments in healthy subjects showed that the platform generated standardised and reproducible perturbations. The peak rotation velocity well exceeded the threshold required to elicit postural responses in the leg muscles. Onset latencies were comparable to those evoked by torque motor-driven platforms. Randomly mixed multidirectional perturbations of large amplitude forced the subject to use compensatory steps (easily possible on the large support surface), with little confounding influence of habituation. We conclude that this gravity-driven multidirectional platform provides a useful and versatile tool for dynamic posturography.

Adult↗
PubMed1996

Postural stability by computerized posturography in minor head trauma.

Mild head injuries are very common among young children. Often, these injuries are followed by a variety of subjective complaints termed posttraumatic syndrome. Posturography (balance test) was performed immediately after the trauma in 21 children who had sustained mild head injury. Significant difference in performance was observed in head-injured children in all subparts of the test as compared with a control group. We conclude that posturography may serve as a simple cost-effective method in qualifying the posttraumatic imbalance.

Adolescent↗
PubMed2001

Computerised dynamic posturography to assess recovery comparing general anaesthesia with sedation and local anaesthesia for day case nasal surgery.

Computerised dynamic posturography (CDP) can be used as an early marker of recovery to street fitness in patients undergoing ambulatory surgery. We studied three groups of patients undergoing nasal surgery. The goal of this study was to determine whether recovery, as assessed by CDP, is more rapid in patients having nasal surgery under sedation coupled with local anaesthesia or those having surgery under general anaesthesia. We further assessed the acceptability of sedation accompanied by local anaesthesia. A control group was included to determine if there is a learning curve to posturography. There was no difference between the two study groups in terms of balance. Balance was not significantly impaired at 3 h postoperative testing.

Adult↗
PubMed1993

Cervicogenic headache: electronystagmography, perception of verticality and posturography in patients before and after C2-blockade.

Fourteen patients with cervicogenic headache (9F, 5M) with a mean age of 42.8 (29-58) years were examined, before and within two hours after unilateral anaesthetic C2-blockades, clinically as well as by means of electronystagmography, subjective visual vertical test and posturography. After C2-blockade, patients exhibited a slight gait deviation to the injected side without eye movement disorder, dysmetria or ataxia. Although in two of nine patients there was a small influence on lateral body sway on posturography, no specific pattern of abnormalities in eye-head-body coordination could be found before or after C2-blockades. Thus, there is no clinical evidence for a significant reproducible influence of the second cervical root on oculomotor or cerebellar function in cervicogenic headache. These findings confirm earlier data in animal experiments.

Adult↗
PubMed2004

[The value of dynamic posturography (Equitest) in preparing an expert's report].

BACKGROUND: Expert appraisals of vestibular disorders and their effects on daily life are essentially based on an evaluation of the patient's subjectively described symptoms. The aim of the present study was to ascertain the extent to which dynamic posturography is able to assist in the preparation of expert's reports. MATERIAL AND METHODS: 60 patients underwent a survey of their balance impairment. Both a nystagmus analysis, with its objective criteria, and dynamic posturography were carried out. The investigation into reduction of fitness for work (MdE) made reference to the criteria specified in the table by STOLL. The data obtained were subjected to both correlation and variance analysis. RESULTS: Although the results of this analysis revealed no direct statistical dependency, they indicated a tendency for the composite values to be correlated with the nystagmus scores and/or the MdE values (when the nystagmus score and/or the MdE increases, the composite value decreases). CONCLUSIONS: The Equitest is, according to the available data, not able to replace the currently valid MdE scores. Nevertheless, it represents a means of providing objective data about the vestibulo-spinal reflex. The test also reveals any tendencies towards simulation and aggravation. In the context of a specific nystagmus analysis, the Equitest offers an additional means of providing an objective background to back up the more subjective assessment of MdE.

Adolescent↗
PubMed2004

Dynamic posturography in humans imagining a fixed spatial reference.

OBJECTIVE: To investigate the effect of imagining a fixed spatial reference on balance control. MATERIAL AND METHODS: Twenty-one healthy subjects were asked to remain as stable as possible while standing on a sway-referenced platform (NeuroCom Equitest posturography system). Subjects were instructed to keep their eyes open in the dark and to either look far into the distance without fixating on any particular point in space or to direct their gaze towards a remembered earth-fixed target (25-cm distant). Room lights were switched off immediately before each 20-s sway recording. Postural stability measures included equilibrium scores and root-mean-square sway amplitudes in the anterior-posterior plane. RESULTS: Postural sway was not influenced by the instruction to gaze towards a remembered target. CONCLUSION: Imagining a fixed spatial reference does not influence postural control, at least during sway-referenced dynamic posturography.

Adolescent↗
PubMed1991

Computerized dynamic posturography: a new method for the evaluation of postural stability following anaesthesia.

Dynamic posturography, a new method to study postural stability in humans, was performed in 11 healthy volunteers before administration of midazolam 0.1 mg/kg body weight i.v., and repeated subsequently at 45, 105 and 165 min. Results indicate that balance was affected significantly (P less than 0.008) up to 45 min after i.v. midazolam and did not return to control values until 105 min. The quantified version of the Romberg test performed with the eyes open or closed using the Equitest did not appear to be sensitive in detecting residual effects of midazolam on balance. We conclude that healthy, young persons should not be considered to have regained postural stability for up to 105 min after sedation with midazolam. Dynamic posturography appears to be a useful test in the objective assessment of balance disturbances.

Adult↗
PubMed2005

"Across the board" posturography abnormalities in vestibular injury.

OBJECTIVE: To analyze a newly defined group of Computerized Dynamic Posturography abnormalities and to determine if these patients' abnormalities are of vestibular origin. STUDY DESIGN: Analysis of results drawn from our larger study of two groups of sequentially referred patients complaining of dizziness and/or imbalance. SETTING: A tertiary and quaternary care ambulatory referral centre. PATIENTS: Two groups of patients were studied. One was a group of patients who had suffered work-related head trauma and had subsequent complaints of dizziness and/or imbalance. The other was a group of patients referred for dizziness and/or imbalance who had no history of head trauma, work related injury. or litigation procedures. INTERVENTIONS: Standard vestibular assessment including Computerized Dynamic Posturography was carried out on all patients. MAIN OUTCOME MEASURES: CDP results of all patients were reanalyzed and all results were pulled which were abnormal on at least 5 of 6 sensory conditions. All results were analyzed using a quantitative method of detecting malingering and also using our newly developed nine point subjective/objective criteria scale. RESULTS: While the standardized formulae categorized most of these results as "aphysiologic," our nine-point protocol showed most of the patients to be legitimate. CONCLUSIONS: These results represent a legitimate subgroup of vestibular patients that we feel have been more or less unrecognized, many of whom are incapacitated by imbalance and disorientation. These results also are helpful in measuring safety of these patients in the workplace.

Craniocerebral Trauma↗
PubMed2005

Posturography can be used to screen for primary orthostatic tremor, a rare cause of dizziness.

OBJECTIVE: Primary orthostatic tremor is a rare neurologic condition of unknown origin characterized by a 10- to 20-Hz tremor in the legs while standing. Patients with primary orthostatic tremor usually complain of dizziness and unsteadiness that is relieved if they sit down or start to walk around. These patients might be referred to neurotology clinics. Previously, the only way to make the diagnosis has been by means of surface electromyographic recordings from the lower limbs during standing. The authors wanted to study whether posturography can be used to screen for primary orthostatic tremor. STUDY DESIGN: Retrospective case review. SETTING: Balance clinic at a tertiary referral center. PATIENTS: From September 2000 to August 2002, 701 patients were investigated at the authors' balance clinic. INTERVENTION: Static posturography on a force platform with 50-Hz sampling frequency. Recordings were made during 120 seconds of quiescent stance with open or closed eyes. MAIN OUTCOME MEASURE: Fast-Fourier transformation (FFT) analysis of recorded torque in the fore-to-aft direction to quantify the spectral power distribution in the range of 0 to 25 Hz. Visual inspection of power spectrum plots was performed. RESULTS: Five patients (0.7%) were identified (1 man and 4 women; mean age, 56 yr; age range, 36-73 yr) with narrow peaks at 8.5 to 18 Hz in the power spectra of their posturographic recordings. Surface electromyographic recordings during standing confirmed their diagnosis of primary orthostatic tremor. CONCLUSION: Analysis of power spectra from posturographic recordings is a simple, quick method to screen for primary orthostatic tremor. The condition might be more common than previously assumed. It is important to identify patients with primary orthostatic tremor because they might be misdiagnosed and left without treatment.

Adult↗
PubMed1993

Sensory interaction posturography in patients with benign paroxysmal positional vertigo.

BPPV (benign paroxysmal positional vertigo) is a very common peripheral vestibular disturbance. The dysfunction becomes manifest mainly by vertigo and typical nystagmus. However, the vestibulospinal reflex (VSR) can also be disturbed. This can be shown by the SPGIII (static posturography type III), which is a platform technique evaluating 'sensory interaction' in a way comparable to that of the Equi-test. Half the patients with BPPV show disturbed posturographic results. By interfering with the sensory input of vision and/or proprioception, the separate contribution of each input can be evaluated. Different 'formulae' are seen, from complete normal results, through 'overall' formulae, i.e. an undifferentiated influence in all test-conditions, to specific formulae, where we find 'eye-closure' and 'head retroflexed'-effect and so-called 'vestibular formulae'. These formulae are an expression of the different degrees of compensation achieved by the centres and especially of the 'substituting' compensation by vision and proprioception. These results confirm that posturography does not provide a typical results-pattern, thus the type of peripheral vestibular disorder cannot be diagnosed by it alone. The results give functional information on how the standing position is achieved in these patients with a disturbed VSR-input. The several formulae prove that indeed different compensatory patterns are possible, as has been shown by experiments on vestibular compensation.

Adolescent↗
PubMed1989

Posturography and the dizzy patient: a neurological study of 133 patients.

A total of 133 dizzy patients under the age of 60 years were examined using a stable balance plate (posturography, PG). All the patients were thoroughly examined neurologically before PG and classified into 7 diagnostic categories. Comparison was made between these categories and PG results. The referent group consisted of 116 healthy individuals. The patients with CNS lesions had more body sway than controls or the patients with peripheral vestibular lesions, whose sway did not significantly differ from that of the controls. The PG parameters that most clearly separated the patients from the controls were the total length of the movement of the center of gravity, and the sway in lateral and antero-posterior directions. Analysis of the frequency of the sway or calculation of the Romberg index did not reveal significant differences between the categories. Men swayed more than women. Age did not correlate with PG results. Stable posturography offers useful quantitative supplementary information as a part of the examination of a dizzy patient. Increased body sway suggests a lesion in the CNS.

Adolescent↗
PubMed1995

Visual vertigo syndrome: clinical and posturography findings.

Neuro-otological and posturography findings in 15 patients with visually induced vertiginous symptoms (visual vertigo) are reported. Thirteen patients were considered to have a peripheral vestibular disorder; seven had abnormal caloric or rotational test results. Two patients had CNS disorder--a cerebellar degeneration and a brainstem stroke. Posturography testing showed that five patients showed abnormally large body sway induced by full field visual motion stimulation. This group included the two patients with CNS disease and four with strabismic symptoms (diplopia, squint surgery, and ocular muscle weakness). It is concluded that visual vertigo is a heterogeneous syndrome with peripheral or central aetiologies and may occur if patients with balance disorders show high visual field dependence. In patients with visual vertigo, the presence of additional CNS or strabismic symptoms may cause inappropriate postural reactions in environments with conflicting or disorienting visual stimuli, probably by reducing the ability to resolve the sensory conflict.

Adult↗
PubMed2005

Postural control in patients with unilateral vestibular lesions is more impaired in the roll than in the pitch plane: a static and dynamic posturography study.

The postural instability of patients with vestibular loss (11 with bilateral and 101 with unilateral vestibular loss) at different times following the lesion was investigated by means of posturography and compared to healthy subjects. In addition, subjects submitted to galvanic vestibular stimulation were also studied to compare their postural performances with those of patients with complete unilateral vestibular lesion. The platform consisted of a static computerized force platform, on which a seesaw platform could be placed to test the subjects in dynamic conditions. The displacement of the center of foot pressure was measured under different conditions: subjects standing on the fixed platform, eyes open and eyes closed and subjects standing on the seesaw platform, eyes open and eyes closed. In the last condition, balance was tested in the subject's pitch plane by allowing the platform to rotate forwards and backwards only and in the patient's roll plane by allowing the platform to rotate to the left and to the right. The results showed that in static conditions, only bilateral vestibular loss patients had abnormal values compared to controls. In contrast, in dynamic eyes-closed conditions, both bilateral and unilateral patients could be differentiated from controls. Bilateral patients were unable to stand up without falling in both pitch and roll planes. Unilateral patients fell in the first week following the lesion and exhibited increased postural oscillations in both planes from the 2-week up to the 1-year postlesion stage. In addition and more importantly, they fell more often or had higher sway in the roll than in the pitch plane. Therefore, this study suggests that dynamic posturography on a seesaw platform could be a valuable tool for clinical diagnosis and quantitative analysis of imbalance in patients suffering from a unilateral vestibular loss up to 1 year after the lesion.

Accidental Falls↗
PubMed1996

An initial evaluation of work fatigue and circadian changes as assessed by multiplate posturography.

The sensitivity of postural responses to the effects of work fatigue and circadian changes was explored in a pilot study using a specific method of multiplate posturography based on the differential assessment of vertical pressure on four separate platforms for each heel and set of toes of each foot, respectively 8 normal subjects, M.D.s, were given six posturographic examinations immediately before and after three 8-hr. work shifts in the emergency room of a major hospital in Tel-Aviv. 3 posturographic measures (stability, spectral power of postural sway at low frequency of 0.1-0.25 Hz, and unilateral weakening of heel-toe synchronisation) were significantly affected by work fatigue whilst also showing interaction with circadian rhythm. 2 additional measures (power of sway at high frequency of 1.00-3.00 Hz and dysharmonic distribution of weight over the four platforms) were not related to workload but showed significant circadian changes. These effects appeared only on positions involving restricted visual and somatosensory feedback causing vestibular stress. Results justify the application of multiplate posturography as an ancillary tool in measuring objectively the effects of fatigue and circadian changes as well as the interaction between endogenous chronobiological processes and their external conditioning factors (Zeitgebers). Pragmatic implications of the findings in the context of industrial medicine and interdisciplinary efforts to prevent road and air accidents are discussed.

Adult↗
PubMed2002

Computerized posturography with sway frequency analysis: application in occupational and environmental health.

To examine the effects of occupational and environmental neurotoxicants on vestibular, cerebellar and spinocerebellar functions, the following three groups of subjects were examined, using a computerized posturography with sway frequency analysis: (1) 49 male chemical factory workers exposed to lead stearate, aged 27-63 (mean 43) years, with concurrent blood lead concentrations (BPbs) of 11-113 (mean 48) microg/100 g and past mean BPbs of 7-52 (mean 24) microg/100 g; (2) 29 male sandal, shoe and leather factory workers, aged 35-73 (mean 51) years, with urinary 2,5-hexanedione (HD) concentrations of 0.41-3.06 (mean 1.20) mg/g creatinine; and (3) 9 females, aged 19-58 (mean 29) years, who were exposed to sarin accidentally 6-8 months before the study (Tokyo Subway Sarin Poisoning, March 20,1995) and showed plasma cholinesterase (ChE) activities of 13-95 (mean 68) IU/l on the day of poisoning. The pattern of posturographic changes in lead workers suggested that the vestibulocerebellum (lower vermis), anterior cerebellar lobe and spinocerebellar afferent pathway were asymptomatically affected; the vestibulocerebellar change reflected concurrent lead absorption and the anterior cerebellar one reflected past absorption. Similarly, vestibulocerebellar and spinocerebellar functions were affected by n-hexane in solvent workers; the effect on the vestibulocerebellar function was probably inhibited by xylene. Also, the chronic (long-term) effect on the vestibulocerebellar function persisted in acute sarin poisoning. It is thus suggested that the vesitibulocerebellar function is most sensitive to all the three chemicals examined. It appears that the computerized posturography with frequency analysis is a useful technique for assessment of vestibular, cerebellar and spinocerebellar effects in occupational and environmental health.

Adult↗
PubMed2002

Subclinical cerebellar anterior lobe, vestibulocerebellar and spinocerebellar afferent effects in young female lead workers in China: computerized posturography with sway frequency analysis and brainstem auditory evoked potentials.

By computerized static posturography with sway frequency analysis, subclinical effects of lead on postural balance was examined in 29 female workers (lead workers) employed at a glass factory for 3-17 (mean 7.9) years in Beijing, China, in relation to brainstem function assessed by brainstem auditory evoked potential (BAEP). Their blood lead concentrations ranged from 26 to 79 (mean 55.7) microg/dl; ages were 21-30 (mean 28) years. Control subjects, aged 22-29 (mean 27.0) years, were 14 healthy female workers at a textile factory located in the same district. With eyes closed, power of the sway of high (2-4 Hz) and low (1 Hz or less) frequencies in lead workers was significantly larger than that in controls; with eyes open, their power of the sway of low frequency was significantly larger (p<0.05). The multiple regression analysis showed that the power of high frequency sway with eyes closed and of low and high frequencies with eyes open were significantly related to blood lead concentrations in lead workers (p<0.05). On the other hand, no significant differences in BAEP latencies between lead workers and controls were observed. The low frequency sway with eyes open was significantly correlated with the high frequency sway with eyes closed in the lead workers. The pattern of changes in postural balance suggested that the anterior cerebellar lobe, vestibulo-cerebellar and spinocerebellar afferent systems were affected asymptomatically in female lead workers; the sway of vestibulo-cerebellar and anterior cerebellar lobe types were simultaneously affected by lead. It appears that a computerized static posturography with sway frequency analysis is useful technique for assessment of subclinical lead neurotoxicity.

Adult↗
PubMed1993

Randomized perturbed posturography: methodology and effects of midazolam sedation.

To study quiescent stance without applying external disturbances is not a theoretically appealing way to unveil the dynamic properties of human equilibrium. Methods to disturb equilibrium range from standing on foam surface, attaching vibrators to the calves to interfere with somatosensation, and exposure to body-position tracking environments, as in dynamic posturography (EquiTest). The EquiTest apparatus was modified by a menu-driven software to allow arbitrary movements of the support surface and visual surround, and force data were recorded for subsequent analysis. The support surface was randomly moved in the antero-posterior direction. First equilibrium was studied on the stable support surface, then low (RMS 1.3 cm) and high (RMS 2.6 cm) amplitude movements were used. Vision was either present or absent at all test amplitudes. Equilibrium was evaluated by the confidence (61%) ellipse sway area and average sway velocity during 45 s. Eleven healthy subjects aged 23-36 years (mean 29) were sedated with a short acting sedative, midazolam 0.1 mg/kg. Randomized perturbed posturography was conducted at baseline, and at about 60, 120 and 180 min after injection. Psychomotor tests were conducted at baseline, and at 30, 90, 150 and 210 min. Large interindividual variations were found. One subject could not be tested at all at 60 min due to sleepiness, whereas some subjects felt nearly full awake at 30 min. Sway areas were larger at 60 min, but not subsequently. At 60 min, sway velocities with open eyes were higher, just as when vision was absent and low amplitude movements were used. Later no effects could be shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Dose-related effects of alcohol on dynamic posturography and oculomotor measures.

Four healthy male volunteers < 30 years of age participated in a blinded study of placebo versus low (0.45 g/kg lean body weight = LBW), medium (0.80 g/kg LBW) and high (1.05 g/kg LBW) dose ethanol ingestion to investigate its effect upon gaze and posture control. Serial electronystagmography and computerized platform posturography were performed at different points along each subject's blood alcohol concentration (BAC) curve as measured by breath analysis. Smooth pursuit and positional testing revealed subtle abnormalities at sub-intoxicating BACs. In addition, instability on posturography was evident on the Sensory Organization Test with no statistically significant influence observed on muscle latency testing as determined by sway analysis. We conclude that even low ethanol BAC levels produce widespread gaze and posture control effects which can be easily documented.

Adult↗