Platform Posturography Research Articles

Postural instability in Meniere's disease

In order to characterize the postural instability by duration of Meniere's disease (MD) we present the results of 180 MD patients tested on posturography. The duration of the disease varied from 4 weeks to 36 years. The patients were clinically examined and they had filled a questionnaire concerning their symptoms. Postural instability was examined by a force platform posturography and the results are expressed as sway velocities (SV). There was no statistically significant difference in the mean SV between groups of different duration of MD. The number of the patients with normal eyes open SV declined by duration of the illness from 73% to 38% but the decline was not statistically significant. The mean age in the different duration groups of MD varied from 47 to 61 years. In general 58% of the patients had their eyes open SV in normal range and 55% when measured eyes closed. When examining the SV between the 4 different hearing stages of MD we found that those belonging into the group III (pure tone average [PTA] 41-70 dB) had significantly higher eyes open and eyes closed SV's than the patients in the group I (PTA under 25 dB).

Development of virtual reality stimuli for force platform posturography

People relying much on vision in the control of posture are known to have an elevated risk of falling. Dependence on visual control is an important parameter in the diagnosis of balance disorders. We have previously shown that virtual reality (VR) methods can be used to produce visual stimuli that affect balance, but suitable stimuli need to be found. In this study, the effect of six different VR stimuli on the balance of 22 healthy test subjects was evaluated using force platform posturography. We report in more detail and expand the results published earlier. According to the tests two of the stimuli have a significant destabilizing effect on balance. In addition a significant displacement effect on the subject's center of pressure (COP) was found. Thus it is shown that the design of VR stimuli to cause different effects on the control of balance is possible.

Computerized Platform Posturography for Children

The purpose of this study was to examine the consistency of scores from typically developing children on the sensory test of the NeuroCom International VSR System. Participants included 18 children between five and nine years of age. Postural sway was measured using the VSR System, a computerized platform posturography assessment tool. The sensory test protocol examines the relative contributions of the visual, somatosensory, and vestibular systems to maintain postural stability by systematically manipulating the availability and accuracy of sensory inputs. Test-retest intraclass correlation coefficients for all four sensory conditions ranged from .76 to .83.

Outcomes in vestibular ablative procedures.

To assess dizziness handicap and postural recovery in 17 patients undergoing a vestibular ablative procedure. Outcomes were compared between nine patients who underwent selective vestibular neurectomy and eight patients who underwent a transmastoid labyrinthectomy. Patients underwent ablative procedures at a tertiary care facility. Patients were tested with posturography (sensory organization test [SOT]) and the Dizziness Handicap Inventory (DHI) before and 4 to 5 weeks after their procedure. The mean change scores for each of the DHI subscales and the total DHI score showed significant improvement for the labyrinthectomy group. For the neurectomy group, only the emotional DHI subscale change score showed significant improvement. No difference was noted between preprocedure and postprocedure SOT scores for either group. The results indicated that the largest proportion of significant correlations existed between DHI and the somatosensory and vestibular subtests of platform posturography. In regression analyses, a model with age (p = 0.04) and vestibular score (p = 0.001) fitted the data well and explained 52.9% of the variance. Persons who were less than 69 years old were three times more likely to report persistent episodes of dizziness after the ablative procedure, and those who had neurectomies were 2.3 times more likely to report episodes of dizziness than those who underwent transmastoid labyrinthectomy. Dizziness handicap after an ablative procedure is influenced by the type of procedure (labyrinthectomy versus neurectomy), age, and preoperative vestibular score on the SOT. Preoperative vestibular SOT score is highly associated with the emotional, physical, and functional domains of perceived handicap and quality of life after the surgery.

The Romberg sign and early instruments for measuring postural sway.

In the first half of the 19th century, European physicians-including Marshall Hall, Moritz Romberg, and Bernardus Brach-described loss of postural control in darkness of patients with severely compromised proprioception. Romberg and Brach emphasized the relationship between this sign and tabes dorsalis. Later, other neurologists evaluated the phenomenon, which is now known as Romberg's sign, in a broader range of neurologic disorders using a variety of simple but increasingly precise and sensitive clinical tests. In the late 19th century, neurologists also developed instruments to measure and record postural sway in patients with neurologic disease. Principal contributors included Philadelphia neurologist Silas Weir Mitchell and his trainees Morris Lewis and Guy Hinsdale. The efforts of these neurologists anticipated later physiologic studies and ultimately the development of computerized dynamic platform posturography.

Computerized Platform Posturography for Children

The purpose of this study was to examine the consistency of scores from typically developing children on the sensory test of the NeuroCom(r) International VSR(tm) System. Participants included 18 children between five and nine years of age. Postural sway was measured using the VSR(tm) System, a computerized platform posturography assessment tool. The sensory test protocol examines the relative contributions of the visual, somatosensory, and vestibular systems to maintain postural stability by systematically manipulating the availability and accuracy of sensory inputs. Test-retest intraclass correlation coefficients for all four sensory conditions ranged from .76 to .83.

Nineteenth-century contributions to the mechanical recording of postural sway.

In the first half of the 19th century, European physicians, including Marshall Hall, Bernardus Brach, and Moritz Romberg, described loss of postural control in darkness by patients with severely compromised proprioception. Late 19th-century neurologists developed instruments to measure and record postural sway in patients with neurologic disease. Principal American contributors were the neurologist Silas Weir Mitchell from Philadelphia, Pa, and his trainees Morris Lewis and Guy Hinsdale. The efforts of these neurologists anticipated later physiologic studies and ultimately the development of computerized dynamic platform posturography.

Past history of otitis media and balance in four-year-old children.

To obtain normative data for a population of children 4 years of age with respect to standard vestibular and balance test protocols and to determine, in the absence of concurrent middle ear effusion (MEE), the possible changes caused by a history of recurrent or persistent MEE. Comparative studies of the results of vestibular and balance tests in a cohort of young children with and without a history of MEE. Seventy-one children, 4 years of age, with a well-documented history since early infancy regarding the presence or absence of MEE were evaluated using pneumatic otoscopy, tympanometry, audiometry, and vestibular and balance (rotational and moving platform posturography) tests. For the results of the vestibular and balance tests, comparisons were made between the group of 31 children (43.7%) without and the group of 40 children (56.3%) with a history of recurrent or persistent MEE, when a positive disease history was defined as at least a 10% cumulative percentage of time with MEE between early infancy and time of testing. When compared with children with a negative history of significant MEE, children with a positive history had a lower average gain to a rotational stimulus of 0.1 Hz, 150 degrees/s (0.57 vs. 0.44; P = .007). There were no significant differences between groups with respect to other measures. These results suggest that a history of recurrent or persistent MEE affects the vestibular and/or balance function of 4-year-old children when tested in the absence of a concurrent episode of MEE. The possible sequelae of the disease should be weighed in future considerations of early intervention for MEE.

Patients with somatoform phobic postural vertigo: the more difficult the balance task, the better the balance performance

The objective was to test, whether the increased body sway activity, shown in patients with phobic postural vertigo (PPV) in a previous posturographic study, impairs postural balance during demanding balance tasks. In 17 patients with PPV and 15 normal subjects body sway was analyzed for two standing positions on a foam rubber-padded posturographic platform with the eyes open or closed: (a) normal upright stance, (b) tandem stance. During normal upright stance patients showed an increase in body sway activity between 0.1 and 19 Hz and in sway path values for lateral and fore/aft directions. During the most difficult balance task, i.e. tandem stance with the eyes closed, body sway activity and sway path values did not differ between patients and controls. Objective balance skills were not impaired in patients with PPV during balance tasks at the limits of postural control.

Effects of T'ai Chi on balance.

To determine if the practice of T'ai Chi significantly improves balance. Twenty-two persons with mild balance disorders were studied. Five measures of balance were obtained, including 3 objective measures (moving platform posturography, Romberg testing, and reach testing) and 2 disability questionnaires (Dizziness Handicap Inventory and a modified Medical Outcomes Study general health survey). To be included, patients were required to be able to stand in the eyes-closed regular Romberg position for 30 seconds. The subjects underwent 8 weeks of T'ai Chi training and practice and then were retested. Highly significant improvements were found on both the posturography test and the Dizziness Handicap Inventory questionnaire scores (P<.001 and P=.004, respectively). Trends toward improvement were also noted in Romberg test results and the Medical Outcomes Study survey (P=.03 for both). Reach was not improved. These findings suggest that T'ai Chi training improves balance.

Validity of visual stabilization conditions used with computerized dynamic platform posturography.

Temporal and spatial relationships between head motion and tilt of a visual surround were evaluated in conditions 3 and 6 of the sensory organization test (SOT) to determine the validity of visual stabilization during computerized dynamic platform posturography (CDP). Seven healthy subjects participated (mean age 42.4 years, SD = 19 years, range 25-72 years). Sagittal head translation and head pitch were evaluated separately with respect to displacement of the visual surround. Overall, the mean correlation between sagittal head motion and surround tilt was r = 0.68 for C3 and r = 0.93 for C6. The average phase (aggregate findings supported with trial-by-trial analysis), however, showed that sagittal head displacement leads motion of the visual surround ( + 452 ms for C3 and + 250 ms for C6). The mean correlation between head pitch and surround tilt was r = -0.30 for C3 and r = -0.72 for C6. Head pitch also leads visual surround motion (+567 ms for C3 and +539 ms for C6), but with greater variability than sagittal head translation. The results showed that visual stabilization was not consistently achieved during SOT conditions 3 and 6. The fundamental assumption that posture behaves as an inverted pendulum, with control of equilibrium originating in the lower extremities, does not appear to be applicable to the voluntary corrections of sway required during the SOT.

Use of Long Loop Reflexes to Assess Postural Control Following Stroke

Objectives To examine the amplitude, latency, and bilateral symmetry of long loop pos tural reflexes after stroke. Rationale: Computerized platform posturography is a new technique for assess ing neural control of posture and balance. It may help quantify stroke-related neuro logic impairments and measure their improvement over time. ABS1:Methods: As part of an ongoing study of postural control after stroke, patients with normal EquiTest sensory analysis scores were randomly selected for study. Their performance was compared with that of normal community volunteers. Postural control was assessed by preprogrammed anterior and posterior horizontal forceplate movements using an EquiTest dynamic posturography system five to eight weeks after an initial stroke. Subjects included 24 patients (13 males and 11 females) with acute stroke admitted to the Burke Rehabilitation Hospital. Patients had a mean age of 63.1 years, and the community controls had a mean age of 69.2 years. Results: Postural control was severely disrupted in the paretic leg. Motor con trol results were abnormal in 75 percent of the patients after stroke (18 of 24) when compared with the controls. Significant differences in the latencies and amplitude of long loop postural reflexes were seen between the affected and nonaffected leg in the same patient during movement forward (p < 0.005) and backward (p < 0.005) and response strength (p < 0.005). The nonaffected leg had normal reflex latencies while the response latencies in the affected leg were either absent or slowed and of decreased amplitude. Conclusion: With posturographic assessment, the amplitude, latency, and bilat eral symmetry of long loop postural reflex latencies are abnormal in hemiparetic pa tients. These reflexes may be useful in the study of the mechanism of gait and bal ance dysfunction in patients after stroke.

Changes in body equilibrium response caused by breathing. A posturographic study with visual feedback

Therapeutical methods involving holistic medicine are of increasing interest. The present study deals with the psychophysical breath work by Middendorf and examines whether it has an effect on reactions of the body's equilibrium system. Different optical patterns were projected on a video screen to the test subject standing on a modified posturographic platform. Subjects were instructed to shift their center of gravity according to the patterns projected on the video screen. The patterns consisted of a line that had to be followed in the anterior-posterior and in the lateral plane, and of a circle which had to be followed clockwise and counterclockwise. Three groups each consisting of 17 healthy persons were tested; group 1: advanced in breath training, group 2: beginners in breath training, group 3: no experience in breath work at all. Group 1 und 2 show significantly better results in the posturographic test with visual feedback than subjects without experience in breast work (group 3). Furthermore, posturographic results immediately after one hour of breath work reveal clear improvements in the body equilibrium. Psychophysical breath work by Middendorf leads to a general improvement of the body equilibrium which is stable over time. The positive results of this study lead to the assumption that breath work by Middendorf is a valuable method for treatment and rehabilitation of balance disorders.

Computerized dynamic platform posturography

Computerized dynamic platform posturography is defined in this technology assessment. The review discusses what computerized dynamic platform posturography measures, what the reliability and validity of the information are, and the uniqueness of the information provided. The clinical contribution and indications for testing are discussed. There are comments on future directions for research on computerized dynamic platform posturography and a summary and conclusion. (Otolaryngol Head Neck Surg 1997;117:394-8.)

Generalizability of the limits of stability test in the evaluation of dynamic balance among older adults

Objective: Reliability of platform posturography tests is essential for the identification and treatment of balance-related disorders. The purposes of this study were to establish the reliability of the limits of stability (LOS) test and to determine the relative variance contributions from identified sources of measurement error. Design: Generalizability theory was used to calculate (1) variance estimates and percentage of variation for the sources of measurement error, and (2) generalizability coefficients. Random effects repeated measures analysis of variance (RM ANOVA) was used to assess consistency of measurements across both days and targets. Participants: Thirty-eight community-dwelling older adults with no recent history of falls. Main Outcome Measures: Outcome measures derived from the LOS tests included movement velocity (MV), maximum center of gravity (COG) excursion (ME), end point COG excursion (EE), and directional control (DC). Results: Estimated generalizability coefficients for 2 and 3 days of testing ranged from .69 to .91. Relative contributions of the day facet were minimal. The RM ANOVA results indicated that for three of the movement variables, no significant differences in scores were observed across days. Conclusions: The 75% and 100% LOS tests are reliable tests of dynamic balance when administered to healthy older adults with no recent history of falls. Dynamic balance measures were generally consistent across multiple evaluations.

Relation between vestibular function and speech recognition in postlingually deafened adults with cochlear implantation.

Thirty-one postlingually deafened adults with 22-channel cochlear implants were evaluated preoperatively using vestibular function tests, the caloric test and stabilometry. The results of caloric response were classified into two diagnostic groups: normo- or hyporeflexia and areflexia. Stabilometric recordings were made using a computerized static posturographic platform. Between the two categories of caloric response, there was a significant difference in consonant recognition, but the recognition of vowels showed no significant difference. The results of the distance of body sway in stabilometry, but not of the area, correlated to the results of consonant recognition in speech perception tests. The degree of residual vestibular function seems to be one of the indicators influencing postoperative speech recognition by cochlear implant patients.

Zur Altersabhängigkeit von Interaktionen zwischen Propriozeptivität und Sehen - eine posturographische Studie

The influence of fixation on the vestibulo-ocular reflex and the synergistic stabilising effect of vision on the body equilibrium are well known. In this study interactions between the visual and the proprioceptive systems in patients of different ages are analysed. We tried to find out whether body equilibrium reactions, recorded by posturography, are influenced qualitatively and quantitatively by visual inputs. 349 neurotologic patients aged between 3 and 80 years were included in this study. We applied different optical patterns by means of a videoscreen to the patients standing on a posturographic platform. The patients were asked to follow the pattern with their centre of the gravity, which was also shown on the video screen. The patterns consisted of a line that had to be followed in the anterior-posterior and in the lateral plane and of a circle which had to be followed clockwise and counterclockwise. We recognised definite age-related changes in all tests used. The precision to follow a visual target with the body equilibrium increased with increasing age to the age of forty. With the beginning fifth decade this postural ability decreases slowly and decreases particularly markedly in patients of over 70 years of age. Posturography in combination with visual feedback is a valuable technique for testing visual-proprioceptive interactions. It can be employed over a large age bracket.

Effect of otitis media on the vestibular system in children.

Forty-one children with otitis media (OM) were evaluated by moving platform posturography (Equitest, NeuroCom) before and after insertion of tympanostomy tubes, and were compared to children with no ear disease (N = 50). Velocity of sway increased with increasing difficulty of test conditions (I-VI) for both groups of children (p < .001), and children less than 7 years of age had a higher velocity than children 7 years old or older (p < .001). Children with OM had a higher velocity than normal children (p < .05). For children tested less than 30 days after insertion of tympanostomy tubes, the velocity for condition VI was significantly lower than before insertion (p < .05). Also, that the 6 children who had fallen on all trials on condition V or VI were able to stand on these trials after insertion of tympanostomy tubes indicates an improvement. These findings indicate that episodes of OM may affect balance, leaving children more clumsy and accident-prone, and possibly impairing motor development.

Relationship between balance system function and agoraphobic avoidance

There is a striking similarity between the situations avoided by people with agoraphobia and the environments which provoke disorientation in people with organic balance disorders. This study investigated the possibility that agoraphobia might be linked to balance system dysfunction by comparing the results of balance system tests in 36 people with symptoms of panic and agoraphobia and 20 normal controls. A traditional battery of audiovestibular tests was supplemented with moving platform posturography, which assesses the postural instability induced by disorienting perceptual conditions. Subjects also completed questionnaire measures of somatic symptoms of dizziness and anxiety, agoraphobic cognitions, avoidance behaviour and state anxiety. Over 60% of the Ss with symptoms of panic and agoraphobia were destabilised by the disorienting perceptual conditions, compared with just 10% of the normal controls. Postural instability was strongly related to reported agoraphobic avoidance ( r = 0.63, P < 0.01), even after controlling for symptoms, anxiety and agoraphobic cognitions. In our discussion we consider alternative interpretations of these findings, future directions for research, and implications for therapy.

Vestibular and Sensory Interaction Deficits Assessed by Dynamic Platform Posturography in Patients with Multiple Sclerosis

Vestibular impairments have not been routinely identified in patients with multiple sclerosis (MS), because of the confounding effects of deficits in other neural systems. In this study, 35 patients with MS were evaluated by means of a systematic alteration of the sensory environment (dynamic posturography) in order to identify those patients who became unstable when vestibular inputs were needed to maintain stance. Subjects were assigned to either a high-function (HF) or a low-function (LF) group on the basis of a functional status assessment score obtained prior to the posturography test. For the HF group, 30% (7/23) had abnormal posturography scores. Of those subjects, 3 had a vestibular dysfunction pattern or a somatosensory-vestibular impairment. In contrast, 58% of the LF group (7/12) had abnormal posturography scores. Nearly all of these LF patients (6/7) had a vestibular dysfunction pattern or a combined visual-vestibular or somatosensory-vestibular impairment. Posturography might serve as one method to evaluate the functional consequences of a vestibular deficit in patients with MS.