Influence of sensory manipulation on postural control in Parkinson's disease

Postural control was assessed on a tilting platform system in 20 patients with idiopathic Parkinson's disease and 20 age-matched controls. The amount of information provided by vision and lower limb proprioception was varied during the experiment to investigate the influence of changes in sensory cues on postural control. The patient group with clinical evidence of impaired postural control (Hoehn and Yahr III) had significantly higher sway scores over all sensory conditions than either the Hoehn and Yahr II group or controls. The pattern of sway scores indicated that no obvious deficit in the quality, or processing, of sensory information was responsible for the postural instability observed in this group. The patients in both Hoehn and Yahr groups were also able to respond appropriately to potentially destabilising sensory conflict situations and significantly improved their sway scores when provided with visual feedback of body sway. The results indicate that in Parkinson's disease, the main site of dysfunction in postural control is likely to be at a central motor level.     

Postural stability among manganese exposed workers

Postural stability was investigated by static posturography in 32 manganese exposed workers with exposure duration of 6.6 (range 1.1-15.7) years and 53 referent subjects. The mean current urine manganese concentration for the exposed was 6.0 micrograms/g creatinine (range 0.6 to 53.3). There was no significant differences between both groups for the postural sway parameters obtained during eyes open condition. However, significant differences were observed for L - length of sway path and Vel - mean velocity of the center of pressure along its path. The Romberg Ratios (the relationship between eyes closed/open conditions) for the exposed's Vel, L, and Ao were also significantly different from the referent. The study showed that manganese exposed workers had significantly poorer postural stability compared to a referent group. We postulate that this could be a subclinical effect of manganese on the basal ganglia (pallidus) resulting in the postural instability when the visual input is cut off. Based on the current urinary manganese levels, we were not able to obtain any significant association with the postural sway parameters.     

Atypical involvement of undifferentiated carcinomas of the nasopharyngeal type. Apropos of 3 cases

This study compared body sway, a measure of postural stability, between regular brisk walkers and control subjects. Furthermore, the relationship between body sway and physical activity duration in postmenopausal women was examined. Subjects were 31 healthy postmenopausal women, aged 61-71 years. They were recruited from a randomized controlled study of the influence of brisk walking on bone: 16 women had been completing 20 min d-1 brisk walking, whilst 15 controls had been completing habitual activities only. Body sway was measured using a swaymeter that measured displacement at the waist whilst subjects stood on a compliant surface, with eyes closed, for 1 min. The activity was measured using activity monitors which were worn at the waist for 3 consecutive days. Body sway (eyes closed, standing on a compliant surface) was lower in walkers than in controls: 2,958 +/- (SE) 270 versus 5,225+/-371 mm2 min-1, respectively (p < 0.05). A negative correlation was found between body sway and minutes of physical activity (r = -0.47, p < 0.01). Analysis of variance revealed that body sway differed significantly (p < 0.05) between groups of differing physical activity participation, being 4,839 +/- 499, 4,167 +/- 516, and 2,877 +/- 362 mm2 min-1, respectively, in women completing <20, 20-40, and >40 min d-1 of physical activity. Body sway was significantly lower in the most active group than in the least active (p < 0.01). These data suggest that postural stability is better in regular walkers than in control subjects. Furthermore, a dose-response relationship was observed between physical activity and postural stability in postmenopausal women. These findings provide a preliminary indication that brisk walking, a low-cost and acceptable form of physical activity for the elderly, could be incorporated into strategies for improving balance in the elderly.     

Step initiation in Parkinson''s disease: influence of levodopa and external sensory triggers

We studied anticipatory postural adjustments contributing to gait initiation deficits in patients with Parkinson's disease (PD) to determine if these deficits could be improved by administration of levodopa or by external stimuli. Ground reaction forces and body kinematics were recorded for self-generated and cutaneous cue-triggered step initiation in normal subjects and in PD subjects when OFF and when ON. The effects of assisting anticipatory postural sway with a surface translation coupled with a cutaneous cue were also examined. Decreased force production, decreased velocity of movement, and slowed execution of the anticipatory postural adjustments for self-generated step characterized step initiation in PD subjects when OFF. These impairments were significantly less evident when the PD subjects were ON. Both PD and normal subjects increased force and velocity of movement when a cutaneous cue was used as a go signal. When subjects voluntarily initiated a step in response to the surface translation, both PD and normal subjects executed the anticipatory postural adjustments for step more rapidly, but the PD subjects, both ON and OFF, failed to increase force to execute push-off more rapidly. In conclusion, dopaminergic therapy and an external stimulus similarly improve the deficient force production for the anticipatory postural adjustments associated with step initiation in PD. The findings also suggest that force production during the postural adjustment phase of self-generated, but not externally triggered, step initiation is influenced by dopaminergic pathways.     

Better postural balance in elderly women receiving estrogens

OBJECTIVE: The amount of bone mass and the tendency to fall are main risk factors for hip fractures and both deteriorate with advancing age. The dynamics between estrogen exposure and fracture protection seem too rapid to be explained by an effect on bone mass only. Postural balance function may be another potential mechanism for the fracture-protecting effect of estrogens. STUDY DESIGN: We examined 16 long-term users of 17 beta-estradiol implants (20 mg) (mean age 67.9 years and mean duration of treatment 17.3 years [3.3 to 34 years]) and 16 age-matched (+/-2 years) nonusers (mean age 68.3 years). Postural balance (sway velocity) was measured by static posturography before and after blindfolding and application of vibration stimulus (20 to 100 Hz) to the calf muscles to disturb the proprioception and to induce imbalance. RESULTS: Sway velocities were significantly lower in estrogen users than in nonusers (p = 0.0067) and similar to those in young premenopausal women. The differences were accentuated after provocation by blindfolding and by increasing frequencies of vibration stimulus to the calf muscle. Serum levels of estradiol and estradiol/sex hormone-binding globulin were negatively and follicle-stimulating hormone levels positively associated with sway velocity (p = 0.0194, p = 0.0036, and p = 0.0052, respectively) and independent of age (p = 0.02 to 0.005), supporting causality between estrogen exposure and postural balance. CONCLUSIONS: These data indicate that postural balance function is better preserved in long-term estrogen users than in nonusers. Effects on postural balance function may be one mechanism explaining the rapid increase in distal forearm fractures early after menopause and the rapid dynamics between estrogen exposure and hip fracture protection and may potentially reduce the fracture risk in elderly women starting estrogen replacement therapy in spite of marginal increases in bone mass.     

Effect of coordination training on proprioception of the functionally unstable ankle

Exercises to improve joint proprioception and coordination of the functionally unstable ankle are advocated throughout the literature, yet there is little evidence that these exercise have any effect on proprioception and balance. The purpose of this study was to determine the effects of a 6-week coordination and balance training program on proprioception of subjects with functional ankle instability. Forty-five subjects (age = 22.53 +/- 3.95 years, height = 172.04 +/- 10.0 cm, weight = 71.72 +/- 15.7 kg) were randomly placed into a control (Group 1), sham (Group 2), or experimental (Group 3) group. The experimental group trained 3 days per week, 10 minutes each day, performing various balance and proprioception exercises. Postural sway and active and passive joint position sense were assessed. Analysis of variance for postural sway modified equilibrium score for anterior and posterior sway, as well as medial and lateral sway revealed significant four-way interactions. Tukey post hoc analyses revealed that Group 3 performed significantly better (p < .05) than Group 1 and Group 2 on the posttests. There were no significant differences for joint position sense or postural sway index. Results suggest that balance and coordination training can improve some measures of postural sway. It is still unclear if joint position sense can be improved in the functionally unstable ankle.     

Comparison of a functional obstacle course with an index of clinical gait and balance and postural sway

BACKGROUND: Older adults commonly experience falls because of balance and mobility problems. Better assessment methods are needed to understand and correct balance and mobility disorders. METHODS: We used a low technology, functional obstacle course (FOC) to measure balance and mobility in 352 community-dwelling elderly participants. To establish concurrent validity of the FOC, we compared performance on the FOC with two established measures of balance and mobility: performance on the Tinetti Index (TI) and postural sway area measured on a force platform. RESULTS: Bivariate correlation analyses revealed significant inverse correlations between FOC completion time, the TI balance and gait subscores, and the TI total score (r = -.73 to -.78). The FOC quality scores and TI balance and subscores gait and TI total scores (r = .76 to .82) were significantly positively correlated. FOC time had significant, but small, positive correlations with sway area with eyes open (r = .18) and closed (r = .17) and nonsignificant correlation with sway area with visual feedback. FOC quality also had significant, but smaller, inverse correlations with sway area with eyes open (r = -.024) and closed (r = -.015), and nonsignificant correlation with sway area with visual feedback. Regression analysis showed that TI gait and balance measures accounted for most of the variance found in FOC performance. CONCLUSIONS: Our findings support the position that the FOC and the TI measure dynamic balance, whereas postural sway measures a different aspect of balance. Advantages of the FOC include the evaluation of environmentally influenced falls and balance problems.     

Sensory strategies in human postural control before and after unilateral vestibular neurotomy

Vestibular inputs tonically activate the anti-gravitative leg muscles during normal standing in humans, and visual information and proprioceptive inputs from the legs are very sensitive sensory loops for body sway control. This study investigated the postural control in a homogeneous population of 50 unilateral vestibular-deficient patients (Ménière's disease patients). It analyzed the postural deficits of the patients before and after surgical treatment (unilateral vestibular neurotomy) of their diseases and it focused on the visual contribution to the fine regulation of body sway. Static posturographic recordings on a stable force-plate were done with patients with eyes open (EO) and eyes closed (EC). Body sway and visual stabilization of posture were evaluated by computing sway area with and without vision and by calculating the percentage difference of sway between EC and EO conditions. Ménière's patients were examined when asymptomatic, 1 day before unilateral vestibular neurotomy, and during the time-course of recovery (1 week, 2 weeks, 1 month, 3 months, and 1 year). Data from the patients were compared with those recorded in 26 healthy, age- and sex-matched participants. Patients before neurotomy exhibited significantly greater sway area than controls with both EO (+52%) and EC (+93%). Healthy participants and Ménière's patients, however, displayed two different behaviors with EC. In both populations, 54% of the subjects significantly increased their body sway upon eye closure, whereas 46% exhibited no change or significantly swayed less without vision. This was statistically confirmed by the cluster analysis, which clearly split the controls and the patients into two well-identified subgroups, relying heavily on vision (visual strategy, V) or not (non-visual strategy, NV). The percentage difference of sway averaged +36.7%+/-10.9% and -6.2%+/-16.5% for the V and NV controls, respectively; +45.9%+/-16.8% and -4.2%+/-14.9% for the V and NV patients, respectively. These two distinct V and NV strategies seemed consistent over time in individual subjects. Body sway area was strongly increased in all patients with EO early after neurotomy (1 and 2 weeks) and regained preoperative values later on. In contrast, sway area as well as the percentage difference of sway were differently modified in the two subgroups of patients with EC during the early stage of recovery. The NV patients swayed more, whereas the V patients swayed less without vision. This surprising finding, indicating that patients switched strategies with respect to their preoperative behavior, was consistently observed in 45 out of the 50 Ménière's patients during the whole postoperative period, up to 1 year. We concluded that there is a differential weighting of visual inputs for the fine regulation of posture in both healthy participants and Ménière's patients before surgical treatment. This differential weighting was correlated neither with age or sex factors, nor with the clinical variables at our disposal in the patients. It can be accounted for by a different selection of sensory orientation references depending on the personal experience of the subjects, leading to a more or less heavy dependence on vision. The change of sensory strategy in the patients who had undergone neurotomy might reflect a reweighting of the visual and somatosensory cues controlling balance. Switching strategy by means of a new sensory selection of orientation references may be a fast adaptive response to the lesion-induced postural instability.     

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.     

Postural and symptomatic improvement after physiotherapy in patients with dizziness of suspected cervical origin

OBJECTIVE: To assess postural performance in patients with dizziness of suspected cervical origin in whom extracervical causes had been excluded, and to assess the effects of physiotherapy on postural performance and subjective complaints of neck pain and dizziness. DESIGN: Prospective, randomized, controlled trial. SETTING: Primary care centers and a tertiary referral center. PATIENTS AND SUBJECTS: Of 65 referrals, 43 patients were excluded because extracervical etiology was suspected. Of the remaining 22 patients, 17 completed the study (15 women, 2 men, x age 37 yr, range 26-49). The controls were 17 healthy subjects (15 women, 2 men, x age 36 yr, range 25-55). INTERVENTION: Physiotherapy based on analysis of symptoms and findings, and aimed to reduce cervical discomfort. Patients were randomized either to receive immediate physiotherapy (n = 9), or to wait 2 months, undergo repeat measurements, and then receive physiotherapy (n = 8). MAIN OUTCOME MEASURES: Posturography, measuring velocity and variance of vibration-induced body sway and variance of galvanically induced body sway. Subjective intensity of neck pain (Visual Analog Scale ratings, 0-100), intensity and frequency of dizziness (subjective score 0-4). RESULTS: The patients manifested significantly poorer postural performance than did healthy subjects (.05 > p > .0001). Physiotherapy significantly reduced neck pain and intensity and the frequency of dizziness (p < .01), and significantly improved postural performance (.05 > p > .0007). CONCLUSIONS: Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.     

Regulation and function of tinman during dorsal mesoderm induction and heart specification in Drosophila

Sensory-motor control of upright human posture may be organized in a top-down fashion such that certain head-trunk coordination strategies are employed to optimize visual and/or vestibular sensory inputs. Previous quantitative models of the biomechanics of human posture control have examined the simple case of ankle sway strategy, in which an inverted pendulum model is used, and the somewhat more complicated case of hip sway strategy, in which multisegment, articulated models are used. While these models can be used to quantify the gross dynamics of posture control, they are not sufficiently detailed to analyze head-trunk coordination strategies that may be crucial to understanding its underlying mechanisms. In this paper, we present a biomechanical model of upright human posture that extends an existing four mass, sagittal plane, link-segment model to a five mass model including an independent head link. The new model was developed to analyze segmental body movements during dynamic posturography experiments in order to study head-trunk coordination strategies and their influence on sensory inputs to balance control. It was designed specifically to analyze data collected on the EquiTest (NeuroCom International, Clackamas, OR) computerized dynamic posturography system, where the task of maintaining postural equilibrium may be challenged under conditions in which the visual surround, support surface, or both are in motion. The performance of the model was tested by comparing its estimated ground reaction forces to those measured directly by support surface force transducers. We conclude that this model will be a valuable analytical tool in the search for mechanisms of balance control.     

Oligoribonucleotides containing 8-oxo-7,8-dihydroguanosine and 8-oxo-7,8-dihydro-2''-O-methylguanosine: synthesis and base pairing properties

OBJECTIVE: To test whether a rigid or a flexible ankle orthosis affects postural sway in single-limb stance as quantified by stabilometry. DESIGN: Crossover trial. SETTING: University laboratory. PARTICIPANTS: Twenty-two athletes with functional ankle instability (consecutive sample of patients with recurrent ankle sprains but without mechanical instability) and 22 healthy athletes (control group of volunteers matched to age, height, weight, physical activity). INTERVENTIONS: Stabilometry in single-limb stance on a force platform. Participants were tested on each leg with and without a rigid or a flexible ankle orthosis. The order of test conditions was randomized. MAIN OUTCOME MEASURES: Sway velocities, sway pattern, and sway area as calculated from center of pressure movements. The two groups were compared by Mann-Whitney test, and the different orthoses within each group were compared by Wilcoxon test, paired samples (type I error 5%, Bonferroni adjustment). RESULTS: In athletes with functional ankle instability, both a rigid and a flexible ankle orthosis significantly reduced mediolateral sway velocity. A flexible ankle orthosis also changed sway pattern significantly, by reducing the percentage of linear movements of less than 5 degrees per .01 sec. CONCLUSIONS: In athletes with functional ankle instability, ankle orthoses reduce mediolateral sway velocity, possibly because of improved mediolateral proprioception.     

Position and velocity coupling of postural sway to somatosensory drive

Light touch contact of a fingertip to a stationary surface provides orientation information that enhances control of upright stance. Slight changes in contact force at the fingertip lead to sensory cues about the direction of body sway, allowing attenuation of sway. In the present study, the coupling of postural sway to a moving contact surface was investigated in detail. Head, center of mass, and center of pressure displacement were measured as the contact surface moved rhythmically at 0.1, 0.2, 0.4, 0.6, and 0.8 Hz. Stimulus amplitude decreased with frequency to maintain peak velocity constant across frequency. Head and body sway were highly coherent with contact surface motion at all frequencies except 0.8 Hz, where a drop-off in coherence was observed. Mean frequency of head and body sway matched the driving frequency 相似文献   

Influence of visual control, conduction, and central integration on static and dynamic balance in healthy older adults

Aging is associated with decreased balance abilities, resulting in an increased risk of fall. In order to appreciate the visual, somatosensory, and central signals involved in balance control, sophisticated methods of posturography assessment have been developed, using static and dynamic tests, eventually associated with electromyographic measurements. We applied such methods to a population of healthy older adults in order to appreciate the respective importance of each of these sensorial inputs in aging individuals. Posture control parameters were recorded on a force-measuring platform in 41 healthy young (age 28.5 +/- 5.9 years) and 50 older (age 69.8 +/- 5.9 years) adults, using a static test and two dynamic tests performed by all individuals first with eyes open, then with eyes closed. The distance covered by the center of foot pressure, sway area, and anteroposterior oscillations were significantly higher, with eyes open or closed, in older people than in young subjects. Significant differences were noted in dynamic tests with longer latency responses in the group of old people. Dynamic recordings in a sinusoidal test had a more regular pattern when performed eyes open in both groups and evidenced significantly greater instability in old people. These data suggest that vision remains important in maintaining postural control while conduction and central integration become less efficient with age.     

Can some facial rejuvenation techniques cause iatrogenia?

Previous research has shown that in healthy subjects during a quiet two-legged stance, sagittal postural sway is greater than lateral postural sway with a ratio approximating 1.5. The purpose of this study was to examine the postural sway profiles of healthy men and women, and men with mental retardation (MR). Subjects consisted of 22 men (M), 22 women (W) and 22 men with MR. Postural sway characteristics were examined using a Kistler force platform. Each subject performed six trials, three with vision and three with vision occluded. Each trial was 15sec in duration, and the subject was instructed to stand motionless on the force platform. A custom-designed computer program sampled the lateral and sagittal sway characteristics for each trial, at a sample rate of 50Hz. Results indicated that the MR group exhibited significantly more lateral sway than the other two groups, and that the sagittal/lateral sway ratio was significantly lower in this group. Moreover, the MR group showed a greater amount of sway in the no-vision condition than either the M or W groups. Using the sagittal/lateral sway ratio, discriminant analyses indicated that group membership could be predicted in 75% to 82% of the cases in the vision condition, and 64% to 73% of the cases in the no-vision condition. It is concluded that the sagittal/lateral sway ratio provides a valid and objective assessment measure to determine the postural control/balance capacities of persons with MR. In addition, it is hypothesized that this ratio may prove useful in quantifying the effectiveness of therapeutic intervention programs on balance performance.     

Postural control--a comparison between patients with chronic anterior cruciate ligament insufficiency and healthy individuals

Postural control in the sagittal plane was evaluated in 22 patients with chronic anterior cruciate ligament (ACL) deficiency and the result was compared to that of a control group of 20 uninjured subjects. Measurement of the body sway was done on a fixed and sway-referenced force plate in both single-limb and two-limb stance, with the eyes open and closed, respectively. Further, an analysis of the postural reactions to perturbations backwards and forwards, respectively, was made in single-limb stance. The results demonstrated statistically significant deficits of the postural control in the patient group compared to the control group, but also within the patient group. There was a significantly higher body sway within the patient group when standing on a stable support surface on the injured limb than standing on the uninjured limb with the eyes open, but no difference with the eyes closed. When standing on a stable support surface, there was a significantly higher body sway in the patient group standing on the injured leg than in the control group, both with eyes open and closed. The patient group also showed a significantly impaired postural control compared to the control group when standing on the uninjured leg with the eyes closed. There was no difference between the groups in the two-limb stance. When standing on the sway-referenced support surface, the patient group had a significantly larger body sway than the control group when the eyes were open, but there was no significant difference between the groups with the eyes closed. The measurement of the postural corrective responses to perturbations backwards and forwards showed that the reaction time measured from the initiation of the force plate translation, and the amplitude of the body sway was significantly greater in the patient group than in the control group. We conclude that patients with a continuing chronic ACL insufficiency several years after injury have an impaired postural control in the antero-posterior direction in single-limb stance on their injured leg. They also show a greater body sway and a prolonged reaction time when subjected to antero-posterior perturbations when standing on their injured leg.     

Systemic autoimmunity due to mercury vapor exposure in genetically susceptible mice: dose-response studies

Six groups of genetically mercury-susceptible female SJL/N (H-2s) mice were exposed to mercury vapor at a concentration of 0.3-1.0 mg Hg/m3 air for 0.5-19 hr/day 5 days a week for 10 weeks. The absorbed doses were calculated to be between 75 and 2365 micrograms Hg/week/kg body wt (micrograms Hg/week/kg). The correlation between the dose and the concentration of Hg in kidney, spleen, and thymus was highly significant (p < 0.0001; Spearman's rank correlation test). The lowest observed adverse effect level (LOAEL) for serum IgG antinucleolar antibodies (ANoA) was 170 micrograms Hg/week/kg, corresponding to a renal mercury concentration of 4.0 +/- 0.76 micrograms Hg/g wet wt. The correlation between the absorbed dose and the ANoA titer was highly significant (p < 0.0001; Spearman's rank correlation test), and all mice were ANoA-positive at a dose of 480 micrograms Hg/week/kg. High-titer ANoA targeted the nucleolar 34-kDa protein fibrillarin. The LOAEL for B-cell stimulation, measured as an increase in serum IgG2a and IgG1 concentrations, was 360 micrograms Hg/week/kg, but the increase was fivefold higher and also included IgE at a dose of 690 and 2365 micrograms Hg/week/kg. The serum Ig concentrations peaked after 2-4 weeks and then slowly declined but, except for IgE, remained significantly increased during the entire exposure time. Glomerular, mesangial IgG immune complex (IC) deposits, accompanied by systemic vessel wall IC deposits, were first detected at a dose of 480 micrograms Hg/week/kg. The mesangium also showed increased titers of IgM IC deposits and complement factor C3c. The correlation between the absorbed dose, and the individual titer of IgG, IgM, and C3c, was highly significant (p < 0.0001; Spearman's rank correlation test). In conclusion, mercury vapor efficiently induced an autoimmune syndrome in genetically susceptible mice, and the LOAEL for the adverse effects varied in the order ANoA < B-cell stimulation < IC deposits. Comparing the body burden of mercury in mice at the LOAEL for autoantibodies with the body burden in populations of occupationally exposed humans suggests that the safety margin may be narrow for genetically susceptible individuals.     

Posturography does not test vestibulospinal function

The clinical usefulness of posturography is unknown, despite its costing more than +500 per test in some areas of the United States, including Boston. We cross-sectionally and prospectively studied blinded vestibulo-ocular and vestibulospinal tests from 29 stable patients with chronic vestibular hypofunction; 22 patients were affected bilaterally (BVH), and 7 were affected unilaterally (UVH). Vestibulo-ocular function was assessed by electronystagmographic caloric stimulation and sinusoidal vertical axis rotation gains at 0.05 Hz. Vestibulospinal function was assessed by moving-platform and visualsurround posturography sensory organization tests (SOTs), paced and free gait in a gait laboratory, and clinical tests of timed gait and standing. Posturography SOT moving-platform tests 4 through 6, designed to assess vestibular function, correlated significantly (r < or = 0.72, P > or = 0.01) with vestibulo-ocular tests in 5 of 6 comparisons among BVH patients. Posturography SOT results, however, correlated poorly with other vestibulospinal measures: correlations were statistically significant for only 7 of 18 comparisons with clinical balance and gait function (r < or = 0.69, P > or = 0.01) and with 2 of 12 comparisons for gait laboratory dynamic stability measures (r < or = 0.55, P > or = 0.01) among the BVH patients. When both the platform and visual surround moved (SOT 6), however, correlations were statistically significant with static standing clinical measures (r = 0.51 to 0.69, P < 0.01) and with whole-body maximum moment arm during paced gait (r = 0.55, P < 0.01). Posturography scores for the UVH patients did not significantly correlate with any vestibulo-ocular or other vestibulospinal measures. These data indicate that among patients with BVH posturography SOT scores relate at best modestly with accepted measure of vestibulo-ocular function, less well with clinical measures of balance control, and poorly with dynamic gait-performance measures. We conclude that posturography SOT does not assess vestibulospinal function.     

Correlation of volumetric magnetization transfer imaging with clinical data in MS

We examined the relations between quantitative volumetric estimates of cerebral lesion load based on magnetization transfer imaging (MTI), clinical data, and measures of neuropsychological function in 44 patients with clinically diagnosed MS. In this population we assessed the correlation between several volumetric MTI measures, measures of neurologic function (Kurtzke Expanded Disability Status Scale and Ambulation Index), and disease duration using Spearman's correlation coefficient. Patients were classified on the basis of neuropsychological test performance as severely impaired, moderately impaired, and normal. We assessed differences between these groups with respect to MTI results using the Kruskal-Wallis test. MTI measures corrected for brain volume were found to correlate with disease duration (p < 0.01) and showed suggestive correlations with measures of neurologic impairment (p < 0.05). Individual neuropsychological tests correlated with MTI measures corrected and not corrected for brain volume (p < 0.001). An MTI measure not corrected for brain volume differed (p < 0.05) between severely impaired, moderately impaired, and normal patients. These preliminary results suggest that volumetric MTI analysis provides new measures that reflect more accurately the global lesion load in the brain of MS patients, and they may serve as a method to study the natural course of the disease and as an outcome measure to evaluate the effect of drugs.     

Postural stability in diabetic polyneuropathy

OBJECTIVE: To examine whether sensory changes in lower limbs associated with diabetic sensory polyneuropathy compromise postural stability in different visual sensory conditions. RESEARCH DESIGN AND METHODS: The presence and severity of sensory neuropathy was evaluated with a clinical scale and measures of nerve conduction velocity in the lower limbs. Balance control was evaluated by testing subjects' postural stability (with a force platform) with vision, without vision, and during a recovery period after being without vision. RESULTS: Neuropathic patients showed larger ranges of sway, a faster sway speed, and a greater dispersion of sway than control subjects in all conditions. They also exhibited similar or less stable postural performance with vision than that of control subjects without vision. There was a strong relationship between the severity of the neuropathy and the postural stability. CONCLUSIONS: This experiment highlights that even with vision, the postural stability of neuropathic patients is impaired and may put them at higher risk of falling when performing more challenging daily tasks.