Biomedical subjects

Patrick J Sparto

Publications and source records attributed to Patrick J Sparto.

11 recordsLinked to original sources

PubMed2007

The reliability and validity of the Four Square Step Test for people with balance deficits secondary to a vestibular disorder.

OBJECTIVE: To determine the reliability and validity of the Four Square Step Test (FSST) for use in people with balance deficits secondary to vestibular disorders, who frequently report falling and have difficulty with changes of direction. DESIGN: Cross-sectional descriptive study. SETTING: Outpatient clinic. PARTICIPANTS: Thirty-two people with balance deficits secondary to vestibular disorders (mean age, 63.7+/-17.8y) who were currently enrolled in a vestibular physical therapy program agreed to participate. INTERVENTIONS: Participants performed the FSST, the Timed Up & Go (TUG) test, an 11-m walk test during which walking speed was recorded, and the Dynamic Gait Index (DGI) and completed the Dizziness Handicap Inventory (DHI) and the Activities-Specific Balance Confidence (ABC) Scale. MAIN OUTCOME MEASURES: The main outcome measures were the FSST time, TUG results, DGI score, gait velocity, and DHI and ABC scores. Number of fall risk factors, as determined by published scores for people at risk for falling on the TUG test and gait speed, and number of falls were compared with FSST scores. RESULTS: The FSST has good reliability (intraclass correlation coefficient, model 3,1: .93; 95% confidence interval, .86-.96) and had good correlations with the other gait measures (correlation coefficients for the TUG, .69; gait speed, .65; DGI, -.51) and poor correlations with the DHI and the ABC (DHI, -.13; ABC, -.12). Multivariate linear regression showed that 51.5% of FSST performance was explained by TUG score and gait speed. The mean FSST time differed significantly between groups with 0 (n=12), 1 (n=12), or 2 to 3 (n=8) risk factors for falls (analysis of variance, F=10.02; P<.01). A cutoff score of greater than 12 seconds on the FSST was associated with a sensitivity of 80% and specificity of 92% for the identification of subjects with 1 or more risk factors for falls. CONCLUSIONS: The FSST is a reliable and valid tool for measuring the ability to perform multidirectional movements in people with balance deficits secondary to vestibular disorders.

Accidental Falls↗

PubMed2006

Spectrally similar periodic and non-periodic optic flows evoke different postural sway responses.

The present study investigated the effect of optic flow periodicity on postural sway. Head and center-of-pressure (COP) displacements in response to an oscillating full-field bullseye-and-checkerboard pattern were recorded in six healthy adults. Scene movement was driven by one of five signals: (1) 0.1 Hz sinusoid, (2) 0.3 Hz sinusoid, (3) 0.5 Hz sinusoid, (4) the periodic sum of these three sinusoids (PSUM), or (5) a non-periodic counterpart (NPSUM = 0.1+ pi/10 + 0.5 Hz). Sway response power at the various stimulus frequencies were compared: (1) among the three pure sinusoidal groups; and (2) between the two sum-of-sinusoid groups. Head and COP responses displayed similar spectral content, though sway magnitude was larger for the head. Sway responses to the moving scenes were significantly larger than those observed during quiet stance. Each sinusoidal moving scene evoked a strong response at the stimulus frequency, as well as increased sway at non-stimulus frequencies, primarily below 0.2 Hz. For the sum-of-sinusoids stimuli, both PSUM and NPSUM signals elicited sway responses at each of their component frequencies. The amplitudes of these responses were similar to one another at 0.1 and 0.3 Hz, but significantly different at 0.5 Hz, with PSUM responses on average four times larger than those for NPSUM. These findings indicate that spectrally similar periodic and non-periodic stimuli elicit quantitatively different sway responses. The observed behaviors may be due to postural sensitivity to the predictability of visual motion, or due to other nonlinear and/or time-varying mechanisms in the postural control system.

Adult↗

PubMed2006

Responses to a virtual reality grocery store in persons with and without vestibular dysfunction.

People with vestibular dysfunction often complain of having difficulty walking in visually complex environments. Virtual reality (VR) may serve as a useful therapeutic tool for providing physical therapy to these people. The purpose of this pilot project was to explore the ability of people with and without vestibular dysfunction to use and tolerate virtual environments that can be used in physical therapy. We have chosen grocery store environments, which often elicit complaints from patients. Two patients and three control subjects were asked to stand and navigate in VR grocery stores while finding products. Perceived discomfort, simulator sickness symptoms, distance traveled, and speed of head movement were recorded. Symptoms and discomfort increased in one subject with vestibular dysfunction. The older subjects traveled a shorter distance and had greater speed of head movements compared with young subjects. Environments with a greater number of products resulted in more head movements and a shorter distance traveled.

Activities of Daily Living↗

PubMed2005

Sensory re-weighting in human postural control during moving-scene perturbations.

The aim of the current study was to further investigate a recently proposed "sensory re-weighting" hypothesis, by evoking anterior-posterior (AP) body sway using visual stimuli during sway-referencing of the support surface. Twelve healthy adults participated in this study. Subjects stood on the platform while looking at a visual scene that encompassed the full horizontal field of view. A sequence of scene movements was presented to the subjects consisting of multiple visual push/pull perturbations; in between the first two push/pull sequences, the scene either moved randomly or was stationary. The peak-squared velocity of AP center-of-pressure (COP) was computed within a 6 s window following each push and pull. The peak-squared velocity was lowest for the push/pull sequence immediately following the random moving scene. These results are consistent with the sensory re-weighting hypothesis, wherein the sensory integration process reduced the contribution of visual sensory input during the random moving scene interval. We also found evidence of habituation to moving scene perturbations with repeated exposure.

Adult↗

PubMed2005

The influence of dynamic visual cues for postural control in children aged 7-12 years.

Young children rely heavily on vision for postural control during the transition to walking. Although by 10 years of age, children have automatic postural responses similar to adults, it is not clear when the integration of sensory inputs becomes fully developed. The purpose of this study was to examine this transition in the sensory integration process in children aged 7-12 years. Healthy children and adults stood on a fixed or sway-referenced support surface while viewing full-field optic flow scenes that moved sinusoidally (0.1 and 0.25 Hz) in an anterior-posterior direction. Center of pressure was recorded, and measures of sway amplitude and phase were calculated at each stimulus frequency. Children and adults had significant postural responses during approximately two-thirds of the trials. In adults, there was a 90% decrease in sway on the fixed surface compared with the sway-referenced surface, but only a 50% decrease in children. The phase between the optic flow stimulus and postural response in children led that of adults by 52 degrees at 0.1 Hz and by 15 degrees at 0.25 Hz. Adults and children aged 7-12 years have similar ability to use dynamic visual cues for postural control. However, 7-12-year-old children do not utilize somatosensory cues to stabilize posture to the same extent as adults when visual and somatosensory cues are conflicting.

Adult↗

PubMed2005

Acrophobia and pathological height vertigo: indications for vestibular physical therapy?

BACKGROUND AND PURPOSE: Acrophobia (fear of heights) may be related to a high degree of height vertigo caused by visual dependence in the maintenance of standing balance. The purpose of this case report is to describe the use of vestibular physical therapy intervention following behavioral therapy to reduce a patient's visual dependence and height vertigo. CASE DESCRIPTION: Mr N was a 37-year-old man with agoraphobia (fear of open spaces) that included symptoms of height phobia. Exposure to heights triggered symptoms of dizziness. Intervention. Mr N underwent 8 sessions of behavioral therapy that involved exposure to heights using a head-mounted virtual reality device. Subsequently, he underwent 8 weeks of physical therapy for an individualized vestibular physical therapy exercise program. OUTCOMES: After behavioral therapy, the patient demonstrated improvements on the behavioral avoidance test and the Illness Intrusiveness Rating Scale, but dizziness and body sway responses to moving visual scenes did not decrease. After physical therapy, his dizziness and sway responses decreased and his balance confidence increased. DISCUSSION: Symptoms of acrophobia and sway responses to full-field visual motion appeared to respond to vestibular physical therapy administered after completion of a course of behavioral therapy. Vestibular physical therapy may have a role in the management of height phobia related to excessive height vertigo.

Adult↗

PubMed2005

Vestibular function in migraine-related dizziness: a pilot study.

Migraine-related dizziness (MRD) refers to a disorder in which vestibular symptoms are an integral part of migraine symptomatology. The purpose of this study was to better define the pathophysiology of MRD, which is incompletely understood and to generate hypotheses regarding MRD by assessing the semicircular canal-ocular reflex, the otolith-ocular reflex, visual-vestibular interaction, vestibulo-spinal function, and visually induced postural sway. Subjects included five subjects with MRD, five subjects with migraine without dizziness, and five headache-free controls. Subjects with migraine were tested interictally. Results indicated that the mean gain of the semicircular canal-ocular reflex during both sinusoidal and constant velocity rotation was reduced in subjects with MRD. No changes were noted in the dynamics of the semicircular canal-ocular reflex. The otolith-ocular reflex, assessed with constant velocity OVAR, indicated that subjects with MRD showed a larger modulation component. No group differences were found in the bias component during constant velocity OVAR, nor in semicircular canal-otolith interaction or visual-vestibular interaction. Computerized dynamic posturography indicated that subjects with MRD demonstrated a surface-dependent pattern. Postural sway during optic flow indicated that subjects with MRD swayed more than the other subjects. We hypothesize that competing processes of serotonergic excitation and inhibition alter central vestibular pathways differently for semicircular canal vs. otolithic responses and for vestibulo-ocular vs. vestibulo-spinal pathways.

Adult↗

PubMed2004

Simulator sickness when performing gaze shifts within a wide field of view optic flow environment: preliminary evidence for using virtual reality in vestibular rehabilitation.

BACKGROUND: Wide field of view virtual environments offer some unique features that may be beneficial for use in vestibular rehabilitation. For one, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders. However, wide FOV devices also have been found to result in greater simulator sickness. Before a wide FOV device can be used in a clinical setting, its safety must be demonstrated. METHODS: Symptoms of simulator sickness were recorded by 9 healthy adult subjects after they performed gaze shifting tasks to locate targets superimposed on an optic flow background. Subjects performed 8 trials of gaze shifting on each of the six separate visits. RESULTS: The incidence of symptoms of simulator sickness while subjects performed gaze shifts in an optic flow environment was lower than the average reported incidence for flight simulators. The incidence was greater during the first visit compared with subsequent visits. Furthermore, the incidence showed an increasing trend over the 8 trials. CONCLUSION: The performance of head unrestrained gaze shifts in a wide FOV optic flow environment is tolerated well by healthy subjects. This finding provides rationale for testing these environments in people with vestibular disorders, and supports the concept of using wide FOV virtual reality for vestibular rehabilitation.

Journal Article↗

PubMed2004

Alterations in lower extremity movement and muscle activation patterns in individuals with knee osteoarthritis.

OBJECTIVE: The purpose of this study was to investigate lower extremity movement and muscle activation patterns in individuals with knee osteoarthritis and healthy age- and gender-matched control subjects. DESIGN: This study utilized a non-randomized case-control design to compare 24 subjects with unilateral symptomatic knee osteoarthritis to 24 age- and gender-matched control subjects without knee osteoarthritis. BACKGROUND: It is hypothesized that knee osteoarthritis is associated with altered lower extremity movement and muscle activation patterns. METHODS: A gait analysis was performed to determine the lower extremity movement and muscle activation patterns when walking on a level surface at 1.12 to 1.34 m/s and while descending a 20 cm step. Paired t-tests were used to compare the average of five trials between the groups. RESULTS: Subjects with knee osteoarthritis demonstrated less excursion of the knee in the sagittal plane from heelstrike to peak flexion before midstance (i.e. during loading). Subjects with knee osteoarthritis also demonstrated reduced peak vertical ground reaction forces relative to body weight. The muscle activity patterns were also different between the groups. The vastus lateralis, medial hamstrings, tibialis anterior and medial gastrocnemius were on approximately 1.5 times longer than the same muscles in the control subjects. Additionally, significant increases in muscle co-activation were also observed in individuals with knee osteoarthritis during walking. Similar findings were observed when the subject descended a 20 cm step.

Aged↗

PubMed2004

Detecting postural responses to sinusoidal sensory inputs: a statistical approach.

A common way for understanding sensory integration in postural control is to provide sinusoidal perturbations to the sensory systems involved in balance. However, not all subjects exhibit a response to the perturbation. Determining whether or not a response has occurred is usually done qualitatively, e.g., by visual inspection of the power spectrum. In this paper, we present the application of a statistical test for quantifying whether or not a postural sway response is present. The test uses an F-statistic for determining if there is significant power in postural sway data at the stimulus frequency. In order to describe the application of this method, 20 subjects viewed sinusoidal anterior-posterior (A-P) optic flow at 0.1 and 0.25 Hz, while their A-P head translation was measured. The test showed that significant postural responses were detected at the stimulus frequency in 12/20 subjects at 0.1 Hz and 13/20 subjects at 0.25 Hz.

Adult↗

PubMedDate not supplied

Comparison of the Ferno Scoop Stretcher with the long backboard for spinal immobilization.

OBJECTIVES: Spinal immobilization is essential in reducing risk of further spinal injuries in trauma patients. The authors compared the traditional long backboard (LBB) with the Ferno Scoop Stretcher (FSS) (Model 65-EXL). They hypothesized no difference in movement during application and immobilization between the FSS and the LBB. METHODS: Thirty-one adult subjects had electromagnetic sensors secured over the nasion (forehead) and the C3 and T12 spinous processes and were placed in a rigid cervical collar, with movement recorded by a goniometer (a motion analysis system). Subjects were tested on both the FSS and the LBB. The sagittal flexion, lateral flexion, and axial rotation were recorded during each of four phases: 1) baseline, 2) application (logroll onto the LBB or placement of the FSS around the patient), 3) secured logroll, and 4) lifting. Comfort and perceived security also were assessed on a visual analog scale. RESULTS: There was approximately 6-8 degrees greater motion in the sagittal, lateral, and axial planes during the application of the LBB compared with the FSS (both p < 0.001). No difference was found during a secured logroll maneuver. The FSS induced more sagittal flexion during the lift than the LBB (p < 0.001). The FSS demonstrated superior comfort and perceived security. CONCLUSION: The FSS caused significantly less movement on application and increased comfort levels. Decreased movement using the FSS may reduce the risk of further spinal cord injury.

Adolescent↗