I. Descriptive Information
Title, Editions, Versions: Sensory Organization Test (SOT) was created in 1982. Head-Shake SOT (HS-SOT) was developed for patients who performed within normal ranges on the SOT, but were still symptomatic of vestibular dysfunction. The Clinical Test of Sensory Interaction on Balance (CTSIB) (’86) & modified CTSIB (’93) were created for clinical assessment of balance, and do not have the technology & monetary requirements like the SOT.
The specific protocol for the SOT was written in 1997.
Author (s) LM Nashner created the idea of SOT computerized dynamic posturography (CDP) for clinical assessment in 1982.
Source (publisher or distributor, address) NeuroCom is the creator of the CDP that is utilized to perform the SOT.
Costs (booklets, forms, kit): $80,000-$180,000 (equipment)
Purpose Assess quantitative data about visual, proprioceptive and vestibular cues in order to maintain postural stability in stance
Type of Test (eg, screening, evaluative; interview, observation, checklist or inventory) Posturography assessment is used to evaluate postural stability in stance.
Target Population and Ages Patients with peripheral and/or vestibular deficits, head injuries, patients with fall risks (elderly, mobility disorders), CNS movement disorders (Parkinson’s) are the primary population, although normal healthy individuals can be assessed for postural stability with the SOT.
Time Requirements ~15 minutes, but up to ~30 (with the actual testing time consisting of 6 minutes)
Administration and Scoring Patient stands on a dual forceplate system, and undergo 6 different conditions. Scoring and objective values are recorded through a computerized system connected to the forceplates.
II. Test Administration
Administration Subjects stand on dual-force plates in a 3 sides surround posturography CDP system. Degree of anterior-posterior sway is recorded. 6 independent sensory conditions are tested, with each condition consisting of three twenty second trials.
The 6 conditions include:
-Eyes open on firm surface
-Eyes closed on firm surface
-Eyes open with sway referenced visual surround (altered vision)
-Eyes open on sway referenced support surface (unsteady surface)
-Eyes closed on sway referenced support surface
-Eyes open on sway referenced support surface and surround (unsteady surface and altered vision)
Scoring
–Equilibrium scoring: COG & postural sway are measured under each condition, and a composite equilibrium score is computed from the weighted average of the sway measured with each of the sensory conditions. Sway and equilibrium scores are calculated as a percentage based on degree of sway from vertical (100% perfect equilibrium & 0% results in a fall).
–Sensory analysis is used to determine how much the patient relies on each of the systems contributing to balance (somatosensory, visual, and vestibular systems). This is analyzed through ratios of individual equilibrium scores (i.e. condition 2 score/condition 1 score)
-COG alignment: reflection of the patient’s COG position relative to center of BOS at start of each trial of the SOT
-A strategy analysis produces quantitative data about relative amount of movement about the ankles & the hips that the patients used to maintain balance during each trial. This determines how much of an “ankle strategy” and “hip strategy” is used, and can be compared to the type of condition in which one strategy predominantly occurs over the other (i.e. ankle strategy is used more often with unsteady surface).
Type of information, resulting from testing (e.g. standard scores, percentile ranks) Quantitative data about patients’ ability to maintain COG over BOS and maintain balance under varying conditions. What types of systems play a predominant role in postural stability can be determined. It can be specifically determined how much of a role the visual, vestibular, and somatosensory systems play in controlling postural stability.
Environment for Testing: Lab setting with computerized dynamic posturography equipment
Equipment and Materials Needed: NeuroCom Balance Master, Equitest, or Smart Equitest. All equipment is made by NeuroCom.
Examiner Qualifications Training suggested, but not required. Use of device manual.
Psychometric Characteristics
-Standard Error of Measurement (SEM): composite score SEM (calculated) = 2.81
-Minimal detectable change (MDC): composite score change of greater than 8 points would indicated change secondary to rehab (tested with healthy young adults)
-MCID not established
Standardization/normative data: SOT composite scores and conditions 2-6 significantly decreases with increased age in healthy individuals: ANOVA and SOT equilibrium score has shown a main effect of age F(3.90) = 23.34 and test condition F(5.90) = 355.91
Evidence of Reliability:
–Test-retest: Healthy non-institutionalized older adults (n = 40): Tested at a one week interval: Composite score: Good test-retest reliability (ICC 0.66, SOT average of three trials ranged from poor (Condition 3: ICC = 0.68) to fair test-retest reliability (condition 5: ICC = 0.68, condition 6: ICC = 0.64); Adequate composite score reliability ICC = 0.67; individual equilibrium scores ranged from poor to adequate ICC = 0.35
-Interrater/Intrarater: not established
Evidence of Validity:
-Content validity: not established
-Face validity: Sensitivity and specificity of the SOT to detect otolith disorders, as measured by VEMP & Subjective Visual Vertical tests (n=22 patients and controls); sensitivity solely in condition 3,5, & 6 is it higher than 50%; specificity decreases with increasing difficulty of the condition
Discriminative:
–SOT, Timed up and Go(TUG), Dizziness Handicap Inventory (DHI) scores of people with unilateral (n = 41) and bilateral (n = 44) vestibular hypofunction: bilateral vestibular hypofunction: Adequate correlation (-0.31) between DHI emotional score and mean SOT sway in condition 3, and in unilateral vestibular hypofunction clients an adequate correlation (-0.35) may be found between mean sway in condition 3 and the physical DHI score; TUG scores are not correlated to any SOT scores for both groups
-The composite score and self-reported falls history within the past 6 months may be significantly related (F3 5.81, p < 0.01) (n = 100 vestibulopathic individuals)
Predictive:
–SOT vestibular condition (condition 5/1) has moderately high sensitivity (85%) and specificity (77%) in identifying vestibulopathies (n = 40 adults, 40 adults with vestibular impairments)
-The review article by Di Fabio (1995) reports that many studies on sensitivity and specificity of using the SOT to identify people with vestibulopathy, most studies found low to moderate sensitivity and specificity. The responsiveness increases when the SOT is combined with rotary chair or caloric test results.
-Basta et al 2005 investigated the influence of pure otolith disorders on SOT scores in 33 adults with minor head injury with utrical or sacculo-utricalar disorders, finding SOT were abnormal in 76.9% of the people with combined sacular-utricular involvement, while the scores were only abnormal in 45% of utricular disorder group.
III. Summary Comments
Strengths: It provides an objective measure, helps to possibly identify small differences & changes in those who are higher functioning in balance, etc.
Weaknesses: It has a high cost, and requires use of technology that is not easy to access in many clinics. The research that provides clinically important differences in score changes, was done in normal healthy adults. More research may be needed to determine significant changes in pathological populations.
Clinical Applications: The Neurology Section of the APTA’s task forces for Parkinson’s disease, SCI, stroke, TBI, & vestibular rehab have made recommendations for utilization of the SOT. Recommendations were based on acuity level of patient, level of care (i.e. acute, OP), ambulatory status after brain injury, and vestibular diagnosis (i.e. peripheral, central, etc.). Most, if not all, recommendations were either not recommended or had reasonable use due to limited studies.
Article References:
Basta, D., Clarke, A., et al. (2007). “Stance performance under different sensorimotor conditions in patients with post-traumatic otolith disorders.” Journal of Vestibular Research 17(1): 25-31.
Basta, D., Todt, I., et al. (2005). “Postural control in otolith disorders.” Human movement science 24(2): 268-279.
Clendaniel, R. A. (2000). “Outcome measures for assessment of treatment of the dizzy and balance disorder patient.” Otolaryngologic Clinics of North America 33(3): 519-533.
Cohen, H., Heaton, L. G., et al. (1996). “Changes in sensory organization test scores with age.” Age Ageing 25(1): 39-44.
Cohen, H. S. and Kimball, K. T. (2008). “Usefulness of some current balance tests for identifying individuals with disequilibrium due to vestibular impairments.” Journal of Vestibular Research 18(5): 295-303.
Di Fabio, R. P. (1995). “Sensitivity and specificity of platform posturography for identifying patients with vestibular dysfunction.” Physical Therapy 75(4): 290-305.
Ford-Smith, C. D., Wyman, J. F., et al. (1995). “Test-retest reliability of the sensory organization test in noninstitutionalized older adults.” Arch Phys Med Rehabil 76(1): 77-81.
Gill-Body, K. M., Beninato, M., et al. (2000). “Relationship among balance impairments, functional performance, and disability in people with peripheral vestibular hypofunction.” Physical Therapy 80(8): 748-758.
Pedalini, M. E., Cruz, O. L., et al. (2009). “Sensory organization test in elderly patients with and without vestibular dysfunction.” Acta Otolaryngol 129(9): 962-965.
Whitney, S. L., Marchetti, G. F., et al. (2006). “The relationship between falls history and computerized dynamic posturography in persons with balance and vestibular disorders.” Archives of physical medicine and rehabilitation 87(3): 402-407.
Wrisley, D. M., Stephens, M. J., et al. (2007). “Learning effects of repetitive administrations of the sensory organization test in healthy young adults.” Arch Phys Med Rehabil 88(8): 1049-1054.
http://resourcesonbalance.com/neurocom/protocols/sensoryImpairment/SOT.aspx
http://resourcesonbalance.com/program/role/cdp/protocols.aspx
Article Summary: Learning Effects of Repetitive Administrations of the Sensory Organization Test in Healthy Young Adults
The objective of this study was to determine the learning effect of multiple trials of the sensory organization test (SOT), and what type of score change would indicate a minimal change in performance secondary to rehab treatment. The researchers in this study performed a descriptive case series in which all subjects performed the SOT with the SMART EquiTest 5 separate times over 2 weeks, and 1 month following the 5 tests. The participants included 13 healthy male and female subjects with a mean age of 24, plus or minus 4 years. Degree of postural sway was measured with the SMART EquiTest, and was measured under 6 varying conditions, with 3 trials performed under each condition. Conditions consisted of changes in the participants’ vision relative to sway in their environment, the stability of the support surface, and whether or not their eyes were open or closed. An equilibrium score was calculated based on an average of the 3 scores of each of the conditions. A composite score was then taken for each of the 6 conditions, which averaged all 6 equilibrium scores. A repeated-measures ANOVA was used to analyze differences in equilibrium and the composite scores.
This study found that there were significant differences between equilibrium and composite scores among all 6 sessions for multiple conditions, indicating a learning effect when administering the SOT. Different recommendations have been made, including the administration of many baseline SOT tests prior to administering an intervention. Researches acknowledged that this idea may not be supported in the clinical setting though, and that multiple SOT tests may also act a balance training program for patients with balance dysfunction. Based on this study, an 8 point improvement in score is indicated to be a result of rehab intervention versus learning. Since this score was determined with younger healthy patients, more research may be indicated in order to determine clinically relevant changes in older patients and those with balance dysfunction. More research is also indicated in order to determine changes in function. Although, these finding in healthy young adults may be a guide for future research in determining clinically relevant SOT score changes in patients of varying ages and with varying balance altering pathologies.
Wrisley, D. M., Stephens, M. J., et al. (2007). “Learning effects of repetitive administrations of the sensory organization test in healthy young adults.” Arch Phys Med Rehabil 88(8): 1049-1054.