Modified head shake sensory organization test: Sensitivity and specificity

doi:10.1016/j.gaitpost.2016.06.024

Gait & Posture

Volume 49, September 2016, Pages 67-72

https://doi.org/10.1016/j.gaitpost.2016.06.024 Get rights and content

Highlights

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A modified head shake sensory organization test (SOT) is proposed.
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Identification of peripheral vestibular asymmetry improved with 15°/s head shake.
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Head shake SOT at 15°/s had strong correlation with caloric weakness.
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Head shake SOT 15°/s useful for screening peripheral vestibular asymmetry.

Abstract

The Sensory Organization Test (SOT) of Computerized Dynamic Posturography (EquiTest™ equipment) is a valuable tool for investigating how an individual uses balance system sensory input (vestibular, vision, proprioception/somatosensory) to maintain quiet stance; however, it is limited as a screening tool for identifying peripheral vestibular system dysfunction. Previous research has shown that adding horizontal head-shake to portions of the standard SOT battery improved the identification of peripheral vestibular system asymmetry; however, flaws in the methods were noted. The objective of this work was to evaluate the sensitivity and specificity of the modified head-shake SOT (HS-SOT) protocol for identification of peripheral vestibular system lesion. Fifteen patients with chief complaint of instability, vertigo, and/or lightheadedness, with and without a caloric unilateral weakness (UW) and fifteen age-matched healthy controls were included in the final analysis. Ten of the 15 patients demonstrated a caloric UW ≥ 25%. Participants completed standard conditions 2 and 5 of SOT with head still and during four horizontal head-shaking tasks (i.e., HS-SOT2-60°/s, HS-SOT2-120°/s, HS-SOT5-15°/s, and HS-SOT5-60°/s). Average equilibrium scores decreased as condition difficulty increased (SOT2, HS-SOT2-60°/s, HS-SOT2-120°/s, SOT 5, HS-SOT5-15°/s, and HS-SOT5-60°/s) for each group; as expected, a lower decline was noted for controls (slope = −6.59) compared to patients (slope = −11.69). The HS-SOT5-15°/s condition was superior for identifying peripheral vestibular asymmetry (AUC = 0.90 sensitivity = 70%, specificity = 100%), with the strongest correlation to caloric UW% (r_s = −0.743, p = 0.000006). HS-SOT5-15°/s appears to be a promising screening measure for peripheral vestibular asymmetry.

Introduction

Our ability to maintain balance is influenced by coordination of sensory input (vestibular, vision, and proprioception) and motor output, which sends commands to lower extremities and muscles. The Sensory Organization Test (SOT) of Computerized Dynamic Posturography evaluates the ability to utilize vision, vestibular and biomechanical sensors at the joints and on the plantar surface of the foot to maintain balance [1], [2]. Changes in center of pressure are quantified during six increasingly challenging conditions that disrupt portions of balance sensory input (Fig. 1). An equilibrium score for each condition trial is calculated by comparing the angular difference between the patient’s calculated maximum and minimum sagittal plane body sway to a theoretical maximum displacement (12.5°), and referenced as a score between 100 (no body sway) to 0 (fall) [3].Equilibrium = 12.5° − (θ_max − θ_min)/12.5° × 100 [3].

The SOT measures the functional ability to coordinate balance after an injury or disease affects the balance system [4], [5]; however, it is a limited tool to screen for peripheral vestibular asymmetry, with respect to site-of-lesion [4], [5], [6], [7], [8]. In many cases, measures of postural control will be normal within a short period of time after unilateral vestibular loss [9], [10], [11].

The addition of horizontal head-shake during standard SOT testing decreases postural control ability [12], [13] and improves SOT performance for identifying unilateral vestibular loss [14]. During head-shake, the vestibular system is stimulated; therefore, the individual’s postural control system is challenged [15]. Furthermore, when the individual is receiving inaccurate visual and/or proprioceptive sensory information and the vestibular system is activated (i.e., head-shake), discrimination between the head-shake and body sway must be made by the brain [16]. Individuals with vestibular dysfunction are unable to distinguish between the body sway and the vestibular system input, which ultimately leads to increased body sway (i.e., reduced postural control). Thus, head-shake SOT (HS-SOT) may be appropriate for individuals presenting with persistent symptoms, but appear to be compensated due to normal or near-normal SOT performance.

Mishra et al. [14] examined HS-SOT 60°/s during conditions 2 (eyes closed and stable support surface; HS-SOT2-60°/s) and 5 (eyes closed and sway reference support; HS-SOT5-60°/s); however, there were ceiling and floor effects. A modification to the HS-SOT protocol was then evaluated in 40 healthy controls [15] that included the same head-shake conditions proposed by Mishra et al. [14], but included head-shake with peak head velocity at 120°/s during SOT condition 2 (HS-SOT2-120°/s), and head-shake with peak head velocity at 15°/s during SOT condition 5 (HS-SOT5-15°/s). The inclusion of the HS-SOT2-120°/s and HS-SOT5-15°/s eliminated the observed ceiling and floor effects, respectively.

Therefore, the purpose of this study was to evaluate the performance of the modified HS-SOT test proposed by Honaker et al. [15] in patients with and without peripheral vestibular asymmetry. We hypothesize the modified HS-SOT will increase sensitivity and specificity for identifying unilateral vestibular dysfunction.

Section snippets

Subjects

Patients were randomly selected from individuals referred to the University of Nebraska-Lincoln (UNL) and Boys Town National Research Hospital (BTNRH) vestibular clinics. Consistent with Mishra et al. [14] all patients presented with the chief complaint of instability, vertigo, and/or lightheadedness, with and without peripheral vestibular system asymmetries as determined by caloric testing. All patients received open loop bithermal (44 °C and 30 °C) caloric irrigations, which were analyzed using

Discussion:

Our results demonstrated that stance is compromised in patients with unilateral peripheral vestibular loss during a head-shake postural control task. These findings are consistent with the literature suggesting that patients with unilateral peripheral hypofunction demonstrate reduced performance on SOT with the addition of provocative head movements [14], [23] and changes in head orientation [24], [25], [26]. Research was conducted in the early 1990’s exploring the effects of head position on

Conclusion

The modified HS-SOT, utilizing head-shake at 15°/s, significantly improved sensitivity and specificity for identifying peripheral vestibular asymmetry. While these results are based on a small sample, test performance on HS-SOT-15°/s, suggests it could be added to traditional SOT testing and used as a screening tool for peripheral vestibular hypofunction.

Julie Honaker is an employee of the University of Nebraska-Lincoln. Julie is a Board Member of the American Balance Society and American Speech, Language, Hearing Association National Advisory Committee. Julie received grant funding from the NCAA-DoD and American Academy of Audiology Foundation for previous work, and is currently funded by the American Nursing Foundation and Bryan Heart Foundation.

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Cited by (17)

Investigation of Head Shake Sensory Organization Test (HS-SOT) in three planes: Test-retest reliability and age-related differences
2023, Gait and Posture
In recent years, it has been determined that SOT sensitivity is insufficient in patients who develop vestibular compensation and therefore the Head Shake Sensory Organization Test (HS-SOT) has been developed.
How differs the balance performance of healthy adults that is tested with HS-SOT according to age and test planes? What is the test-retest reliability level of the HS-SOT in three planes?
Our prospective study, which has a methodological research design, included 80 participants divided into three groups by age range (Group 1: 20–39 years (n = 30); Group 2: 40–49 years (n = 30) and Group 3: 50–64 years (n = 20)). SOT and HSSOT ( yaw, pitch, roll) were performed to all participants. To investigate the testretest reliability of the HS-SOT, a total of 27 participants were re-evaluated one week later. The HS-SOT performance of the participants was compared between age groups and test planes. Intra-class correlation coefficient and minimum detectable change values (MDC) was calculated to test-retest reliability of HS-SOT.
HS-SOT scores (HS-2 and HS-5) did not differ significantly between age groups. The balance performance of individuals for the pitch plane was lower than other planes. Only the HS-5 score showed a significant difference between the sessions. HS-5 scores were higher in the re-test; for the first group in the pitch plane and for the third group in the yaw plane. The test-retest reliability level of these conditions was "moderate-good" for both groups. The corresponding MDC value was highest (14.01) for the HS-5 (yaw) score of the elderly group.
The findings from this study demonstrated that the test plane influences the HS-SOT, a learning/practice effect may occur because of repeated HS-SOT evaluation, and this effect is more explicit in the elderly. This study provides a perspective for the evaluation and follow-up processes of patients with balance problems.
Conversational head movement decreases close-contact exposure to expired respiratory droplets
2023, Journal of Hazardous Materials
Citation Excerpt :
Thus, the source manikin nodded twice within a 2-s period of expiration, and this double-nod was repeated from 4.0 to 6.0 s. In both Scenario 2 and Scenario 3, the angular velocity of the source manikin’s head was 90°/s, which is an average of the values in condition 2 of Honaker et al. (2016) (60°/s and 120°/s). This resulted in a maximum rotation angle of 45°, consistent with Zhang et al. (2020b), who found that the head-yaw angle of a standing person in 78.9% of circumstances is less than or equal to ± 45°.
People constantly move their heads during conversation, as such movement is an important non-verbal mode of communication. Head movement alters the direction of people’s expired air flow, therefore affecting their conversational partners’ level of exposure. Nevertheless, there is a lack of understanding of the mechanism whereby head movement affects people’s exposure. In this study, a dynamic meshing method in computational fluid dynamics was used to simulate the head movement of a human-shaped thermal manikin. Droplets were released during the oral expiration periods of the source manikin, during which it was either motionless, was shaking its head or was nodding its head, while the head of a face-to-face target manikin remained motionless. The results indicate that the target manikin had a high level of exposure to respiratory droplets when the source manikin was motionless, whereas the target manikin’s level of exposure was significantly reduced when the source manikin was shaking or nodding its head. The source manikin had the highest level of self-exposure when it was nodding its head and the lowest level of self-exposure when its head was motionless. People’s level of exposure during close contact is highly variable, highlighting the need for further investigations in more realistic conversational scenarios.
Vestibular training promotes adaptation of multisensory integration in postural control
2019, Gait and Posture
Citation Excerpt :
This protocol was designed to challenge sensorimotor coordination, while activating the vestibular system by encouraging gaze stability and smooth pursuit. Such headshake approaches have been used for postural assessment (e.g. HS SOT, [20]), but in this study we proposed to use it for training purposes. There were rest periods of 30 s between each exercise and 2 min.
Postural stability depends on the integration of the multisensory system to produce motor outputs. When visual and somatosensory input is reliable, this reduces reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction. Training one or more of the three sensory systems through vestibular habituation and adaptation can alter sensory weighting and change postural behavior.
The purpose of this study was to assess sensory reweighting of postural control processing after combined vestibular activation with voluntary weight shift training in healthy adults.
Thirty-three healthy individuals (18–35 y.o.) were randomly assigned to one of three groups: No training (control), visual feedback weight shift training (WST) coupled with an active horizontal headshake (HS) activity to elicit a vestibular perturbation, or the same WST without HS (NoHS). Training was performed 2x/day, every other day (M, W, F), totaling six sessions. Pre- and post- assessments on the Sensory Organization Test (SOT) were performed. Separate between- and within- repeated measures ANOVAs were used to analyze the six SOT equilibrium scores, composite scores, sensory ratios and center of pressure (COP) variables by comparing baseline to post-training. Alpha level was set at p < .05.
There was a significant group x session x condition change (p = .012) in the COP multiscale entropy (MSE) velocity sway in the HS group during SOT conditions 5 and 6. Similarly, COP medio-lateral standard deviation sway (ML Std) showed group x session x visual condition (p = .028), due to HS in condition 6 relative to other two groups.
Postural training can alter sensory organization after a visual feedback-vestibular activation training protocol, suggesting a possible sensory reweighting through vestibular adaptation and/or habituation.
Translating these findings into a vestibular-impaired population can stimulate the design of a rehabilitation balance protocol.
Clinical significance of head shake movement in three planes in individuals with dizziness
2020, American Journal of Otolaryngology - Head and Neck Medicine and Surgery
Citation Excerpt :
Our HS-SOT-5 scores are lower than Cripps et al., but HS-SOT-2 scores are similar to their study. Most of the studies about HS-SOT only the yaw plane was used [8,20–23]. Because the head movements in the yaw plane predominantly affect the horizontal semicircular canal, the test could be supported with the caloric test.
This study aims to evaluate the efficacy of head shake movement on three head movement planes (yaw, pitch and, roll) in patients with dizziness despite normal vestibular test results.
Twenty individuals aged between 20 and 51 years with complaints of dizziness were included in the study, and their results were compared with the results from twenty age- and gender-matched controls. Participants were assessed using the Sensory Organization Test, Head Shake-Sensory Organization Test which is based on the modification of the Sensory Organization Test on the yaw, pitch, and roll planes, videonystagmography, caloric test, and Dizziness Handicap Inventory.
Significant differences were found in the yaw (p = 0.007), pitch (p < 0.001), and roll (p = 0.002) planes between the study and control groups of the Head Shake-Sensory Organization Test-5 scores. There were no statistically significant differences between the two groups of the Head Shake-Sensory Organization Test-2 scores in the yaw (p = 0.448), pitch (p = 0.213), and roll (p = 0.531) planes. When the sensitivity and specificity of Head Shake-Sensory Organization Test-5 conditions were examined, the highest specificity was observed in the pitch plane (100%), followed by the yaw (95%) and roll plane (95%).
Dynamic head movements are an important parameter for the evaluation of balance performance. The head shake modification could be used effectively in three-movement planes in individuals with dizziness.
Effects of Proprioceptive Vestibular Rehabilitation on Balance, Functional Mobility, Posture, Sensory Profile, and Quality of Life in Patients with Peripheral Vestibular Disorders
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Impact of Concussions on Postural Stability Performance Using the Head Shake-Sensory Organization Test
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Kristen Janky is an employee of Boys Town National Research Hospital, and a consultant for Otometrics/Audiology systems. Kristen is a Board Member of the American Balance Society.

Jessie Patterson is student at the University of Nebraska-Lincoln. Jessie is a Board Member of the American Balance Society.

Neil Shepard is an employee of Mayo Clinic-Rochester and Board Member of the American Balance Society. Neil is a course instructor for the Vestibular rehabilitation: a competency-based course, Emory University School of Medicine. In addition, he is co-editor of textbook, Balance Function Assessment and Management.

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Full length articleModified head shake sensory organization test: Sensitivity and specificity

Highlights

Abstract

Introduction

Section snippets

Subjects

Discussion:

Conclusion

Gait Posture

J. Electromyog. Kinesiol.

Contin. Educ. Anaesth. Crit. Care

Otolaryngol. Head Neck Surg.

Computerized dynamic posturography

Altered sensory function and balance in older persons

J. Gerontol.

Evaluation of clinical measures of equilibrium

Laryngoscope

Computerized dynamic posturography

An overview of the clinical use of dynamic posturography in the differential diagnosis of balance disorders

J. Vestib. Res.

Clinical utility of lateral head tilt Posturography

Am. J. Otol.

Postural control in young and elderly adults when stance is challenged: clinical versus laboratory measurements

Ann. Otol. Rhinol. Laryngol.

Effects of unilateral loss of vestibular function on the vestibulo-ocular reflex and postural control

Ann. Otol. Rhinol. Laryngol.

Posturography: uses and limitations

Baillieres Clin. Neurol.

Recovery of postural control after an acute unilateral vestibular lesion in humans

J. Vestib. Res.

Head movement modification to sensory organization protocol of EquiTest: clinical utility in a random sample of balance disorder patients

Full length article
Modified head shake sensory organization test: Sensitivity and specificity