and Balance A Study of the Clinical Test of Sensory Interaction

Transcription

1 Research Report A Study of the Clinical Test of Sensory Interaction and Balance Background and Purpose. The ability to maintain an upright position dun'ng quiet standing is a usefil motor skill. The Clinical Test of Sensory Interaction and Balance is an inexpensive, easily administered test that provides information about the ability to stand upright under several sensory conditions. Subjects. Three groups of neurologically asymptomatic (AS) adults, divided by age into younger, middleaged, and older groups, participated in the study. A fourth group comprked subjects diagnosed with vestibular disorders. Metbods. Timed perjormances under six dzrerent conditions were compared across groups. Results. Subjects with vestibular disorders were signifcantly impaired on perjormance when compared with agematched AS subjects. Older AS and vestibularly impaired subjecrs had greater variation in their scores than did younger AS subjects. Concluston and Dlscussfon. This test is a usehl screening tool for examining static standing balance. [Coben H, Blatchly GI, Gombash LL. A study of the Clinical Test of Sensory Interaction and Balance. Phys Ther. 1993; 73: ] Helen Cohen Cathleen A Blatchly Laurle L Gombash Key Words: Balance, Equilibrium, Posture, Tests and measurements, Vestibular system. A Successful performance of some daily life tasks, such as reading the titles of books on a shelf, requires the ability to maintain an upright position. For this reason, many physical therapists are concerned with their patients' ability to perform this motor skill. We will refer to the ability to maintain an upright position during quiet standing as "balance." Force platforms, electromyography, and motion analysis systems have all been used for assess ment of balance.' These sophisticated systems, however, are expensive and often impractical for use by a therapist in a typical hospital or private practice. They require considerable floor space, special training, and computers. These resources may be unavailable to the clinician who would like to be able to test patients' balance, but who lacks funds to purchase sophisticated equipment or who must carry equipment from place to place. H Cohen, EdD, OTR, is Assistant Professor, Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, One Baylor Plaza, Houston, TX (USA). She was Assistant Professor, Program in Rehabilitation Science, and Assistant Professor, Departrnent of Otolaryngology, Medical College of Ohio, Toledo, OH 43699, at the time of this study. Address all correspondence to Dr Cohen. CA Blatchly, PT, is Assistant Professor, Program in Physical Therapy, Medical College of Ohio LL Gombash, PT, is Physical Therapist, Medical College Hospital, and Clinical Lecturer, Departrnent of Otolaryngology, Medical College of Ohio. This study was approved by the Institutional Rwiew Board of the Medical College of Ohio. This article was submitted February 18, 1992, and was accepted January 29, Therefore, a simpler, less expensive, valid, and reliable test is needed. The Clinical Test of Sensoq Interaction and Balance (CTSIB) is a timed test that was developed for systematically testing the influence of visual, vestibular, and somatosensoq input on standing balance.2 This test is inexpensive, requires minimal equipment, and is currently in use by some clinicians. Conditions 1,2, and 3 involve standing on the floor with eyes open, eyes closed, and wearing a visualconflict dome. The dome provides a sensoq conflict by depriving the subject of peripheral vision and introducing a swayreferenced image. Use of the conflict dome results in a discrepancy between vestibular input stimulated by postural sway and visual flow.' Thus, conditions 2 and 3 should examine different aspects of sensoq organization of visual information that may Physical Therapy/Volume 73, Number 6/June / 9

2 require different postural adjustments.3 That is, condition 2 examines how well subjects maintain balance in the absence of any vision, and condition 3 examines how well subjects maintain balance when vision is present but that information conflicts with vestibular information. Conditions 4, 5, and 6 involve standing on foam and repeating the visual conditions described for conditions 1 through 3. For each condition, the length of time the subject can maintain standrng and the amount of body sway that occurs are assessed. Although norms for this test have been established for children and young adults, norms for performance on the CTSIB have not been established for older adults and patients with vestibular deficits.4.5 Currently, the CTSIB requires performance of at least one trial on each of the six conditions. Some investigators have questioned whether the eyesclosed and the visuab'vestibularconflict conditions produce different performance. BillekSawhney5 found no differences on measures of duration and sway amplitude in the eyesclosed and visualconflict conditions in neurologically asymptomatic (AS) young adults. No studies in the literature address these issues in older adults and individuals with vestibular disorders. It is unclear whether patients improve on repeated trials on the CTSIB, because different investigator+ have used different methods for calculating performance times and amount of sway. Physical therapists have advocated the use of balance retraining that involves repeated exposure to different sensory conditions when standing,7 but no studies have distinguished between motor performance on this test and motor learning as a result of practice. Determining the need for repeated trials during assessment would be useful. 'Alimed Inc, 68 Harrison Ave, Boston, MA These findings suggest that the CTSIB should be studied further. Previous findings suggest that therapists using the CTSIB should expect performance on this test to vary with respect to age and health status.6.s10 This study had several goals: (1) to determine whether healthy adults of different ages had different timed balance scores on the CTSIB, (2) to determine whether healthy subjects performed differently on each of the six conditions, (3) to learn whether individuals diagnosed with vestibular disorders performed differently than AS subjects, and (4) to determine whether subjects' performance improved over trials. Method Subjects Pilot data were collected from 22 senior physical therapy students (9 men, 13 women), aged 20 to 24 SD=0.85). Subjects in the experiment were divided into four groups. Groups 1, 2, and 3 each comprised 15 AS subjects. Group 1 comprised 5 men and 10 women, aged 25 to 44 SD=5.5). Group 2 comprised 4 men and 11 women, aged 45 to 64 SD=6.2). Group 3 comprised 1 man and 14 women, aged 65 to 84 SD=5.9). No subjects were obese. Subjects were screened for major health problems, and only individuals with no history of "dizziness," balance disorders, or recent orthopedic problems were included. Subjects in groups 1 and 2 were recruited from among the physical therapy students, SUE, and faculty at the Medical College of Ohio, Toledo, Ohio. Group 3 subjects were retired elderly people living in the community. Group 4 comprised 17 patients (7 men, 10 women), aged 30 to 87 SD= 18.9), diagnosed with vestibular disorders by a boardcertified otolaryngologist specializing in vestibular disorders. In addition to the clinical evaluation, diagnostic tests included computerized harmonic acceleration tests of the vestibuloocular reflex, optokinetic nystagmus, ocular pursuit and saccades, and caloric tests, during which eye movements were recorded with electrooculography. Patients' diagnoses included benign paroxysmal positional vertigo, vestibular neuronitis, cupulolithiasis, labyrinthitis, and vestibular disorder of idiopathic origin. Their initial complaints included vertigo, disequilibrium, and blurred vision. The physician referred all patients for physical therapy at the Medical College Hospital. All subjects gave informed consent before participating in this study. Equipment The materials for this test included a x x 7.62cm piece of mediumdensity Sunmate* foam,2 a visuauvestibularconflict dome made from a Chinese lantern attached to a plastic sun visor, and a stopwatch. (A sun visor is a hatless brim attached to an elastic band covered in terry cloth, which holds the brim over the forehead to shade the eyes.) We used a sun visor that could be detached from its elastic band, so that ditferent bands could be used with each subject. Between test sessions, the elastic bands were washed. This detail eliminated any concerns subjects might have had about hygiene. The dome was constructed according to the description by ShumwayCook and Horak2 so that the subject saw a fixation point, a large black cross, centered in visual field. The total cost for materials was approximately $40. Because the materials needed for this test are inexpensive, even clinics with small budgets can afford to obtain the necessary equipment. Procedure All subjects were tested for three trials on each of the six conditions, in stocking feet. The conditions were (1) quiet standing on the floor, looking straight ahead; (2) quiet standing on the floor with eyes closed; (3) quiet standing on the floor wearing the conflict dome; (4) quiet standmg 10 / 347 Physical Therapy /Volume 73, Number 6/June 1993

3 b on the foam, with eyes open; (5) quiet standing on the foam, with eyes closed; and (6) quiet standing on the foam wearing the conflict dome. Between trials for conditions 4 through 6, the foam was turned over and rotated 90 degrees to prevent the foam from wearing unevenly over many trials. Subjects rested between trials, for 30 to 60 seconds, to eliminate the confounding effect of fatigue. Pilot work showed no effect of order of conditions, with subjects who understooci the nature of the task, when conditions 1 through 3 were given before or after conditions 4 through 6. Similarly, no daerences were found when the orders of conditions 2 and 3 and conditions 5 and 6 were reversed. Performance is known to be aeected by the performer's level of understanding of the skdl.ll Although the postural control aspect of the test is presumably automatic, assuming the correct position of the feet and hands could require some practice to understand the nature of the task. Therefore, the experimental paradigm was always administered using conditions 1 through 3 first to give the subjects the idea of the position required. For that reason, condition 1, the least complicated condition, always preceded all other conditions, and condition 4 always preceded conditions 5 and 6. Prior to testing in each condition, the investigator demonstrated the task. The test was administered with the conditions in the same order each time. For all conditions, the subject was instructed to stand quietly, with arms comfortably across the waist, feet together, for as long as possible, up to 30 seconds. This period of time had been specified in the original description of the test.2 The instructions given by all investigators were standardized and were changed slightly for each condtion. Do this until I tell you to stop." The instructional set for the other conditions included the instruction to "close your eyes" for condition 2 and "Now I'd like you to wear this hat and look at the cross" for condition 3. For conditions 4 through 6, subjects were given the same instruction regarding visual conditions and were also asked to stand on the center of the foam. The length of time the subject could maintain balance was recorded. A trial was terminated when the subject's arms or feet changed position. For subjects who were able to perform all 18 trials for 30 seconds, the test took approximately 20 minutes. All subjects were tested in a quiet, welllighted room with a linoleum floor. Data Analysis The data were analyzed using the mean time performing the test, over the three trials for each condition. Testretest reliability and interrater reliability were determined using Pearson ProductMoment Correlation Coefficients. Differences among experimental groups were determined using an analysis of variance (ANOVA) for repeated measures. Significant differences were then subjected to post hoc Tukey's tests. Differences between AS subjects and agematched vestibularly impaired subjects were examined with t tests using the Bonferroni correction. Results Both testretest and interrater reliability were high (r=.99, Pc.01). These measures were taken with the pilot group. Interrater reliability was evaluated by having two investigators at a time test five subjects simultaneously, using identical digital stopwatches. Values were rounded to the nearest half second. Testretest reliability was tested by having the same investigator test five subjects twice. wearing the conflict dome, for all three trials. The results were somewhat different for conditions 4, 5, and 6 (eyes open, eyes closed, and wearing the conflict dome, respectively, while standing on the foam). As shown in Figure 1, and confirmed with the ANOVA, subjects in groups 1, 2, and 3 performed condition 4 for significantly longer than condition 5 (F[16,34] = 11.35, P<,001). This difference stemmed from differences across conditions among the older subjects. Group 3 showed a performance decrement on condtions 5 and 6, and their scores on conditions 5 and 6 did not differ significantly. Performance of the subjects in group 4 was slightly different. As with the AS subjects, their performance on condition 4 was significantly better than on condition 5, but unlike AS subjects their performance on condition 6 was significantly poorer than on condition 4. Figure 1 shows that their scores on conditions 5 and 6 did not d8er significantly. When the data were evaluated by conditions (Fig. 2), no sigmficant differences were found between the scores of groups 1 and 2, on any conditions. On condition 4 (eyes open on the foam), no differences were found among scores of subjects in groups 1, 2, and 3. Subjects in group 4, however, scored significantly lower than subjects in the other groups (F[16,34] =2.12, P<.04). On condition 5 (eyes closed on the foam), group 3 had scores significantly lower than those of groups 1 and 2, but not significantly different from those of group 4. Although group 3 performed significantly worse than groups 1 and 2 on condition 6 (foam and dome), the scores of group 3 were significantly higher than those of group 4, as shown in Figure 2. As the figure indicates, both groups 3 and 4 had considerable variabihty in their scores. Prior to starting the test, subjects were told that each trial would last for up to 30 seconds. For condition 1, the investigator told the subject, "Stand with your feet together, hands across your waist, and look straight ahead. The ANOVA showed no significant differences among groups for conditions 1 through 3. That is, all subjects could stand on the floor for 30 seconds with eyes open, eyes closed, and When subjects were matched by age and mean scores were compared with relatedmeasures t tests, no differences were found between AS and vestibularly impaired subjects on condition 4. Figure 3 shows that Physical Therapy /Volume 73, Number 6/June / 11

4 . n J 8 40 Condition 30 n m Group Figure 1. Mean duration of balance in each group, by condition. Error bars represent standard deviations. Condition 4=standing on foam with eyes open, condition 5=standing on foam with eyes closed, condition 6=standing on foam wearing visual/ vestibularconflict dome. Group I =asymptomatic subjects aged 25 to 44 years, group 2=asymptomatic subjects aged 45 to M years, group 3=asymptomatic subjects aged 65 to 84 years, group 4=uestibukarly impaired subjects. groups 1,2, and 3 performed significantly better than group 4 on conditions 5 and 6 (condition 5: t[l6]=4.17, P<.001; condition 6: t[l6]=5.58; P<.001). Under these conditions, vision was eliminated or conflicted with vestibular input. Group 4 also had much more variability than did the other groups. In general, these data show that older AS subjects (group 3) and subjects with vestibular impairments (group 4) had consistently lower scores on conditions 5 and 6. The data were also analyzed by trials to look for a practice effect. Groups 1 and 2 had no significant differences across trials for any condition. Similarly, for groups 3 and 4, no d8erences were found across trials on condition 4. On conditions 5 and 6, however, groups 3 and 4 had differences between scores on trials 1 and 2 (F(3,58,8,24] =7.22, PC,001) (Table). Some subjects in both groups improved their performance on both conditions. The importance of this finding, however, is unclear because both of these groups had such great variability in their scores. The means and standard deviations of these data are shown in the Table. n 42 C Group Condition Figure 2. Mean duration of balance in each condition, by group. Error bars represent standard deviations. See Fig. I legend for desn'ptons of groups and conditions..4 The CTSIB is an inexpensive, easily administered test of standing balance that is useful in the typical physical therapy clinic. These results suggest that it can be modified for even easier administration. Because no differences were found among groups on the first three conditions, these conditions could be eliminated for subjects with only peripheral vestibular disorders. Norre et a112 and other investigators (CA Blatchly, SL Whitney, and JMRF Furman; unpublished data) have reported differences in conditions 1 and 2, but these differences may be attributed to the use of different foot positions in each study, as well as to the presence of central neurological problems. Asymptomatic older adults can perform condition 4 as well as younger subjects, although people with vestib 12 / 349 Physical Therapy/Volume 73, Number 6June 1993

5 VesUbulady Impaired Subjects 1 Condition 1 Flgure 3. Dz$wences in balance duration between vestibularly impaired subjects and agematched asymptomatic subjects. Ewor bars represent standard deviations. See Fig. 1 legend for descriptions of conditions. Table 1. Mean Balance Scores (in Seconds)" for Each Group by Trial Condttlon 4' Condltlon 5" Condttlon 6. Groupb Trlal 1 Trlal 2 Trlal 3 Trlal 1 Trlal 2 Trlal 3 Trlal 1 Trlal 2 Trlal 3 *Standard deviations shown in parentheses b~roup l=asymptomatic subjects (n=15) aged 25 to 44 years, group 2=asymptomatic subjects (n=15) aged 45 to 64 years, group 3=asymptomatic subjects (n=15) aged 65 to 84 years, group 4=vestibularly impaired subjects (n = 17). 'Condition 4=standing on foam with eyes open d~ondition 5=standing on foam with eyes closed. "Condition 6=standing on foam wearing visuavvestibularconflict dome. ular disorders cannot. Therefore, this condition may serve as a useful baseline, particularly when assessing older patients with vestibular disorders and other balance problems. On condition 5, both the older group and the vestibularly impaired group performed more poorly than did the younger AS groups. These findings are consistent with those of previous work.10 The vestibularly impaired group performed at the same level as the older AS group, regardless of age. On the measure reported in this study, younger subjects with vestibular impairments performed as if they were older people. On condition 6, although the elderly AS subjects had lower scores than did their younger counterparts, they were better able to perform this condition than subjects with vestibular disorders. These data suggest that a score of 20 seconds on conditions 4, 5, and 6 with the feet together is within normal limits for older subjects. Condition 6 may also be useful in discriminating between older people with and without vestibular disorders. When a therapist suspects a vestibular disorder in a patient without such a diagnosis, these data may help the physical therapist make a referral to the appropriate physician for evaluation. Such a difference may also be useful in reassessing patients after a course of physical therapy. Older AS and vestibularly impaired subjects tended to show higher scores with successive trials on the two conditions in which vision was eliminated or not useful. This finding suggests that these subjects may have used an unsuccessful movement strategy initially, but were able to mod* their motor plans with practice. This finding may indicate that these subjects took longer than younger AS subjects to understand the motor requirements of the task. Because the subjects with vestibular lesions had more variability than other subjects, and because those subjects did improve over trials, it might be useful to administer this test using three or more Physical Therapy/Volume 73, Number 64une 1993

6 trials and take the mean of those trials. This study examined subjects' ability to maintain quiet upright standing when sensory inputs were systematically altered. Measures of sway could provide further insight into performance abilities of individuals in different age groups, but that issue was not examined in this study because obseming sway in the clinic would have required two observers or more sophisticated, expensive equipment. One purpose of this study was to make it easy for a single physical therapist to administer this test. Although the CTSIB does not spec@ the exact nature of a subject's balance problem, it is useful in differentiating between individuals with and without vestibular disorders. The test is also useful for obtaining data about patients' performance before and after therapy, and thus in documenting the efficacy of treatment, for the benefit of Commentary thirdparty payers. Because the CTSIB is inexpensive, it is a useful option for clinics in which expensive dynamic posturography testing equipment is unavailable, but where the therapists still need objective data about balance. Acknowledgments We thank Rebecca Koch, FT, and Millicent Branch, FT, for their assistance. References 1 Horak FB. Clinical measurement of postural control in adults. Phys Ther 1987;67: ShumwayCook A, Horak FB. Assessing the influence of sensory interaction on balance: suggestion from the field. Phys Ther 1986;66: Nashner LM, McCollum G. The organization of human postural movements: a formal basis and experimental synthesis. Behav Brain Sci. 1985;8: Crowe TK, Deitz JC, Richardson PK, Atwater SW. Interrater reliability of the pediatric clinical test of sensory interaction for balance. Physical and Occupational Therapy in Pediatrics. 199O;lO:l27. 5 BillekSawhney B. Clinical and Objective Assessment of Postural Stabilify. Pittsburgh, Pa: University of Pittsburgh; Thesis. 6 Di Fabio RP, Badke MB. Relationship of sensory organization to balance function in patients with hemiplegia. Phys Ther. 1990;70: Toal Tangeman P, Wheeler J. Inner ear concussion syndrome: vestibular implications and physical therapy treatment. ~opiis in Acute Care Trauma Rehabilitation. 1986;1: Pyykko I, Aalto H, Hytonen M, et al. Effect of age on posture control. In: Amblard B, Benhoz A, Clarack E, eds. Posture and Gait: Development, Adaptation, and Modulation. Amsterdam, the Netherlands: Elsevier; 1988: Straube A, Botzel K, Hawken M, et al. Postural control in the elderly: differential effects of visual, vestibular and somatosensory input. In: Amblard B. Benhoz A Clarack E, eds. Posture and Gait:' ~evelo~mtkzt, Adaptation, and Modulation. Amsterdam, the Netherlands: Elsevier; 1988: Woollacott MH. Aging, posture control and movement preparation. In: Woollacott MH, ShumwayCook A, eds. Posture and Gait Across the LiJespan. Columbia, SC: University of South Carolina Press; 1989: Gentile AM. A working model of skill acquisition with application to teaching. Quest, 1972;17:% Norre ME, Forrez G, Beckers A. Vestibular habituation training and posturography on benign paroxysmal positioning vertigo. ORL J Otorhinolaryngol Relat Spec. 1987, The development of effective methods for assessing and treating adults with vestibular deficits is a prominent issue for physical therapists and occupational therapists involved with "vestibular rehabilitation." The article by Cohen et al provides a vehicle for the kind of dialogue that is needed about this important topic. I would consider their study preliminary, however, in view of several issues related to the broad generalization of their results, the inconsistency of agematched comparisons, the recommendation to delete various aspects of the Clinical Test of Sensory Interaction on Balance (CTSIB), and the absence of a documented relationship between stance duration and functional status in patients with vestibular impairments. Generallzatlon of Flndlngs The primary conclusion reported by Cohen and colleagues was that the CTSIB "... is useful in differentiating between individuals with and without vestibular disorders." I believe that this conclusion is potentially misleading for several reasons: 1. Subjects with and without active vertigo have equivalent scores on tests of sensory interaction acquired with posturography.' The conditions used for evaluating balance with posturography and the CTSIB are essentially the same. Posturography, however, incorporates a force platform and a visual enclosure that can be referenced to spontaneous displacements of the subject's center of force.2 Posturography provides a more sensitive measure of balance compared with the CTSIB because manipulation of the sensory environment is precisely controlled and equilibrium scores are derived from vertical floor reaction forces. It is unlikely, therefore, that the CTSIB will identify sensory integration deficits in many patients with vertigo, because more sensitive measures do not detect deficits related to this symptom. Subjects with compensated (chronic) unilateral peripheral vestibular impairments often have normal balance responses when tested 14 / 351 Physical Therapy /Volume 73, Number G/June 1993