J Head Trauma Rehabil Vol. 31, No. 1, pp. E13–E19 c 2016 Wolters Kluwer Health, Inc. All rights reserved. Copyright
Decreased Movement Path Tortuosity Is Associated With Improved Functional Status in Patients With Traumatic Brain Injury William D. Kearns, PhD; Steven Scott, DO; James L. Fozard, PhD; Christina Dillahunt-Aspillaga, PhD; Jan M. Jasiewicz, PhD Objective: To determine if movement path tortuosity in everyday ambulation decreases in Veterans being treated in a residential setting for traumatic brain injury. Elevated path tortuosity is observed in assisted living facility residents with cognitive impairment and at risk for falls, and tortuosity may decrease over the course of cognitive rehabilitation received by the Veterans. If observed, decreased tortuosity may be linked to improved clinical outcomes. Design: Longitudinal observational study without random assignment. Setting: Veterans Affairs Medical Center inpatient residential polytrauma treatment facility. Patients: Twenty-two Veterans enrolled in a postacute predischarge residential polytrauma treatment facility. Interventions: None, observation-only. Main Outcome Measure: Mayo-Portland Adaptability Index-4, and movement path tortuosity measured by Fractal Dimension (Fractal D). Fractal D was obtained continuously from an indoor movement tracking system primarily used to provide machine-generated prompts and reminders to facilitate activities of daily living. Patients were deemed “responders” (N = 10) if a significant linear decline in Fractal D occurred over the course of treatment, or nonresponders (N = 12) if no significant decline was observed. Results: Responders had lower discharge Mayo-Portland Adaptability Inventory scores (mean = 32.6, SD = 9.53) than non-responders (mean = 39.5, SD = 6.02) (F = 2.07, df = 20, P = .05). Responders and nonresponders did not differ on initial injury severity or other demographic measures. Conclusions: Fractal D, a relatively simple measure of movement path tortuosity can be linked to functional recovery from traumatic brain injury. Key words: brain injuries, military personnel, movement variability in everyday ambulation, rehabilitation
Author Affiliations: James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR); Department of Rehabilitation & Mental Health Counseling, College of Behavioral and Community Sciences, University of South Florida, Tampa (Dr Kearns, Dr Dillahunt-Aspillaga); Physical Medicine and Rehabilitation Service, James A. Haley Veterans Administration Hospital, Tampa, Florida (Dr Scott); James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR); School of Aging Studies, College of Behavioral and Community Sciences, University of South Florida, Tampa (Dr Fozard); and James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR), James A. Haley Veterans Administration Hospital, Tampa, Florida (Dr Jasiewicz). This work was supported by the US Department of Veterans Affairs T-21 NonInstitutional Long-Term Care grant entitled “Design of a Patient Centered ‘Welcome Home’ for Independent Living” awarded by the Office of Geriatric and Extended Care to Jan M. Jasiewicz. The authors thank Mss Kristina Martinez and Jay Larsen for their efforts in compiling clinical measures for this article. The views, opinions, and/or findings contained in this article are those of the authors and should not be construed as an official position, policy, or decision of the Department Veterans Affairs unless so designated by other official documentation.
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S THE FUNCTIONAL IMPROVEMENT in Veteran patients being treated for traumatic brain injury (TBI) reflected in declining movement path tortuosity in unrestricted indoor ambulation? Our working answer to this question was “Yes,” based on results from prior research linking both short- and long-term changes in cognitive functioning to irregularities in voluntary ambulation. A common example of such a short-term relationship is the suspected drunk driver being requested to walk a straight line in response to the arresting officer’s demand; inability to walk a straight line is legally acceptable evidence of impaired driving ability.1 In a
Corresponding Author: William D. Kearns, PhD, James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR), AND Department of Rehabilitation & Mental Health Counseling, College of Behavioral and Community Sciences, University of South Florida, Tampa, FL 33620 ([email protected]). DOI: 10.1097/HTR.0000000000000125
E13 Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
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study of mild cognitive decline preceding a clinical diagnosis of dementia, physicians are more likely to note irregularities in gait rather than memory as the earliest of 3 major signs used to make the clinical diagnosis.2 The spatial irregularities of dementia-related wandering are well documented.3–5 Prior studies5,6 directly measured a type of spatial variability—“tortuosity” in movement paths; assisted living facilities residents who exhibited greater tortuosity in casual ambulation as measured by Fractal Dimension (Fractal D) had greater cognitive impairment as measured by the Mini-Mental State Examination 7 and were more likely to have a clinical diagnosis of dementia.6 Fractal D is a dimensionless number that ranges from 1 to 2; when the path traveled between 2 points is a perfectly straight line, it is describable by a single dimension (length) and Fractal D has a value of 1, whereas a path that consumes all of a 2-dimensional plane (x and y) and is completely chaotic would have a Fractal D value of 2 (see Figure 1). An analogy is the “Drunkard’s Walk” or Brownian motion, which has Fractal D’s approaching 2. We adopted Fractal D as our measure of indoor movement variability since it had a long history of use in ecological studies directed at characterizing mammalian spatial orientation in outdoor settings using GPS technologies.8 The transfer of the study methodology from outdoor to indoor environments involved a modification of the subject matter, the measurement scale, and accuracy of the tracking system. The bridge linking increased ambulatory variability and cognitive deficits observed in middle-aged and elderly to those found in young and middle-age adults being treated for TBI requires some discussion. The central tenet is that cognitive deficits seen in middle-
Figure 1. Examples of 3 different ambulation patterns with associated Fractal D levels. Greater path tortuosity is associated with greater cognitive impairment in Veterans with TBI and in assisted living facility residents. Fractal D, fractal dimension; TBI, traumatic brain injury.
aged and elderly persons resemble those of persons with TBI in important ways. The signature injury from the conflicts in Afghanistan (Operation Enduring Freedom) and Iraq (Operation Iraqi Freedom) is polytrauma and TBI9,10 caused either by blast injuries from improvised explosive devices or noncombat injuries such as falls, sports activities, motor vehicle, and training accidents.11 The emotional, cognitive, and behavioral consequences of TBI require multiple courses of rehabilitation.12 Irregularities in ambulation and visual function13 have been observed following injury; and these often resolve over time. Cognitive rehabilitation focuses on the recovery of memory, executive function and carrying out activities. Mild injuries, managed properly, have excellent recovery prospects, whereas moderate to severe injuries often require specialized care and intensive early rehabilitation and lifelong assistance with the performance of routine daily activities.14–16 The US Department of Veterans Affairs Polytrauma Transitional Rehabilitation Program (PTRP) located at the James A. Haley Veterans Administration Hospital in Tampa, Florida is an interdisciplinary residential therapy program that assists service members and their families transitioning from acute injury to optimal functional independence in the community. The length of stay in the program varies from a few months to more than a year. The major goal of the cognitive component of the PTRP treatment program is to raise the Veteran’s awareness of barriers interfering with community reintegration, specifically developing strategies that allow them to independently plan, organize, and complete important everyday activities. In earlier studies with assisted living facility residents, Fractal D was negatively correlated with poorer performance on the Mini-Mental State Examination geographic orientation items.17 The Mini-Mental State Examination geographic orientation items (ie, “What state are we in?” “What city are we in?” “What is the street address of this place?” etc) are the same as those in the Novack Orientation Log,18 a commonly used TBI assessment, suggesting that Fractal D might be useful metric for understanding the long term effects of TBI. Indeed, elevated Fractal D values have been observed in GPS tracking data of Veterans whose TBI occurred as many as 10 years earlier.19 Our working assumption, informed by these studies, is that difficulties with spatial orientation and the ability to plan, organize, and carry out activities are common features of the cognitive deficits in both groups described, and that cognitive rehabilitation will be reflected in decreased path tortuosity (straighter paths and lower Fractal D) over time in at least some of the patients with TBI being treated. Evaluating our assumption was possible because the PTRP is the only facility, to our knowledge, equipped with a highly precise patient tracking system for
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Path Tortuosity and Functional Status in TBI delivering “smart” patient care by providing time and location-dependent behavioral prompts to patients.20 The tracking data inform software that generates machine-based prompts and reminders primarily for activities of daily living, such as taking medications and attending appointments. Tracking all casual ambulation by patients residing in the PTRP generated the data for evaluating the assumption that declining movement path tortuosity would be associated with improvements in cognitive functioning as measured by the Mayo-Portland Adaptability Inventory (MPAI)-4. METHODS Patients The location data and MPAI-4 data were gathered on 22 male Veteran polytrauma patients consecutively admitted to the James A. Haley Veterans Administration Hospital PTRP Smart Home between August 2011 and February 2013. At admission patients received a tracking
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tag physically attached to their PTRP ID badge. All patients had been diagnosed with moderate to severe TBI within 3 years of admission. Patients were excluded from admission to the PTRP if they were not medically stable, used alcohol or illicit substances, or required more than basic supervision of activities of daily living. Use of assistive technologies and wheelchairs was permissible. Patient age, gender, ethnicity, marital status, level of education, injury type, and injury date were obtained from the patients’ electronic health record. The evaluation study was judged to not be research according to the Veterans Health Administration handbook 1058.05 but deemed an operational activity to improve quality of care and consequently exempt from normal institutional review board oversight and informed consent. The demographic descriptions of the patients are displayed in Table 1. The patients had incurred injuries between 2007 and 2011 with slightly greater than half occurring in 2011; Glasgow Coma Scale scores ranged from 3 to 15. Patients ranged from 21 to 52 years of age
Mean admission and discharge MPAI scores, length of stay, and demographic characteristics for responder and nonresponder groups TABLE 1
Variable Admission MPAI Discharge MPAI MPAI change Length of stay, d Age, y Total social supports Race/ethnicity Caucasian Hispanic African American Marital status Single Married Divorced Separated Education (highest) High school Some college College graduate Postgraduate degree Mobility aids used None Cane Rolling walker Manual wheelchair Mobility aid usage Continuously On uneven surfaces Alternates among aids Discontinued use
Responder (n = 10)
Nonresponder (n = 12)
46.6 (6.38) 32.6 (9.53) 14 (8.48) 137.7 (51.3) 32.3 (10.3) 2.4 (1.08)
49.6 (7.37) 39.5 (6.02) 10.08 (4.16) 147.0 (66.4) 32.7 (9.4) 2.2 (.75)
50% 40% 10%
66.7% 25% 8.3%
70% 20% 10% 0%
58.3% 16.7% 16.7% 8.3%
50% 40% 0% 10%
75% 16.7% 8.3% 0%
60% 20% 10% 10%
58.3% 25% 16.7% 0%
0% 10% 10% 20%
0% 8.3% 0% 33.3%
t = 1.00, df = 20, P = NS t = 2.01, df = 20, P < .05 t = 1.41, df = 20, P = NS t < 1, df = 20, P = NS t < 1, df = 20, P = NS t < 1, df = 20, P = NS
Abbreviations: MPAI, Mayo-Portland Adaptability Inventory.
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(mean = 32.6, SD = 9.0). Patients reported varying levels of social support: parent (72.7%), sibling (45.5%), aunt/uncle (4.5%), spouse (36.4%), children (22.7%), friends (18.2%), other (22.7%), and 9.1% reported no social support; the mean number of reported social supports was 2.3 (SD = 2.0). Measures Mayo-Portland Adaptability Inventory-4 Functional assessment was performed by the MPAI-4.21,22 “MPAI-4 is the standard brain injury rehabilitation outcomes assessment instrument for both the Veterans Health Administration Polytrauma Rehabilitation Centers and the Polytrauma Transitional Rehabilitation Programs.”11(p2418) In the present evaluation, the MPAI had been administered at PTRP program admission and discharge, however; only the clinician assessments were routinely gathered. Functional assessments conducted at admission helped establish treatment plans, whereas those administered at release assisted the staff in determining readiness for discharge. The MPAI-4 has 3 indices: (1) Ability (eg, sensory, motor, and cognitive abilities), (2) Adjustment (eg, mood, interpersonal interactions), and (3) Participation (eg, social contact, initiation, and money management).23 The indices have 12, 8, and 9 items respectively in the range from 0 (no functional disabilities) to 4 (impairment interferes most of the time); a total score is generated for each index and the MPAI full-scale score may range from 0 to 110 with higher scores indicating greater impairment. The 3 subscale indices are converted to T scores using both normative national data, and a Mayo clinic sample of ratings by individuals with TBI, their significant others, and clinical staff.21–23 Full-scale T scores under 30 indicate a favorable outcome, whereas T scores above 60 indicate severe limitations; and scores of 30, 40, 50, and 60 indicate mild, mild to moderate, and moderate to severe limitations, respectively. Until recently, the Participation index (independent of the entire MPAI-4) “ . . . has not been used extensively in research applications, although studies support the use of the entire MPAI4 with pediatric and adult populations”.11,22,24–26,27 A 7-point decline in full-scale MPAI-4 is considered the minimally clinically significant change by PTRP staff. Movement path fractal dimension The PTRP Smart Home high-precision tracking system resolves patients’ indoor position to 20 cm in 3-dimensions relative to a fixed reference point in the SW corner of the building, enabling the delivery of location-based behavioral prompts contingent on person, place, and time.20 The tracking system uses ultra-
wideband radio and is commercially available from Ubisense LLC (Cambridge, United Kingdom). Patients wear a lightweight (32 g) tag in a transparent plastic pouch on a neck lanyard that also contained their identity badge and key card. The tag emits a radio signal every 0.8 seconds that is detected by wall-mounted sensors. Position is calculated by resolving the time difference of arrival and by the angle of arrival of the tag signal. The raw location data were processed in real time to generate longitudinal Fractal D information on patients’ movement paths using the “Real-Time Fractal Path Analysis” program created by Craighead.28 Procedure Each patient admitted to the PTRP was assigned a tracking tag integral to the PTRP smart home system. Clinical staff using the MPAI evaluated each patient’s functional status, and upon completion of the clinical review a personalized therapeutic program was developed to address the specific physical and cognitive needs that maximize successful community reintegration. For the duration of their treatment in the PTRP the smart home continuously recorded the movement of the patient within the facility. Data reduction and analysis Fractal D Mean daily Fractal D was calculated for each patient by averaging Fractal D values obtained for each movement path29 across 24 hours. A visual inspection of the first several patients’ longitudinal Fractal D data indicated that some showed consistent declines in Fractal D over the weeks of their treatment in the PTRP smart home; a subsequent fitting of linear trend lines to the data across the course of month-long treatment indicated approximately 50% of patients showed declines in Fractal D. To examine if Fractal D was associated with improved outcomes, it was necessary to constitute 2 contrast groups, those whose Fractal D declined and those that did not. The following rule was instated: Those patients having 4% or more of the variance in Fractal D accounted for by a descending linear trend over the extended course of therapy in the PTRP made up the “responder” group (n = 10) and those with no discernible downward trend constituted the “nonresponder” group (n = 12). The subsequent analyses of the MPAI clinical measure is presented for these 2 groups. RESULTS A t test for independent groups on the full-scale MPAI T scores obtained at discharge from the PTRP was conducted to evaluate the stability of the association. As anticipated, the group effect (responder
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Path Tortuosity and Functional Status in TBI
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Figure 2. Patient 4: responder. Weekly longitudinal Fractal D between data collection began on November 3, 2011 and ended April 4, 2012. His intake MPAI was 43, and 32 at discharge; his LOS was 176 days. Fractal D, fractal dimension; LOS, length of stay; MPAI, Mayo-Portland Adaptability Inventory.
vs nonresponder) was significant (t = 2.07; df = 20; P = .05). Table 1 presents the mean and standard deviations for the 2 groups at admission and discharge. MPAI scores at admission were relatively similar for the 2 groups; there were no discernible differences between the groups on social support, marital status, education, or the use of mobility aids. As expected, the MPAI scores
on the 2 administrations were significantly and positively correlated (r = 0.64; n = 22; P < .01). Figure 2 presents longitudinal data for a patient categorized as a “responder”; each datum represents the daily mean Fractal D for the patient, and the longitudinal mean for each participant is represented by the horizontal line through the data showing Fractal D
Figure 3. Patient 18: nonresponder. Weekly Fractal D data collection began January 13, 2012 and ended July 8, 2012. No change was discernible in the patient’s Fractal D scores over time. His MPAI at intake was MPAI was 71 and 53 at his discharge: his total length of stay was 271 days. Fractal D, fractal dimension; MPAI, Mayo-Portland Adaptability Inventory.
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declined over the course of treatment. Figure 3 displays data for a nonresponder whose daily average Fractal D did not decline during treatment. DISCUSSION The major finding in this evaluation was that patients with TBI with reliable declines in Fractal D (responders) also had significantly lower MPAI-4 full-scale scores at discharge than nonresponders. The groups did not differ at the time of intake on their average full-scale MPAIs, length of stay, nor on the demographic measures. To our knowledge, this is the first report of a decrease in path tortuosity over the course of treatment being associated with lower total discharge MPAIs. It is not known why a decline in path tortuosity is associated with low MPAI-4 discharge scores in some but not all the patients discharged over this time period. The MPAI-4 is a multifaceted instrument; intake and discharge scores support, but do not determine, the consensus-based clinical decision to discharge a patient. None of the available patient information suggests a reason for the differences. The significant correlation between intake and discharge MPAI scores (r = 0.64) indicates that the patient’s condition at admission is a significant contributing factor to the later decision to discharge a patient. The criterion for creating the responder and nonresponder groups was empirical and may have masked some other unmeasured difference between the groups. Long length of stay and high MPAI-4 intake scores were not significant contributors to the observed results. However, inspection of the figures show that the non-
responder, patient 18, declined from an MPAI-4 admission score of 71 to a discharge score of 53 271 days later. His discharge MPAI-4 was in the moderate to severe range, somewhat higher than the intake MPAI scores of the responder, patient 4, who also had a shorter length of stay. Earlier studies have demonstrated that path tortuosity in casual outdoor ambulation is significantly higher in community dwelling Veterans with a history of TBI than controls.19 The time since injury was much longer in these Veterans than those in this study. As indicated previously, increased path tortuosity is associated with cognitive deficits as well as a clinical diagnosis of dementia, and greater fall risk.5,6,29 Confusion and disorientation are early consequences of TBI. Together, these results suggest that reduced path tortuosity (Fractal D) may reflect cognitive rehabilitation of Veterans being treated for TBI. In conclusion, our evaluation of cognitive rehabilitation in a PTRP indicates that for some patients, declines in path tortuosity over the course of treatment are reflected in reduced path tortuosity. Determination of the basis for the relationship requires a dedicated study. The results of the evaluation reported has resulted in the weekly Fractal D scores being included in the clinical progress notes of the patients with PTRP; the weekly trends have been consistent with the results in this report. In addition to evaluation studies, research studies are needed to further investigate how Fractal D, a relatively simple measure of movement path tortuosity, can be linked to functional recovery from TBI. This new measure may prove useful for clinicians for rehabilitation planning purposes.
REFERENCES 1. Stuster J. Development of a Standardized Field Sobriety Test (SFST) Training Management System. In: Administration NHTS, ed Alexandria, VA: National Technical Information Service; 2002: 25. 2. Verghese J, Lipton RB, Hall CB, Kuslansky G, Katz MJ, Buschke H. Abnormality of gait as a predictor of nonAlzheimer’s dementia. N Engl J Med. 2002;347(22):1761–1768. 3. Kearns WD, Algase D, Moore DH, Ahmed S. Ultra wideband radio: A novel method for measuring wandering in persons with dementia. Gerontechnology. 2008;7(1):48–57. 4. Algase D, Moore D, Vandeweerd C, Gavin-Dreschnack DJ. Mapping the maze of terms and definitions in dementia-related wandering. Aging Ment Health. 2007;11(6):686–698. 5. Kearns WD, Nams VO, Fozard JL. Tortuosity in movement paths is related to cognitive impairment wireless fractal estimation in assisted living facility residents. Methods Inf Med. 2010;49(6):592– 598. 6. Kearns W, Fozard JL, Nams VO, Craighead JD. Wireless telesurveillance system for detecting dementia. Gerontechnology. 2011;10:90–102.
7. Crum RM, Anthony JC, Bassett SS, Folstein MF. Populationbased norms for the Mini-Mental State Examination by age and educational level. JAMA. 1993;269(18):2386–2391. 8. Nams VO. Detecting oriented movement of animals. Anim Behav. 2006;72:1197–1203. 9. Kupersmith J, Lew HL, Ommaya AK, Jaffee M, Koroshetz WJ. Traumatic brain injury research opportunities: Results of Department of Veterans Affairs Consensus Conference. J Rehabil Res Dev. 2009;46(6):vii-xvi. 10. Levin HS. Neuroplasticity following nonpenetrating traumatic brain injury. Brain Inj. 2003;17(8):665–674. 11. Kean J, Malec JF, Cooper DB, Bowles AO. Utility of the MayoPortland Adaptability Inventory-4 for self-reported outcomes in a military sample with traumatic brain injury. Arch Phys Med Rehabil. 2013;94(12):2417–2424. 12. Bergman MM. A proposed resolution of the remediationcompensation controversy in brain injury rehabilitation. Cogn Technol. 1998;3:45–51. 13. Kapoor N, Ciuffreda KJ. Vision disturbances following traumatic brain injury. Curr Treat Options Neurol. 2002;4(4):271–280.
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Path Tortuosity and Functional Status in TBI 14. O’Neil ME, Carlson KF, Storzbach D, et al. Factors associated with mild traumatic brain injury in veterans and military personnel: a systematic review. J Int Neuropsychol Soc. 2014;20(3): 249–261. 15. Ettenhofer ML, Melrose RJ, Delawalla Z, Castellon SA, Okonek A. Correlates of functional status among OEF/OIF veterans with a history of traumatic brain injury. Mil Med. 2012;177(11):1272– 1278. 16. Hoge CW, McGurk D, Thomas JL, Cox AL, Engel CC, Castro CA. Mild traumatic brain injury in U.S. Soldiers returning from Iraq. N Engl J Med. 2008;358(5):453–463. 17. Kearns W, Fozard JL. Tracking natural human movements identifies differences in cognition and health. In: J.C. Augusto et al. (Eds.). Handbook of Ambient Assisted Living. Amsterdam, The Netherlands: IOS Press; 2012:331–345. 18. Jackson WT, Novack TA, Dowler RN. Effective serial measurement of cognitive orientation in rehabilitation: the Orientation Log. Arch Phys Med Rehabil. 1998;79(6):718–720. 19. Kearns WD, Fozard JL, Schonfeld L, Scott S, Marshall K. Elevated movement path tortuosity in voluntary outdoor ambulation in community-dwelling veterans with a history of traumatic brain injury [published online ahead of print February 28, 2014]. J Head Trauma Rehabil. 2014. doi:10.1097/HTR.0000000000000021. 20. Jasiewicz J, Kearns W, Craighead J, Fozard JL, Scott S, McCarthy J Jr. Smart rehabilitation for the 21st century: the Tampa Smart Home for veterans with traumatic brain injury. J Rehabil Res Dev. 2011;48(8):vii–xviii. 21. Malec JF. The Mayo-Portland Participation Index: a brief and psychometrically sound measure of brain injury outcome. Arch Phys Med Rehabil. 2004;85(12):1989–1996. 22. Wilde EA, Whiteneck GG, Bogner J, et al. Recommendations for the use of common outcome measures in traumatic
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Decreased Movement Path Tortuosity Is Associated With Improved Functional Status in Patients With Traumatic Brain Injury William D. Kearns, PhD; Steven Scott, DO; James L. Fozard, PhD; Christina Dillahunt-Aspillaga, PhD; Jan M. Jasiewicz, PhD Objective: To determine if movement path tortuosity in everyday ambulation decreases in Veterans being treated in a residential setting for traumatic brain injury. Elevated path tortuosity is observed in assisted living facility residents with cognitive impairment and at risk for falls, and tortuosity may decrease over the course of cognitive rehabilitation received by the Veterans. If observed, decreased tortuosity may be linked to improved clinical outcomes. Design: Longitudinal observational study without random assignment. Setting: Veterans Affairs Medical Center inpatient residential polytrauma treatment facility. Patients: Twenty-two Veterans enrolled in a postacute predischarge residential polytrauma treatment facility. Interventions: None, observation-only. Main Outcome Measure: Mayo-Portland Adaptability Index-4, and movement path tortuosity measured by Fractal Dimension (Fractal D). Fractal D was obtained continuously from an indoor movement tracking system primarily used to provide machine-generated prompts and reminders to facilitate activities of daily living. Patients were deemed “responders” (N = 10) if a significant linear decline in Fractal D occurred over the course of treatment, or nonresponders (N = 12) if no significant decline was observed. Results: Responders had lower discharge Mayo-Portland Adaptability Inventory scores (mean = 32.6, SD = 9.53) than non-responders (mean = 39.5, SD = 6.02) (F = 2.07, df = 20, P = .05). Responders and nonresponders did not differ on initial injury severity or other demographic measures. Conclusions: Fractal D, a relatively simple measure of movement path tortuosity can be linked to functional recovery from traumatic brain injury. Key words: brain injuries, military personnel, movement variability in everyday ambulation, rehabilitation
Author Affiliations: James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR); Department of Rehabilitation & Mental Health Counseling, College of Behavioral and Community Sciences, University of South Florida, Tampa (Dr Kearns, Dr Dillahunt-Aspillaga); Physical Medicine and Rehabilitation Service, James A. Haley Veterans Administration Hospital, Tampa, Florida (Dr Scott); James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR); School of Aging Studies, College of Behavioral and Community Sciences, University of South Florida, Tampa (Dr Fozard); and James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR), James A. Haley Veterans Administration Hospital, Tampa, Florida (Dr Jasiewicz). This work was supported by the US Department of Veterans Affairs T-21 NonInstitutional Long-Term Care grant entitled “Design of a Patient Centered ‘Welcome Home’ for Independent Living” awarded by the Office of Geriatric and Extended Care to Jan M. Jasiewicz. The authors thank Mss Kristina Martinez and Jay Larsen for their efforts in compiling clinical measures for this article. The views, opinions, and/or findings contained in this article are those of the authors and should not be construed as an official position, policy, or decision of the Department Veterans Affairs unless so designated by other official documentation.
I
S THE FUNCTIONAL IMPROVEMENT in Veteran patients being treated for traumatic brain injury (TBI) reflected in declining movement path tortuosity in unrestricted indoor ambulation? Our working answer to this question was “Yes,” based on results from prior research linking both short- and long-term changes in cognitive functioning to irregularities in voluntary ambulation. A common example of such a short-term relationship is the suspected drunk driver being requested to walk a straight line in response to the arresting officer’s demand; inability to walk a straight line is legally acceptable evidence of impaired driving ability.1 In a
Corresponding Author: William D. Kearns, PhD, James A. Haley Veterans Administration Hospital Center of Innovation on Disability and Rehabilitation Research (CINDRR), AND Department of Rehabilitation & Mental Health Counseling, College of Behavioral and Community Sciences, University of South Florida, Tampa, FL 33620 ([email protected]). DOI: 10.1097/HTR.0000000000000125
E13 Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
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study of mild cognitive decline preceding a clinical diagnosis of dementia, physicians are more likely to note irregularities in gait rather than memory as the earliest of 3 major signs used to make the clinical diagnosis.2 The spatial irregularities of dementia-related wandering are well documented.3–5 Prior studies5,6 directly measured a type of spatial variability—“tortuosity” in movement paths; assisted living facilities residents who exhibited greater tortuosity in casual ambulation as measured by Fractal Dimension (Fractal D) had greater cognitive impairment as measured by the Mini-Mental State Examination 7 and were more likely to have a clinical diagnosis of dementia.6 Fractal D is a dimensionless number that ranges from 1 to 2; when the path traveled between 2 points is a perfectly straight line, it is describable by a single dimension (length) and Fractal D has a value of 1, whereas a path that consumes all of a 2-dimensional plane (x and y) and is completely chaotic would have a Fractal D value of 2 (see Figure 1). An analogy is the “Drunkard’s Walk” or Brownian motion, which has Fractal D’s approaching 2. We adopted Fractal D as our measure of indoor movement variability since it had a long history of use in ecological studies directed at characterizing mammalian spatial orientation in outdoor settings using GPS technologies.8 The transfer of the study methodology from outdoor to indoor environments involved a modification of the subject matter, the measurement scale, and accuracy of the tracking system. The bridge linking increased ambulatory variability and cognitive deficits observed in middle-aged and elderly to those found in young and middle-age adults being treated for TBI requires some discussion. The central tenet is that cognitive deficits seen in middle-
Figure 1. Examples of 3 different ambulation patterns with associated Fractal D levels. Greater path tortuosity is associated with greater cognitive impairment in Veterans with TBI and in assisted living facility residents. Fractal D, fractal dimension; TBI, traumatic brain injury.
aged and elderly persons resemble those of persons with TBI in important ways. The signature injury from the conflicts in Afghanistan (Operation Enduring Freedom) and Iraq (Operation Iraqi Freedom) is polytrauma and TBI9,10 caused either by blast injuries from improvised explosive devices or noncombat injuries such as falls, sports activities, motor vehicle, and training accidents.11 The emotional, cognitive, and behavioral consequences of TBI require multiple courses of rehabilitation.12 Irregularities in ambulation and visual function13 have been observed following injury; and these often resolve over time. Cognitive rehabilitation focuses on the recovery of memory, executive function and carrying out activities. Mild injuries, managed properly, have excellent recovery prospects, whereas moderate to severe injuries often require specialized care and intensive early rehabilitation and lifelong assistance with the performance of routine daily activities.14–16 The US Department of Veterans Affairs Polytrauma Transitional Rehabilitation Program (PTRP) located at the James A. Haley Veterans Administration Hospital in Tampa, Florida is an interdisciplinary residential therapy program that assists service members and their families transitioning from acute injury to optimal functional independence in the community. The length of stay in the program varies from a few months to more than a year. The major goal of the cognitive component of the PTRP treatment program is to raise the Veteran’s awareness of barriers interfering with community reintegration, specifically developing strategies that allow them to independently plan, organize, and complete important everyday activities. In earlier studies with assisted living facility residents, Fractal D was negatively correlated with poorer performance on the Mini-Mental State Examination geographic orientation items.17 The Mini-Mental State Examination geographic orientation items (ie, “What state are we in?” “What city are we in?” “What is the street address of this place?” etc) are the same as those in the Novack Orientation Log,18 a commonly used TBI assessment, suggesting that Fractal D might be useful metric for understanding the long term effects of TBI. Indeed, elevated Fractal D values have been observed in GPS tracking data of Veterans whose TBI occurred as many as 10 years earlier.19 Our working assumption, informed by these studies, is that difficulties with spatial orientation and the ability to plan, organize, and carry out activities are common features of the cognitive deficits in both groups described, and that cognitive rehabilitation will be reflected in decreased path tortuosity (straighter paths and lower Fractal D) over time in at least some of the patients with TBI being treated. Evaluating our assumption was possible because the PTRP is the only facility, to our knowledge, equipped with a highly precise patient tracking system for
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Path Tortuosity and Functional Status in TBI delivering “smart” patient care by providing time and location-dependent behavioral prompts to patients.20 The tracking data inform software that generates machine-based prompts and reminders primarily for activities of daily living, such as taking medications and attending appointments. Tracking all casual ambulation by patients residing in the PTRP generated the data for evaluating the assumption that declining movement path tortuosity would be associated with improvements in cognitive functioning as measured by the Mayo-Portland Adaptability Inventory (MPAI)-4. METHODS Patients The location data and MPAI-4 data were gathered on 22 male Veteran polytrauma patients consecutively admitted to the James A. Haley Veterans Administration Hospital PTRP Smart Home between August 2011 and February 2013. At admission patients received a tracking
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tag physically attached to their PTRP ID badge. All patients had been diagnosed with moderate to severe TBI within 3 years of admission. Patients were excluded from admission to the PTRP if they were not medically stable, used alcohol or illicit substances, or required more than basic supervision of activities of daily living. Use of assistive technologies and wheelchairs was permissible. Patient age, gender, ethnicity, marital status, level of education, injury type, and injury date were obtained from the patients’ electronic health record. The evaluation study was judged to not be research according to the Veterans Health Administration handbook 1058.05 but deemed an operational activity to improve quality of care and consequently exempt from normal institutional review board oversight and informed consent. The demographic descriptions of the patients are displayed in Table 1. The patients had incurred injuries between 2007 and 2011 with slightly greater than half occurring in 2011; Glasgow Coma Scale scores ranged from 3 to 15. Patients ranged from 21 to 52 years of age
Mean admission and discharge MPAI scores, length of stay, and demographic characteristics for responder and nonresponder groups TABLE 1
Variable Admission MPAI Discharge MPAI MPAI change Length of stay, d Age, y Total social supports Race/ethnicity Caucasian Hispanic African American Marital status Single Married Divorced Separated Education (highest) High school Some college College graduate Postgraduate degree Mobility aids used None Cane Rolling walker Manual wheelchair Mobility aid usage Continuously On uneven surfaces Alternates among aids Discontinued use
Responder (n = 10)
Nonresponder (n = 12)
46.6 (6.38) 32.6 (9.53) 14 (8.48) 137.7 (51.3) 32.3 (10.3) 2.4 (1.08)
49.6 (7.37) 39.5 (6.02) 10.08 (4.16) 147.0 (66.4) 32.7 (9.4) 2.2 (.75)
50% 40% 10%
66.7% 25% 8.3%
70% 20% 10% 0%
58.3% 16.7% 16.7% 8.3%
50% 40% 0% 10%
75% 16.7% 8.3% 0%
60% 20% 10% 10%
58.3% 25% 16.7% 0%
0% 10% 10% 20%
0% 8.3% 0% 33.3%
t = 1.00, df = 20, P = NS t = 2.01, df = 20, P < .05 t = 1.41, df = 20, P = NS t < 1, df = 20, P = NS t < 1, df = 20, P = NS t < 1, df = 20, P = NS
Abbreviations: MPAI, Mayo-Portland Adaptability Inventory.
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(mean = 32.6, SD = 9.0). Patients reported varying levels of social support: parent (72.7%), sibling (45.5%), aunt/uncle (4.5%), spouse (36.4%), children (22.7%), friends (18.2%), other (22.7%), and 9.1% reported no social support; the mean number of reported social supports was 2.3 (SD = 2.0). Measures Mayo-Portland Adaptability Inventory-4 Functional assessment was performed by the MPAI-4.21,22 “MPAI-4 is the standard brain injury rehabilitation outcomes assessment instrument for both the Veterans Health Administration Polytrauma Rehabilitation Centers and the Polytrauma Transitional Rehabilitation Programs.”11(p2418) In the present evaluation, the MPAI had been administered at PTRP program admission and discharge, however; only the clinician assessments were routinely gathered. Functional assessments conducted at admission helped establish treatment plans, whereas those administered at release assisted the staff in determining readiness for discharge. The MPAI-4 has 3 indices: (1) Ability (eg, sensory, motor, and cognitive abilities), (2) Adjustment (eg, mood, interpersonal interactions), and (3) Participation (eg, social contact, initiation, and money management).23 The indices have 12, 8, and 9 items respectively in the range from 0 (no functional disabilities) to 4 (impairment interferes most of the time); a total score is generated for each index and the MPAI full-scale score may range from 0 to 110 with higher scores indicating greater impairment. The 3 subscale indices are converted to T scores using both normative national data, and a Mayo clinic sample of ratings by individuals with TBI, their significant others, and clinical staff.21–23 Full-scale T scores under 30 indicate a favorable outcome, whereas T scores above 60 indicate severe limitations; and scores of 30, 40, 50, and 60 indicate mild, mild to moderate, and moderate to severe limitations, respectively. Until recently, the Participation index (independent of the entire MPAI-4) “ . . . has not been used extensively in research applications, although studies support the use of the entire MPAI4 with pediatric and adult populations”.11,22,24–26,27 A 7-point decline in full-scale MPAI-4 is considered the minimally clinically significant change by PTRP staff. Movement path fractal dimension The PTRP Smart Home high-precision tracking system resolves patients’ indoor position to 20 cm in 3-dimensions relative to a fixed reference point in the SW corner of the building, enabling the delivery of location-based behavioral prompts contingent on person, place, and time.20 The tracking system uses ultra-
wideband radio and is commercially available from Ubisense LLC (Cambridge, United Kingdom). Patients wear a lightweight (32 g) tag in a transparent plastic pouch on a neck lanyard that also contained their identity badge and key card. The tag emits a radio signal every 0.8 seconds that is detected by wall-mounted sensors. Position is calculated by resolving the time difference of arrival and by the angle of arrival of the tag signal. The raw location data were processed in real time to generate longitudinal Fractal D information on patients’ movement paths using the “Real-Time Fractal Path Analysis” program created by Craighead.28 Procedure Each patient admitted to the PTRP was assigned a tracking tag integral to the PTRP smart home system. Clinical staff using the MPAI evaluated each patient’s functional status, and upon completion of the clinical review a personalized therapeutic program was developed to address the specific physical and cognitive needs that maximize successful community reintegration. For the duration of their treatment in the PTRP the smart home continuously recorded the movement of the patient within the facility. Data reduction and analysis Fractal D Mean daily Fractal D was calculated for each patient by averaging Fractal D values obtained for each movement path29 across 24 hours. A visual inspection of the first several patients’ longitudinal Fractal D data indicated that some showed consistent declines in Fractal D over the weeks of their treatment in the PTRP smart home; a subsequent fitting of linear trend lines to the data across the course of month-long treatment indicated approximately 50% of patients showed declines in Fractal D. To examine if Fractal D was associated with improved outcomes, it was necessary to constitute 2 contrast groups, those whose Fractal D declined and those that did not. The following rule was instated: Those patients having 4% or more of the variance in Fractal D accounted for by a descending linear trend over the extended course of therapy in the PTRP made up the “responder” group (n = 10) and those with no discernible downward trend constituted the “nonresponder” group (n = 12). The subsequent analyses of the MPAI clinical measure is presented for these 2 groups. RESULTS A t test for independent groups on the full-scale MPAI T scores obtained at discharge from the PTRP was conducted to evaluate the stability of the association. As anticipated, the group effect (responder
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Path Tortuosity and Functional Status in TBI
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Figure 2. Patient 4: responder. Weekly longitudinal Fractal D between data collection began on November 3, 2011 and ended April 4, 2012. His intake MPAI was 43, and 32 at discharge; his LOS was 176 days. Fractal D, fractal dimension; LOS, length of stay; MPAI, Mayo-Portland Adaptability Inventory.
vs nonresponder) was significant (t = 2.07; df = 20; P = .05). Table 1 presents the mean and standard deviations for the 2 groups at admission and discharge. MPAI scores at admission were relatively similar for the 2 groups; there were no discernible differences between the groups on social support, marital status, education, or the use of mobility aids. As expected, the MPAI scores
on the 2 administrations were significantly and positively correlated (r = 0.64; n = 22; P < .01). Figure 2 presents longitudinal data for a patient categorized as a “responder”; each datum represents the daily mean Fractal D for the patient, and the longitudinal mean for each participant is represented by the horizontal line through the data showing Fractal D
Figure 3. Patient 18: nonresponder. Weekly Fractal D data collection began January 13, 2012 and ended July 8, 2012. No change was discernible in the patient’s Fractal D scores over time. His MPAI at intake was MPAI was 71 and 53 at his discharge: his total length of stay was 271 days. Fractal D, fractal dimension; MPAI, Mayo-Portland Adaptability Inventory.
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declined over the course of treatment. Figure 3 displays data for a nonresponder whose daily average Fractal D did not decline during treatment. DISCUSSION The major finding in this evaluation was that patients with TBI with reliable declines in Fractal D (responders) also had significantly lower MPAI-4 full-scale scores at discharge than nonresponders. The groups did not differ at the time of intake on their average full-scale MPAIs, length of stay, nor on the demographic measures. To our knowledge, this is the first report of a decrease in path tortuosity over the course of treatment being associated with lower total discharge MPAIs. It is not known why a decline in path tortuosity is associated with low MPAI-4 discharge scores in some but not all the patients discharged over this time period. The MPAI-4 is a multifaceted instrument; intake and discharge scores support, but do not determine, the consensus-based clinical decision to discharge a patient. None of the available patient information suggests a reason for the differences. The significant correlation between intake and discharge MPAI scores (r = 0.64) indicates that the patient’s condition at admission is a significant contributing factor to the later decision to discharge a patient. The criterion for creating the responder and nonresponder groups was empirical and may have masked some other unmeasured difference between the groups. Long length of stay and high MPAI-4 intake scores were not significant contributors to the observed results. However, inspection of the figures show that the non-
responder, patient 18, declined from an MPAI-4 admission score of 71 to a discharge score of 53 271 days later. His discharge MPAI-4 was in the moderate to severe range, somewhat higher than the intake MPAI scores of the responder, patient 4, who also had a shorter length of stay. Earlier studies have demonstrated that path tortuosity in casual outdoor ambulation is significantly higher in community dwelling Veterans with a history of TBI than controls.19 The time since injury was much longer in these Veterans than those in this study. As indicated previously, increased path tortuosity is associated with cognitive deficits as well as a clinical diagnosis of dementia, and greater fall risk.5,6,29 Confusion and disorientation are early consequences of TBI. Together, these results suggest that reduced path tortuosity (Fractal D) may reflect cognitive rehabilitation of Veterans being treated for TBI. In conclusion, our evaluation of cognitive rehabilitation in a PTRP indicates that for some patients, declines in path tortuosity over the course of treatment are reflected in reduced path tortuosity. Determination of the basis for the relationship requires a dedicated study. The results of the evaluation reported has resulted in the weekly Fractal D scores being included in the clinical progress notes of the patients with PTRP; the weekly trends have been consistent with the results in this report. In addition to evaluation studies, research studies are needed to further investigate how Fractal D, a relatively simple measure of movement path tortuosity, can be linked to functional recovery from TBI. This new measure may prove useful for clinicians for rehabilitation planning purposes.
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