Case 2 (B.B.)
B.B. was a 55-year-old woman diagnosed with HD at 50 years of age. At evaluation, she required assistance to manage her finances, home maintenance, and food preparation. B.B. did not work, lived alone in a first-floor apartment, and had a carer 4 days per week to assist with ADL activities. Her medical history is notable for depression, hyperthyroidism, and hypertension. Her medications are listed in Table 2.
Over the past 5 years, B.B. experienced a gradual progression of symptoms and was referred to physical therapy by her neurologist. Her primary activity limitations were poor balance and difficulty walking independently. B.B.'s primary concern was fear of falling following a previous fall that resulted in multiple injuries and hospitalization.
B.B. was independent with dressing and bathing but used a walker for ambulation inside the home and a wheelchair for community mobility. Her mobility was assessed as described in the “Outcomes” Section later and in Figures 2 and 3.
Measures of Activities
Physical Performance Test. The Physical Performance Test (PPT)25 requires individuals to perform 9 tasks that mimic basic to standard ADLs. Each item is rated on a 4-point scale for a maximum score of 36. The PPT is an appropriate measure of function in individuals with HD26 that demonstrates excellent test-retest reliability in individuals with manifest (ie, motor symptoms are present) HD and has a minimal detectible change (MDC) of 5.27
Walking Speed. During the 10-m walk test (10MWT),28 participants ambulate at their self-selected comfortable pace across 14 m: 2 m to allow for acceleration, 10 m where their time to walk is measured, and 2 m to allow for deceleration. The time to complete the 10 m is recorded and gait speed (distance/time) is calculated. The 10MWT gait speed measure has excellent test-retest reliability and an established MDC of 0.3 m/s for individuals with HD.27
Timed Up and Go. The Timed Up and Go (TUG)29 requires participants to stand from a chair, walk 3 m, turn, and return to a seated position in the chair. The participant performs 1 practice and 1 test trial, and the time is complete the task is recorded. The TUG is a good disease-specific measure of mobility in HD,26 with excellent test-retest reliability and an established MDC of 2.98 seconds in individuals with HD.27 Individuals with HD are at increased risk of falls if TUG score is 14 seconds or more.4
Six-Minute Walk Test. The 6-minute walk test (6MWT)30 was collected in case 1 only as a measure of walking endurance. During the 6MWT, an individual ambulates for 6 minutes and the total distance in meters is recorded. The 6MWT has good-excellent test-retest reliability and an established MDC of 86.57 m in individuals with HD.27
Measures of Impairments in Body Function
Berg Balance Scale. The Berg Balance Scale (BBS)31 is a 14-item scale that assesses static balance performance. Quality of performance on each item is scored using a 4-point scale for a maximum score of 56. The BBS is a good disease-specific mobility measure in HD26 that has excellent test-retest reliability in individuals with HD and MDC of 5 for individuals with manifest HD.27 Individuals with HD are at increased risk of falls if BBS score is 40 or less.4
Four Square Step Test. The Four Square Step Test (FSST)32 was collected in case 2 only as a measure of dynamic standing balance. The FSST requires an individual to step over 4 canes, placed in a cross configuration on the floor, in a specific sequence (forward, right, backward, left) and then repeat this sequence in the reverse order. The time to complete this task is recorded as the final score. The FSST has good test-retest reliability and an established MDC of 15.27 seconds in individuals with manifest HD.27
Measures of Quality of Life
36-Item Short Form Survey. The 36-Item Short Form Survey (SF-36)33 was collected in case 2 only to assess health-related quality of life in both the mental and physical domains. The SF-36 is reliable and valid for individuals with HD and their carers.34
Despite enrollment in parent studies, both cases met criteria for classification in TBC C: Mobility, Balance, and Falls Risk, in the HD Clinical Guidelines, including interventions such as balance training, strength training, task-specific practice of functional activities including transfers and walking tasks, and family/carer education (see Table 1, and alsoTable C from Quinn and Busse, 2012.21)
A.A. received one-on-one physical therapy for 8 weeks, delivered 1×/wk for 1 hour. The program consisted of home-based physical therapy focusing on walking, balance, and transfer practice. The therapist also educated and trained the family and carers. The intervention focused on 3 main concepts: (a) mobility and skills training; (b) motivation and goal setting; and (c) opportunity and enablement. Between physical therapy visits, the lead carer conducted independent sessions for 1 h/d over the 8-week intervention.
Mobility training consisted of task-specific balance and strength training in functional transfers, gait, reaching, bed mobility, stair-climbing, and turning. To progress the difficulty, gait was performed both indoors and outdoors, car transfers were practiced, turning was performed in tight spaces, and the time spent on each activity was increased to build endurance. An emphasis was placed on simple verbal instructions and positive reinforcement.
The motivation component of the intervention consisted of setting achievable, meaningful goals to allow A.A. to demonstrate her abilities and build confidence. An ultimate goal of a family holiday motivated A.A. to participate in functional tasks and outdoor ambulation.
The opportunity component of the intervention focused on enabling A.A. to participate in her daily life, family life, and physical activities.
The intervention for B.B. took place within B.B.'s home also over a period of 8 weeks and was focused on the following concepts: (a) gait and postural control; (b) functional mobility; and (c) health-related quality of life. B.B. was instructed to perform exercises at home 3×/wk using a purpose-developed exercise DVD36. Briefly, the DVD consisted of 5 sections: (a) warm-up and flexibility; (b-d) strength and balance exercises tailored specifically for individuals with HD; and (e) cool down and relaxation. The balance exercises were divided into 2 sections. The first section focused on practicing narrowed and altered functional base of support exercises. The easiest of the exercises required the participant to maintain balance while the heels and toes of the feet were touching. To progress the difficulty, these movements were performed with eyes closed, standing on 1 leg, tandem stance, or during forward and side lunges. Level of support was also progressed from holding onto a table/chair to using support only as needed. The second section of balance exercise focused on performance of task-specific activities that required alterations of dynamic balance, such as transfers from sitting to standing, turning, and stepping up onto stairs. To progress the difficulty, the number of repetitions was increased and the number of rest breaks was decreased.
During an initial home visit, the therapist taught each exercise to the participant and instructed B.B. on how to progress the exercises. The therapist also discussed the benefits and precautions for each exercise. All instruction took place in the presence of a carer, who agreed to assist B.B. as needed. In addition to performing the DVD exercises, B.B. also began a 30-minute gradual progressive walking program by walking 1×/wk on level ground around her home and neighborhood. She was instructed to walk at her self-selected comfortable pace and to take rest breaks as needed. She was encouraged to progress her walk by increasing the time walked until she reached 30 minutes. B.B. was asked to keep a record of her daily exercise program in an exercise diary.
The therapist called B.B. weekly to monitor her progress and discuss any issues.
A.A. demonstrated marked improvements in function following 8 weeks of physical therapy intervention. A.A.'s performance on the PPT improved from 4 to 16; her BBS performance improved from 22 to 45, and her TUG performance improved from 47.2 seconds to 33.3 seconds following training. Similarly, gait speed and endurance also improved; at baseline, A.A. was not walking, but following training, she ambulated at 1.18 m/s and walked 297.4 m during the 6MWT (Figures 2A-D and 3A).
A.A.'s carer was actively involved in the intervention, advocating on her behalf and encouraging A.A. to engage in training on days when the physical therapist was not present. Qualitatively, A.A.'s carer noted that although she still required close supervision and occasional assistance:
She does the weekly shopping herself, she goes out, she collects her prescriptions, everything that she needs that now has made her become a wife and mother ... again. Since she's been doing exercises, speech has improved as well.
B.B. also demonstrated improvements in function following 8 weeks of physical therapy intervention. B.B.'s performance on the PPT improved from 13 to 15; her BBS performance improved from 45 to 47, and her TUG performance improved from 22.8 seconds to 13.9 seconds following training. She also demonstrated marked improvements in gait speed, ambulating at 0.39 m/s prior to training and 0.72 m/s posttraining. In addition, she completed the FSST more quickly following training (12.6 seconds pre; 11.9 seconds post) and reported improvements on the physical functioning subscale of the SF-36 with a rise from 20 to 75 (Figures 2A-D and 3B-C).
B.B.'s carer was actively involved in supporting the walking program, where her adherence was excellent, and went above the suggested amount of 30 minutes per week, walking 3 times per week for 30 to 40 minutes total as part of shopping trips with her carer. Conversely, B.B. did not experience as much support from her carer in completing the exercises shown in the DVD, and her adherence rate with the exercise DVD was 2/24 (8.3%). Qualitatively, B.B.'s carer reported:
There is a big improvement from the first time I saw her [two months ago], she is no longer using the wheelchair. She walked from the car park to [the laboratory] today and I would say that is a big improvement.
The purpose of this case series was to demonstrate the use of TBCs to guide physical therapy treatment planning for 2 individuals with HD. Both individuals presented with primary activity limitations in mobility, balance, and falls risk (TBC C; Table 1) and demonstrated improvements in function following 8 weeks of physical therapy targeting gait, balance, and fall risk reduction. Both A.A. and B.B. met the MDC values established for late-stage HD for gait speed and TUG, with increases in gait speed of 1.18 m/s and 0.33 m/s, respectively, and reductions in time to complete the TUG score of 13.9 seconds and 8.9 seconds, respectively (Figure 2A-B). While B.B. demonstrated improvements on the BBS and PPT, only A.A. exceeded the established MDCs for late-stage HD, with improvements of 23 points and 12 points, respectively (Figure 2C-D). Furthermore, both A.A. and B.B. experienced changes in function that indicate a reduced fall risk. Berg Balance Scale scores of 40 or less indicate increased fall risk for individuals with HD4; following training, A.A. moved from a BBS score of 22 to 45, marking a change in fall status from high risk to lower risk. Similarly, individuals with a TUG score of 14 seconds or more are at higher risk for falls4; following training, B.B. moved from a TUG score of 22.8 seconds to 13.9 seconds, demonstrating a shift to lower fall risk. These improvements are particularly notable given that both individuals were the later stage of HD.
Within the guidelines of TBC C, the general aims of physical therapy are to (a) improve mobility status by increasing independence, gait speed, and distance walked; (b) reduce risk of falls or actual falls; (c) maintain independent transfers and walking; and (d) reduce fear of falling.16 Although A.A. and B.B. both demonstrated improvements in gait, balance, and function following 8 weeks of task-specific training, one notable difference in these cases was the involvement of the primary carer. While A.A.'s carer was involved in all aspects of the intervention, B.B.'s carer actively supported only the walking program. Their adherence results support prior work stating that individuals with HD experience more success with exercise when their caregiver is actively involved in the intervention35 and highlight the importance of carer support and encouragement for task-specific practice (ie, walking).
At initial development, we anticipated that the TBCs would have a relationship with disease stage. The TBCs had subcategories related to premanifest (TFC 13; no clinical signs of HD), early (TFC 10-13), middle (TFC 7-9), and late stages (TFC 0-6). Thus, our original article introducing the TBCs suggested that TBC C was applicable to individuals in early- midstage HD.21 However, as this case series shows, individuals with late-stage disease can still be functional and respond to similar interventions as those in earlier disease stages. This case series extends the literature to demonstrate that later-stage clients with HD may benefit from physical therapy services under TBC C and should be referred to physical therapy when (or before) they experience declines. These cases provide proof-of-principle to support the use of TBCs to guide physical therapy management for individuals with HD. Although the TBCs require further validation across disease stages, the clear guidelines within each classification have the potential to address 2 key barriers identified by therapists treating individuals with HD: insufficient use of routine physical therapy–related outcome measures at different stages of HD36 and clearer reporting of intervention protocols so as to generate a better understanding of the impact of exercise and physical therapies on the symptoms of HD.37 Given the changing nature of HD and the variability associated with functional deficits, TBCs have the potential to inform treatment planning, intervention development, and subsequent evaluation in line with the Medical Research Council framework for complex interventions.
Despite the favorable outcomes reported, the case series design limits us from drawing conclusions about the benefit of physical therapy for all individuals with late-stage HD. We acknowledge that some of the benefits may be from social contact with the physical therapists, but this effect was not directly measured. Prospective recordings of falls following the interventions were not obtained, so it is unknown whether these task-specific interventions influenced future fall risk. TBC C recommends interdisciplinary consultations, including occupational therapy, nutrition, and speech therapy, which were not utilized in these studies and may have further improved more global outcomes in these participants. In addition, these cases demonstrate the implementation of outcomes and interventions with regard to only one of the TBCs; future work should not only validate the TBCs, but also examine their utility across disability levels and with regard to current evidence-based literature.
This case series provides proof-of-principle that physical therapy for mobility, balance, and fall risk is feasible and confers benefit for some individuals with late-stage HD. Larger studies with a control group are necessary to confirm these outcomes, and future work should examine the validity of the TBCs to inform physical therapy management of individuals with HD.
The authors gratefully acknowledge the participants and Dr. Deborah Kegelmeyer, Hanne Ludt Fossmo, and Veena Agrawal for review of the manuscript and thoughtful edits. Exercise videos used in Case 2's intervention may be accessed at: https://www.youtube.com/channel/UCH7_ed2__mkzXNWPZqVIosw.
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balance; falls; gait; human movement system; mobility; quality of life; task-specific training
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