Functional freezing of gait: lessons from compensation.

We highlight a specific and hitherto poorly characterised phenotype of functional gait impairments: functional freezing of gait. Unique to the presented case is the use of compensation strategies, many of which at first sight might appear to hint towards the presence of freezing of gait typical of Parkinson's disease or another form of Parkinsonism. Importantly, however, this patient's compensation strategies involved various inconsistent and incongruent elements, supporting the diagnosis of a functional neurological disorder. Recognising the features of functional freezing also helps to appreciate better the classical manifestations of freezing of gait in Parkinson's disease.

The effect of walking with reduced trunk motion on dynamic stability in healthy adults.

BACKGROUND: Most people with Parkinson's disease (PD) walk with a smaller mediolateral base of support (BoS) compared to healthy people, but the underlying mechanisms remain unknown. Reduced trunk motion in people with PD might be related to this narrow-based gait. Here, we study the relationship between trunk motion and narrow-based gait in healthy adults. According to the extrapolated center of mass (XCoM) concept, a decrease in mediolateral XCoM excursion would require a smaller mediolateral BoS to maintain a constant margin of stability (MoS) and remain stable. RESEARCH QUESTION: As proof of principle, we assessed whether walking with reduced trunk motion results in a smaller step width in healthy adults, without altering the mediolateral MoS. METHODS: Fifteen healthy adults walked on a treadmill at preferred comfortable walking speed in two conditions. First, the 'regular walking' condition without any instructions, and second, the 'reduced trunk motion' condition with the instruction: 'Keep your trunk as still as possible'. Treadmill speed was kept the same in the two conditions. Trunk kinematics, step width, mediolateral XCoM excursion and mediolateral MoS were calculated and compared between the two conditions. RESULTS: Walking with the instruction to keep the trunk still significantly reduced trunk kinematics. Walking with reduced trunk motion resulted in significant decreases in step width and mediolateral XCoM excursion, but not in the mediolateral MoS. Furthermore, step width and mediolateral XCoM excursion were strongly correlated during both conditions (r = 0.887 and r = 0.934). SIGNIFICANCE: This study shows that walking with reduced trunk motion leads to a gait pattern with a smaller BoS in healthy adults, without altering the mediolateral MoS. Our findings indicate a strong coupling between CoM motion state and the mediolateral BoS. We expect that people with PD who walk narrow-based, have a similar mediolateral MoS as healthy people, which will be further investigated.

Gait-Adaptability Training in People With Hereditary Spastic Paraplegia: A Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: In people with hereditary spastic paraplegia (HSP), reduced gait adaptability is common and disabling. Gait impairments result from lower extremity spasticity, muscle weakness, and impaired proprioception. The aim of this study was to assess the efficacy of a 5-week gait-adaptability training in people with pure HSP. METHOD: We conducted a randomized clinical trial with a cross-over design for the control group, and a 15-week follow-up period after training. Thirty-six people with pure HSP were randomized to 5 weeks of (i) gait-adaptability training (10 hours of C-Mill training-a treadmill equipped with augmented reality) or (ii) a waiting-list control period followed by 5 weeks gait-adaptability training. Both groups continued to receive usual care. The primary outcome was the obstacle subtask of the Emory Functional Ambulation Profile. Secondary outcome measures consisted of clinical balance and gait assessments, fall rates, and spatiotemporal gait parameters assessed via 3D motion analysis. RESULTS: The gait-adaptability training group (n = 18) did not significantly decrease the time required to perform the obstacle subtask compared to the waiting-list control group (n = 18) after adjusting for baseline differences (mean: -0.33 seconds, 95% CI: -1.3, 0.6). Similar, non-significant results were found for most secondary outcomes. After merging both groups (n = 36), the required time to perform the obstacle subtask significantly decreased by 1.3 seconds (95% CI: -2.1, -0.4) directly following 5 weeks of gait-adaptability training, and this effect was retained at the 15-week follow-up. CONCLUSIONS: We found insufficient evidence to conclude that 5 weeks of gait-adaptability training leads to greater improvement of gait adaptability in people with pure HSP.

Comparison of ground reaction force and marker-based methods to estimate mediolateral center of mass displacement and margins of stability during walking.

Dynamic balance control during human walking can be described by the distance between the mediolateral (ML) extrapolated center of mass (XCoM) position and the base of support, the margin of stability (MoS). The ML center of mass (CoM) position during treadmill walking can be estimated based on kinematic data (marker-based method) and a combination of ground reaction forces and center of pressure positions (GRF-based method). Here, we compare a GRF-based method with a full-body marker-based method for estimating the ML CoM, ML XCoM and ML MoS. Fifteen healthy adults walked on a dual-belt treadmill at comfortable walking speed for three minutes. Kinetic and kinematic data were collected and analyzed using a GRF-based and marker-based method to compare the ML CoM, ML XCoM and ML MoS. High correlation coefficients (r > 0.98) and small differences (Root Mean Square Difference < 0.0072 m) in ML CoM and ML XCoM were found between the GRF-based and marker-based methods. The GRF-based method resulted in larger ML XCoM excursion (0.0118 ± 0.0074 m) and smaller ML MoS values (0.0062 ± 0.0028 m) than the marker-based method, but these differences were consistent across participants. In conclusion, the GRF-based method is a valid method to determine the ML CoM, XCoM and MoS. One should be aware of higher ML XCoM and smaller ML MoS values in the GRF-based method when comparing absolute values between studies. The GRF-based method strongly reduces measurement times and can be used to provide real-time CoM-CoP feedback during treadmill gait training.

Increased trunk movements in people with hereditary spastic paraplegia: do these involve balance correcting strategies?

OBJECTIVE: Hereditary spastic paraplegia (HSP) is characterized by a bilaterally spastic gait pattern. During gait, increased trunk movements are often observed. People with HSP likely generate trunk movements to improve foot clearance and step length, but there may be additional explanations. Here, we investigate whether there is an association between reduced balance performance and increased trunk movements, as an increase in trunk movements may partly reflect balance correcting strategies. METHODS: We analyzed an historic cohort of 86 people with HSP who underwent gait analysis and balance examination. Two researchers reviewed gait analyses videos and classified the observed trunk movement as (1) normal, (2) moderately increased, or (3) markedly increased, and categorized participants as 'toe walkers' (yes/no). Balance performance and spatiotemporal gait parameters were collected from the medical files. Parameters were compared between people with normal vs. moderately increased trunk movements, moderately vs. markedly increased trunk movements, and normal vs. markedly increased trunk movements. RESULTS: Patients with moderately increased trunk movements during gait scored lower on the Berg Balance Scale (p = 0.002) and/or the Mini Balance Evaluation Test (p = 0.043) than patients with normal trunk movements. Likewise, patients with markedly increased trunk movements performed worse on the BBS (p = 0.037) and/or the Mini-BESTest (p = 0.004) than patients with moderately increased trunk movements. Patients with markedly increased trunk movements were more often toe walkers than patients with moderately increased (68% vs. 6%; p < 0.001). CONCLUSIONS: We found an association between increased trunk movements and reduced balance capacity. This may have several-not mutually exclusive-explanations. One of these explanations is that trunk movements, at least partly, reflect balance correcting strategies. With the disease progression, ankle strategies and foot placement strategies become impaired and insufficient to restore balance after intrinsic perturbations. Hip strategies are then potentially recruited to maintain balance, resulting in increased trunk movements.

Improving gait adaptability in patients with hereditary spastic paraplegia (Move-HSP): study protocol for a randomized controlled trial.

BACKGROUND: People with hereditary spastic paraplegia (HSP) experience difficulties adapting their gait to meet environmental demands, a skill required for safe and independent ambulation. Gait adaptability training is possible on the C-Mill, a treadmill equipped with augmented reality, enabling visual projections to serve as stepping targets or obstacles. It is unknown whether gait adaptability can be trained in people with HSP. AIM: The aim of Move-HSP is to study the effects of ten 1-h sessions of C-Mill training, compared with usual care, on gait adaptability in people with pure HSP. In addition, this study aims to identify key determinants of C-Mill training efficacy in people with pure HSP. METHOD: Move-HSP is a 5-week, two-armed, open-label randomized controlled trial with a cross-over design for the control group. Thirty-six participants with pure HSP will be included. After signing informed consent, participants are randomized (1:1) to intervention or control group. All participants register (near) falls for 15 weeks, followed by the first assessment (week 16), and, thereafter, wear an Activ8 activity monitor for 7 days (week 16). The intervention group receives 10 sessions of C-Mill training (twice per week, 1-h sessions; weeks 17-21), whereas control group continues with usual care (weeks 17-21). Afterwards, both groups are re-assessed (week 22). Subsequently, the intervention group enter follow-up, whereas control group receives 10 sessions of C-Mill training (weeks 23-27), is re-assessed (week 28), and enters follow-up. During follow-up, both groups wear Activ8 activity monitors for 7 days (intervention group: week 23, control group: week 29) and register (near) falls for 15 weeks (intervention group: weeks 23-37, control group: weeks 29-43), before the final assessment (intervention group: week 38, control group: week 44). The primary outcome is the obstacle subtask of the Emory Functional Ambulation Profile. Secondary outcomes consist of clinical tests assessing balance and walking capacity, physical activity, and fall monitoring. DISCUSSION: Move-HSP will be the first RCT to assess the effects of C-Mill gait adaptability training in people with pure HSP. It will provide proof of concept for the efficacy of gait adaptability training in people with pure HSP. TRIAL REGISTRATION: Clinicaltrials.gov NCT04180098 . Registered on November 27, 2019.

The effect of trunk training on muscle thickness and muscle activity: a systematic review.

Objective: A systematic review to examine the effect of static or dynamic trunk training compared to standard care or control therapy on muscle activity and muscle thickness of the trunk and lower limb muscles in stroke survivors. Materials and methods: This review was registered on PROSPERO (no: CRD42017063771) and was written according to the PRISMA guidelines. The search strategy included studies from the first indexed article until September 2017 and was performed in the electronical databases PubMed, Web of Science, Cochrane Library, Ovid Medline and PEDro. Two independent reviewers screened, assessed risk of bias by means of the PEDro scale and extracted data. Results: Eight studies were included of which three investigated the effects of trunk training on muscle thickness, the remaining five investigated muscle activity. The following muscles were investigated: erector spinae, multifidi, paravertebralis, transversus abdominis, internal and external oblique abdominis, rectus abdominis, quadriceps femoris, hamstrings, soleus and tibialis anterior. Trunk exercises significantly improved the muscle activity of the internal oblique abdominis and increased muscle thickness of transversus abdominis. Conclusions: Trunk training is effective in restoring symmetry in muscle thickness to improve muscle strength. The gain in muscle thickness is specific to the applied exercise program, suggesting that therapeutic goal setting is of great importance. However, no conclusion could be made concerning changes in muscle activity due to a high risk of bias. Implications for rehabilitation: Trunk training seems to be effective in restoring symmetry in trunk muscle thickness. Not all muscle groups benefit from specific trunk exercises. Patients suffering from chronic stroke are still capable of restoring muscle function.