Muscle paresis and passive stiffness: key determinants in limiting function in Hereditary and Sporadic Spastic Paraparesis

The use of digital tools in rare neurological diseases towards a new care model: a narrative review

Rare neurological diseases as a whole share peculiar features as motor and/or cognitive impairment, an elevated disability burden, a frequently chronic course and, in present times, scarcity of therapeutic options. The rarity of those conditions hampers both the identification of significant prognostic outcome measures, and the development of novel therapeutic approaches and clinical trials. Collection of objective clinical data through digital devices can support diagnosis, care, and therapeutic research. We provide an overview on recent developments in the field of digital tools applied to rare neurological diseases, both in the care setting and as providers of outcome measures in clinical trials in a representative subgroup of conditions, including ataxias, hereditary spastic paraplegias, motoneuron diseases and myopathies.

Gait analysis patterns and rehabilitative interventions to improve gait in persons with hereditary spastic paraplegia: a systematic review and meta-analysis

Background

Hereditary spastic paraplegias (HSPs) are a group of inheritance diseases resulting in gait abnormalities, which may be detected using instrumented gait analysis. The aim of this systematic review was 2-fold: to identify specific gait analysis patterns and interventions improving gait in HSP subjects.

Methods

A systematic review was conducted in PubMed, Cochrane Library, REHABDATA, and PEDro databases, in accordance with reporting guidelines of PRISMA statement and Cochrane's recommendation. The review protocol was recorded on the PROSPERO register. Patients with pure and complicated HSP of any age were included. All types of studies were included. Risk of bias, quality assessment, and meta-analysis were performed.

Results

Forty-two studies were included: 19 were related to gait analysis patterns, and 24 were intervention studies. The latter ones were limited to adults. HSP gait patterns were similar to cerebral palsy in younger subjects and stroke in adults. Knee hyperextension, reduced range of motion at knee, ankle, and hip, reduced foot lift, and increased rapid trunk and arm movements were reported. Botulinum injections reduced spasticity but uncovered weakness and improved gait velocity at follow-up. Weak evidence supported intrathecal baclofen, active intensive physical therapy (i.e., robot-assisted gait training, functional exercises, and hydrotherapy), and functional electrical stimulation. Some improvements but adverse events were reported after transcranial magnetic stimulation, transcutaneous spinal direct current stimulation, and spinal cord stimulation implant.

Conclusion

Knee hyperextension, non-sagittal pelvic movements, and reduced ROM at the knee, ankle, and hip represent the most peculiar patterns in HSP, compared to diplegic cerebral palsy and stroke. Botulinum improved comfortable gait velocity after 2 months. Nonetheless, interventions reducing spasticity might result in ineffective functional outcomes unveiling weakness. Intensive active physical therapy and FES might improve gait velocity in the very short term.

Dysfunctional neuro-muscular mechanisms explain gradual gait changes in prodromal spastic paraplegia

BACKGROUND

In Hereditary Spastic Paraplegia (HSP) type 4 (SPG4) a length-dependent axonal degeneration in the cortico-spinal tract leads to progressing symptoms of hyperreflexia, muscle weakness, and spasticity of lower extremities. Even before the manifestation of spastic gait, in the prodromal phase, axonal degeneration leads to subtle gait changes. These gait changes - depicted by digital gait recording - are related to disease severity in prodromal and early-to-moderate manifest SPG4 participants.

METHODS

We hypothesize that dysfunctional neuro-muscular mechanisms such as hyperreflexia and muscle weakness explain these disease severity-related gait changes of prodromal and early-to-moderate manifest SPG4 participants. We test our hypothesis in computer simulation with a neuro-muscular model of human walking. We introduce neuro-muscular dysfunction by gradually increasing sensory-motor reflex sensitivity based on increased velocity feedback and gradually increasing muscle weakness by reducing maximum isometric force.

RESULTS

By increasing hyperreflexia of plantarflexor and dorsiflexor muscles, we found gradual muscular and kinematic changes in neuro-musculoskeletal simulations that are comparable to subtle gait changes found in prodromal SPG4 participants.

CONCLUSIONS

Predicting kinematic changes of prodromal and early-to-moderate manifest SPG4 participants by gradual alterations of sensory-motor reflex sensitivity allows us to link gait as a directly accessible performance marker to emerging neuro-muscular changes for early therapeutic interventions.

Treatment of spasticity

Spasticity is characterized by an enhanced size and reduced threshold for activation of stretch reflexes and is associated with "positive signs" such as clonus and spasms, as well as "negative features" such as paresis and a loss of automatic postural responses. Spasticity develops over time after a lesion and can be associated with reduced speed of movement, cocontraction, abnormal synergies, and pain. Spasticity is caused by a combination of damage to descending tracts, reductions in inhibitory activity within spinal cord circuits, and adaptive changes within motoneurons. Increased tone, hypertonia, can also be caused by changes in passive stiffness due to, for example, increase in connective tissue and reduction in muscle fascicle length. Understanding the cause of hypertonia is important for determining the management strategy as nonneural, passive causes of stiffness will be more amenable to physical rather than pharmacological interventions. The management of spasticity is determined by the views and goals of the patient, family, and carers, which should be integral to the multidisciplinary assessment. An assessment, and treatment, of trigger factors such as infection and skin breakdown should be made especially in people with a recent change in tone. The choice of management strategies for an individual will vary depending on the severity of spasticity, the distribution of spasticity (i.e., whether it affects multiple muscle groups or is more prominent in one or two groups), the type of lesion, and the potential for recovery. Management options include physical therapy, oral agents; focal therapies such as botulinum injections; and peripheral nerve blocks. Intrathecal baclofen can lead to a reduction in required oral antispasticity medications. When spasticity is severe intrathecal phenol may be an option. Surgical interventions, largely used in the pediatric population, include muscle transfers and lengthening and selective dorsal root rhizotomy.

Specific Gait Changes in Prodromal Hereditary Spastic Paraplegia Type 4: preSPG4 Study

BACKGROUND

In hereditary spastic paraplegia type 4 (SPG4), subclinical gait changes might occur years before patients realize gait disturbances. The prodromal phase of neurodegenerative disease is of particular interest to halt disease progression by future interventions before impairment has manifested.

OBJECTIVE

The objective of this study was to identify specific movement abnormalities before the manifestation of gait impairment and quantify disease progression in the prodromal phase.

METHODS

Seventy subjects participated in gait assessment, including 30 prodromal SPAST pathogenic variant carriers, 17 patients with mild-to-moderate manifest SPG4, and 23 healthy control subjects. An infrared-camera-based motion capture system assessed gait to analyze features such as range of motion and continuous angle trajectories. Those features were correlated with disease severity as assessed by the Spastic Paraplegia Rating Scale, neurofilament light chain as a fluid biomarker indicating neurodegeneration, and motor-evoked potentials.

RESULTS

Compared with healthy control subjects, we found an altered gait pattern in prodromal pathogenic variant carriers during the swing phase in the segmental angle of the foot (Dunn's post hoc test, q = 3.1) and heel ground clearance (q = 2.8). Furthermore, range of motion of segmental angle was reduced for the foot (q = 3.3). These changes occurred in prodromal pathogenic variant carriers without quantified leg spasticity in clinical examination. Gait features correlated with neurofilament light chain levels, central motor conduction times of motor-evoked potentials, and Spastic Paraplegia Rating Scale score.

CONCLUSIONS

Gait analysis can quantify changes in prodromal and mild-to-moderate manifest SPG4 patients. Thus, gait features constitute promising motor biomarkers characterizing the subclinical progression of spastic gait and might help to evaluate interventions in early disease stages. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Hereditary Spastic Paraplegia in Koreans: Clinical Characteristics and Factors Influencing the Disease Severity

Background and Purpose

Hereditary spastic paraplegia (HSP) progresses over time and is associated with locomotive dysfunction. Understanding the factors affecting disease severity and locomotive function is important in HSP. This study investigated the factors influencing disease severity and ambulation status of HSP.

Methods

We consecutively enrolled 109 Korean patients (64 males, and 45 females)from 84 families with a clinical diagnosis of HSP. HSP was primarily diagnosed based on clinical criteria including clinical findings, family history, and supported by genetic studies. Epidemiological and clinical features of the patients were analyzed, and the Spastic Paraplegia Rating Scale (SPRS) score and ambulatory status were used to evaluate disease severity.

Results

Ninety-two (84.4%) patients had pure HSP, and 55 (50.4%) had a dominant family history. Thirty-one (28.4%) patients required a mobility aid for locomotion. A Kaplan-Meier analysis showed that HSP patients lost their independent gait ability after a median disease duration of 34 years. Those with an age at onset of ≤18 years had a longer median independent walking time. Pure HSP is characterized by predominant bilateral lower extremity weakness and spasticity, whereas complicated HSP presents more complex neurological findings such as ocular and bulbar symptoms, ataxia, and cognitive impairment. Complicated HSP was significantly correlated with the SPRS mobility score (β=3.70, 95% confidence interval=0.45–6.94). The age at onset and disease duration were significantly correlated with disease severity, and they were significant predictors of the use of a mobility aid (p<0.05).

Conclusions

These findings suggest that a later age at onset and longer disease duration are significant factors affecting the disease severity and ambulatory function in patients with HSP. These findings can help clinicians to identify subjects at risk of locomotive impairment.

Functional gait measures correlate to fear of falling, and quality of life in patients with Hereditary Spastic Paraplegia: A cross-sectional study

OBJECTIVE

Gait impairment is the cardinal motor symptom in hereditary spastic paraplegias (HSPs) possibly linked to increased fear of falling and reduced quality of life (QoL). Disease specific symptoms in HSP are rated using the Spastic Paraplegia Rating Scale (SPRS). However, limited studies evaluated more objectively easy-to-apply gait measures by comparing these standardized assessments with patients' self-perceived impairment and clinically established scores. Therefore, the aim of this study was to correlate functional gait measures with self-rating questionnaires for fear of falling and QoL, and with the SPRS as clinical gold standard.

METHODS

HSP patients ("pure" phenotype, n = 22) fulfilling the clinical diagnostic criteria for HSP and age-and gender-matched healthy subjects (n = 22) were included in this study. Motor impairment was evaluated using the SPRS, fear of falling by the Falls Efficacy Scale-International (FES-I), and QoL by SF-12. Functional gait measures included gait speed and step length (10-meter-walk-test), the Timed up and go test (TUG), and maximum walking distance (2-min-walking-test).

RESULTS

Functional gait measures correlated to fear of falling (gait speed: r = -0.726; step length: r = -0.689; TUG: r = 0.721; 2-min: r = -0.709) and the physical component of QoL (gait speed: r = 0.541; step length: r = 0.531; TUG: r = -0.512; 2-min: r = 0.548). Furthermore, FES-I (r = 0.767) and QoL (r = -0.728) correlated with the clinical gold standard (SPRS). Gait measures strongly correlated with SPRS (gait speed: r = -0.787; step length: r = -0.821; TUG: r = 0.756; 2-min: r = -0.791).

CONCLUSION

Functional gait measures reflect fear of falling, QoL, and mobility in HSP. The metric, semi-quantitative gait measures complement the clinician's evaluation and support the clinical workup by more objective parameters.

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.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13063-020-04932-9.

Gastrocnemius Medialis Muscle Geometry and Extensibility in Typically Developing Children and Children With Spastic Paresis Aged 6-13 Years

Gait of children with spastic paresis (SP) is frequently characterized by a reduced ankle range of motion, presumably due to reduced extensibility of the triceps surae (TS) muscle. Little is known about how morphological muscle characteristics in SP children are affected. The aim of this study was to compare gastrocnemius medialis (GM) muscle geometry and extensibility in children with SP with those of typically developing (TD) children and assess how GM morphology is related to its extensibility. Thirteen children with SP, of which 10 with a diagnosis of spastic cerebral palsy and three with SP of unknown etiology (mean age 9.7 ± 2.1 years; GMFCS: I-III), and 14 TD children (mean age 9.3 ± 1.7 years) took part in this study. GM geometry was assessed using 3D ultrasound imaging at 0 and 4 Nm externally imposed dorsal flexion ankle moments. GM extensibility was defined as its absolute length change between the externally applied 0 and 4 Nm moments. Anthropometric variables and GM extensibility did not differ between the SP and TD groups. While in both groups, GM muscle volume correlated with body mass, the slope of the regression line in TD was substantially higher than that in SP (TD = 3.3 ml/kg; SP = 1.3 ml/kg, p < 0.01). In TD, GM fascicle length increased with age, lower leg length and body mass, whereas in SP children, fascicle length did not correlate with any of these variables. However, the increase in GM physiological cross-sectional area as a function of body mass did not differ between SP and TD children. Increases in lengths of tendinous structures in children with SP exceeded those observed in TD children (TD = 0.85 cm/cm; SP = 1.16 cm/cm, p < 0.01) and even exceeded lower-leg length increases. In addition, only for children with SP, body mass (r = -0.61), height (r = -0.66), muscle volume (r = - 0.66), physiological cross-sectional area (r = - 0.59), and tendon length (r = -0.68) showed a negative association with GM extensibility. Such negative associations were not found for TD children. In conclusion, physiological cross-sectional area and length of the tendinous structures are positively associated with age and negatively associated with extensibility in children with SP.

Physics-Based Simulations to Predict the Differential Effects of Motor Control and Musculoskeletal Deficits on Gait Dysfunction in Cerebral Palsy: A Retrospective Case Study

Physics-based simulations of walking have the theoretical potential to support clinical decision-making by predicting the functional outcome of treatments in terms of walking performance. Yet before using such simulations in clinical practice, their ability to identify the main treatment targets in specific patients needs to be demonstrated. In this study, we generated predictive simulations of walking with a medical imaging based neuro-musculoskeletal model of a child with cerebral palsy presenting crouch gait. We explored the influence of altered muscle-tendon properties, reduced neuromuscular control complexity, and spasticity on gait dysfunction in terms of joint kinematics, kinetics, muscle activity, and metabolic cost of transport. We modeled altered muscle-tendon properties by personalizing Hill-type muscle-tendon parameters based on data collected during functional movements, simpler neuromuscular control by reducing the number of independent muscle synergies, and spasticity through delayed muscle activity feedback from muscle force and force rate. Our simulations revealed that, in the presence of aberrant musculoskeletal geometries, altered muscle-tendon properties rather than reduced neuromuscular control complexity and spasticity were the primary cause of the crouch gait pattern observed for this child, which is in agreement with the clinical examination. These results suggest that muscle-tendon properties should be the primary target of interventions aiming to restore an upright gait pattern for this child. This suggestion is in line with the gait analysis following muscle-tendon property and bone deformity corrections. Future work should extend this single case analysis to more patients in order to validate the ability of our physics-based simulations to capture the gait patterns of individual patients pre- and post-treatment. Such validation would open the door for identifying targeted treatment strategies with the aim of designing optimized interventions for neuro-musculoskeletal disorders.

Exploratory Randomized Double-Blind Placebo-Controlled Trial of Botulinum Therapy on Grasp Release After Stroke (PrOMBiS)

Background. OnabotulinumtoxinA injections improve upper-limb spasticity after stroke, but their effect on arm function remains uncertain. Objective. To determine whether a single treatment with onabotulinumtoxinA injections combined with upper-limb physiotherapy improves grasp release compared with physiotherapy alone after stroke. Methods. A total of 28 patients, at least 1 month poststroke, were randomized to receive either onabotulinumtoxinA or placebo injections to the affected upper limb followed by standardized upper-limb physiotherapy (10 sessions over 4 weeks). The primary outcome was time to release grasp during a functionally relevant standardized task. Secondary outcomes included measures of wrist and finger spasticity and strength using a customized servomotor, clinical assessments of stiffness (modified Ashworth Scale), arm function (Action Research Arm Test [ARAT], Nine Hole Peg Test), arm use (Arm Measure of Activity), Goal Attainment Scale, and quality of life (EQ5D). Results. There was no significant difference between treatment groups in grasp release time 5 weeks post injection (placebo median = 3.0 s, treatment median = 2.0 s; t(24) = 1.20; P = .24; treatment effect = -0.44, 95% CI = -1.19 to 0.31). None of the secondary measures passed significance after correcting for multiple comparisons. Both groups achieved their treatment goals (placebo = 65%; treatment = 71%), and made improvements on the ARAT (placebo +3, treatment +5) and in active wrist extension (placebo +9°, treatment +11°). Conclusions. In this group of stroke patients with mild to moderate spastic hemiparesis, a single treatment with onabotulinumtoxinA did not augment the improvements seen in grasp release time after a standardized upper-limb physiotherapy program.

A spasticity model based on feedback from muscle force explains muscle activity during passive stretches and gait in children with cerebral palsy

Muscle spasticity is characterized by exaggerated stretch reflexes and affects about 85% of the children with cerebral palsy. However, the mechanisms underlying spasticity and its influence on gait are not well understood. Here, we first aimed to model the response of spastic hamstrings and gastrocnemii in children with cerebral palsy to fast passive stretches. Then, we evaluated how the model applied to gait. We developed three models based on exaggerated proprioceptive feedback. The first model relied on feedback from muscle fiber length and velocity (velocity-related model), the second model relied on feedback from muscle fiber length, velocity, and acceleration (acceleration-related model), and the third model relied on feedback from muscle force and its first time derivative (force-related model). The force-related model better reproduced measured hamstrings and gastrocnemii activity during fast passive stretches (coefficients of determination (R2): 0.73 ± 0.10 and 0.60 ± 0.13, respectively, and root mean square errors (RMSE): 0.034 ± 0.031 and 0.009 ± 0.007, respectively) than the velocity-related model (R2: 0.46 ± 0.15 and 0.07 ± 0.13, and RMSE: 0.053 ± 0.051 and 0.015 ± 0.009), and the acceleration-related model (R2: 0.47 ± 0.15 and 0.09 ± 0.14, and RMSE: 0.052 ± 0.050 and 0.015 ± 0.008). Additionally, the force-related model predicted hamstrings and gastrocnemii activity that better correlated with measured activity during gait (cross correlations: 0.82 ± 0.09 and 0.85 ± 0.06, respectively) than the activity predicted by the velocity-related model (cross correlations: 0.49 ± 0.17 and 0.71 ± 0.22) and the acceleration-related model (cross correlations: 0.51 ± 0.16 and 0.67 ± 0.20). Our results therefore suggest that force encoding in muscle spindles in combination with altered feedback gains and thresholds underlie activity of spastic muscles during passive stretches and gait. Our model of spasticity opens new perspectives for studying movement impairments due to spasticity through simulation.

Effects of superficial heating and insulation on walking speed in people with hereditary and spontaneous spastic paraparesis: A randomised crossover study

OBJECTIVES

Cooling of the lower limb in people with Hereditary and Spontaneous Spastic Paraparesis (pwHSSP) has been shown to affect walking speed and neuromuscular impairments. The investigation of practical strategies, which may help to alleviate these problems is important. The potential of superficial heat to improve walking speed has not been explored in pwHSSP. Primary objective was to explore whether the application of superficial heat (hot packs) to lower limbs in pwHSSP improves walking speed. Secondary objective was to explore whether wearing insulation after heating would prolong any benefits.

METHODS

A randomised crossover study design with 21 pwHSSP. On two separate occasions two hot packs and an insulating wrap (Neo-G™) were applied for 30minutes to the lower limbs of pwHSSP. On one occasion the insulating wrap was maintained for a further 30minutes and on the other occasion it was removed. Measures of temperature (skin, room and core), walking speed (10 metre timed walk) and co-ordination (foot tap time) were taken at baseline (T1), after 30 mins (T2) and at one hour (T3).

RESULTS

All 21 pwHSSP reported increased lower limb stiffness and decreased walking ability when their legs were cold. After thirty minutes of heating, improvements were seen in walking speed (12.2%, P<0.0001, effect size 0.18) and foot tap time (21.5%, P<0.0001, effect size 0.59). Continuing to wear insulation for a further 30minutes gave no additional benefit; with significant improvements in walking speed maintained at one hour (9.9%, P>0.001) in both conditions.

CONCLUSIONS

Application of 30minutes superficial heating moderately improved walking speed in pwHSSP with effects maintained at 1hour. The use of hot packs applied to lower limbs should be the focus of further research for the clinical management of pwHSSP who report increased stiffness of limbs in cold weather and do not have sensory deficits.

Increased lower limb muscle coactivation reduces gait performance and increases metabolic cost in patients with hereditary spastic paraparesis

BACKGROUND

The aim of this study was to investigate the lower limb muscle coactivation and its relationship with muscles spasticity, gait performance, and metabolic cost in patients with hereditary spastic paraparesis.

METHODS

Kinematic, kinetic, electromyographic and energetic parameters of 23 patients and 23 controls were evaluated by computerized gait analysis system. We computed ankle and knee antagonist muscle coactivation indexes throughout the gait cycle and during the subphases of gait. Energy consumption and energy recovery were measured as well. In addition to the correlation analysis between coactivation indexes and clinical variables, correlations between coactivation indexes and time-distance, kinematic, kinetic, and energetic parameters were estimated.

FINDINGS

Increased coactivity indexes of both knee and ankle muscles throughout the gait cycle and during the subphases of gait were observed in patients compared with controls. Energetic parameters were significantly higher in patients than in controls. Both knee and ankle muscle coactivation indexes were positively correlated with knee and ankle spasticity (Ashworth score), respectively. Knee and ankle muscle coactivation indexes were both positively correlated with energy consumption and both negatively correlated with energy recovery.

INTERPRETATION

Positive correlations between the Ashworth score and lower limb muscle coactivation suggest that abnormal lower limb muscle coactivation in patients with hereditary spastic paraparesis reflects a primary deficit linked to lower limb spasticity. Furthermore, these abnormalities influence the energetic mechanisms during walking. Identifying excessive muscle coactivation may be helpful in individuating the rehabilitative treatments and designing specific orthosis to restrain spasticity.

Clinical and genetic study of hereditary spastic paraplegia in Canada

Objective:

To describe the clinical, genetic, and epidemiologic features of hereditary spastic paraplegia (HSP) in Canada and to determine which clinical, radiologic, and genetic factors determine functional outcomes for patients with HSP.

Methods:

We conducted a multicenter observational study of patients who met clinical criteria for the diagnosis of HSP in the provinces of Alberta, Ontario, and Quebec from 2012 to 2015. Characteristics of the participants were analyzed using descriptive statistics. The main outcome measure for a subset of the cohort (n = 48) was the Spastic Paraplegia Rating Scale. We also used the SPATAX-EUROSPA disability stage (disability score) to assess disability (n = 65).

Results:

A total of 526 patients were identified with HSP across the country, and 150 patients had a confirmed genetic diagnosis. Mutations were identified in 15 different genes; the most common were SPAST (SPG4, 48%), ATL1 (SPG3A, 16%), SPG11 (8%), SPG7 (7%), and KIAA0196 (SPG8, 5%). The diagnosis of SPG4 was associated with older age at symptom onset (p = 0.0017). SPG4 and SPG3A were less associated with learning disabilities compared to other subtypes of HSP, and SPG11 was strongly associated with progressive cognitive deficits (odds ratio 87.75, 95% confidence interval 14.04–548.24, p < 0.0001). SPG3A was associated with better functional outcomes compared to other HSP subtypes (p = 0.04) on multivariate analysis. The strongest predictor of significant disability was abnormal brain MRI (p = 0.014).

Conclusions:

The most important predictors of disability in our HSP cohort were SPG11 mutations and abnormal brain MRI. Accurate molecular characterization of well-phenotyped cohorts and international collaboration are essential to establish the natural history of these rare neurodegenerative disorders.

Gait Patterns in Patients with Hereditary Spastic Paraparesis

Background

Spastic gait is a key feature in patients with hereditary spastic paraparesis, but the gait characterization and the relationship between the gait impairment and clinical characteristics have not been investigated.

Objectives

To describe the gait patterns in hereditary spastic paraparesis and to identify subgroups of patients according to specific kinematic features of walking.

Methods

We evaluated fifty patients by computerized gait analysis and compared them to healthy participants. We computed time-distance parameters of walking and the range of angular motion at hip, knee, and ankle joints, and at the trunk and pelvis. Lower limb joint moments and muscle co-activation values were also evaluated.

Results

We identified three distinct subgroups of patients based on the range of motion values. Subgroup one was characterized by reduced hip, knee, and ankle joint range of motion. These patients were the most severely affected from a clinical standpoint, had the highest spasticity, and walked at the slowest speed. Subgroup three was characterized by an increased hip joint range of motion, but knee and ankle joint range of motion values close to control values. These patients were the most mildly affected and had the highest walking speed. Finally, subgroup two showed reduced knee and ankle joint range of motion, and hip range of motion values close to control values. Disease severity and gait speed in subgroup two were between those of subgroups one and three.

Conclusions

We identified three distinctive gait patterns in patients with hereditary spastic paraparesis that correlated robustly with clinical data. Distinguishing specific features in the gait patterns of these patients may help tailor pharmacological and rehabilitative treatments and may help evaluate therapeutic effects over time.

Kinematic gait deficits at the trunk and pelvis: characteristic features in children with hereditary spastic paraplegia

AIM

To examine the kinematic gait deviations at the trunk and pelvis of children with hereditary spastic paraplegia (HSP).

METHOD

This exploratory observational study quantified gait kinematics for the trunk and pelvis from 11 children with HSP (7 males, 4 females) using the Gait Profile Score and Gait Variable Scores (GVS), and compared the kinematics to data from children with typical development using a Mann-Whitney U test.

RESULTS

Children with HSP (median age 11y 4mo, interquartile range 4y) demonstrated large deviations in the GVS for the trunk and pelvis in the sagittal and coronal planes when compared to the gait patterns of children with typical development (p=0.010-0.020). Specific deviations included increased range of movement for the trunk in the coronal plane and increased excursion of the trunk and pelvis in the sagittal plane. In the transverse plane, children with HSP demonstrated later peaks in posterior pelvic rotation.

INTERPRETATION

The kinematic gait deviations identified in this study raise questions about the contribution of muscle weakness in HSP. Further research is warranted to determine contributing factors for gait dysfunction in HSP, especially the relative influence of spasticity and weakness.

Spasticity and its contribution to hypertonia in cerebral palsy

Spasticity is considered an important neural contributor to muscle hypertonia in children with cerebral palsy (CP). It is most often treated with antispasticity medication, such as Botulinum Toxin-A. However, treatment response is highly variable. Part of this variability may be due to the inability of clinical tests to differentiate between the neural (e.g., spasticity) and nonneural (e.g., soft tissue properties) contributions to hypertonia, leading to the terms “spasticity” and “hypertonia” often being used interchangeably. Recent advancements in instrumented spasticity assessments offer objective measurement methods for distinction and quantification of hypertonia components. These methods can be applied in clinical settings and their results used to fine-tune and improve treatment. We reviewed current advancements and new insights with respect to quantifying spasticity and its contribution to muscle hypertonia in children with CP. First, we revisit what is known about spasticity in children with CP, including the various definitions and its pathophysiology. Second, we summarize the state of the art on instrumented spasticity assessment in CP and review the parameters developed to quantify the neural and nonneural components of hypertonia. Lastly, the impact these quantitative parameters have on clinical decision-making is considered and recommendations for future clinical and research investigations are discussed.

The relation between spasticity and muscle behavior during the swing phase of gait in children with cerebral palsy

There is much debate about how spasticity contributes to the movement abnormalities seen in children with spastic cerebral palsy (CP). This study explored the relation between stretch reflex characteristics in passive muscles and markers of spasticity during gait. Twenty-four children with CP underwent 3D gait analysis at three walking velocity conditions (self-selected, faster and fastest). The gastrocnemius (GAS) and medial hamstrings (MEHs) were assessed at rest using an instrumented spasticity assessment that determined the stretch-reflex threshold, expressed in terms of muscle lengthening velocity. Muscle activation was quantified with root mean square electromyography (RMS-EMG) during passive muscle stretch and during the muscle lengthening periods in the swing phase of gait. Parameters from passive stretch were compared to those from gait analysis. In about half the children, GAS peak muscle lengthening velocity during the swing phase of gait did not exceed its stretch reflex threshold. In contrast, in the MEHs the threshold was always exceeded. In the GAS, stretch reflex thresholds were positively correlated to peak muscle lengthening velocity during the swing phase of gait at the faster (r = 0.46) and fastest (r = 0.54) walking conditions. In the MEHs, a similar relation was found, but only at the faster walking condition (r = 0.43). RMS-EMG during passive stretch showed moderate correlations to RMS-EMG during the swing phase of gait in the GAS (r = 0.46-0.56) and good correlations in the MEHs (r = 0.69-0.77) at all walking conditions. RMS-EMG during passive stretch showed no correlations to peak muscle lengthening velocity during gait. We conclude that a reduced stretch reflex threshold in the GAS and MEHs constrains peak muscle lengthening velocity during gait in children with CP. With increasing walking velocity, this constraint is more marked in the GAS, but not in the MEHs. Hyper-activation of stretch reflexes during passive stretch is related to muscle activation during the swing phase of gait, but has a limited contribution to reduced muscle lengthening velocity during swing. Larger studies are required to confirm these results, and to investigate the contribution of other impairments such as passive stiffness and weakness to reduced muscle lengthening velocity during the swing phase of gait.

The effect of hydrotherapy treatment on gait characteristics of hereditary spastic paraparesis patients

BACKGROUND

Hereditary spastic paraparesis (HSP) is a group of neurological disorders characterised by slowly progressive increasing muscle tone, predominantly in the lower limbs, with relatively preserved power. This leads to progressive difficulties in motor control and walking.

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of hydrotherapy treatment when used as a means to increase locomotor function in individuals with late onset HSP. This paper discusses the analysis of the effect on gait characteristics.

METHODS

Nine people with HSP were asked to participate in pre- and post-hydrotherapy gait analyses. Ground reaction force and motion trajectories were recorded and used to calculate spatiotemporal gait parameters, joint angles and moments.

RESULTS

The normalised joint kinematics and kinetics profile revealed that the biomechanics of people with HSP were similar to that of controls for most of the joints, but with lower range of motion. Walking speed increased significantly (11%) after the course of hydrotherapy. Though part of this was achieved through increased ROM there was also a further increase in hip internal rotation and in peak hip extension moment.

CONCLUSIONS

Although participants had increased walking speed and step length, it appears that hydrotherapy increases the ability to perform compensatory strategies rather than resulting in a more typical kinematic and kinetic approach.

Sensory feedback to ankle plantar flexors is not exaggerated during gait in spastic hemiplegic children with cerebral palsy

It is still widely believed that exaggerated stretch reflexes and increased muscle tone in ankle plantar flexors contribute to reduced ankle joint movement during gait in children with cerebral palsy (CP). However, no study has directly measured stretch reflex activity during gait in these children. We investigated sensory feedback mechanisms during walking in 20 CP children and 41 control children. Stretch responses in plantar flexor muscles evoked in stance showed an age-related decline in control but not CP children. In swing the responses were abolished in control children, but significant responses were observed in 14 CP children. This was related to reduced activation of dorsiflexors in swing. Removal of sensory feedback in stance produced a drop in soleus activity of a similar size in control and CP children. Soleus activity was observed in swing to the same extent in control and CP children. Removal of sensory feedback in swing caused a larger drop in soleus activity in control children than in CP children. The lack of age-related decline in stretch reflexes and the inability to suppress reflexes in swing is likely related to lack of maturation of corticospinal control in CP children. Since soleus activity was not seen more frequently than in control children in swing and since sensory feedback did not contribute more to their soleus activity, spasticity is unlikely to contribute to foot drop and toe walking. We propose that altered central drive to the ankle muscles and increased passive muscle stiffness are the main causes of foot drop and toe walking.

Balance dysfunction in hereditary and spontaneous spastic paraparesis

OBJECTIVE

To determine how postural sway is affected in people with spastic paraparesis (pwSP) and the impact of different impairments.

METHODS

In 20 pwSP and 18 matched healthy controls standing postural sway was measured with eyes open and closed. Vibration threshold, isometric ankle and hip muscle strength and ankle stiffness with the participant at rest or preactivating the muscle was measured.

RESULTS

Antero-posterior (AP) and medio-lateral (ML) sway was higher in pwSP. Muscle strength was reduced and ankle stiffness increased in pwSP. Increased vibratory threshold was seen in 35% of participants. Higher total ankle stiffness (R2=0.44) was associated with lower AP sway with eyes open whilst hip abductor weakness was associated with increased ML sway with eyes open (R2=0.36) or closed (R2=0.47) or AP sway with the eyes closed (R2=0.48).

CONCLUSIONS

The degree of postural sway was related to muscle paresis of the hip abductors particularly in the ML direction and under conditions of reduced sensory input. People with higher total ankle stiffness have less AP sway suggesting that this may help to stabilise the body.