Lower extremity muscle force measures and functional ambulation in patients with amyotrophic lateral sclerosis

Clinical Tests for Predicting Fallers Among Ambulatory Patients with Amyotrophic Lateral Sclerosis: A Preliminary Cohort Study

BACKGROUND

Few studies have examined falls and their predictors in patients with amyotrophic lateral sclerosis (ALS).

OBJECTIVE

The aim of this study was to survey fall incidence and to identify variables predicting the presence or absence of falls occurring within 3 months after discharge of patients with ALS from hospital.

METHODS

The following variables were evaluated in 14 patients with ALS: timed up and go test (TUG), functional reach test, 10-m comfortable gait speed, single-leg stance time, manual muscle test (MMT) scores for the lower limb, total modified Ashworth scale score for the lower limbs, fear of falling, and pull test score. The primary outcome variable was the occurrence of a fall within 3 months after discharge. The fall rate was calculated based on fall record forms. The specific circumstances of each fall were also recorded. Univariate and multiple regression analyses were used to identify fall predictors.

RESULTS

Seven of the 14 ALS patients (50%) experienced a fall within 3 months. Five fallers reported experiencing a fall that had caused injury, and three reported experiencing a fall that had required a hospital visit. Univariate logistic regression analysis identified TUG time, gait speed and MMT of the ankle dorsiflexors as factors associated with falls (p = 0.02-0.04). Multiple linear regression analysis of fall numbers identified age and TUG time as predictor models (p = 0.03).

CONCLUSION

TUG time and MMT of ankle dorsiflexors may help predict falls in ALS patients. Validation studies in larger cohorts are needed.

Measuring disease progression in primary lateral sclerosis

Quantitative measures of disease severity are essential outcome measures for clinical trials. The slow progression of disease in primary lateral sclerosis (PLS) requires clinical measures that are sensitive to changes occurring within the time frame of a clinical trial. Proposed clinical outcome measures include the PLS functional rating scale (PLSFRS), burden scores derived from clinical examination findings, and quantitative measures of motor performance. The PLSFRS has good inter-rater reliability and showed greater longitudinal change over 6- and 12-months compared to the revised ALS functional rating scale. Examination-based upper motor neuron burden (UMNB) scales also have good reliability, and longitudinal studies are in process. Quantitative measures of strength, dexterity, gait, and speech have the potential to provide objective and precise measures of clinical change, but have been the least studied in persons with PLS.

Effects on physical performance of high protein intake for critically ill adult patients admitted to the intensive care unit: A retrospective propensity-matched analysis

OBJECTIVES

This study aimed to examine the effects of protein intake on physical performance in critically ill adult patients admitted to the intensive care unit (ICU).

METHODS

This was a retrospective cohort study of adult patients mechanically ventilated over 48 h in the ICU who were classified into two groups based on the amount of protein intake: >1.0 g/kg/d (high-protein group) or <1.0 g/kg/d (low-protein group). After adjustment for possible confounding factors with propensity score matching, we compared muscle strength at the time of ICU discharge and the rate of recovery to independent walking between the two groups.

RESULTS

One-to-one propensity score matching created 20 pairs. The high-protein group had significantly higher muscle strength than the low-protein group at the time of discharge from the ICU. In addition, the rate of recovery to independent walking before hospital discharge was higher in the high-protein group than the low-protein group (16 of 20 patients [80%] vs. 8 of 20 patients [40%]; P = 0.032).

CONCLUSIONS

Our findings indicate that a sufficient amount of protein intake may lead to a higher rate of recovery to independent walking before discharge from the hospital in critically ill patients admitted to the ICU. This finding is likely related to preserved muscle strength at the time of ICU discharge.

Correlation of falls in patients with Amyotrophic Lateral Sclerosis with objective measures of balance, strength, and spasticity

BACKGROUND

Persons diagnosed with Amyotrophic Lateral Sclerosis (ALS) often demonstrate neurological deficits that predispose them to repeated falls and associated adverse consequences. Determining contributing factors to falls in this population is critical to improve safety and patient outcomes.

OBJECTIVE

The purpose of this study was to correlate clinical measures of gait speed, balance, strength, spasticity, and a self-reported rating scale of function with fall incidence in individuals with ALS.

METHODS

Thirty-one participants with a confirmed ALS diagnosis were recruited from an outpatient clinic. Each participant performed the following tests: timed gait speed, Berg Balance Scale (BBS), manual muscle testing (MMT) for lower extremity (LE) strength, Modified Ashworth Scale (MAS) for LE spasticity, and the ALS Functional Rating Scale-Revised (ALSFRS-R). Each participant reported number of falls that occurred in the past three months. Pearson correlation coefficients were calculated to determine correlations between variables.

RESULTS

Significant correlation was found between fall incidence and composite LE strength score (rp = 0.385, p = 0.032).

CONCLUSIONS

There is a relationship between LE weakness and number of falls in the ALS population. Preventing disuse-related LE muscle weakness and education of need for external support may decrease the number of falls experienced by individuals with ALS.

Association of Muscle Strength and Walking Performance in Adult Patients With Pompe Disease

BACKGROUND

The loss of the ability to walk is among the most prominent signs of Pompe disease. The associations with muscle strength have not been described.

OBJECTIVE

The objective of this study was to estimate the associations of walking performance with muscle strength in 4 specific lower extremity muscle groups along with other factors in adult patients with Pompe disease.

DESIGN

This was a single-center, cross-sectional study.

METHODS

Muscle strength (hand-held dynamometry of hip flexion and abduction and knee extension and flexion) and walking performance (unable to walk, able with aids, walking without aids but with a waddling gait, or walking without aids and with a normal gait) were assessed in 107 patients at their first visit. Relationships between walking performance and muscle strength were studied through multivariate analyses and regression modeling. Age, sex, body mass index (BMI), disease duration, and use of ventilator support were taken into account as potential confounders. The results were transformed into a nomogram to allow the probability of a patient having a certain level of walking performance to be calculated based on the values of the independent variables.

RESULTS

Walking performance declined significantly with decreasing muscle strength of hip flexion and abduction and knee extension and flexion. The final selected model, including strength of the hip abductor and knee extensor, BMI, age, sex, and use of ventilation, predicted 66% of the cases accurately.

LIMITATIONS

These results are based on cross-sectional data and do not predict future changes.

CONCLUSIONS

In adult people with Pompe disease, walking performance can be explained by muscle strength, BMI, age, sex, and ventilation use. The proposed model gives insight into how an individual is expected to walk based on his or her risk factors and serves as a starting point to unraveling factors associated with walking performance and ultimately to developing a prognostic model.

Active Hip Flexion is a predictor of mobility in Amyotrophic Lateral Sclerosis

BACKGROUND

Muscle Force (MF) and amplitude of active movement (AAM) are progressively affected in amyotrophic lateral sclerosis (ALS). These measurements are correlated with mobility but influence it in a distinct manner.

OBJECTIVE

To determine the influence of MF and AAM on the mobility of the subjects with ALS.

METHODS

The formula for identifying the covariables and scale of mobility of the Amyotrophic Lateral Sclerosis Assessment Questionnaire were applied to 23 subjects with ALS. The MF data of the knee and ankle flexors and extensors were collected in the most affected limb. In conjunction, the AAM of hip and knee flexion were captured. Multiple linear regressions were used, considering alpha ≤0.05.

RESULTS

MF and AAM interfered in mobility and are responsible for 63.6% of the variation in mobility. The variable that explained this variation was the AAM of hip flexion. The stage of disease was considered a covariable.

CONCLUSION

AAM of hip flexion is a safe predictor of mobility in ALS. Retarding loss of this AAM may maintain these subjects functional for a longer time. It was not possible to use MF of the muscles evaluated to predict mobility.

Lower extremity peak force and gait kinematics in individuals with inclusion body myositis

OBJECTIVE

To determine the relationship between peak isometric muscle force and temporal characteristics of gait in individuals with sporadic inclusion body myositis (s-IBM).

METHODS

An observational study of 42 individuals with s-IBM (12 women; mean ± SD age 61.8 ± 7.3 years and mean ± SD disease duration 8.9 ± 4.3 years) was conducted at a federal hospital. Peak isometric force measurements for lower extremity (LE) muscle groups were obtained using quantitative muscle testing. Temporal characteristics of gait during habitual and fast walking conditions were measured using a portable gait analysis system.

RESULTS

All observed muscle force values were significantly lower than predicted values (P ≤ 0.001). During habitual walking, the subjects' gait speed and cadence were ≤83% of normative literature values. During fast walking, total gait cycle time was 133% of normal, while gait speed and cadence were 58% and 78% of normative literature values, respectively. Scaled LE peak muscle forces showed significant moderate correlations with temporal gait variables. Weaker subjects had greater limitations in gait speed and cadence compared with stronger subjects (P < 0.05). Peak isometric force of the knee flexors and ankle plantar flexors was significantly correlated with most temporal features of habitual gait.

CONCLUSION

Muscle weakness associated with s-IBM disease activity may contribute to diminished gait kinematics. Temporal features of gait were not substantially influenced by knee extensor weakness alone, considering the knee flexors and ankle plantar flexors played a compensatory role in maintaining the walking ability of individuals with s-IBM.

A case study of gait compensations for hip muscle weakness in idiopathic inflammatory myopathy

BACKGROUND

The purpose of this case series was to quantify different strategies used to compensate in gait for hip muscle weakness.

METHODS

An instrumented gait analysis was performed of three females diagnosed with idiopathic inflammatory myopathies and compared to a healthy unimpaired subject. Lower extremity joint moments obtained from the gait analysis were used to drive an induced acceleration model which determined each moment's contribution to upright support, forward progression, and hip joint acceleration.

FINDINGS

Results showed that after midstance, the ankle plantar flexors normally provide upright support and forward progression while producing hip extension acceleration. In normal gait, the hip flexors eccentrically resist hip extension, but the hip flexor muscles of the impaired subjects (S1-3) were too weak to control extension. Instead S1-3 altered joint positions and muscle function to produce forward progression while minimizing hip extension acceleration. S1 increased knee flexion angle to decrease the hip extension effect of the ankle plantar flexors. S2 and S3 used either a knee flexor moment or gravity to produce forward progression, which had the advantage of accelerating the hip into flexion rather than extension, and decreased the demand on the hip flexors.

INTERPRETATION

Results showed how gait compensations for hip muscle weakness can produce independent (i.e. successful) ambulation, although at a reduced speed as compared to normal gait. Knowledge of these successful strategies can assist the rehabilitation of patients with hip muscle weakness who are unable to ambulate and potentially be used to reduce their disability.

The relationship of lower-limb muscle force to walking ability in patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

The purpose of this study was to determine the level of muscle force associated with ability to walk in the community without assistance, in the community with assistance, or at home only in individuals with amyotrophic lateral sclerosis (ALS).

SUBJECTS AND METHODS

Percentage of predicted maximal muscle force (%PMF) of lower-extremity muscles was determined, and walking ability was categorized in 118 patients with ALS during periodic visits to the Neuromuscular Research Unit. Data were derived from consecutive visits in which subjects demonstrated declines in walking ability. Means for %PMF of each muscle group and a limb average were calculated at each consecutive visit.

RESULTS

The mean lower-extremity average %PMF was: (1) 54.01% (SD=12.76%) for subjects who walked independently in the community and 50.19% (SD=14.38%) during the next visit when these same subjects required assistance in the community (difference=3.82%, 95% confidence interval [CI]= 2.45-5.19);(2) 37.52% (SD=15.17%) during the last visit that subjects walked with assistance in the community and 32.18% (SD=13.83%) during the next visit when they walked only at home (difference=5.33%, 95% CI=3.61-7.06); and (3) 19.12% (SD=9.08%) during the visit when subjects were last able to ambulate at home versus 13.70% (SD=7.36%) when they became unable to walk (difference=5.42%, 95% CI=2.97-7.96).

CONCLUSION AND DISCUSSION

The findings suggest there are required levels of lower-extremity muscle force for various categories of walking ability. Variations in forces within and between categories of walking ability, however, indicate the complexity of this relationship.