Assessment of spasticity using isokinetic dynamometry in patients with spinal cord injury

Spinal cord stimulation improves motor function and gait in spastic paraplegia type 4 (SPG4): Clinical and neurophysiological evaluation

INTRODUCTION

Hereditary spastic paraplegia is a heterogeneous group of genetic disorders characterized by degeneration of the corticospinal tracts, coursing with progressive weakness and spasticity of the lower limbs. To date, there are no effective treatments for progressive deficits or disease-modifying therapy for those patients. We report encouraging results for spastic paraparesis after spinal cord stimulation.

METHODS

A 51-year-old woman suffering from progressive weakness and spasticity in lower limbs related to hereditary spastic paraplegia type 4 underwent spinal cord stimulation (SCS) and experienced also significant improvement in motor function. Maximum ballistic voluntary isometric contraction test, continuous passive motion test and gait analysis using a motion-capture system were performed in ON and OFF SCS conditions. Neurophysiologic assessment consisted of obtaining motor evoked potentials in both conditions.

RESULTS

Presurgical Spastic Paraplegia Rating Scale (SPRS) score was 26. One month after effective SCS was initiated, SPRS went down to 15. At 12 months follow up, she experienced substantial improvement in motor function and in gait performance, with SPRS scores 23 (OFF) and down to 20 (ON). There was an increased isometric muscle strength (knee extension, OFF: 41 N m; ON: 71 N m), lower knee extension and flexion torque values in continuous passive motion test (decrease in spastic tone) and improvement in gait (for example, step length increase).

CONCLUSION

Despite being a case study, our findings suggest innovative lines of research for the treatment of spastic paraplegia.

Assessing Stiffness, Joint Torque and ROM for Paretic and Non-Paretic Lower Limbs during the Subacute Phase of Stroke Using Lokomat Tools

The efficacy of Lokomat on motor recovery in stroke patients is well known. However, few studies have examined Lokomat tools to assess stiffness, joint torque and range of motion (ROM) during the subacute phase of stroke. The purpose of this retrospective observational study is to assess the changes of joint torque, ROM and stiffness that were estimated with Lokomat tools, namely L-FORCE (lower limb-force), L-ROM (lower limb-range of motion)and L-STIFF (lower limb-stiff), for paretic and non-paretic lower limbs in the subacute phase of stroke, assuming that the tools were able to measure these changes. The data come from 10 subjects in the subacute phase who had their first ever-stroke and followed a treatment that included Lokomat. The measurements came from basal assessments (T0) and one-month follow-up (T1). The measures were compared between paretic and non-paretic legs, and between T0 and T1. Significant differences in stiffness, joint torque and ROM were obtained between the paretic and non-paretic limbs at both T0 and T1. A non-significant trend was obtained for reduced stiffness and increased torque and ROM between T0 and T1 of the paretic limbs. The Lokomat tools were able to measure the changes between paretic and non-paretic legs and the small changes between T0 and T1 measurements.

Cable-Driven Robotic Interface for Lower Limb Neuromechanics Identification

This paper presents a versatile cable-driven robotic interface to investigate the single-joint joint neuromechanics of the hip, knee and ankle in the sagittal plane. This endpoint-based interface offers highly dynamic interaction and accurate position control (as is typically required for neuromechanics identification), and provides measurements of position, interaction force and electromyography (EMG) of leg muscles. It can be used with the subject upright, corresponding to a natural posture during walking or standing, and does not impose kinematic constraints on a joint, in contrast to existing interfaces. Mechanical evaluations demonstrated that the interface yields a rigidity above 500 N/m with low viscosity. Tests with a rigid dummy leg and linear springs show that it can identify the mechanical impedance of a limb accurately. A smooth perturbation is developed and tested with a human subject, which can be used to estimate the hip neuromechanics.

The Influence of Posture, Applied Force and Perturbation Direction on Hip Joint Viscoelasticity

Limb viscoelasticity is a critical neuromechanical factor used to regulate the interaction with the environment. It plays a key role in modelling human sensorimotor control, and can be used to assess the condition of healthy and neurologically affected individuals. This paper reports the estimation of hip joint viscoelasticity during voluntary force control using a novel device that applies a leg displacement without constraining the hip joint. The influence of hip angle, applied limb force and perturbation direction on the stiffness and viscosity values was studied in ten subjects. No difference was detected in the hip joint stiffness between the dominant and non-dominant legs, but a small dependency was observed on the perturbation direction. Both hip stiffness and viscosity increased monotonically with the applied force magnitude, with posture being observed to have a slight influence. These results are in line with previous measurements carried out on upper limbs, and can be used as a baseline for lower limb movement simulation and further neuromechanical investigations.

Lower limb angular velocity during walking at various speeds

BACKGROUND

Although it is well established that lower limb joint angles adapt to walking at various speeds, limited research has examined the modifications in joint angular velocity. There is currently no normative dataset for joint angular velocity during walking, which would be useful to allow comparisons for patient cohorts. Additionally, understanding normal joint angular velocity may assist clinical assessment and treatment procedures to incorporate methods that replicate the movement speed of the lower limb joints during walking.

RESEARCH QUESTION

This study aimed to examine lower limb joint angles and angular velocities in a healthy population walking at various gait speeds.

METHODS

Thirty-six healthy adult participants underwent three-dimensional gait analysis while walking at various speeds during habitual and slowed walking. The peak joint angles and angular velocities during important phases of the gait cycle were examined for the hip, knee and ankle in the sagittal plane. Data were grouped in 0.2 m/s increments from a walking speed of 0.4 m/s to 1.6 m/s to represent the range of walking speeds reported in studies of people with gait impairments.

RESULTS

For joint angles and angular velocities, the shape of the gait traces were consistent regardless of the walking speed. However as walking speed increased, so did the peak joint angles and angular velocities for the hip, knee and ankle. The largest angular velocity occurred when the knee joint extended at the terminal swing phase of gait. For the ankle and hip joints, the largest angular velocity occurred during the push-off phase.

SIGNIFICANCE

This study examined how lower limb joint angular velocities change with various walking speeds. These data can be used as a comparator for data from clinical cohorts, and has the potential to be used to match clinical assessment and treatment methods to joint angular velocity during walking.

Clinical Assessment of Spasticity in People With Spinal Cord Damage: Recommendations From the Ability Network, an International Initiative

A thorough assessment of the extent and severity of spasticity, and its effect on functioning, is central to the effective management of spasticity in persons with spinal cord damage (SCD). These individuals however do not always receive adequate assessment of their spasticity. Inadequate assessment compromises management when the effect of spasticity and/or need for intervention are not fully recognized. Assessment is also central to determining treatment efficacy. A barrier to spasticity assessment has been the lack of consensus on clinical and functional measures suitable for routine clinical practice. To extend on existing work, a working group of the Ability Network identified and consolidated information on possible measures, and then synthesized and formulated findings into practical recommendations for assessing spasticity and its effect on function in persons with SCD. Sixteen clinical and functional measures that have been used for this purpose were identified using a targeted literature review. These were mapped to the relevant domains of the International Classification of Functioning, Disability and Health to assess the breadth of their coverage; coverage of many domains was found to be lacking, suggesting a focus for future work. The advantages, disadvantages, and usefulness of the measures were assessed using a range of criteria, with a focus on usefulness and feasibility in routine clinical practice. Based on this evaluation, a selection of measures suitable for initial and follow-up assessments are recommended. The recommendations are intended to have broad applicability to a variety of health care settings where people with SCD are managed.

Development of a clinical spasticity scale for evaluation of dogs with chronic thoracolumbar spinal cord injury

OBJECTIVE To develop a spasticity scale for dogs with chronic deficits following severe spinal cord injury (SCI) for use in clinical assessment and outcome measurement in clinical trials. ANIMALS 20 chronically paralyzed dogs with a persistent lack of hind limb pain perception caused by an acute SCI at least 3 months previously. PROCEDURES Spasticity was assessed in both hind limbs via tests of muscle tone, clonus, and flexor and extensor spasms adapted from human scales. Measurement of patellar clonus duration and flexor spasm duration and degree was feasible. These components were used to create a canine spasticity scale (CSS; overall score range, 0 to 18). Temporal variation for individual dogs and interrater reliability were evaluated. Gait was quantified with published gait scales, and CSS scores were compared with gait scores and clinical variables. Owners were questioned regarding spasticity observed at home. RESULTS 20 dogs were enrolled: 18 with no apparent hind limb pain perception and 2 with blunted responses; 5 were ambulatory. Testing was well tolerated, and scores were repeatable between raters. Median overall CSS score was 7 (range, 3 to 11), and flexor spasms were the most prominent finding. Overall CSS score was not associated with age, SCI duration, lesion location, or owner-reported spasticity. Overall CSS score and flexor spasm duration were associated with gait scores. CONCLUSIONS AND CLINICAL RELEVANCE The CSS could be used to quantify hind limb spasticity in dogs with chronic thoracolumbar SCI and might be a useful outcome measure. Flexor spasms may represent an integral part of stepping in dogs with severe SCI.

Motorized versus manual instrumented spasticity assessment in children with cerebral palsy

AIM

We compared the outcomes of manual and motorized instrumented ankle spasticity assessments in children with cerebral palsy (CP).

METHOD

Ten children with spastic CP (three males, seven females; mean age 11y [standard deviation 3y], range 6-14y; Gross Motor Function Classification System levels I-III) were included. During motorized assessments, fast (100°/s) rotations were imposed around the ankle joint by a motor-driven footplate; during manual assessments, rotations of comparable speed were applied by a therapist using a foot orthotic. Angular range of motion, maximum velocity, acceleration, work, and muscle activity (electromyography [EMG]) of the triceps surae and tibialis anterior were compared during passive muscle stretch between motorized and manual assessments. Both movement profiles were also compared to CP gait ankle movement profile.

RESULTS

The imposed movement profile differed between methods, with the motorized assessment reaching higher maximum acceleration. Despite equal maximum velocity, the triceps surae were more often activated in motorized assessments, with low agreement of 44% to 72% (κ≤0) for EMG onset occurrence between methods. The manually applied ankle velocity profile matched more closely with the gait profile.

INTERPRETATION

The differences in acceleration possibly account for the different muscle responses, which may suggest acceleration, rather than velocity-dependency of the stretch reflex. Future prototypes of instrumented spasticity assessments should standardize movement profiles, preferably by developing profiles that mimic functional tasks such as walking.

Mechanical and neural changes in plantar-flexor muscles after spinal cord injury in humans

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To determine the effect of injury duration on plantar-flexor elastic properties in individuals with chronic spinal cord injury (SCI) and spasticity.

SETTING

National Rehabilitation Center for Persons with Disabilities, Japan.

METHODS

A total of 16 chronic SCI patients (age, 33±9.3 years; injury localization, C6-T12; injury duration, 11-371 months) participated. Spasticity of the ankle plantar-flexors was assessed using the Modified Ashworth Scale (MAS). The calf circumference and muscle thickness of the medial gastrocnemius (MG), lateral gastrocnemius and soleus were assessed using tape measure and ultrasonography. In addition, the ankle was rotated from 10° plantar-flexion to 20° dorsiflexion at 5 deg s(-1) with a dynamometer, and the ankle angle and torque were recorded. After normalizing the data (the initial points of angle and torque were set to zero), we calculated the peak torque and energy. Furthermore, angle-torque data (before and after normalization) were fitted with a second- and fourth-order polynomial, and exponential (Sten-Knudsen) models, and stiffness indices (SISOP, SIFOP, SISK) and AngleSLACK (the angle at which plantar-flexor passive torque equals zero) were calculated. The stretch reflex gain and offset were determined from 0-10° dorsiflexion at 50, 90, 120 and 150 deg s(-1). After logarithmic transformation, Pearson's correlation coefficients were calculated.

RESULTS

MAS, calf circumference, MG thickness, peak torque and SIFOP significantly decreased with injury duration (r log-log=-0.63, -0.69, -0.63, -0.53 and -0.55, respectively, P<0.05). The peak torque and SIFOP maintained significant relationships even after excluding impacts from muscle morphology.

CONCLUSION

Plantar-flexor elasticity in chronic SCI patients decreased with increased injury duration.

Comprehensive quantification of the spastic catch in children with cerebral palsy

In clinical settings, the spastic catch is judged subjectively. This study assessed the psychometric properties of objective parameters that define and quantify the severity of the spastic catch in children with cerebral palsy (CP). A convenience sample of children with spastic CP (N=46; age range: 4-16 years) underwent objective spasticity assessments. High velocity, passive stretches were applied to the gastrocnemius (GAS) and medial hamstrings (MEH). Muscle activity was measured with surface electromyography (sEMG), joint angle characteristics using inertial sensors and reactive torque using a force sensor. To test reliability, a group of 12 children were retested after an average of 13 ± 9 days. The angle of spastic catch (AOC) was estimated by three biomechanical definitions: joint angle at (1) maximum angular deceleration; (2) maximum change in torque; and (3) minimum power. Each definition was checked for reliability and validity. Construct and clinical validity were evaluated by correlating each AOC definition to the averaged root mean square envelope of EMG (RMS-EMG) and the Modified Tardieu Scale (MTS). Severity categories were created based on selected parameters to establish face validity. All definitions showed moderate to high reliability. Significant correlations were found between AOC3 and the MTS of both muscles and the RMS-EMG of the MEH, though coefficients were only weak. AOC3 further distinguished between mild, moderate and severe catches. Objective parameters can define and quantify the severity of the spastic catch in children with CP. However, a comprehensive understanding requires the integration of both biomechanical and RMS-EMG data.

Cycling with functional electrical stimulation in an adult with spastic diplegic cerebral palsy

BACKGROUND AND PURPOSE

Adults with cerebral palsy (CP) are at risk for decreased mobility and health complications, and exercise may combat some of these negative changes. Because people with CP have difficulty generating sufficient muscle force, exercise augmented with functional electrical stimulation (FES) is an option for increasing exercise intensity. This mixed-method (quantitative-qualitative) case report describes the effects-across the International Classification of Functioning, Disability and Health (ICF) model-of cycling with FES (FES cycling) in an adult with CP.

CASE DESCRIPTION

An ambulatory 49-year-old man with spastic diplegic CP cycled with FES at home for 30 minutes, 3 times per week, for 12 weeks. Volitional efforts were augmented by FES of the bilateral quadriceps, gastrocnemius, and gluteal muscles. Testing was performed before and after the intervention and 4 weeks after intervention withdrawal.

OUTCOMES

After training, quadriceps muscle strength (force-generating capacity) improved by 22.2%, hamstring muscle strength improved by 18.5%, and the Timed "Up & Go" Test time decreased from 11.9 to 9.0 seconds. The patient reported increased performance and satisfaction for self-identified goals at the ICF level of participation, and his score on the Medical Outcomes Study 36-Item Health Survey questionnaire increased from 62.1 to 77.6. However, he reported increased back pain, which he attributed to positioning while cycling. Qualitative interviews provided context (the patient's perspective) for some of the quantitative results.

DISCUSSION

The patient made gains in body structure and function, activity, and participation (ICF levels) after FES cycling. The mixed-method approach provided insight into his experiences and perceptions about the measures assessed quantitatively. Further investigation on FES cycling in this population as well as positioning during cycling is warranted.

Biomechanical and electromyographic assessment of spastic hypertonus in motor complete traumatic spinal cord-injured individuals

STUDY DESIGN

Between-groups design with repeated measures.

OBJECTIVE

To quantify spastic hypertonia in spinal cord-injured (SCI) individuals.

SETTING

Rehabilitative Center, Italy.

SUBJECTS

29 individuals with a motor complete SCI (American Spinal Injury Association impairment scale grade A or B) and 22 controls.

METHODS

According to the modified Ashworth scale (MAS), patients were subgrouped as SCI-1 (MAS=1, 1+) and SCI-2 (MAS=2, 3). Passive flexo-extensions of the knee were applied using an isokinetic device (LIDO Active) at 30°, 60°, 90° and 120° s(-1). We measured the peak torque, mean torque (MT) and work. Simultaneous electromyography (EMG) was recorded from leg muscles.

RESULTS

At the speed of 120° s(-1) all SCI-2 patients presented EMG reflex activities in the hamstring muscle. All biomechanical parameter values increased significantly according to speed, but analysis of variance revealed a significant interaction between the angular velocity and group (F(d.f. 6, 138) = 8.89, P < 0.0001); post hoc analysis showed significantly greater torque parameter values in the SCI-2 group compared with the SCI-1 group and the control group at 90° and 120° s(-1). Receiver operating characteristic curves showed that using peak torque values the probability of correctly classifying a patient into SCI-1 and SCI-2 was 95%, compared with 70% for MT and 68% for work.

CONCLUSIONS

The isokinetic device is useful for distinguishing individuals with a high level of spastic hypertonus. Examination of EMG activity may help ascertain whether increased muscle tone is caused by reflex hyper excitability and to determine whether muscle spasm is present. Peak torque and simultaneous EMG assessment should be considered for the evaluation of individuals with SCI in the rehabilitative context, that is, in measuring therapeutic interventions.

Examination of spasticity of the knee flexors and knee extensors using isokinetic dynamometry with electromyography and clinical scales in children with spinal cord injury

BACKGROUND/OBJECTIVE

To examine the role of reflex activity in spasticity and the relationship between peak passive torque, Ashworth Scale (AS), and Spasm Frequency Scale (SFS) of the knee flexors and extensors during the measurement of spasticity using an isokinetic dynamometer in children with spinal cord injury (SCI).

METHODS

Eighteen children with chronic SCI and 10 children of typical development (TD) participated. One set of 10 passive movements was completed using an isokinetic dynamometer at 15, 90, and 180 degrees per second (deg/s) while surface electromyographic data were collected from the vastus lateralis (VL) and medial hamstrings (MH). Spasticity was clinically assessed using the AS and SFS.

RESULTS

There were no significant differences in peak passive torque of the knee flexors and extensors at any velocity for children with SCI compared to children with TD. Children with TD demonstrated significantly more reflex activity of the MH during the assessment of knee flexor spasticity at all movement velocities than did children with SCI. Children with TD demonstrated significantly more reflex activity of the VL during the assessment of knee-extensor spasticity with movements at 180 deg/s. The relationship between peak passive torque, AS, and SFS was significant during movements at a velocity of 90 deg/s only.

CONCLUSIONS

The role of increased reflexes in spasticity needs further examination. Isokinetic dynamometry may be measuring a different aspect of spasticity than the AS and SFS do in children with SCI.

Spasticity-assessment: a review

STUDY DESIGN

Review of the literature on the validity and reliability of assessment of spasticity and spasms.

OBJECTIVES

Evaluate the most frequently used methods for assessment of spasticity and spasms, with particular focus on individuals with spinal cord lesions.

SETTING

Clinic for Spinal Cord Injuries, Rigshospitalet, University Hospital of Copenhagen, and Department of Medical Physiology, University of Copenhagen, Denmark.

METHODS

The assessment methods are grouped into clinical, biomechanical and electrophysiological, and the correlation between these is evaluated.

RESULTS

Clinical methods: For assessment of spasticity, the Ashworth and the modified Ashworth scales are commonly used. They provide a semiquantitative measure of the resistance to passive movement, but have limited interrater reliability. Guidelines for the testing procedures should be adhered to. Spasm frequency scales seem not to have been tested for reliability. Biomechanical methods such as isokinetic dynamometers are of value when an objective quantitative measure of the resistance to passive movement is necessary. They play a minor role in the daily clinical evaluation of spasticity. Electrophysiological methods: These techniques have provided valuable insight to the pathophysiological mechanisms involved in spasticity, but none of these techniques provide an easy and reliable assessment of spasticity for use in the daily clinic.

CONCLUSION

A combination of electrophysiological and biomechanical techniques shows some promise for a full characterization of the spastic syndrome. There is a need of simple instruments, which provide a reliable quantitative measure with a low interrater variability.

Biomechanical assessment with electromyography of post-stroke ankle plantar flexor spasticity

Spasticity has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflex (muscle tone). Muscle tone consists of mechanical-elastic characteristics, reflex muscle contraction and other elements. The aims of this study were to determine whether to assess spasticity quantitatively, and to characterize biomechanical and electromyographic spasticity assessment parameters. These assessment parameters were described by investigating the correlation between clinical measures and the response to passive sinusoidal movement with consecutive velocity increments. Twenty post-stroke hemiplegic patients and twenty normal healthy volunteers were included in the study. Five consecutive sinusoidal passive movements of the ankle were performed at specific velocities (60, 120, 180, and 240 degrees/ sec). We recorded the peak torque, work, and threshold angle using a computerized isokinetic dynamometer, and simultaneously measured the rectified integrated electromyographic activity. We compared these parameters both between groups and between different velocities. The peak torque, threshold angle, work, and rectified integrated electromyographic activity were significantly higher in the post-stroke spastic group at all angular velocities than in the normal control group. The threshold angle and integrated electromyographic activity increased significantly and linearly as angular velocity increased, but the peak torque and work were not increased in the post-stroke spastic group. Peak torque, work, and threshold angle were significantly correlated to the Modified Ashworth scale, but the integrated electromyographic activity was not. The biomechanical and electromyographic approach may be useful to quantitatively assess spasticity. However, it may also be very important to consider the different characteristics of each biomechanical parameter.

Quantitative assessment of the velocity-dependent increase in resistance to passive stretch in spastic plantarflexors

BACKGROUND

Although numerous studies revealed that isokinetic dynamometers were valuable tools for assessing spastic hypertonia, no standard methodology using such devices is currently widespread in clinical setting. The aim of this study was to standardize a protocol to assess spastic hypertonia in the triceps surae.

METHODS

The passive resistance during dorsiflexions imposed from 10 to 300 degrees /s with an isokinetic dynamometer was measured at the neutral position in 15 patients with spastic hypertonia and 12 healthy subjects. The normalized passive resistance was obtained by expressing raw passive resistance as a percent of the values measured at the lowest velocity (10 degrees /s). EMG signals from plantar and dorsiflexors were also recorded.

FINDINGS

While no significant difference between spastic patients and control subjects was observed in raw passive resistance values, the difference was significant for each tested velocity when considering the normalized values. Furthermore, the Ashworth score was significantly correlated with the normalized passive resistance for each velocity whereas no correlation was observed with the raw passive resistance. For the patients, except at the highest velocity, the normalized passive resistance was not affected by the fact that reflex responses in the triceps surae were elicited or not.

INTERPRETATION

The normalized passive resistance, expressed with respect to the initial one, i.e., measured at very low velocity, seems a very effective parameter to quantify the velocity-dependent increase in resistance to passive stretch in spastic plantarflexors. However, while the simplicity of the isokinetic tests and the reduced time of data treatment seems to support the clinical use of this methodology, further investigations are required to definitely standardize the protocol.

The effect of passive cycling movements on spasticity after spinal cord injury: preliminary results

OBJECTIVE

To investigate the influence of rhythmic passive movements of the legs on the reduction of spasticity after spinal cord injury (SCI).

SETTING

Swiss Paraplegic Centre Nottwil, Switzerland.

METHODS

A total of 10 subjects with motor complete SCI were treated with a cycling device for half an hour. Before and after cycling their spasticity was tested with an isokinetic dynamometer. The subjects were tested one week later by exactly the same procedure with a half an hour break instead of the cycling. Subjects were asked about their spasticity before and after the cycling and break.

RESULTS

There was no significant difference in elicited peak torque either before and after the cycling, or before and after the break (MANOVA, P<0.05). Six out of 10 subjects estimated their spasticity as less after the cycling.

CONCLUSION

With the isokinetic dynamometer, it was not possible to show an effect of passive cycling on spasticity reduction. However, six out of 10 of the subjects estimated their spasticity to be less after cycling. This positive effect might be attributed to a reduced spasticity in the trunk and/or to the attention the subjects perceived during the intervention.

Differences in kinematic parameters and plantarflexor reflex responses between manual (Ashworth) and isokinetic mobilisations in spasticity assessment

OBJECTIVE

The purpose of this study was first to compare the kinematic parameters of imposed ankle mobilizations measured during Ashworth or isokinetic tests and, second, to better understand why the stretch reflex was more or less easily elicited by one method or the other.

METHODS

Passive dorsiflexions were applied on eight adult patients with plantarflexor spasticity in two conditions: (i) manually, using the Ashworth test where passive dorsiflexions were performed freely by seven rehabilitation clinicians, and (ii) instrumentally, using an isokinetic device (Cybex Norm) and a dorsiflexion velocity at 300 degrees /s. Mean values of initial ankle position, maximal angular velocity (theta;'(max)), maximal angular acceleration (theta;''(max)) and plantarflexor reflex responses obtained with each method were compared.

RESULTS

During the Ashworth test, all the patients presented reflex activities in the triceps surae while, during the isokinetic mobilization, only three out of the eight patients tested shown reflex responses. theta;'(max) values were significantly higher (P<0.05) in the manual test (308+/-80 degrees /s vs 216+/-5.5 degrees /s for the isokinetic test). The most marked difference concerned the theta;''(max) values (5046+/-2181 degrees /s(2) for the Ashworth test vs 819+/-18 degrees /s(2) for the isokinetic test, P<0.001). This parameter was significantly correlated with the mean rms-EMG values of the gastrocnemius lateralis (GL) and the soleus (SOL).

CONCLUSIONS

This study indicates that passive dorsiflexions imposed during Ashworth and isokinetic tests largely differ in velocity and acceleration, and the higher dynamic parameters evaluated during the Ashworth test could mainly explain that the stretch reflex was more easily elicited during this manual testing.

SIGNIFICANCE

If isokinetic devices offer numerous advantages in the assessment of passive resistance to spastic muscle stretch, they cannot be used to simulate the manual test.

The importance of posture on the isokinetic assessment of spasticity

OBJECTIVE

To measure spasticity of the knee flexors and extensor muscles in two different hip positions.

SETTING

Swiss Paraplegic Center Nottwil, Switzerland.

METHODS

Twenty spinal cord injured (SCI) patients with complete lesions were tested with a torque-velocity dynamometer in the following positions: (1) supine with a hip angle of 0 degrees; (2) sitting with a hip angle of 90 degrees. The excursion of the knee was measured for both positions using a goniometer. Two flexion/extension movements of the knee were performed at a speed of 10 degrees per sec. A further four flexion/extension movements over the same trajectory were made at a speed of 120 degrees per sec. Eccentric peak torques were measured continuously during movement of both legs for both speeds.

RESULTS

At a speed of 120 degrees per second, there was a significant difference in stretch reflex of the hamstrings and quadriceps femoris muscles for the two positions (Wilcoxon's paired t-test, P<0.05). Excitability was higher for the quadriceps femoris muscles in supine than in sitting position. For the hamstrings, the effect was reversed. Significant differences between sitting and supine position were not found for the speed of 10 degrees per sec. Test-retest reliability was high for the movements of 120 degrees per sec but low for 10 degrees per sec.

CONCLUSIONS

Our findings indicate that for a reliable and comparable measurement of spasticity, an exact description of test position and procedure is essential.

Clinical measurement of muscle tone using a velocity-corrected modified Ashworth scale

OBJECTIVE

To develop a new form of the modified Ashworth scale (MAS) for muscle-tone assessment that combines the MAS score with the passive muscle-stretching velocity during the assessment of muscle tone, resulting in a measure that has higher intertester reliability than the MAS.

DESIGN

Twenty-two volunteer subjects with spinal cord injuries at a tertiary care outpatient and inpatient spinal cord injury rehabilitation center affiliated with a university were recruited for this study.

RESULTS

A decision tree in which V-MAS scores were obtained was developed. The data obtained from three independent raters, when adjusted by means of the V-MAS, showed an excellent interrater reliability.

CONCLUSIONS

Results indicated that the V-MAS is a more reliable measure. In addition, the resulting units of the V-MAS, ranging from 0 to 1, are of the same form as pendulum test data. The V-MAS method is quite simple to use because the rater need only measure the angular range and duration of the passive movement to calculate average velocity during the MAS assessment in addition to the normal MAS rating of muscle tone.