Quantitative measurement of spasticity in children with cerebral palsy

Acupuncture for the treatment of spasticity after stroke: a meta-analysis of randomized controlled trials

OBJECTIVES

Acupuncture has been suggested as a treatment for spasticity in patients with stroke. The available literature was reviewed in an effort to assess its efficacy in this situation.

METHODS

Randomized trials assessing the effects of acupuncture for the treatment of spasticity after stroke were identified by searching the Cochrane Library, PubMed, ProQuest, EBSCOhost, SCOPUS, CINAHL, EMBASE, Alternative Medicine Database, and Chinese and Korean medical literature databases. Two reviewers independently extracted data on study characteristics, patient characteristics, and spasticity outcomes.

RESULTS

Eight trials with 399 patients met all the inclusion criteria. Compared with controls without acupuncture, acupuncture had no effect on improving clinical outcomes (as measured by validated instruments such as the Modified Ashworth Scale) or physiologic outcomes (assessed by measures such as the H-reflex/M-response [H/M] ratio at the end of the treatment period). H/M ratios did decrease significantly immediately after the first acupuncture treatment. Methodologic quality of all evaluated trials was considered inadequate.

CONCLUSIONS

The effect of acupuncture for spasticity in patients with stroke remains uncertain, primarily because of the poor quality of the available studies. Larger and more methodologically sound trials are needed to definitively confirm or refute any effect of acupuncture as a treatment for spasticity after stroke.

Passive muscle properties are altered in children with cerebral palsy before the age of 3 years and are difficult to distinguish clinically from spasticity

AIM

Clinical determination of spasticity is confounded by the difficulty in distinguishing reflex from passive contributions to muscle stiffness. There is, therefore, a risk that children with cerebral palsy (CP) receive antispasticity treatment unnecessarily. To investigate this, we aimed to determine the contribution of reflex mechanisms to changes in the passive elastic properties of muscles and tendons in children with CP.

METHOD

Biomechanical and electrophysiological measures were used to determine the relative contribution of reflex and passive mechanisms to ankle muscle stiffness in 35 children with spastic CP (21 males, 14 females; mean age 9 y, SD 3 y 4 mo; range 3-15 y) and 28 control children without CP (19 males, nine females; mean age 8 y 11 mo, SD 2 y 10 mo; range 3-15 y). Twenty-seven children were diagnosed as having spastic hemiplegia, six with spastic diplegia, and two with spastic tetraplegia. According to the Gross Motor Function Classification System, 31 children were classified in level I, two in level II, and two in level III.

RESULTS

Only seven children with spastic CP showed reflex stiffness outside the range of the control children. In contrast, 20 children with spastic CP showed abnormal passive muscle stiffness (p<0.001). No correlation between increased reflex or increased passive muscle stiffness and age was observed within the age range studied.

INTERPRETATION

These data suggest that increased reflex-mediated muscle stiffness is difficult to distinguish clinically from changes in passive muscle stiffness and that signs of changes in muscle properties are already present from the age of 3 years in children with CP. This emphasizes the importance of accurately distinguishing different contributions to muscle stiffness to avoid unnecessary antispasticity treatment.

Prediction of Natural History of Neuromuscular Properties After Stroke Using Fugl-Meyer Scores at 1 Month

Background. The link between spasticity and impaired voluntary movement after stroke remains unclear because of the lack of suitable tools characterizing properties of spastic muscles. Describing this relationship early poststroke can potentially help predict the extent and time course of recovery. Objective. To describe the time course of changes in neuromuscular properties after stroke using the upper extremity Fugl-Meyer Assessment (FMA) at 1 month to predict recovery patterns over 1 year. Methods.Using a parallel cascade system identification technique, this study characterized intrinsic and reflex behaviors for different mean elbow joint angles, at specified times poststroke. Then the “growth mixture” model was used to characterize recovery patterns over 1 year. Logistic regression analyses were applied to predict these patterns. The impact of patient characteristics was also investigated. Results. In 21 stroke survivors, 14 had sustained hemorrhage and 7 had thromboses. The study observed several recovery classes, relating intrinsic and reflex stiffness magnitudes with changing elbow angle at different time points. The largest group (48%) showed progressive increase in reflex stiffness over time, but 33% showed declining reflex stiffness over the same period. A third class (19%) showed invariant reflex properties. These differences were linked to the initial reflex magnitudes. The FMA at 1 month showed an inverse relationship with key reflex patterns and proved to be a strong predictor of class membership. Stroke type was also influential. Conclusions. The logistical regression class may enable us to accurately predict reflex responses during the first year, allowing us to apportion impairment between central and peripheral mechanisms.

Evaluation of the catch in spasticity assessment in children with cerebral palsy

OBJECTIVE

To evaluate whether the catch in clinical spasticity assessment in cerebral palsy (CP) is the consequence of a sudden velocity-dependent increase in muscle activity, resulting from hyperexcitability of the stretch reflex in spasticity.

DESIGN

Cross-sectional study.

SETTING

A special school for children with physical disabilities.

PARTICIPANTS

Children with CP (N=20; age range, 5-14y; mean weight +/- SD, 35+/-14kg; mean length +/- SD, 139+/-19cm).

INTERVENTIONS

Spasticity assessment tests (using slow and fast passive stretch) were performed in the medial hamstrings, soleus, and medial gastrocnemius muscles of the children by 2 experienced examiners.

MAIN OUTCOME MEASURES

Surface electromyography (EMG) was recorded and joint motion was simultaneously measured using 2 inertial sensors. The encounter of a catch by the examiner was compared with the presence of a sudden increase in muscle activity ("burst"). The average rectified value (ARV) of the EMG signal was calculated for each test.

RESULTS

The study shows a sudden increase in muscle activity in fast passive stretch, followed by a catch (hamstrings 100%, soleus 95%, gastrocnemius 84%). The ARV in slow passive stretch was significantly lower.

CONCLUSIONS

The results confirm that in children with CP, an increase in muscle activity is primarily responsible for a catch in fast passive muscle stretch.

Neuromuscular properties of different spastic human joints vary systematically

We quantified the mechanical abnormalities of the spastic wrist in chronic stroke survivors, and determined whether these findings were representative of those recorded at the elbow and ankle joints. System identification techniques were used to characterize the mechanical abnormalities of these joints and to identify the contribution of intrinsic and reflex stiffness to these abnormalities. Modulation of intrinsic and reflex stiffness with the joint angle was studied by applying PRBS perturbations to the joints at different joint angles over the range of motion. Age-matched healthy subjects were used as control.

Reliability of Ashworth and Modified Ashworth scales in children with spastic cerebral palsy

BACKGROUND

Measurement of spasticity is a difficult and unresolved problem, partly due to its complexity and the fact that there are many factors involved. In the assessment of spasticity in the pediatric disabled population, methods that are easily used in practice are ordinal scales that still lack reliability. A prospective cross-sectional observational study was planned to determine the reliability of the Ashworth Scale (AS) and the Modified Ashworth Scale (MAS) in children with spastic cerebral palsy (CP).

METHODS

The study included 38 children with spastic diplegic CP. The mean age for the children was 52.9 months (SD: 19.6) ranging from 18 to 108 months. The functional levels of children were classified according to the Gross Motor Function Classification System. 20 children were in Level II (52.6%), 18 were in Level III (47.4%) and 9 were in Level I (23.7%). Spasticity in hip flexors, adductors, internal rotators, hamstrings, gastrocnemius were assessed by AS and MAS. Each child was assessed by three physiotherapists in two different sessions, a week apart. The intrarater reliability was determined by paired comparison of measurements for each therapist for the two assessments. Interrater reliability was determined by paired comparisons of the three therapists' measurements on the same day. The inter and intrarater reliability of the scales were evaluated by the intraclass correlation coefficient (ICC).

RESULTS

According to ICC scores, interrater reliability of AS and MAS varied from moderate to good. ICC scores of AS were between 0.54 and 0.78 and MAS were between 0.61-0.87. Test-retest results of AS and MAS varied from poor to good. ICC values were between 0.31 and 0.82 for AS and between 0.36 and 0.83 for MAS.

CONCLUSION

The interrater and intrarater reliability of AS and MAS are related to muscle and joint characters. The repetition of measurements by the same physiotherapist, and experience may not affect reliability. These scales are not very reliable and assessments of spasticity using these scales should be therefore interpreted with great caution.

Muscle and reflex changes with varying joint angle in hemiparetic stroke

Background

Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint.

Methods

Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls.

Results

Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position.

Conclusion

In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated.

Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non-paretic limb may not be a suitable control for studying neuromuscular properties of the ankle joint.

Our findings will help elucidate the origins of the neuromuscular abnormalities associated with stroke-induced spasticity.

Botulinum toxin for spasticity in children with cerebral palsy: a comprehensive evaluation

BACKGROUND

Spasticity is a prevalent disabling clinical symptom for children with cerebral palsy. Treatment of spasticity with botulinum toxin in children with cerebral palsy was first reported in 1993. Botulinum toxin provides a focal, controlled muscle weakness with reduction in spasticity. Interpretation of the literature is difficult because of the paucity of reliable measures of spasticity and challenges with measuring meaningful functional changes in children with disabilities.

OBJECTIVE

This study documents the effects of botulinum toxin A injections into the gastrocnemius muscles in children with spastic diplegia. Outcomes are evaluated across all 5 domains of the National Centers for Medical and Rehabilitation Research domains of medical rehabilitation.

METHODS

A randomized, double-masked, placebo-controlled design was applied to 33 children with spastic diplegia with a mean age of 5.5 and Gross Motor Function Classification System Levels of I through III. Participants received either 12 U/kg botulinum toxin A or placebo saline injections to bilateral gastrocnemius muscles. Outcomes were measured at baseline and 3, 8, 12, and 24 weeks after injection.

RESULTS

Significant decreases in the electromyographic representation of spasticity were documented 3 weeks after botulinum toxin A treatment. A significant decrease in viscoelastic aspects of spasticity was present at 8 weeks, and subsequent increases in dorsiflexion range were documented at 12 weeks for the botulinum toxin A group. Improvement was found in performance goals at 12 weeks and in maximum voluntary torque and gross motor function at 24 weeks for the botulinum toxin A. There were no significant differences between groups in satisfaction with performance goals, energy expenditure, Ashworth scores, or frequency of adverse effects.

CONCLUSIONS

The safety profile of 12 U/kg of botulinum toxin A is excellent. Although physiologic and mechanical effects of treatment with botulinum toxin A were documented with functional improvement at 6 months, family satisfaction with outcomes were no different. Communication is needed to ensure realistic expectations of treatment.

Neuromuscular abnormalities associated with spasticity of upper extremity muscles in hemiparetic stroke

Our objective was to assess the mechanical changes associated with spasticity in elbow muscles of chronic hemiparetic stroke survivors and to compare these changes with those recorded in the ankle muscles of a similar cohort. We first characterized elbow dynamic stiffness by applying pseudorandom binary positional perturbations to the joints at different initial angles, over the entire range of motion, with subjects relaxed. We separated this stiffness into intrinsic and reflex components using a novel parallel cascade system identification technique. In addition, for controls, we studied the nonparetic limbs of stroke survivors and limbs of age-matched healthy subjects as primary and secondary controls. We found that both reflex and intrinsic stiffnesses were significantly larger in the stroke than in the nonparetic elbow muscles, and the differences increased as the elbow was extended. Reflex stiffness increased monotonically with the elbow angle in both paretic and nonparetic sides. In contrast, the modulation of intrinsic stiffness with elbow position was different in nonparetic limbs; intrinsic stiffness decreased sharply from full- to mid-flexion in both sides, then it increased continuously with the elbow extension in the paretic side. It remained invariant in the nonparetic side. Surprisingly, reflex stiffness was larger in the nonparetic than in the normal control arm, yet intrinsic stiffness was smaller in the nonparetic arm. Finally, we compare the angular dependence of paretic elbow and ankle muscles and show that the modulation of reflex stiffness with position was strikingly different.

Measurement of plantarflexor spasticity in traumatic brain injury: correlational study of resistance torque compared with the modified Ashworth scale

OBJECTIVES

To examine the usefulness of a biomechanical measure, resistance torque (RT), in quantifying spasticity by comparing its use with a clinical scale, the modified Ashworth scale (MAS), and quantitative electrophysiological measures.

DESIGN

This is a correlational study of spasticity measurements in 34 adults with traumatic brain injury and plantarflexor spasticity. Plantarflexor spasticity was measured in the seated position before and after cryotherapy using the MAS and also by strapping each subject's foot and ankle to an apparatus that provided a ramp and hold stretch. The quantitative measures were (1) reflex threshold angle (RTA) calculated through electromyographic signals and joint angle traces, (2) Hdorsiflexion (Hdf)/Hcontrol (Hctrl) amplitude ratio obtained through reciprocal inhibition of the soleus H-reflex, (3) Hvibration (Hvib)/Hctrl ratio obtained through vibratory inhibition of the soleus H-reflex, and (4) RT calculated as the time integral of the torque graph between the starting and ending pulses of the stretch.

RESULTS

Correlation coefficients between RT and MAS scores in both pre-ice (0.41) and post-ice trials (0.42) were fair (P = 0.001). The correlation coefficients between RT scores and RTA scores in both the pre-ice (0.66) and post-ice trials (0.75) were moderate (P <or= 0.001).

CONCLUSION

RT is a measure of the cumulative torque during an imposed stretch. The MAS is a subjective measure of the cumulative resistance perceived by the clinician during an imposed stretch. RT seems to be a fair quantitative correlate of the MAS in assessing spasticity.

Human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis: viral load and muscle tone are correlated

Human T-lymphotropic virus type 1 (HTLV-1) infections are associated with varying degrees of HTLV-1 viral load and spasticity. Increased viral load is associated with higher risk of developing HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The authors performed a cross-sectional study of 24 people with HAM/TSP in Lima, Perú, to determine if higher HTLV-1 viral load was correlated with increased muscle tone, measured with a device providing quantitative spasticity assessment (QSA). Median HTLV-1 viral load was 17.0 copies/100 peripheral blood mononuclear cells and QSA value was 39.9 Newton-meters/radian. HTLV-1 viral load was significantly correlated with QSA value (Spearman rho = .48, P = .02), suggesting viral load may play a role in expression of symptomatic neurologic disease. Longitudinal studies are needed to determine if treatments that reduce viral load will reduce muscle tone.

A radiographic technique for the assessment of ankle and midfoot equinus

BACKGROUND

Both clinical and radiographic techniques have been used to evaluate foot and ankle position and orientation. Clinical measurements have been shown to be less reliable than radiographic measurements. Because midfoot equinus deformity may coexist with ankle joint equinus deformity, a radiographic method of separating and measuring these two components is desirable. The purpose of this study was to evaluate a new radiographic technique, the Lateral Mid-Tibia to Toes (LMTT), weightbearing view of the foot and ankle.

METHOD

Twenty LMTT images were randomly selected from the study population of patients treated in our center for lower limb equinus deformity. Validation was achieved by a study involving three observers, assessing 20 images on two consecutive occasions, 4 weeks apart. Analysis was performed using Kappa statistics.

RESULTS

The plantigrade and midfoot equinus angles provided substantial (p = 0.000) and moderate (p = 0.005) agreement, respectively.

CONCLUSIONS

Awareness of midfoot equinus and its correction may avoid residual deformity when surgery is performed to correct equinus deformity of the ankle.

Quantitative assessment of spasticity in human T-cell lymphotropic virus type I–associated myelopathy/tropical spastic paraparesis

People with human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) develop spasticity. The authors examined 34 patients with HAM/TSP in Perú using a device that measures tone in the gastroc-soleus-Achilles tendon unit and provides a quantitative spasticity assessment (QSA). Tone in the 34 patients was more than double that of women with asymptomatic HTLV-I infection. The device may help to track progression in HTLV-I infection.

Intra- and interrater reliabilities of the Myotonometer when assessing the spastic condition of children with cerebral palsy

The purposes of this study were to assess intra- and interrater reliabilities by novice users of the Myotonometer (Neurogenic Technologies, Inc., Missoula, MT), a portable electronic device that quantifies muscle tone (stiffness) and paresis, in assessing children with cerebral palsy. Two raters used the Myotonometer to assess the biceps brachii and medial gastrocnemius muscles of 10 children with spastic-type cerebral palsy. Muscles were measured in a relaxed state and during a voluntary isometric contraction. Intraclass correlation coefficients and repeatability coefficients were calculated for each muscle and for each condition (relaxed and contracted). Intrarater reliabilities ranged from 0.82 to 0.99 (biceps brachii muscles) and 0.88 to 0.99 (medial gastrocnemius muscles). Interrater reliabilities ranged from 0.74 to 0.99 (biceps brachii muscles) and 0.84 to 0.99 (medial gastrocnemius muscles). Repeatability coefficients indicated a 98% level of agreement between raters across all conditions. Novice users of the Myotonometer, with few exceptions, had high to very high intra- and interrater reliabilities for measurements of the biceps brachii and medial gastrocnemius muscles of children with spastic-type cerebral palsy.

Active stiffness of the ankle in response to inertial and elastic loads

Effective stiffness of the musculoskeletal system was examined as a function of the characteristics of an external load. Thirteen healthy subjects provided active contraction of the ankle plantarflexion musculature in a neutral ankle posture to support an external load. Musculoskeletal stiffness was computed from kinetic data recorded in response to dorsiflexion/plantarflexion perturbations. Ankle dynamics were recorded while supporting external loads of 19 and 38 kg with and without antagonistic co-contraction. External loads were applied using pure gravitational mass. In separate trials external loads were applied from stretch of steel springs in parallel with the plantarflexion musculature that also provided added parallel stiffness to the system. Adding external stiffness of 4.9 and 8.1 kN/m surprisingly failed to significantly change the stiffness of the ankle-plus-spring system. This suggests contributions from intrinsic muscle stiffness and reflex stiffness declined in response to added external stiffness. This could not be explained by load magnitudes, ankle postures, or co-activation as these were similar between the inertial and elastic loading conditions. However, non-linear parametric analyses suggest mean intrinsic stiffness of 35.5 kN/m and reflex gain of 11.6 kN/m with a constant reflex delay of 70 ms accurately described the empirical results. The phase response between the mechanical dynamics of the musculoskeletal system and delayed neuromotor feedback combine to provide robust control of system behavior.

Mechanical Measurements of the Effects of Intrathecal Baclofen Dosage Adjustments in Cerebral Palsy

OBJECTIVE

The purpose of this pilot study was to determine the feasibility of using mechanical measures of stretch reflexes to monitor spasticity after intrathecal baclofen dosage changes.

DESIGN

Mechanical measures were made in studying six participants with cerebral palsy who were undergoing treatment for spasticity using intrathecal baclofen therapy. Mechanical measurements of stretch reflexes were made before and after pump implant in four of the six participants and after dosage changes in all participants, for a period of up to 2 yrs. The measurements comprised electromyograms and resistive torque responses to movement of the ankle, imposed with an isokinetic dynamometer. For each test session, random movements were applied to the ankle at each of four to seven speeds, repeated three or five times.

RESULTS

Stretch reflex excitability decreased in three of four participants after initiation of intrathecal baclofen therapy and decreased with increasing dosages in three of the six participants. Broken catheters coincided with heightened mechanical measures in two cases.

CONCLUSION

Mechanical measures of stretch reflexes change after intrathecal baclofen dosage adjustments, reflecting the clinical course of intrathecal baclofen therapy.

Myotonometer intra- and interrater reliabilities

OBJECTIVES

To assess the intra- and interrater reliabilities of the Myotonometer, a hand-held, computerized, electronic device that quantifies muscle stiffness (tone/compliance).

DESIGN

Reliability study.

SETTING

Research laboratory.

PARTICIPANTS

Thirty-five healthy, nondisabled adults (age range, 22-42 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two raters used the Myotonometer to evaluate subjects' lateral gastrocnemius and biceps brachii muscles. Muscles were measured in a relaxed state and during a voluntary isometric contraction. Coefficients were calculated for each muscle and each condition (relaxed, contracted). Results were analyzed by using Design II intraclass correlation coefficients.

RESULTS

Reliability coefficients were highest when the instrument exerted moderate to strong forces against the muscle (range, 0.50-2.00 kg; intrarater reliability R range, .84 - .99; interrater reliability R range, .75 - .96).

CONCLUSIONS

Myotonometer measurements had high to very high intra- and interrater reliabilities for measurements of the lateral gastrocnemius and biceps brachii muscles.

Outcome measurement of effectiveness of botulinum toxin type A in children with cerebral palsy: an ICIDH-2 approach

The ICIDH-2 serves as a useful framework for differentiating measurement by dimensions of the disabling process. Such differentiation is important to achieve more valid measurement of health related outcomes. We have attempted to examine one intervention, treatment with botulinum toxin type A, for one patient population, children with cerebral palsy, and to describe the outcome measures used in the evaluation of that intervention using this evolving classification system. This process supports the concept that measurement of health outcomes should focus on the nature and extent of functional limitations in physical, social and psychological domains. The selection of measurement outcomes must be determined not only by the requirements of the scientific process but also by the needs of the patients who are the intended beneficiaries of the intervention.

Quantifying muscle activity in non-ambulatory children with spastic cerebral palsy before and after selective dorsal rhizotomy

Cerebral palsy is a condition that results in varying degrees of functional deficits. The goal of this study was to develop an objective measure of muscle activity during a prescribed voluntary motor task in non-ambulatory children with spastic cerebral palsy. While performing a simultaneous hip/knee flexion task from the supine position, followed by return to the starting position, electromyographic and kinematic data were obtained from the right leg of eight children before and after selective dorsal rhizotomy and compared with eight age-matched controls. The electromyographic and kinematic data were combined to determine for each muscle of interest (tibialis anterior, soleus, vastus lateralis, biceps femoris) the percentage of the movement cycle for which the muscle was acting concentrically, eccentrically, isometrically or was considered inactive. Averaged over the four muscles, isometric activity decreased by 38% post-op and the time the muscles were inactive increased by 37% following surgery. The percentages of concentric and eccentric activity did not differ significantly between pre- and post-op conditions. Post-operatively, the percentage muscle activity patterns of the children with cerebral palsy more closely resembled that of the control children: averaged across all muscles and contraction types, the difference between the control children and the children with cerebral palsy was reduced by 50% following surgery. This measurement technique indicates promise as a method for quantifying muscle activity during voluntary motor tasks in non-ambulatory children with cerebral palsy.

Electromechanical delay and reflex response in spastic cerebral palsy

OBJECTIVE

Electromechanical delay (EMD) and reflex response in patients with spastic cerebral palsy (CP) were quantified and compared with those in normally developing individuals. It was hypothesized that the increased muscle stiffness associated with spasticity must make EMD shorter than the EMD of normally functioning muscles.

DESIGN

Electromechanical reflex behavior was assessed in a case-control study.

SETTING

Motion Analysis and Motor Performance Laboratory, University of Virginia, a tertiary clinical referral center and research facility.

PARTICIPANTS

A volunteer sample of 12 children diagnosed with spastic CP and 12 age-matched, normally developing children recruited from the local community and clinical services.

RESULTS

EMD in the patients with spasticity was significantly shorter than in the normally developing subjects, 40.5 msec and 54.7 msec, respectively. The spastic group also had greater reflex activity, rate of force development, and antagonistic muscle activation. Knee flexion angle did not influence EMD in either group.

CONCLUSIONS

Increased biomechanical stiffness in spastic muscle results in abnormally reduced EMD. Reciprocal excitation of antagonistic cocontraction was uniquely observed in the spastic group, but did not explain the reduced EMD.

Quantitative assessment of subclinical spasticity in human T-cell lymphotropic virus type I infection

OBJECTIVE

To compare human T-cell lymphotrophic virus type I (HTLV-I) seropositive and seronegative women for symptoms and signs of spasticity.

BACKGROUND

Infection with HTLV-I causes tropical spastic paraparesis/ HTLV-I-associated myelopathy (TSP/HAM). Certain populations, including female commercial sex workers (FSW), are at increased risk of developing this infection. Fewer than 5% of HTLV-I-seropositive persons develop TSP/HAM, which is typically associated with spasticity.

METHODS

Cross-sectional study of 255 registered FSW in Callao, Perú, involving a questionnaire detailing demographics and neurologic symptoms, standard neurologic examination, quantitative assessment of spasticity (QSA) of muscle tone, and serologic testing for HTLV-I. Participants and examiners were blinded to serology results.

RESULTS

On the questionnaire and neurologic examination, none of the 32 HTLV-I-seropositive or 223 seronegative women had signs or symptoms of spasticity. However, mean values on QSA were significantly higher among seropositive women (27.1 Newton-meters/radian [N-m/r]) than among seronegative women (21.6 N-m/r, p = 0.01), indicating a subclinical increase in lower extremity tone. With values of QSA divided into tertiles, and the first tertile serving as the comparison group, the odds ratio for seropositivity was 1.4 (95% confidence interval [CI] 1.0 to 2.0) in the second and 3.1 (95% CI 2.2 to 4.3) in the third tertile, after adjusting for age and place of birth.

CONCLUSIONS

Although a standard neurologic evaluation could not distinguish between women with and without HTLV-I infection, QSA indicated significantly increased lower extremity tone in those with infection. Long-term follow-up will determine whether these subclinical findings in asymptomatic women progress to overt TSP/HAM.

Adaptive motor strategy for squatting in spastic diplegia

Motor strategies, defined by kinetic, kinematic and/or muscle activation patterns, reflect neural planning of movement, which takes into account central as well as peripheral constraints. Major alteration is expected in cerebral palsy, a condition characterized by abnormal posture and movement secondary to early lesion of the brain. The objective of this study was to characterize the motor strategies involved in disruption of posture in cerebral palsy of the spastic diplegia type and compare them with normal controls. The optoelectronic ELITE system was used to record and analyse the movement of squatting from the standing position with the arms extended forward in 11 children with spastic diplegia aged between 3 and 12 years and 11 age-matched normal controls. Normal children maintained gaze and arm horizontality and trunk verticality throughout the movement. The knee followed an oblique trajectory. Its angular velocity profile showed a short, single-peaked, ascending phase. The onset of movement was preceded by deactivation of the semimembranous muscle. In diplegic children, gaze and arm horizontality and trunk verticality were lost. The ankle was rigidified, resulting in spatial fixation of the knee. The ascending phase of the knee velocity profile was prolonged and multi-peaked. There was widespread muscle co-contraction from the outset of movement. No anticipatory deactivation was evidenced, but anticipatory bursts appeared in the soleus. Patients with cerebral palsy have to organize a limited motor repertoire from a restricted neural potential. Consequent motor strategies presently demonstrated in spastic diplegia are distinct and appear as an original alternative to those of normal subjects.

Selective dorsal rhizotomy: efficacy and safety in an investigator-masked randomized clinical trial

The objective of this single-center investigator-masked randomized clinical trial was to investigate the efficacy and safety of selective dorsal rhizotomy (SDR) in children with spastic diplegia. Forty-three children with spastic diplegia were randomly assigned on an intention-to-treat basis to receive SDR plus physical therapy (PT), or PT alone. Thirty-eight children completed follow-up through 24 months. Twenty-one children received SDR (SDR+PT group) and 17 received PT (PT Only group). SDR was guided with electrophysiological monitoring and performed by one experienced neurosurgeon. All subjects received equivalent PT. Spasticity was quantified with an electromechanical torque measurement device (spasticity measurement system [SMS]). The Gross Motor Function Measure (GMFM) was used to document changes in functional mobility. Primary outcome measures were collected at baseline, 6, 12, and 24 months by evaluators masked to treatment. At 24 months, the SDR+PT group exceeded the PT Only group in mean reduction of spasticity by SMS measurement (-8.2 versus +5.1 newton meters/radian, P=0.02). The SDR+PT group and the PT Only group demonstrated similar improvements in independent mobility on the GMFM (7.0 versus 7.2 total percent score, P=0.94). Outcomes on secondary variables were consistent with primary outcomes. There were no serious adverse events. We conclude that SDR is safe and reduces spasticity in children with spastic diplegia. SDR plus PT and equivalent PT without SDR result in equal improvements in independent mobility at 24 months. SDR may not be an efficacious treatment for children with mild spastic diplegia.

Impaired viscoelastic behaviour of spastic plantarflexors during passive stretch at different velocities

OBJECTIVE: The aim of this study was to evaluate the effect of velocity on non-reflexly induced resistive torque (RT) responses of the spastic plantarflexors (PFs) of subjects with spinal cord injuries. DESIGN: Descriptive study, transversal. BACKGROUND: In spastic muscles, non-reflex changes such as increased muscle stiffness, contractures and atrophy have been reported. These changes probably alter muscle tensile properties and viscoelastic behaviour. METHODS: Six subjects with chronic (1-3 yr) spinal cord injuries (SCI) and 12 normal controls (CTLs) participated in this study. Passive ankle dorsiflexions (DFs), ranging from -35 degrees to 5 degrees of DF, were randomly imposed at 5 degrees /s, 10 degrees /s, 20 degrees /s, 40 degrees /s, 60 degrees /s, 120 degrees /s and 180 degrees /s using an isokinetic dynamometer (Kin-Com(TM)). Unwanted muscle activity was detected using surface electrodes on the soleus and tibialis anterior muscles. RESULTS: The results show first that RT rose with increasing velocity; the RT increment reached statistical (analysis of variance (ANOVA); Scheffé post-hoc procedure) significance (P < 0.01) at a lower velocity for the CTLs (40 degrees /s) group than for the SCI group (60 degrees /s). Second, significantly (t-test; P < 0.001) larger net increments of RT (RT at each velocity minus RT at 5 degrees /s) were found for the CTLs at 180 degrees /s than for the SCI group whose RT plateaued at 60 degrees /s. Finally, whereas the RT-velocity relationship was linear (r = 0.94) in the CTLs, that of the SCI group followed a power regression model (r = 0.85). CONCLUSIONS: These results show that the spastic PFs of the subjects with SCIs have an impaired velocity-sensitive behaviour, especially at high velocities of stretch where greater resistance is expected.

Developmental skills of children with spastic diplegia: functional and qualitative changes after selective dorsal rhizotomy

OBJECTIVE

This study examined changes in muscle tone, passive range of motion, stability, and mobility in developmental skills at 6 months and 1 year after selective dorsal rhizotomy (SDR).

DESIGN

Prospective outcome study of a consecutive sample.

SETTING

Private children's hospital.

PATIENTS

Twenty-six children with spastic diplegia: 13 independent and 13 dependent ambulators (assistive devices).

RESULTS

A decrease in spasticity was seen at 6 months after SDR, with no further decrease at 1 year. Increases in passive range of motion of the hip and ankle were seen at 6 months after SDR. The ability to assume and maintain developmental positions with improved alignment and stability was seen more frequently at 6 months after SDR, whereas an improvement in the ability to perform transitional movements was seen more frequently at 1 year after SDR.

CONCLUSION

SDR decreases spasticity and increases lower extremity range of motion in children with spastic diplegia and appears to be associated with the ability to assume a greater variety of developmental positions with improved alignment, thus greater stability. Improvements in the ability to perform difficult transitional movements at 1 year after SDR are most likely the result of the combined effect of maturation, SDR, and intensive therapeutic intervention.

Quantitative clinical measure of spasticity in children with cerebral palsy

OBJECTIVE

This investigation developed an objective measure to quantify the degree of spasticity.

DESIGN

Specifications included a single variable that integrated key elements characterizing spasticity: velocity, range of motion, and resistance to passive motion. A dynamometer at a children's hospital quantified the passive resistance of the hamstrings to knee extension for a range of motion at 4 different speeds for the prospective descriptive investigation.

PATIENTS

A convenience sample of six children with able bodies and 17 children with spastic diplegic cerebral palsy volunteered. DATA PROCESSING: Torque-angle data were processed to calculate the work done by the machine on the children for each speed and then determine the slope of the work-velocity curves. This slope was considered to be the measure of spasticity and it was hypothesized that children with cerebral palsy would have a greater slope than children with able bodies. An independent test determined whether a significant difference existed between groups (p < .05).

RESULTS

Torque-angle data for children with able bodies indicated little change in passive resistance as a function of speed. Similar data for children with cerebral palsy indicated larger resistive torques with increasing speed. Slope from the work-velocity data was close to zero for children with able bodies [.003 J/(degrees/sec)], while the corresponding slope for children with cerebral palsy was approximately 10 times greater [.031 J/(degrees/sec)] and significantly different (p < .05).

CONCLUSION

The slope of the work-velocity data integrates three major components characterizing spasticity, it is a single number that can easily be evaluated and interpreted in a clinical setting, and it utilizes a machine that is available at many centers.

The stretch reflex response in the normal and spastic ankle: effect of ankle position

OBJECTIVE

The influence of stretch of the gastrocnemiussoleus muscle on the stretch reflex activity was studied, by varying the ankle angle in steps from 10 degrees of plantarflexion (PF) to 5 degrees of dorsiflexion (DF).

DESIGN

Nonrandomized control trial.

SETTING

Department of Rehabilitation Medicine of a university medical center.

PATIENTS

Sixteen subjects with and 16 subjects without spasticity.

MAIN OUTCOME MEASURES

The passive elastic stiffness and active reflex response, expressed by the total and elastic path lengths, were determined at each ankle angle as a sinusoidal displacement of 5 degrees was applied to the joint at frequencies from 3 to 12 Hz.

RESULTS

The elastic stiffness showed no difference between the spastic and normal subjects for all ankle angles (p > .05). The elastic stiffness increased linearly similarly in both groups when the ankle was dorsiflexed. The reflex response was significantly greater in the spastic group for all positions (p < or = .01). The total and elastic path lengths showed a linear increase in both groups when the ankle angle was varied from PF to DF. The spastic group, however, had a significantly faster increase (p < or = .005). Between-group comparison showed a significant quadratic trend in the elastic path length for the spastic group (p < or = .05), with a maximum at 2.5 degrees of DF.

CONCLUSIONS

This study showed that the stretch reflex activity varies with the ankle position. This must be considered when performing spasticity tests subsequent to an intervention that has changed the available range of motion and when comparing subjects measured at different ankle positions.

The role of selective dorsal rhizotomy in cerebral palsy: critical evaluation of a prospective clinical series

This is a prospective observational study of a consecutive series of 34 children with spastic cerebral palsy treated at a single center. 10 had spastic quadriplegia and 24 had spastic diplegia. All were followed for at least one year. After selective dorsal rhizotomy (SDR), all children received one month of physical therapy at the center and were prescribed a program of physical therapy in their community. The children were assessed before and one year after SDR and physical therapy, using the Ashworth Scale, deep tendon reflex response, range of motion and the Gross Motor Function Measure. The results show that there is often a decrease in lower-extremity spasticity and functional improvement after SDR with physical therapy, but that there is considerable variability in outcome. Randomized prospective clinical trials with masked objective outcome measures are needed to determine the efficacy of SDR.

Influence of different sitting positions and abduction orthoses on leg muscle activity in children with cerebral palsy

A surface electromyogram (EMG) was recorded from four leg muscles to measure the effects of various seat inclinations and an abduction orthosis on eight children with cerebral palsy and controls during performance of an upper-extremity task and while listening to a story. EMG responses were lowest in the forward-leaning and horizontal positions with the abduction orthosis, and highest in reclined and horizontal positions without the orthosis for both groups of children during the performance of an upper-extremity task. While listening to a story, there was no median EMG activity in any muscles of the controls, but there were wide variations in those of the children with cerebral palsy. The results indicate that the use of an abduction orthosis and horizontal and forward-leaning seats decrease lower-extremity muscle activity, and so it is possible that it might also improve upper-extremity function.