Decrease of muscle extensibility and reduction of sarcomere number in soleus muscle following a local injection of tetanus toxin

Immunogenicity induced by botulinum toxin injections for limb spasticity: A systematic review

BACKGROUND

The imputability of neutralizing antibodies (NABs) in secondary non-response (SnR) to botulinum toxin (BoNT) injections for limb spasticity is still debated.

OBJECTIVE

This systematic literature review aimed to determine the prevalence of NABs after BoNT injections for limb spasticity and analyze their determinants and their causal role in SnR.

METHODS

We searched MEDLINE via PubMed, Cochrane and Embase databases for articles published during 1990-2018. Two independent reviewers extracted the data and assessed the quality of studies with a specific scale (according to PRISMA and STROBE guidelines). Because the techniques used to detect NABs did not influence the results, we calculated the global (all studies) sensitivity and specificity of NAB positivity to reveal SnR.

RESULTS

We included 14 articles published from 2002 to 2018 (including an epublication) describing 5 randomized controlled trials and 5 interventional and 4 observational studies. The quality was satisfactory (mean score 18/28 arbitrary units). NAB detection was the primary criterion in 5 studies and a secondary criterion in 9. In total, 1234 serum samples for 1234 participants (91% with stroke) were tested after injection. NAB prevalence was about 1%, with no significant difference among formulations. NAB positivity seemed favoured by long-duration therapy with high doses and a short interval between injections. The identification of non-response by NAB positivity had poor global sensitivity (56%) but very high specificity (99.6%). No consensual criteria were used to diagnose non-response to BoNT injection.

CONCLUSIONS

NAB prevalence is much lower after BoNT treatment for limb spasticity than cervical dystonia. Consensual criteria must be defined to diagnose non-response to BoNT injection. Because immunogenicity is not the most common cause of non-response to BoNT injection, NABs should be sought in individuals with SnR with no other cause explaining the treatment inefficacy. A test with 100% specificity is recommended. In cases for which immunogenicity is the most likely cause of non-response to BoNT injections, some biological arguments suggest trying another BoNT, but no clinical evidence supports this strategy.

Nociception contributes to the formation of myogenic contracture in the early phase of adjuvant-induced arthritis in a rat knee

It is unknown how joint contracture is generated in inflamed joints. This study aimed to clarify the role of nociception on the formation of joint contracture secondary to arthritis. Monoarthritis was induced by intra-articular injections of complete Freund's adjuvant (CFA) into rat knees. On day 5 after CFA injection, the passive extension range of motion (ROM) of knee joints were measured, both before and after myotomy of knee flexors, to evaluate the extent of muscular contribution to CFA-induced joint contracture. The steroidal anti-inflammatory drug dexamethasone could prevent ROM restrictions completely, both before and after myotomy. On the other hand, the opioid analgesic drug morphine did not prevent the development of restricted ROM observed after myotomy, while it did before myotomy. This indicates that nociception contributes to joint contracture through alterations in muscular structure (myogenic factors). Next, we tested the hypothesis that nociception-induced reflexive flexor muscle contractions cause myogenic contracture in arthritic joints. To do this, chemical denervation was performed by Botulinum toxin type A (BTX-A) injections into knee flexor muscles, simultaneously with CFA injections into the knee. As expected, BTX-A could alleviate ROM restrictions observed before myotomy. These findings suggest that nociceptive-related muscle contractions play an essential role in the formation of joint contracture. Thus, our study indicates that analgesic management during an early stage of joint arthritis is an essential mean to prevent the formation of joint contracture. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1404-1413, 2017.

Cyclooxygenase-2 inhibitor celecoxib attenuates joint contracture following immobilization in rat knees

Background

The aim of this study is to clarify the following two points: First, whether a cyclooxygenase-2 mediated pathway is involved in the formation of immobilization-induced joint contracture and, second, the effectiveness of oral administration of non-steroidal anti-inflammatory drug celecoxib (CBX) for the prevention of myogenic and arthrogenic contracture following immobilization in a rat model.

Methods

Thirty male rats were randomly divided into three groups: immobilization (Im), Im + CBX, and control (n = 10 each). External fixation immobilized the right knee joint of Im and Im + CBX groups in flexion for 3 weeks. 50 mg/kg of CBX was administrated daily to the Im + CBX group during this period. The passive range of motion (ROM) of knee joints was measured before and after transection of knee flexor muscles and myogenic and arthrogenic ROM restrictions were calculated. The semitendinosus muscles and knee joints were investigated histologically to elucidate factors responsible for contracture.

Results

Myogenic ROM restrictions were exhibited both in Im and Im + CBX groups (44 ± 5 and 36 ± 8 °, respectively), but restrictions significantly decreased in the Im + CBX group compared to the Im group. Significant reductions of the muscle length ratios (Rt/Lt) and sarcomere number ratios (Rt/Lt) in knee flexor semitendinosus muscle, which are responsible for myogenic contracture, were also seen both in Im group (92 ± 5 and 92 ± 4 %, respectively) and Im + CBX group (97 ± 3 and 97 ± 3 %, respectively), but were inhibited by CBX administration (P < 0.05). Im and Im + CBX groups exhibited arthrogenic ROM restrictions with no significant differences (82 ± 3 and 83 ± 5 °, respectively). Posterior synovial length shortening and pathological changes (hemorrhage in joint cavities and capsule edema) in the knee joints were comparable between Im and Im + CBX groups.

Conclusions

Oral administration of celecoxib partially reduced myogenic ROM restriction concomitantly with knee flexor muscle shortening following immobilization. These results imply that inflammation and nociception are involved in myogenic contracture formation independently of joint immobilization, and that CBX is effective in preventing joint contracture following immobilization in rats.

The passive mechanical properties of muscle and their adaptations to altered patterns of use

The length and stiffness of a relaxed muscle are determined by the mechanical properties of its intramuscular connective tissue and/or intracellular structures. Viscous deformation of these components of muscle is responsible for the increase in muscle length seen immediately after stretching, but this increase is transient. Lasting changes in muscle length can only be brought about by adaptations of the structure of muscle. An understanding of the nature of the stimulus for muscle to adapt can provide therapists with a theoretical basis for therapeutic intervention aimed at producing changes in muscle length.

Botulinum toxin A treatment in toddlers with cerebral palsy

AIMS

In this study the aim was to evaluate the effect of botulinum toxin A (BoNT-A) treatment on muscle tone, contracture development and gait pattern in young children with cerebral palsy (CP).

METHOD

Fifteen children with spastic CP (mean age = 16 months) were included in a randomized control study. All received a daily stretching programme and children in the BoNT-A group additionally received two injections, 6 months apart in the gastrocnemius muscle. Outcomes were assessed at baseline, and after 1 and 3.5 years. A 3D gait-analysis was performed at 5 years of age.

RESULTS

Plantarflexor muscle tone in the BoNT-A group was significantly reduced after 3.5 years, while the muscle tone at the ankle and knee in the control group remained unchanged. The change-score in knee-flexion muscle tone between the groups was significantly different after 3.5 years. The knee joint ROM was significantly increased at 1 year in the BoNT-A group but reduced at the knee and ankle joints in the control group after 3.5 years. No group differences were found for gait analysis, GMFM-66 or PEDI.

CONCLUSION

Early treatment of BoNT-A in children with spastic CP may decrease muscle tone and decelerate contracture development after 3.5 years. The effect on gait development remains inconclusive.

Botulinum toxin type A injections for the management of muscle tightness following total hip arthroplasty: a case series

BACKGROUND

Development of hip adductor, tensor fascia lata, and rectus femoris muscle contractures following total hip arthroplasties are quite common, with some patients failing to improve despite treatment with a variety of non-operative modalities. The purpose of the present study was to describe the use of and patient outcomes of botulinum toxin injections as an adjunctive treatment for muscle tightness following total hip arthroplasty.

METHODS

Ten patients (14 hips) who had hip adductor, abductor, and/or flexor muscle contractures following total arthroplasty and had been refractory to physical therapeutic efforts were treated with injection of botulinum toxin A. Eight limbs received injections into the adductor muscle, 8 limbs received injections into the tensor fascia lata muscle, and 2 limbs received injection into the rectus femoris muscle, followed by intensive physical therapy for 6 weeks.

RESULTS

At a mean final follow-up of 20 months, all 14 hips had increased range in the affected arc of motion, with a mean improvement of 23 degrees (range, 10 to 45 degrees). Additionally all hips had an improvement in hip scores, with a significant increase in mean score from 74 points (range, 57 to 91 points) prior to injection to a mean of 96 points (range, 93 to 98) at final follow-up. There were no serious treatment-related adverse events.

CONCLUSION

Botulinum toxin A injections combined with intensive physical therapy may be considered as a potential treatment modality, especially in difficult cases of muscle tightness that are refractory to standard therapy.

Non-surgical management of ankle contracture following acquired brain injury

BACKGROUND AND PURPOSE

The purpose of this study was to document the outcome of non-surgical management of equinovarus ankle contracture in a cohort of patients with acquired brain injury admitted to a specialist Neurosurgical Rehabilitation Unit.

METHODS

This prospective descriptive study examined all patients with a new diagnosis of moderate to severe acquired brain injury (Glasgow Coma Scale score </=12) admitted for rehabilitation over a 1 year period. Ankle dorsiflexion range and plantarflexor/invertor muscle activity were evaluated weekly during the period of hospitalization. Contracture was defined as maximal passive range of motion </= 0 degrees dorsiflexion, with the knee extended, on a minimum of two measurement occasions. Patients were retrospectively allocated to one of four treatment outcome categories according to ankle dorsiflexion range, type of intervention required and response to treatment.

RESULTS

Ankle contracture was identified in 40 of the 105 patients studied. Contracture resolved with a standard physiotherapy treatment programme, including prolonged weight-bearing stretches and motor re-education, in 23 patients. Contracture persisted or worsened in 17 of 40 cases, all of whom exhibited dystonic muscle overactivity producing sustained equinovarus posturing. Ten of 17 cases required serial plaster casting (+/- injection of botulinum toxin type A) in order to achieve a functional range of ankle motion. Remediation of ankle contracture was not considered a priority in the remaining seven patients due to the severity of their overall disability.

CONCLUSION

The incidence of ankle contracture identified in this population was considerably less than previously reported. Reduced dorsiflexion range was remediated with standard physiotherapy treatment in over half of the cases. Additional treatment with serial casting +/- botulinum toxin type-A injection was required to correct persistent or worsening contracture in one quarter of cases. Dystonic extensor muscle overactivity was a major contributor to persistent or progressive ankle contracture.

Stretching with children with cerebral palsy: what do we know and where are we going?

PURPOSE

To review research regarding mechanisms of muscle contracture in cerebral palsy (CP) and the effectiveness of stretching, and to discuss current physical therapy stretching practices. Community-based recreation opportunities that encourage flexibility and fitness are explored as alternatives to traditional therapy stretching approaches.

SUMMARY OF KEY POINTS

Mechanisms of muscle contracture in children with CP are unclear and clinical research evaluating the effects of stretching is inconclusive. Recent shifts in thinking about the management of children with CP suggest an increased emphasis on flexibility, fitness, and participation in activities that are meaningful to children and families.

STATEMENT OF CONCLUSIONS

Additional research is needed to explore the structural changes that occur in the shortened muscles of children with CP and the effects of stretching practices used in pediatric physical therapy.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Physical therapists can consider innovative alternatives that integrate flexibility and fitness goals with community-based recreation programs.

Comparison of muscular and articular factors in the progression of contractures after spinal cord injury in rats

STUDY DESIGN

Experimental, controlled trial.

OBJECTIVES

To identify the relationship between the muscular and articular factors in the progression of contractures after spinal cord injury (SCI).

SETTING

Hiroshima University, Hiroshima, Japan.

METHODS

In total, 48 female Wistar rats were used. The 24 experimental rats that underwent a spinal cord transection and the other 24 control rats that underwent a sham-operation were assessed at 2, 4, 8, 12, 16, or 24 weeks postsurgery. Knee joint motion was measured for flexion and extension. Myotomy of the transarticular muscles was then performed and range of motion was measured again. The degree of contractures was assessed by goniometry measuring the femorotibial angle before and after the myotomies.

RESULTS

The spinal cord-injured rats demonstrated flaccid paralysis during the first few days postsurgery and thereafter spastic paralysis. Intra- and inter-rater reliabilities for all measurements were >0.814. Knee flexion contractures developed in the all experimental rats, and progressed for the first 12 weeks and plateaued thereafter. Both the muscular (48+/-5%) and articular (52+/-5%) factors contributed almost equally to the overall progression of the contracture.

CONCLUSION

The present findings may shed light on the underlying pathophysiology of contractures and should help guide research towards finding the elucidation of contracture development after SCI.

Adaptation of the properties of spastic muscle with wrist extension deformity

To show that human muscle may adapt to tendon transfer, adaptation of flexor carpi ulnaris (FCU) function was studied by measuring active and passive length-force characteristics at initial operation and at reoperation in a case of extension deformity secondary to FCU tendon transfer. At reoperation, FCU was 20 mm shorter; active force decreased approximately 10%, indicating atrophy; and passive force increased, reflecting increased stiffness. FCU fiber length was unchanged. The presented case shows that human forearm muscle may adapt to a transferred function.

Pathophysiology of spastic paresis. II: Emergence of muscle overactivity

In the subacute and chronic stages of spastic paresis, stretch-sensitive (spastic) muscle overactivity emerges as a third fundamental mechanism of motor impairment, along with paresis and soft tissue contracture. Part II of this review primarily addresses the pathophysiology of the various forms of spastic overactivity. It is argued that muscle contracture is one of the factors that cause excessive responsiveness to stretch, which in turn aggravates contracture. Excessive responsiveness to stretch also impedes voluntary motor neuron recruitment, a concept termed stretch-sensitive paresis. None of the three mechanisms of impairment (paresis, contracture, and spastic overactivity) is symmetrically distributed between agonists and antagonists, which generates torque imbalance around joints and limb deformities. Thus, each may be best treated focally on an individual muscle-by-muscle basis. Intensive motor training of the less overactive muscles should disrupt the cycle of paresis-disuse-paresis, and concomitant use of aggressive stretch and focal weakening agents in their more overactive and shortened antagonists should break the cycle of overactivity-contracture-overactivity.

Reduction of caveolin-3 expression does not inhibit stretch-induced phosphorylation of ERK2 in skeletal muscle myotubes

Mechanotransduction is critical to the maintenance and growth of skeletal muscle, but the mechanism by which cellular deformations are converted to biochemical signals remains unclear. Among the earliest and most ubiquitous responses to mechanical stimulation is the phosphorylation and activation of mitogen-activated protein kinases, in particular ERK2. Caveolin-3 (CAV-3) binds ERK2 and its upstream activators in inactive states on the caveolae of resting muscle. Caveolae are deformed by stretch, and it was hypothesized that this deformation might disrupt the CAV-3-dependent inhibition of ERK2 to affect stretch-induced activation. Stretch-induced phosphorylation of ERK2 in myotubes was both amplitude and velocity dependent, consistent with a viscoelastic mechanism, such as deformation of caveolae. Chemical disruption of caveolae by cholesterol depletion increased ERK2 activation by up to 176%. Small interfering RNA oligomers were then used to knock down expression of CAV-3 in cultured myotubes before mechanical stimulation, with the expectation that reducing CAV-3 expression would eliminate the stretch-induced activation of ERK2. Knockdown reduced CAV-3 protein content by 55% but did not significantly alter the stretch-induced increase in ERK2 phosphorylation, suggesting that CAV-3 is not an essential element of the mechanotransduction pathway, although the limited extent of knockdown limits the strength of this conclusion.

Incidence of ankle contracture after moderate to severe acquired brain injury

OBJECTIVE

To examine an adult population undergoing rehabilitation after brain injury to determine the incidence of ankle contracture and factors contributing to the development of this deformity.

DESIGN

Descriptive study

SETTING

Specialist inpatient neurosurgical rehabilitation unit in Australia.

PARTICIPANTS

Patients (N=105) admitted with a new diagnosis of moderate to severe brain injury over a 12-month period.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Maximal ankle dorsiflexion range and the presence of abnormal muscle tone affecting the lower limb(s) were evaluated at weekly intervals. Ankle contracture was defined as maximal passive range of less than 0 degrees dorsiflexion with the knee in extension. Patients were grouped into 3 muscle tone categories: normal, predominantly spastic, or predominantly dystonic. Age, sex, mechanism and severity of brain injury, time to onset of ankle contracture, total length of hospital stay, and discharge mobility status data were also recorded.

RESULTS

Muscle tone was designated as normal in 68 (64.7%), as spastic in 14 (13.3%), and as dystonic in 23 (21.9%) patients. The incidence of ankle contracture was 16.2% (17/105 cases). Ankle deformity correlated closely with muscle tone category. Of 23 cases with dystonic muscle overactivity, 17 developed contracture at some point between 1 and 16 weeks after brain injury, although no subject with normal tone or spasticity developed the deformity. There was a weak association between the severity of brain injury and development of ankle contracture.

CONCLUSIONS

The incidence of ankle contracture was much lower than previously reported. Dystonic overactivity of the plantarflexor and invertor muscles is a major predisposing factor to ankle contracture.

Physiological effects of botulinum toxin in spasticity

There is considerable evidence that injection of botulinum toxin (BTX) into muscles with spastic overactivity reduces resistance to passive movement in joints supplied by the injected muscles. The demonstration of improvement in active performance of the paretic limbs has been only anecdotal to date, and represents the most difficult challenge in research on BTX therapy in spastic paralysis. Data are reviewed that indicate several neurophysiological actions of BTX, other than the blocking of acetylcholine release at the neuromuscular ending: effects on the central nervous system, including retrograde axonal transport, reduced motoneuronal excitability, action on central synapses such as decreased Renshaw inhibition and increased presynaptic inhibition; action on gamma motoneuronal endings; action on most active terminals; spread of BTX to neighboring muscles; spread of BTX effects to remote muscles. Several of these neurophysiological actions are likely to contribute to improvement in active movements, as they may antagonize the primary mechanisms of functional impairment in patients with spastic paralysis: weakness, spastic cocontraction, spastic dystonia, and muscle shortening. We review the evidence for reduction of spastic cocontraction in both the injected muscle and its antagonist, and for improvement of antagonist weakness after BTX injection. The capacity of intramuscular BTX to reduce spastic dystonia and lengthen shortened muscles is also discussed based on prior literature. When injected into the more overactive of a pair of spastic antagonists around a joint, BTX should affect all the main mechanisms impairing active function around the joint.

The effect of botulinum toxin type A on the functional ability of the child with spastic hemiplegia a randomized controlled trial

It has been demonstrated that botulinum toxin type A (BTX-A) injections reduce spasticity and improve muscle growth in children with spasticity. It has been postulated that BTX-A allows the learning of more normal movement patterns. The aim of this study was to measure the effect of this treatment on functional ability, as measured by the Gross Motor Function Measure (GMFM), in children with spastic hemiplegic cerebral palsy. Children of 3--13 years and meeting the selection criteria were randomly allocated to the control or injection group using a matched pair design. A match constituted a child within 6 months of age with the same Modified Ashworth Score (MAS) for the gastroc-soleus and within 10% of the same goal scores on the Gross Motor Function Measure. Twelve matched pairs were enrolled. Outcomes were measured on enrolment and at 1, 3 and 6 months post injection. The time course of the response to BTX-A was assessed with measurements of the MAS, dynamic range of motion (R1) and static muscle length (R2). Motor function was assessed using the 88-item GMFM and parental satisfaction with a 10-point visual analogue scale. Within pair comparisons of the GMFM using the Wilcoxon signed rank test indicated that the treatment group made significantly greater gains than controls at 3 months (P=0.02) with even greater differences seen at 6 months (P=0.004). Using parametric statistics, the intrapair difference in proportional change of GMFM increased from 35% (4 to 65) at 3 months to 52% (17--87) at 6 months. Response to injection was confirmed by a decrease in MAS in the treatment group and very little change in controls. This difference was significant (P=0.002) at 3 months and was attenuated but still significant (P=0.016) at 6 months; the difference in proportional change decreased from 44% at 3 months to 22% at 6 months. Changes in R1 reflected those of MAS in the treatment group and deteriorated significantly over the study period in controls. Parents of children in the treatment group were more satisfied than controls, but satisfaction scores did not correlate with changes in function or technical outcomes suggesting that this may be a placebo effect. The changes in GMFM correlated with changes in technical outcomes at 3 months, suggesting a causal relationship. The intrapair differences in GMFM continued to increase even after the local response to injection had started to wane.

Passive extensibility of skeletal muscle: review of the literature with clinical implications

The purpose of this article was to review the literature on passive extensibility of skeletal muscle with reference to its anatomic and physiologic properties, mechanisms of adaptations and clinical implications. Studies with animal muscles have shown that passive extensibility is influenced by the size (mass) and length of muscle fibers, and the amount and arrangement of the connective tissues of the muscle belly. The resistance to passive lengthening is influenced by the readily adaptable amount of muscle tissue, including the contractile proteins and the non-contractile proteins of the sarcomere cytoskeletons. The relationship of adaptable changes in the muscle tissue and in the extracellular connective tissues remains unclear. Muscle length adaptations result from changes in the number of sarcomeres in series, which depend on the imposed length of muscles, not on the level of muscle activation and tension. This mechanism of muscle length adaptations, termed 'myogenic', has not been demonstrated in human muscles, but it has been intimated by therapeutic lengthening studies showing that both healthy and neurologically impaired human muscles can undergo increased length adaptations in the presence of muscle activations. Studies have suggested that optimal muscle function is probably achieved by increasing muscle length, length extensibility, passive elastic stiffness, mass and strength, but additional studies are needed to investigate these relationships, particularly for aged muscles and for muscles affected by clinical disorders, disease and injury. Such studies could contribute to the development of new intervention strategies designed to promote the passive muscle extensibility that enhances total muscle function, and ultimately improves the ability to complete functional activities and excel in athletic performances.

Spasticity: orthopedic perspective

The orthopedic management of spasticity is based on the effects of this neurologic condition on the bones and tissues of the growing child. The goal of such intervention is to maximize function, reduce disability, and facilitate mobility. Goal-directed treatment plans are tailored for each patient and may include a combination of modalities such as physical and occupational therapy, casting, orthoses, and surgery. Physical and occupational therapy is emphasized up to 4 to 5 years of age, whereas surgery is best between 5 and 7 years of age. Education and psychosocial development should be emphasized beginning at age 7 years through adulthood, with surgery reserved for more involved cases of contracture or bony dysplasia. In adulthood, treatment should be focused on integration into society and maximizing functional independence. Although there are many undisputed benefits of therapy, no consensus exists regarding the most beneficial modality, the age group that would benefit most, or whether continued treatment is beneficial in adulthood. Whereas the use of serial casting and tone-reducing casts has lessened, lower extremity orthoses have gained widespread acceptance with improvements in design and fabrication and have been demonstrated to help restore normal heel-toe gait. Surgical techniques such as tendon lengthening, transfer, bony osteotomy, and joint fusion are time-honored techniques that continue to be refined with current advances in the use of computerized gait analysis for preoperative planning. Further research in long-term results and outcomes measurement will be necessary to fully assess the impact of current treatment.

Force during stretches of rat skeletal muscles after hypertonia at short and long lengths

Following injection of tetanus toxin into rat gastrocnemius muscle to produce hypertonia, plantar flexor muscles were allowed to shorten (S, n=5) without restraint or held lengthened (L, n=3) by splinting. Saline injected rats served as control (n=5). One week after injection, peak forces during 3 stretches with passive muscles and acute isometric force deficits produced by 15 stretches of electrically stimulated muscles were examined under pentobarbital anesthesia. Isometric force and mass of plantar flexors were similar in S rats but 16% lower in L rats compared to control. Peak passive forces were highest in S rats but not different between L rats and control. At the end of the stretch protocol, isometric force deficits were 26% larger in S rats compared to L rats and 17% smaller in L rats compared to control. Acute isometric force deficits produced by stretches of active skeletal muscles were dependent on the muscle length maintained during hypertonia. Our animal model could be used to test rehabilitation interventions during hypertonia of skeletal muscles.

Lycra garments designed for patients with upper limb spasticity: mechanical effects in normal subjects

OBJECTIVE

To assess the stretch of pronator muscles produced by a specifically designed upper-limb Lycra garment that could have a better acceptability than rigid splints in treating upper-limb spasticity.

DESIGN

Double-blind comparison among three garments. They were designed to produce a supinating, a pronating, and no torsional force, and were individually manufactured and tested in 10 healthy volunteers.

MAIN OUTCOME MEASURE

Angular position and passive rotational stiffness of the forearm were measured with and without each of the garments immediately after the garment was fitted and every hour for 6 hours.

RESULTS

When put on by a trained person, the supinator garment supinated the forearm in all subjects (mean, 17 degrees; p < .01; range, 5 degrees to 44 degrees) while the pronator garment pronated the forearm in 8 of 10 subjects (mean, 5 degrees; p < .01). These effects gradually decayed over 6 hours, as garment position was not readjusted. Passive rotational stiffness of the forearm increased by about 30% with each type of garment. The garments designed to produce no torsional force exerted no intrinsic rotational effect.

CONCLUSION

Individually made Lycra garments can produce continuous stretch of muscles for several hours and may be useful in the treatment of spasticity. The garments, however, must be put on by a trained person and their position adjusted when necessary.

Botulinum toxin A in the hemiplegic upper limb: a double-blind trial

In a randomised, double-blind study, the effects of intramuscular injection of botulinum toxin type A (BtA) into the upper limb were compared with those of normal saline solution in 14 patients with cerebral palsy; their mean age was 9 years. Range of movement and function were assessed before injection and at 2 and 12 weeks after injection. BtA injection significantly increased maximum active elbow and thumb extension and significantly reduced tone at wrist and elbow. The hand grasp-and-release score improved, representing a modest functional change, but fine motor function, assessed by the ability to pick up coins, did not improve and in some cases deteriorated temporarily. The most notable subjective change was the cosmetic benefit of reduced involuntary elbow flexion. The tone-reducing effect of BtA was clinically detectable in comparison with the placebo and patients and parents perceived the change as beneficial. The median of changes in the treatment group was small but the range was large, suggesting that BtA can be useful in selected patients.

Air-splint pressure effect on soleus muscle alpha motoneuron reflex excitability in subjects with spinal cord injury

OBJECTIVE

This study investigated circumferential pressure effect on soleus motoneuron reflex excitability in subjects with spinal cord injury (SCI).

SETTING

A university neuromuscular research laboratory.

SUBJECTS

Six men with SCI, clinical level above L1. OUTCOME MEASURES AND INTERVENTION: Soleus motoneuron reflex excitability was assessed by measuring the average change in the peak-to-peak amplitude of 10 H-reflexes before (baseline), during (1, 3, and 5min) and after (1, 3, and 5min) pressure application. Pressure was applied to the lower leg by manually inflating an air-splint to a maintained range of 36.7 to 40.8mmHg for 5 minutes, after which it was deflated.

DESIGN

Repeated measures, planned comparison. Dependent variables compared with baseline values only in post hoc tests.

RESULTS

A one-way analysis of variance for repeated measures demonstrated significant difference (F6,30 = 4.03; p = .004) in the H-reflex amplitude across test conditions. Post hoc t tests (with Bonferroni's correction for multiple comparisons, p < or = .008) revealed a significant H-reflex amplitude reduction at 1, 3, and 5 minutes of pressure application when measurements were compared with the baseline value. Postpressure measurements returned to baseline; however, the third minute measurement was significantly greater than baseline values.

CONCLUSIONS

Circumferential pressure applied to the lower leg decreased soleus muscle alpha motoneuron reflex excitability in subjects with SCI. This inhibition lasted only as long as the pressure was applied. Circumferential pressure application may be useful when a temporary decrease in muscle activity is a therapeutic goal in patients with SCI.

Effects of myotoxins on skeletal muscle fibers

This review highlights various aspects of a number of experimental myological alterations, induced by different chemical toxicants, including anticholinesterase, colchicine, vincristine, chloroquine, tetanus toxin, botulinum toxin, reserpine and emetine. Despite their chemical diversity and mechanism(s) of action, it is evident from the data discussed here that remarkably different toxic agents exert quite similar effects and induce toxic myopathies. The latter include preferential involvement of slow-twitch red muscle, mitochondrial derangement, denervation-like alterations, formation of membranous whorls, tubular aggregates, autophagic vacuoles and axonal sprouts. The non-invasive experimental models discussed here are valuable in studying various aspects of myopathology in the absence of any mechanical damage to the innervating elements from neurons to axonal terminals.

Botulinum toxin in the management of the lower limb in cerebral palsy

The role of intramuscular botulinum toxin A in the treatment of 26 children with cerebral palsy was evaluated. The indication for injection was the presence of a dynamic contracture of lower-limb muscles interfering with positioning or walking. Spastic target muscles were identified by clinical examination and, in ambulant children, by gait analysis. Between 50 and 320 units of botulinum toxin were injected into each muscle group to a total dose of 100 to 400 units per child. The effects of injection were monitored by repeated clinical examination and gait analysis. There were no clinically detectable systemic side-effects, and all but one patient had a reduction in tone, which occurred within three days and persisted for two to four months. There were significant improvements in ambulatory status and in sagittal-plane kinematics. In some cases these gains persisted after the tone-reducing effects of the toxin had worn off.

Neurophysiological aspects of tetanus toxin effects on the motor system

The action of tetanus toxin on the motor system in experimental tetanus relating to the clinical one was reviewed. Special attention was paid to several controversial results in recent years.

Permanent tetraplegia as a consequence of tetanus neonatorum. Evidence for widespread lower motor neuron damage

It is generally believed that no permanent neurological damage is found among survivors of tetanus neonatorum. Newborns dying shortly after the onset of tetanus also lack significant neurological abnormalities. In adults a variety of neuromuscular lesions have been reported; however, a uniform pathological picture is absent. We report a case of a newborn with severe tetanus in whom striking evidence of anterior horn neuronal damage was documented, causing permanent nonprogressive tetraplegia. We suggest that the mechanism responsible for this lesion involves the retrograde axoplasmic flow of tetanus toxin reaching the spinal cord via nerve endings in the infected umbilical cord stump.

Experimental rapid sarcomere loss with concomitant hypoextensibility

Slow soleus muscle in guinea pigs was actively shortened by constant electrical stimulation of the sciatic nerve for 12 hours. At the end of this period, hypoextensibility and a 25% decrease in the numbers of sarcomeres were observed. When a 36- or 48-hour period was allowed to elapse after the end of stimulation, some recovery occurred, and the sarcomere numbers were then found to be diminished by only 5%. If the stimulation was performed when the muscle was prevented from shortening (by ankle fixation in dorsiflexion), there was no decrease in sarcomere numbers and no hypoextensibility after neuroaxis lesions, when abnormal contractions maintain lasting shortening of the muscle.

Trophic muscle regulation in children with congenital cerebral lesions

A decrease in sarcomere number and hypoextensibility of ankle extensors was observed in certain children with congenital cerebral lesions. This phenomenon was reproducible and reversible in normal animals, i.e. trophic regulation adapted the muscle to the imposed length. The form of the torque-ankle angle curve was studied in 30 children. Its modification after treatment was considered as a sign of muscle adaptation. This adaptation was present in one group of 14 children. The steepness of the curve increased or diminished depending on the initial disorder and the treatment administered. In another group, treatment failed to modify the shape of the curve. In certain cases trophic regulation of the muscle appeared to be absent.