Barby Singer

Botulinum toxin assessment, intervention and aftercare for lower limb disorders of movement and muscle tone in adults: international consensus statement

Lower limb disorders of movement and muscle tone in adults significantly impact quality of life. The management of the patient with hypertonia is complex and requires a multidisciplinary team working with the patient and family/carers. Botulinum neurotoxin type A (BoNT‐A) has been used as a component of this management to reduce lower limb hypertonia, increase passive range of motion and reduce associated pain and requirements for bracing. Adjunctive treatments to augment the effect of BoNT‐A include electrical muscle stimulation of the injected muscles and stretching. When determining suitability for injection, the patient’s main goals for intervention need to be established. Muscle overactivity must be distinguished from contracture, and the effect of underlying muscle weakness taken into account. Explanation of the injection process, potential adverse effects and post‐injection interventions is essential. Assessment at baseline and post‐treatment of impairments such as hypertonia, range of motion and muscle spasm are appropriate; however, the Goal Attainment Scale and other validated patient‐centred scales can also be useful to assess therapy outcomes. In the future, initiatives should be directed towards examining the effectiveness of BoNT treatment to assist with achievement of functional and participation goals in adults with hypertonia and dystonia affecting the lower limb.

International consensus statement for the use of botulinum toxin treatment in adults and children with neurological impairments – introduction

Botulinum neurotoxin (BoNT) is most commonly used to reduce focal over‐activity in skeletal muscle, although newer indications such as management of drooling, pain and tremor are emerging. Treatment of spasticity incorporating BoNT is usually part of an integrated multidisciplinary rehabilitation programme. Prior to initiating this therapy, specific functional limitations, goals and expected outcomes of treatment should be discussed with the patient/carers. Muscle selection and the order/priority of treatment should be agreed. Treatment goals may involve increasing active or passive function or the avoidance of secondary complications or impairment progression. This paper describes the basic science mechanisms of the action of BoNT and subsequent nerve recovery and introduces a supplement comprising the best available evidence and expert opinion from international panels on questions of assessment, indications, BoNT regimen, adjunctive therapy, expected outcomes and recommended monitoring. Speciality areas reviewed include Paediatric Lower Limb Hypertonicity, Paediatric Upper Limb Hypertonicity, Adult Lower Limb Hypertonicity, Adult Upper Limb Hypertonicity, Cervical Dystonia, Drooling and Pain and Niche Indications. There is good quality scientific evidence to support the efficacy of BoNT to reduce muscle over‐activity in the limbs secondary to central nervous system disorders in adults and children, to address primary or secondary cervical dystonia, to reduce saliva flow and to treat some pain syndromes. There is emergent evidence for the efficacy of BoNT to reduce focal tremor, to treat other types of pain including neuropathic pain and also to improve function following treatment of focal muscle over‐activity.

Velocity dependent passive plantarflexor resistive torque in patients with acquired brain injury.

OBJECTIVES This study sought to determine whether factors other than stretch reflex excitability contribute to velocity dependent passive plantarflexor resistive torque following brain injury. BACKGROUND In patients with acquired brain injury increased resistance to passive muscle lengthening commonly results from abnormal muscle contraction, secondary to disinhibition of descending motor pathways, in addition to rheologic changes within the musculo-tendinous unit. Hyper-excitable tonic stretch reflex responses (spasticity) have traditionally been considered to be the main factor influencing resistance that is velocity dependent. METHODS Ten adults with brain injury and eighteen age matched controls were studied. A computer controlled torque measurement system was utilised to evaluate resistance to dorsiflexion stretches at two velocities (5 degrees and 25 degrees s(-1)). Only stretches which did not evoke muscle contraction were included in the data analysis. The mean difference and 95% confidence limits in passive plantarflexor resistive torque at two stretch velocities, measured over a defined portion of the test movement, were compared between subject groups. RESULTS A velocity dependent increase in passive plantarflexor resistive torque was evident when the ankle was dorsiflexed past the neutral position in both subjects with brain injury and controls. However, the mean difference was approximately 10 times greater in neurologically impaired limbs compared with control values. CONCLUSIONS These data indicate that an important component of velocity dependent resistance to passive muscle lengthening in adults with brain injury can be mechanical, and unrelated to stretch induced reflex muscle contraction. RELEVANCE Increased resistive torque during rapid muscle lengthening may represent a compensatory adaptation for reduced distal motor control following brain injury. A velocity dependent increase in passive plantarflexor resistive torque has the potential to improve stability during gait and provide mechanical resistance to sudden external perturbations.

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° 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.

Evaluation of extensibility, passive torque and stretch reflex responses in triceps surae muscles following serial casting to correct spastic equinovarus deformity

Primary objective : Spastic equinovarus deformity of the ankle in adults with acquired brain injury can severely limit the achievement of rehabilitation goals. This study examined changes in triceps surae muscle extensibility, passive resistive torque and soleus stretch reflex responses in 10 adult brain injured subjects undergoing serial casting to correct ankle equinovarus deformity. Method : Goniometric measurement of maximal passive dorsiflexion was used to evaluate extensibility of the triceps surae muscles. Computer controlled ankle dynamometry and surface electromyography were used to identify passive resistive torque and soleus stretch reflex onset angle in response to stretches at two velocities. Results : The mean casting period was 5 weeks. Casting was discontinued in one subject due to failure to achieve measurable gain in ankle range over three consecutive cast changes. Median improvements in maximal ankle dorsiflexion, with the knee flexed or extended, of 30° and 15°, respectively, were achieved in the remaining nine subjects ( p < 0.0001). The median passive ankle range in response to a displacing torque of 10 Nm increased 4.3° over the intervention period ( p < 0.0001). Consistent soleus reflex activity in response to passive stretches at 25°.s m 1 was elicited in only four subjects. A trend for the stretch reflex onset to move further into the available range was demonstrated in these subjects. Conclusion : In the present study, serial casting contributed to significant change in triceps surae extensibility and passive resistive torque, corresponding with improved maximal passive ankle dorsiflexion range and an increase in the angle achieved with a displacing torque of 10 N.m. Increased stretch reflex threshold was observed in some subjects. The use of pre-determined outcome criteria and careful measurement of responses to this intervention were important to prevent premature discontinuation of casting when gains were slower than expected.

Serial plaster casting to correct equino-varus deformity of the ankle following acquired brain injury in adults

Purpose : Proposed mechanisms via which serial casting might effect increased joint range, muscle extensibility and reduced reflex excitability are outlined in this review. Support for these mechanisms stems largely from animal experimental studies. The applicability of these data to human muscle is unknown. Issues : Equino-varus deformity of the ankle is a common secondary complication of acquired brain injury. It results from a combination of sequelae of the brain injury and subsequent immobility, including hypertonia, reduced muscle length and increased stiffness. Some evidence exists for the efficacy of serial plaster casts in the treatment of equino-varus deformity, although most reported studies are uncontrolled and involve small numbers of subjects. Serial casting has been shown to result in decreased resistance to passive lengthening and a reduction in dynamic reflex excitability within the lengthened muscles in children with cerebral palsy. Currently documented effects of serial casting in brain injured adults are limited to changes in range of maximal passive dorsiflexion. Conclusion : Serial casting should be considered as an adjunct to therapy aimed at improving functional mobility. A variety of therapeutic interventions have been used to augment the effect of the casting regime. Factors that have been demonstrated to be associated with a favourable outcome from serial casting, and recommendations for future research are also discussed in this review.

An open label pilot investigation of the efficacy of Botulinum toxin type A [Dysport] injection in the rehabilitation of chronic anterior knee pain

Purpose. To examine the effect of intramuscular injection of botulinum toxin type A [Dysport®] to reduce relative overactivity of the vastus lateralis [VL] muscle, in conjunction with re-training of vastus medialis [VM] muscle as an adjunct to rehabilitation for chronic anterior knee pain. Method. Eight females with chronic (>6 months) history of anterior knee pain, who had failed conservative management, were studied in this open label pilot study. Intramuscular Dysport® injection [300 – 500 units] to the distal third of VL muscle was followed by a 12-week customized home exercise programme to improve recruitment of VM muscle and functional knee control. VL and VM muscle cross sectional area from a standardized spiral CT sequence, isometric quadriceps strength (dynamometry), timed stair task, self-reported pain and disability were assessed. Results. Subjects reported reduced knee pain and brace dependency and increased participation in sporting and daily living activities. Isometric quadriceps muscle strength was maintained or improved despite significant atrophy, evident on CT, of the distal component of VL in the treated limb. Time taken to ascend and descend a flight of stairs improved in all subjects. Subjective and objective improvements were maintained at 24-week follow-up. Conclusions. These pilot data provide preliminary support for the role of Dysport® as an adjunct to non-surgical management of individuals with chronic anterior knee pain. Larger double blind, randomized, placebo-injection controlled studies of this novel approach to improving patellofemoral mechanics are needed to establish the efficacy of this intervention.

Botulinum toxin injection to facilitate rehabilitation of muscle imbalance syndromes in sports medicine

Intramuscular injection of Botulinum toxin to produce reduction of focal muscle overactivity, and localized muscle spasm, has been utilized therapeutically for almost two decades. Muscle overactivity in neurologically normal muscle, where an imbalance exists between a relatively overactive muscle and its less active synergist or antagonist, can inhibit control of the antagonist producing a functional muscle imbalance. This brief review provides an overview of the role of muscle imbalance in sports-related pain and dysfunction, and outlines the potential for intramuscular injection of Botulinum toxin to be used as an adjunct to specific muscle re-education and functional rehabilitation in this patient group. A comprehensive understanding of normal movement and the requirements of the sporting activity are essential to allow accurate diagnosis of abnormal motor patterns and to re-educate more appropriate movement strategies. Therapeutic management of co-impairments may include stretching of tight soft tissues, specific re-education aimed at isolation of the non-dominant weak muscles and improvement in their activation, ‘unlearning’ of faulty motor patterns, and eventual progression onto functional exercises to anticipate gradual return to sporting activity. Intramuscular injection of Botulinum toxin, in carefully selected cases, provides short term reduction of focal muscle overactivity, and may facilitate activation of relatively ‘inhibited’ muscles and assist the restoration of more appropriate motor patterns.

Velocity dependent passive muscle stiffness

We refer to the interesting study by Lee et al concerning quantification of velocity dependent properties of the elbow flexors in patients with spasticity and rigidity.1 Their main finding was a velocity dependent increase in reactive torque in both groups, although this was only related to muscle length in subjects with spasticity. However, the authors’ conclusion that their observations reflect stretch reflex hyperexcitability underlying spasticity is difficult to understand, as is their assumption that the contribution of passive mechanical change, if any, should be minor and uniform during stretch. The investigators used online …

The role of Botulinum toxin injection in achieving balanced muscle function

This special issue of Disability and Rehabilitation reports contemporary applications of Botulinum toxin for managing muscle overactivity and associated muscle imbalance. Clostridium botulinum, a gram-positive anaerobic bacterium, produces a potent poison, Botulinum toxin, which, when ingested, can induce transient muscle weakness, which in severe cases can be life-threatening. Despite this potential risk, minute doses of the purified neurotoxin confer an option for efficacious treatment of painful muscle spasms, focal muscle overactivity, and muscle imbalance of neurological and musculoskeletal origin. Intramuscular injection with therapeutic preparations of Botulinum toxin decreases contractile activity by blocking acetylcholine release at the neuromuscular junction, rendering the muscle relatively weakened for a variable period until the nerve terminal has recovered. In many conditions treated using Botulinum toxin injection, the main goal is to achieve a balance between the activity of a tight/short/overactive agonist and a weak/lengthened/inhibited antagonist, with synergistic muscles often contributing in a variety of complex ways. This special issue addresses a range of conditions where the main goal of treatment is to achieve a better balance of muscle function and, as a consequence, better movement control. In the preface to this material, Dr Alan Scott, describes the development of the therapeutic application of this toxin based upon pioneering studies using Botulinum toxin type A in monkeys and subsequently in humans to treat strabismus. From these fundamental origins, clinical applications have broadened extensively and continue to expand. Some of these applications are highlighted in sections within this issue and give insights into indications, efficacy and future issues for the therapeutic use of Botulinum toxin. The pharmacological basis for Botulinum toxin is reviewed by Dressler and Benecke who describe the versatility of its applications; including the potential to block cholinergic neuromuscular innervation of intraand extrafusal muscle fibres as well as cholinergic autonomic innervation of sweat, lacrimal, and salival glands and smooth muscles. In general it would appear that long-term clinical application does not produce additive adverse effects, although the potential for autoimmunity remains a problem in some applications. The development of commercial preparations of Botulinum toxin type B has offered options for individuals with auto-resistance and there is some evidence that this serotype may be more efficacious in the treatment of autonomic disorders. The role of Botulinum toxin injection in the management of axial and cervical dystonia is reviewed by Benecke and Dressler. Intramuscular injection of Botulinum toxin has revolutionalized the treatment of this group of conditions. Precise identification of dystonic muscles and careful quantification of their involvement is necessary to optimize patient outcomes. Sheean reports on the pathophysiology of the excessive and inappropriate muscle contractions which occur during fine motor tasks in individuals with focal task specific hand dystonia; and the efficacy of Botulinum toxin therapy, at least in the short term, in conjunction with other therapeutic approaches for this cohort. Gracies and colleagues provide an overview of the role of Botulinum toxin therapy in the management of muscle imbalance in the lower limb in adult onset central nervous system injury/dysfunction. These authors point to the key interactions between muscle overactivity, adaptive shortening and loss of strength