Margaret Mayston

A neurophysiological study of mirror movements in adults and children.

The mechanism underlying mirrored activity/movements in normal individuals is unknown. To investigate this, we studied 11 adults and 39 children who performed sequential finger–thumb opposition or repetitive index finger abduction. Surface electromyographic (EMG) activity recorded from the left and right first dorsal interosseous muscles (1DI) during unilateral sequential finger–thumb opposition (voluntarily activated muscle, 1DIvol) showed mirrored EMG activity (homologous muscle of the opposite hand, 1DImm) that decreased with increasing age. The time of onset of involuntary compared with voluntary EMG activity was variable but could start at the same time. A significant increase in E2 (transcortical component) size of the cutaneomuscular reflex recorded from the 1DImm indicated increased excitability of the motor cortex ipsilateral to the 1DIvol during active index finger abduction compared with the 1DIvol relaxed. Transcranial magnetic stimulation, using the Bistim technique, indicated that the transcallosal inhibitory pathway in children may not operate in the same way as in the adult. Cross‐correlation analysis did not detect shared synaptic input to motoneuron pools innervating homologous left and right hand muscles. We conclude that the mirrored movements/activity observed in healthy adults and children are produced by simultaneous activation of crossed corticospinal pathways originating from both left and right motor cortices. Ann Neurol 1999;45:583–594

Changes in EMG coherence between long and short thumb abductor muscles during human development

In adults, motoneurone pools of synergistic muscles that act around a common joint share a common presynaptic drive. Common drive can be revealed by both time domain and frequency domain analysis of EMG signals. Analysis in the frequency domain reveals significant coherence in the range 1–45 Hz, with maximal coherence in low (1–12 Hz) and high (16–32 Hz) ranges. The high‐frequency range depends on cortical drive to motoneurones and is coherent with cortical oscillations at ∼20 Hz frequencies. It is of interest to know whether oscillatory drive to human motoneurone pools changes with development. In the present study we examined age‐related changes in coherence between rectified surface EMG signals recorded from the short and long thumb abductor muscles during steady isometric contraction obtained while subjects abducted the thumb against a manipulandum. We analysed EMG data from 36 subjects aged between 4 and 14 years, and 11 adult subjects aged between 22 and 59 years. Using the techniques of pooled coherence analysis and the χ2 difference of coherence test we demonstrate that between the ages of 7 and 9 years, and 12 and 14 years, there are marked increases in the prevalence and magnitude of coherence at frequencies between 11 and 45 Hz. The data from subjects aged 12–14 years were similar to those obtained from adult controls. The most significant differences between younger children and the older age groups were detected at frequencies close to 20 Hz. We believe that these are the first reported results demonstrating significant late maturational changes in the ∼20 Hz common oscillatory drive to human motoneurone pools.

Physiological tremor in human subjects with X-linked Kallmann's syndrome and mirror movements

1 Human physiological tremor consists of mechanical‐reflex and neurogenic components. The origin of the neurogenic component, classically detected in the frequency range 7‐12 Hz, has been much debated. We have studied six subjects with X‐linked Kallmanns syndrome (XKS) and mirror movements. In these subjects unilateral magnetic brain stimulation results in abnormal bilateral EMG responses. Furthermore, abnormal sharing of central nervous inputs between the left and right motoneurone pools results in both abnormal motor unit synchronisation between left and right EMGs and abnormal sharing of long but not short‐latency cutaneomuscular reflexes. XKS subjects with mirror movements thus provide a model for studying the central origin of physiological tremor. 2 During sustained co‐extension of the left and right index fingers, simultaneous finger tremor and extensor indicis (EI) EMGs were recorded and cross‐correlated. The tremor and EMG signals were also subjected to time and frequency domain analysis. 3 Results of frequency domain analysis between ipsilateral finger tremor and EI EMG were similar for both control and XKS subjects. However, in contrast to the controls, short‐term synchronisation of left and right EI motor unit activity and significant coherence between left and right EMG, left and right tremor, left EMG and right tremor and right EMG and left tremor were found in XKS subjects. The frequency range (6‐40 Hz) and coherence values between left and right were similar to ipsilateral coherence values of rectified EMG and tremor. 4 These data provide strong evidence to support the hypothesis that the neurogenic component of physiological tremor is supraspinal in origin and ranges from 6 to 40 Hz.

Evidence-based physical therapy for the management of children with cerebral palsy

evidence base. Whilst the ICF model can provide a framework for clinical reasoning, i.e. it can help the therapist to decide ‘what’ to do, it cannot tell the therapist ‘how’ to do it in order to provide the most appropriate intervention in the light of emerging evidence. How can therapists translate the results from experimental trials into clinical practice to provide effective evidence-based intervention? Therapists can acquaint themselves with current literature and emerging ideas. But they also need a way to gain practical skills in applying these new – and probably some not so new – methods of intervention, such as muscle strengthening and task-specific training. It seems a worldwide problem that few possibilities exist for therapists to acquire clinical skills other than ‘on the job’, to attend neurodevelopmental (NDT/Bobath) or other ‘named-approach’ courses, or to participate in the limited variety of short course options. It is hoped that the increasing availability of specialist post-graduate degrees and short courses will gradually ensure that all paediatric physical therapists are given the appropriate clinical skills to put research findings into practice. Higher degree programmes already give therapists the opportunity to participate in ongoing research and to design and implement their own research projects. Such research will expand the therapeutic evidence base and can motivate therapists to participate in further research. It may take some time, but there is a growing confidence that sound, evidence-based physical therapy can, and so will, become a reality.

The sharing principle.

Publisher Summary Even the simplest movements require the co-contraction of many different muscles acting around different joints. Making a fist, for example, involves flexion at the interphalangeal and metacarpophalangeal joints, combined with extension at the wrist: co-contraction of the intrinsic hand muscles and forearm finger flexor muscles is combined with the co-contraction of forearm wrist extensor muscles. Another example might be touching the tip of the shoulder with the index finger, where flexion at the wrist is combined with flexion at the elbow. Contraction of the forearm wrist flexor muscles is combined with contraction of the elbow flexor muscles. Cross-correlation analysis of simultaneously recorded multiunit electromyographic (EMG) signals has been used to study the distribution of common synaptic input shared among motoneurons innervating different muscles in man. From these experiments, a simple new generalization emerged for the organization of synaptic drive to motoneurons, which is called the “sharing principle”; motoneurons innervating muscles that share a common mechanical action share a common pre-synaptic input. The converse is also true; motoneurons innervating co-contracting muscles that do not share a common action do not share a common input either. The sharing principle extends to the control of different motoneuron pools, the mechanism envisaged by Henneman to be responsible for the coherent action of motoneurons within a single pool: the sharing of synaptic input. Sharing of common synaptic input within a motoneuron pool ensures that the motor units sharing a common mechanical action operate as a functional entity. Sharing of common pre-synaptic input among motoneuron pools allows different combinations of muscles to operate as different functional entities. The group of motoneuron pools sharing synaptic input in a particular task works as a functional unit.

Feasibility study of a randomized controlled trial protocol to examine clinical effectiveness of shoulder strapping in acute stroke patients

Objective: The majority of stroke patients experience upper limb motor impairment and reduced ability to perform basic activities. Shoulder strapping has been reported as a beneficial adjunct to rehabilitation therapies but has not been rigorously trialled. This study tested the feasibility of recruitment, intervention and outcome assessment protocols for future trial of the clinical effectiveness of shoulder strapping. Design and setting: Feasibility study using a randomized controlled trial in an East London stroke service. Subjects: Fourteen acute stroke patients with mild to moderate upper limb hemiparesis were recruited between October 2004 and July 2005. Intervention: Five strapping methods and criteria for use were identified from the literature. Shoulder strapping applied for one month in addition to routine rehabilitation was compared to routine rehabilitation only. Main measures: The Motor Assessment Scale, Fugl Meyer Scale – Arm section and the Nine Hole Peg Test were measured at baseline and 1, 2, 3 and 5 weeks later. The Stroke-specific Quality of Life questionnaire was delivered at 6 and 12 weeks post stroke. Results: Useful findings were demonstrated in relation to the feasibility of all elements of the protocol. Motor Assessment Scale findings showed a small-moderate (0.27) effect size for the strapping intervention used as an adjunct to routine rehabilitation compared to routine rehabilitation alone. Sample size calculation indicated 312 participants would be adequate to test a null hypothesis of nil benefit additional to routine rehabilitation. Conclusion: Findings supported the value of pilot-testing, and enabled revision of the study protocol for future definitive trial.

Reactive control of precision grip does not depend on fast transcortical reflex pathways in X-linked Kallmann subjects.

1 It has been shown that subjects maintain grasp stability by automatically regulating grip force in response to loads applied tangentially to a manipulandum held using a precision grip. Signals from cutaneous mechanoreceptors convey the information necessary for both the initiation and scaling of responses. The central neural pathways that support these grip reactions are unknown. However, the latency of the increase in force is similar to that of ‘long‐latency’ transcortical reflexes recorded from muscles following muscle stretch or electrical stimulation of digital nerves. 2 This study assessed the importance of fast transcortical pathways for reactive grip responses by examining these responses in subjects with X‐linked Kallmanns syndrome (XKS). Subjects were selected whose corticospinal projection, as assessed by magnetic brain stimulation, is essentially ipsilateral, and in whom the long‐latency reflex components following digital nerve stimulation are only found contralateral to the stimulated side. 3 Despite this anomaly of the fast corticospinal pathway, these XKS subjects responded in the same way as control subjects; grip response latencies were similar and responses were appropriately scaled. However, the non‐operating hand of these XKS subjects often mirrored the grip force changes of the operating hand. Reflex force mirroring was most marked during the first 50 ms and the force output was always less than 20 % of that of the operating hand. 4 We conclude, firstly, that somatosensory driven precision grip responses that support grasp stability do not depend on fast conducting corticospinal pathways in these subjects and, secondly, that such responses do not use those ‘long‐latency’ reflex pathways probed by cutaneomuscular reflexes elicited by electrical stimulation of digital nerves.

Gross Motor Function Measure-66 trajectories in children recovering after severe acquired brain injury

To explore the appropriateness of using the interval‐scale version of the Gross Motor Function Measure (GMFM‐66) in paediatric acquired brain injury (ABI), and to characterize GMFM‐66 recovery trajectories and factors that affect them.

Bobath and NeuroDevelopmental Therapy: what is the future?

For many years, the multidisciplinary therapy approach developed by Bertha and Karel Bobath for cerebral palsy (CP) was met with a very positive response. Families flocked to the Bobath Centre in London for treatment and a home programme, and the training courses for therapists had up to 4-year waiting lists. In 1965 it was hailed in the UK parliament as a breakthrough in the management of CP. The approach was taken by trainees to many countries, and courses and professional associations were established worldwide. As a result, it became the main approach to the management of CP, almost to the exclusion of all other interventions. It was also applied to early intervention of high-risk infants, which was unusual at that time. In the last few years, Bobath/NeuroDevelopmental Therapy (NDT) for most professionals in the world of childhood disability management has fallen from favour and use, and this is related to the lack of an evidence base. It has even been suggested in this journal that the approach should be discontinued. This is unsurprising, though perhaps not for the reasons stated in that particular systematic review. Bobath/NDT are both systems of intervention, not single treatment modalities. But there are far more reaching issues than that. Over time, the terms Bobath and NDT have to an extent been used synonymously, though they are not the same. Bobath and NDT both aim to offer a holistic, multidisciplinary intervention with the objective of optimal participation in daily life, but in practice there are fundamental differences in how each achieves that objective. NDT interpreted the original multidisciplinary neurophysiologically-based Bobath approach in terms of biomechanics, which resulted in a different emphasis in clinical practice which is in my view more passive. Some practitioners focus on the hands-on rather than the original emphasis on the importance of activity for function (activity and participation). Some include all treatments under the Bobath/NDT umbrella, while others identify what is Bobath/NDT and see other interventions as adjuncts. The Bobath/NDT approach to management is also often different in children and adults. Development is a good thing; however, practitioners have developed Bobath/NDT in many different directions, resulting in a diversity of approaches. This has produced a situation for which there is no universally agreed definition of what Bobath/NDT is, or what it means to be a Bobathor NDT-trained therapist. Given this diversity, the essence of ‘What is Bobath?’ cannot be universally identified, agreed, practised, or taught, and ultimately cannot submit itself to rigorous research. While the Bobath name has high heritage value, it no longer stands for a valid universal therapy approach. What does this mean for the future? Centres and hospitals named after Bobath represent that heritage, but like the already-established Bobath/NDT associations, they need to change their emphasis of activity to offer effective child/ family-centred interventions which can lead to optimal activity and participation. My personal view is that the contribution of Bobath/NDT to the management of CP has historical value, but it would be more realistic and respectful to discontinue use of the name as a therapy approach. Let us all take a step back, not just those who associate themselves with Bobath/NDT. The future is about promoting current practice which draws on the various guidelines such as those offered by the National Institute of Clinical Excellence (NICE), whose rigorous approach to review of the literature is unbiased and also identifies research needs. Given that the research evidence base is lacking for CP intervention, sound clinical reasoning with reference to current knowledge on neuroplasticity, development, motor learning, muscle physiology, biomechanics, and the International Classification of Functioning, Disability and Health, Children & Youth Version (http://www.who.int/classifications/icf/en/) can provide a rational basis for intervention. This is the responsibility of all therapists and practitioners, including the various Bobath/NDT associations and centres worldwide. Optimal participation in daily life comes from a common-sense, realistic approach to management.

Please proceed with caution

SIR–There is no doubt that a robust evidence base is needed to underpin the management of children and adults with cerebral palsy (CP), and the recent review by Novak et al. aims to makes a significant contribution to that literature. We are not experts on the methodology of a systematic review, let alone a systematic review of systematic reviews which includes lower levels of evidence in lieu of a systematic review. While the authors accept the limitations of the review, we consider that some comment or response is required. Firstly, the idea of a traffic light system seems very appealing but is surely vastly over-simplistic. The changing nature of the state of the evidence, and the potential for an overreadiness to rely on this simplistic system, warrants the use of caution. Young and less experienced professionals with little experience of the literature, analysing data and interpreting reviews, and those who lack time to do so, will be attracted by this simple directive system, but does it really provide a pathway for intervention? These categorizations will surely alter as new evidence emerges thus consideration needs to be given to the future use of such a review. Despite some interventions being given the green light (only 16%), all of the interventions presented need further research to enable professionals to decide what works best for whom and at what stage of their life. This question is not addressed. Secondly, we are concerned that although the review is embedded within the International Classification of Functioning, Disability and Health, it does not go as far as making recommendations for intervention on the basis of age, Gross Motor Function Classification System level, or type of CP (e.g. spastic hypertonic, dyskinetic). Neither does this traffic light system approach seem to consider the child holistically. For example, constraint-induced movement therapy is usually recommended for people with unilateral upper limb impairments; spasticity medications are only appropriate for those with spasticity as a primary impairment and it is highly doubtful that medication alone will achieve significant effect unless some type of activity training is provided. While on the surface the method of the review seems appropriate, a wide range of interventions are included, some are a systems approach whereas others are specific interventions and these are hardly comparable, and some are not interventions at all (e.g. hip surveillance), which further limits confidence in the proposed traffic light system. Thus our third point is that sections of the discussion reflect a lack of understanding of some interventions and here we use as an example neurodevelopmental therapy (NDT; also known as Bobath), which is given the redlight. It is interesting that NDT was even included in this review, as whole discipline reviews were excluded (exclusion criterion 5 in Novak et al.). NDT/Bobath is usually provided by an interdisciplinary team and is a system of therapy which advocates ‘CP therapists’ not individual discipline therapists. Another difficulty for any review of NDT/Bobath is that it is not practiced and taught uniformly throughout the world, thus studies of NDT/ Bobath intervention will also differ and cannot be viewed collectively. What perplexes us is that of the 64 interventions reviewed, at least 20 are included within and are integral to the NDT/Bobath approach, such as home programmes, parent training, and dysphagia management. Many are used to complement the use of NDT/Bobath such as the use of treadmill training, orthotics, and anti-spastic medication (the Bobaths could only recommend phenol in their working life in lieu of the currently used botulinum toxin). Bobath is a clinical approach, not ‘a treatment’, which utilizes scientific knowledge as available to support its practice, and accordingly applies current theories of motor control and learning, muscle physiology, and neuroplasticity to underpin its practice, therefore it is interesting that NDT/Bobath therapists are criticized in this review for using principles of motor learning. Novak et al. propose that their review ‘... could form the basis of policy, educational, and knowledge translation material because it is a comprehensive summary of the evidence base’. This should stir all professionals to reflect on their practice and to continue to evaluate the available intervention options, rather than simply accepting this review as the way forwards. It should especially challenge NDT/Bobath practitioners to review their practice and teaching of the approach. Ultimately what matters is that people with CP receive the interventions that give them the best possible chance to participate in daily life. This review should be given the orange light of caution and its shortcomings discussed openly.