Abstract
Functional problems in patients with cerebral palsy are still barely understood today. The situation is extremely complex. The neurological damage changes brain functions which affect the shape and tissue composition of the locomotor system and vice versa. Both have an influence on development and cognition. Growth and brain plasticity come in as additional factors. Still, the individual wants to meet the demands of the family and society. Within this extremely complex situation, patients seek help and treatment. Accordingly, treatment is challenging. It is difficult to maintain an overview of current concepts, their inconsistencies and flaws. Questions arise but research does not always provide a clear answer: different studies yield contradicting results. Still, better insight and knowledge of the pathologies and their interactions provide the basis for improved treatment.
The present book is extremely interesting in this context. It summarises the content of a meeting held 2019 which was organised by Tom F. Novacheck and Michael H. Schwartz of the famous Gillette Hospital, St. Paul, MN, USA. The underlying idea of the attractive meeting design and the resultant book is to provide a platform to experts in the field. The editors profit from their large network of researchers who were involved in co-operational projects. The specialists have continued their research, further developed research and knowledge in their field, became experts in their field. On this basis, a book with an excellent overview on the current situation regarding clinical application and scientific attainments is presented. Each topic is covered by at least one clinician and one basic scientist. This team describes today's standards, their research in this respect and their concepts. However, it is far from a textbook with a simple description of therapeutic procedures. The current standard is only the introduction for a fascinating discussion formed of expert opinion and the frank description of limitations of our current knowledge, explaining the flaws and contradictions well justified by their research results. Original and innovative ideas are presented and established as a logical consequence of previous work. This context of invited contributions makes it possible to present new ideas and concepts which has become difficult in the modern scientific world of numbers and statistics. The combined contribution of clinicians and basic researchers closes the link between research and clinical work. At the end of each chapter, open and strategic questions are listed which again gives an insight into the conceptual thinking of the experts. It also may help to stimulate and direct future research.
Katherine M. Steele and Andrew G. Georgiadis cover the topic of lever arm dysfunction. Jim Gage described this pathology as one major cause for the abnormal gait in patients with cerebral palsy in the early 1990s. Surgical correction of skeletal abnormalities, femoral anteversion to improve hip abductors and foot rotation for the plantar flexion knee extension couple, have improved walking for countless patients since. The authors describe three very relevant gaps of knowledge: 1) These skeletal deformities are the result of growth and remodelling under the altered load during daily activities. 2) There is still the assumption that bone in cerebral palsy reacts the same as in normal developing children. For muscles it was shown that this is not true. 3) Another important issue is the understanding of the foot and its bone and soft tissue structures in a given situation and over time.
Moran Sangeux and Thomas Dreher describe the cooperation between an engineer and an orthopaedic surgeon for indicating, planning, and performing interventions aiming at an improvement of gait. Besides the surgical skills, a more thorough understanding of a pathology and its importance to the individual, provided by engineering, improve indication and thus outcome. Type and amount of deformity correction, however, are only possible respecting both clinical (anatomical) and functional data. For bony corrections, especially osteotomies, the combination of engineering and surgery results in the development of navigation systems which improve the precision of a correction. While there is good evidence for bony corrections, respective data applicable to corrections of soft tissues, especially muscle-tendon units, is lacking. Finally, musculoskeletal modelling may present more insight into the complex relationships of the structures of the locomotor system.
Benjamin J. Shore, Kaat Desloovere and Unni G. Narayanan stress the importance of outcome measurements. Different tools are available for the various interests and levels of investigation. They are all seen within the framework of the International Classification of Functioning, Disability, and Health (ICF) model of the World Health Organisation. Very different parameters can have an influence on a given outcome measure of interest, and the aim of the patient may not be congruent with the goal of the parents or doctors. Nevertheless, it is important to cover all aspects, the purely technical as well as the expectations of the patient and the related and involved persons. The authors describe tools for general purposes and for gait assessment, which gives a good overview on the current standards and the challenges encountered when they are used. This critical summary may be a helpful guideline for researchers. More goal-specific tests, user-friendlier and mobile measurement equipment as well as large databases collected with standard tools are required in order to link the various dimensions aimed at treatment improvement in a more generalised context and more individual decision making.
While we have relatively good concepts for biomechanics and outcome, the problem with muscle tone already starts with our understanding of muscle tone and spasticity. Kaat Desloovere and Warren A. Marks describe this problem and the confusion about muscle tone thoroughly and very well. Management is covered by Kristina Tedroff and Marjolein van der Krogt. Non-neural (muscular) resistance needs to be distinguished from neural resistance to fast movement, and spasticity defined against dystonia. The authors propose the term ‘hyper-resistance’ instead of spasticity, with the non-neural and neural component. The neural component is then divided into ‘stretch hyper-reflexia’ and ‘involuntary background activation’. This concept is more descriptive of the clinical picture but clear about its different components. The neurological symptoms, especially spasticity, need to be seen in a larger context where they influence the development of the components of the locomotor system. The role of spasticity, however, is still unclear, and especially its impact on gait. The situation is even more complex as other changes of tone such as dystonia are often present in the same patient and are often not separated. The next problem is with measuring spasticity. The possibilities are described well, but they all are fast and inexact or depend on devices which are difficult to use in clinical settings. The results from spasticity treatment on function and gait parameters remain confusing. Even less elaborate are diagnostics and treatment outcome for dystonia which is commonly underestimated. The future needs to bring a better understanding of the pathophysiology and the interactions of hyper-resistance and its components as well as of other neurological signs such as dystonia, and especially their role in function such as gait.
Motor control links the brain with motor function. It consists of planning, performing, judging and correcting a movement as well as learning, which leads to motor development. Damage to the brain thus has an influence on motor control and on the outcome of treatment interventions. Katherine M. Steele and Warren A. Marks explain very clearly the complexity of motor control and the difficulties of the assessment. Altered arm and hand function today can be studied by functional neurological diagnostics, while this is hardly possible for the lower extremities. Synergies as contemporary EMG muscle activities are calculated from motion analysis as an indicator for the development of motor control. In a damaged brain, neuroplasticity augments the complexity. The chapter gives an excellent overview on this topic where our understanding is still poor and sensory impairment is insufficiently considered.
The chapters on muscle-tendon pathologies and treatment by Rick Lieber, Tim Theologis, Jason J. Howard, H. Kerr Graham, Adam P. Shortland, Jon R. Davids, Anahid Ebrahimi, and Darryl G. Thelen very briefly and clearly summarise the current state of knowledge on muscle pathophysiology and treatment. CP muscle shows a large variety of pathological characteristics. Sarcomeres are longer and thus less functional, the extracellular matrix is stiffer, and the stem cell number is lower than in normal muscle. The effect of various anatomical situations on function are exposed and current muscle surgery techniques such as lengthening are regarded very critically. A very rough technique is applied on a delicate organ and with only gross effects. The aim is still to gain length without weakening the muscle. The various surgical possibilities for lengthenings are described but more nuanced diagnostic and surgical techniques are wanted. Especially the conventional view of developing structural contractures and bony deformities as a consequence is challenged. A comparison over principally different diseases with different conditions shows that similar pathologies emerge. Regarding treatment, the correction of muscle contractures does not necessarily bring the expected result. Especially interesting is the statement that spasticity treatment has little effect on the prevention of muscle shortenings. Little is known on the influence of muscle surgery on the changes of muscle function during a given task. Gait analysis as a tool for planning treatment can be expanded when musculoskeletal modelling is applied to the individual. Already, cohort studies on principles have gained essential and valuable information on effects of muscle tendon surgery and the effect on certain muscles. The uncertainties and flaws of this method are discussed but still there is the possibility of an improved approach for planning in the future. For a better understanding of combinations of muscle and bony surgery, modelling studies can be of help in the future as well as randomised clinical outcome studies.
Patients and the people who treat them have to learn to live with CP. While patients are forced to do their best because the condition is part of their daily life, the people who treat and care give their best according to their knowledge and the scientific evidence, but they have never experienced CP. They evaluate the situation of a CP patient and aim at normality. However, they do not live with CP and thus their efforts may help the patient's individual problems only little. Even more difficult is the treatment of children unable to express their expectations at least in the early years. Only a more thorough understanding of the pathomechanics and the influence of CP on the daily life of the patient and the family will produce a treatment which reflects the goals of the individual patient. This book is a step in this direction. For each covered topic, on the basis of the current standard knowledge, critical scientific questions and tasks are formulated for the next five years and beyond. It is interesting being made aware of how shaky our current basis for treatment is. The critical views and hypothetical considerations of specialists in the field broaden the horizon and question our current basis for treatment. Another important point of this book is the step away from a simple mechanical appraisal. The influence of sensory and cognitive deficits of the individual patient needs to be integrated in our considerations as this impacts the present mechanical situation, the development and the outcome of every treatment. Another strength of this book may be that on the basis of such interactions, lively networks bundle the research across different topics, influence each other by interacting, and thus can produce a more holistic view. For all topics, larger databases within such a research network are required to improve our understanding of the problems, their interaction and outcome. This book is excellently structured and written. The authors fulfil the expectation to provide a thorough overview of their field. They develop critical considerations on the standard knowledge and conclude with questions and tasks for the future as a consequence. I strongly recommend this book to all who are interested in the complex problem of cerebral palsy, in its research and functional treatment.