The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories of the methods used to extract parameters of the signal is vital to the application of the signal during experimental and clinical practices, especially in areas where electromyograms are contraindicated or have limited application. As we highlight the underpinning technical guidelines and domains where each method is well-suited, the limitations of the methods are also presented to position the state of the art in MMG parameters extraction, thus providing the theoretical framework for improvement on the current practices to widen the opportunity for new insights and discoveries. Since the signal modality has not been widely deployed due partly to the limited information extractable from the signals when compared with other classical techniques used to assess muscle performance, this survey is particularly relevant to the projected future of MMG applications in the realm of musculoskeletal assessments and in the real time detection of muscle activity.
We report two patients with myopathic dropped head syndrome, a rare and interesting neuromuscular syndrome characterised by a predominant weakness of the neck extensor muscles. The first patient, a middle aged Chinese man, presented with progressive weakness of neck extension but his clinical course later stabilised despite a lack of response to corticosteroids. Muscle biopsy revealed a necrotising myopathy with no evidence of inflammation. This patient supports the existence of an idiopathic restricted non-inflammatory myopathy, a so called isolated neck extensor myopathy syndrome which is recognised to pursue a less progressive, more benign course. Our second patient had histopathological evidence for polymyositis; there was a favourable response to steroids. Our cases underscore the fact that there may be a spectrum of pathological processes associated with the myopathic dropped head syndrome ranging from non-inflammatory muscle necrosis to a full blown inflammatory myositis.
INTRODUCTION: Acute muscle injury is one of the commonest injuries that often result in loss of training and competition time. The best management for muscle injury has not been identified. Sports medicine practitioners used several approaches in attempt to accelerate time to recovery from muscle injury. More recently growing interest focussed on autologous blood product injection.
METHODS: A literature search was conducted systematically using OvidMEDLINE, PubMed, EMBASE, SPORTDiscus and CINAHL databases to retrieve articles published until December 2012. Controlled trials and controlled laboratory studies comparing different strategies to promote early recovery of muscle injury were included. The methodological quality of studies was assessed.
RESULTS: There are limited studies on the effects of PRP therapy for muscle injury. Three in vivo laboratory studies and one pilot human study were reviewed. The laboratory studies reported histological evidence on significant acceleration of muscle healing in animals treated with autologous conditioned serum (ACS), platelet-rich plasma (PRP) and platelet rich fibrin matrix (PRFM). A pilot human study found athletes treated with repeated ACS injection recovers significantly faster than retrospective controls.
CONCLUSION: Several in vivo laboratory studies suggest beneficial effects of ACS, PRP and PRFM in accelerating muscle recovery. Evidence to suggest similar effects on humans is however limited, as valuable information from robust human controlled trials is still not available at this moment. Hence, more studies of satisfactory methodological quality with platelet-rich plasma interventions on muscle injury are justified.