Temporomandibular Disorders (TMD) are characterised by pain and limited jaw movement and are a significant issue. Current management is influenced by the view of a simple association between pain and limited movement. This study will test a new theory that an individual's motor response to pain is influenced by the complexity of the jaw motor system as well as the individual's pain experience. This project will point towards individualised recommendations for effective management of TMD.
Effects Of Jaw Muscle Pain On Jaw Muscle Activity And Jaw Movement In Humans
Funder
National Health and Medical Research Council
Funding Amount
$337,770.00
Summary
Chronic facial muscle pain is a significant community health problem that is poorly understood. Current treatments are based on the idea that structural or stress-related factors result in increased jaw muscle activity which then generates pain that in turn leads to more muscle activity - the so-called Vicious Cycle Theory. Treatments therefore aim to break the cycle by focussing on reducing muscle activity and thereby alleviate the pain. There is currently, however, little scientific evidence f ....Chronic facial muscle pain is a significant community health problem that is poorly understood. Current treatments are based on the idea that structural or stress-related factors result in increased jaw muscle activity which then generates pain that in turn leads to more muscle activity - the so-called Vicious Cycle Theory. Treatments therefore aim to break the cycle by focussing on reducing muscle activity and thereby alleviate the pain. There is currently, however, little scientific evidence for this Theory. Another theory has been recently proposed in the Pain Adaptation Model. This model says that changes in muscle activity and movement are protective against further pain rather than the cause of the pain. The evidence, however, for this model is limited and conflicting. The current lack of understanding of facial muscle pain limits advancement in its management. Our long-term goal is to improve the management of patients with facial pain. The present application aims to determine whether muscle pain alters jaw muscle activity and jaw movement. Our preliminary clinical data provide compelling evidence for the Pain Adaptation Model. We are confident of a better understanding of what goes wrong in the jaw muscles in chronic facial pain and this will have implications for muscle pains elsewhere in the body. The outcome may help to refute the Vicious Cycle Theory, and help shift the focus away from signs and symptoms associated with the jaw muscles, and re-direct the focus to the alleviation of pain as the primary management goal. The information obtained should also provide a solid basis on which treatments can be tested for optimal resolution of symptoms, and an evidence-based approach in the management of facial pain.Read moreRead less
Human Muscle Stretch Reflexes: The Effects Of Stimulus Properties, Muscle State And Subject Intention
Funder
National Health and Medical Research Council
Funding Amount
$170,604.00
Summary
The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch ....The best known muscle reflex is the tendon jerk, which is usually evoked by tapping the muscle tendon with a small hammer. This tap imposes a very rapid stretch on the muscle, which produces a stretch reflex. Different stretch responses, however, can be observed to slow or fast stretches, or to vibration of muscle. Normally, when the muscles of a relaxed person are stretched, no active response is observed. However, when the person is engaged in a task and contracting their muscles, then stretch modulates the muscle activity such that an increase in contraction of the muscle opposes the stretch and defends the position of the joint against the external disturbance. This is the everyday situation in which stretch reflexes operate. Despite extensive investigation for over a hundred years, there is still no consensus among researchers about the behaviour of stretch reflexes nor about their role in the control of movement. Even the demarcation of reflex from voluntary muscle activity is not always certain. One of the outstanding features of stretch reflexes is the variability of their behaviour, which depends on the particular muscle involved, its level of contraction, the type of stretch and the task in which the person is engaged. This variability has made it difficult for researchers to determine the role of reflexes in the control of movement. In order to study stretch reflex behaviour in human subjects, we will measure the electrical activity of elbow muscles, the elbow position and the force generated at the joint under a variety of conditions. A series of five experiments will investigate specific unresolved issues such as the effect of subject intention on the modulation of muscle activity and how altered modulation of muscle activity may change the stiffness of our limbs. The objective of the experimental series is to fill in important gaps in the picture of the behaviour of the stretch reflex.Read moreRead less
Physiology And Pathophysiology Of Trunk Control Mechanisms
Funder
National Health and Medical Research Council
Funding Amount
$168,958.00
Summary
The overall aim of this series of experiments is to understand how the spine is controlled and how this changes in disease. Altered control has been identified in people with low back pain, yet we still know very little about the normal mechanisms for protection and support of the spine. Back pain is a common affliction that affects about 5% of Australians each year and is the most common and expensive work-related injury in western society. An understanding of normal control and the mechanism o ....The overall aim of this series of experiments is to understand how the spine is controlled and how this changes in disease. Altered control has been identified in people with low back pain, yet we still know very little about the normal mechanisms for protection and support of the spine. Back pain is a common affliction that affects about 5% of Australians each year and is the most common and expensive work-related injury in western society. An understanding of normal control and the mechanism of dysfunction is critical for identification of risk factors and development of strategies for rehabilitation and prevention. The experiments are divided into two series. The first series addresses normal spinal control. The questions to be asked deal with how the brain copes with the challenge of using trunk muscles for breathing and spinal control at the same time, how the activity of the trunk muscles is affected by input from sensory receptors in the joints, ligaments and muscles of the spine, and whether intra-abdominal pressure can support the trunk. The second series deals with clinical populations. The first aim is to identify whether people with respiratory diseases use trunk muscles for spinal control and breathing at the same time. If they cannot, we predict that they will be more prone to low back pain. We will test this in a large study of incidence of low back pain in people with and without respiratory disease. The second study will investigate the pelvic floor muscles which are important for continence and assist with spinal control. We will investigate whether people with incontinence have poor spinal control and whether this leads to back pain. The final experiment will identify whether people with low back pain interpret sensory information from the spine differently. By answering these questions we hope to intervene in the enormous personal, social and economic consequences of LBP which affects between 60-90% of the population at some stage in their life.Read moreRead less
I will use non-invasive brain stimulation to study the operation of the corticospinal pathway in humans while they perform tasks requiring precise control of fingers and thumb. This pathway from brain to spinal cord is important for independent finger movements, and these experiments will provide insight into the cortical mechanisms by which independent finger movements are produced. I will also investigate relationships between patterns of corticospinal activation (which I have shown differ bet ....I will use non-invasive brain stimulation to study the operation of the corticospinal pathway in humans while they perform tasks requiring precise control of fingers and thumb. This pathway from brain to spinal cord is important for independent finger movements, and these experiments will provide insight into the cortical mechanisms by which independent finger movements are produced. I will also investigate relationships between patterns of corticospinal activation (which I have shown differ between subjects and hands) and digital dexterity. While it seems reasonable to assume that digital dexterity is dependent on the operation of the corticospinal system, the relationship is obscure, even at a gross level. Digital dexterity can vary considerably between subjects, and even between hands in the same subject. Are people more skilled with their hands because they are better able to engage the corticospinal system in control of the digits? The present study will address this fundamental question. The brain stimulation techniques that I will use are the only techniques presently available which can answer these questions in humans. This information will assist us to understand how normal subjects perform skilled tasks with their hands, as well as helping us to understand how damage to the nervous system (e.g., stroke, multiple sclerosis, Parkinson's disease) produces deficits in movement control. The information gained may suggest training regimes for skill acquisition in normal subjects, and to promote recovery of function in patients with neurological damage or disease.Read moreRead less
Reflex Control Of Human Jaw Muscles By Periodontal Mechanoreceptors
Funder
National Health and Medical Research Council
Funding Amount
$405,173.00
Summary
An understanding of the functional connection between the jaw muscles and various receptor organs in and around the mouth is necessary to elucidate the process of chewing and its underlying rules. Unless the details of this functional connection in health and disease are thoroughly understood, the diagnosis and treatment of chewing related disorders will remain at the present state. For example: a We still do not know why chewing in edentulous subjects is less efficient and why the bite forces i ....An understanding of the functional connection between the jaw muscles and various receptor organs in and around the mouth is necessary to elucidate the process of chewing and its underlying rules. Unless the details of this functional connection in health and disease are thoroughly understood, the diagnosis and treatment of chewing related disorders will remain at the present state. For example: a We still do not know why chewing in edentulous subjects is less efficient and why the bite forces in these individuals immediately fall to about 20 % of the teethed value. Do jaw muscles in these subjects get weak because they get less support from the receptor organs around the teeth? a We still do not understand the cause-causes of the temporomandibular dysfunction (a painful disease involving jaw muscles) which forms 18.7 % of total dental patients consulted per week in South Australia. This South Australian study indicated that the current treatments (such as pain killers, night plates, massage) Ocures? only about the half of all patients. We cannot increase the success of the treatment if we do not fully understand the control mechanisms of chewing? It is expected that the results of this study will establish the functional connection between one of the most important receptor organs in the mouth (periodontal mechanoreceptors) to the jaw muscle motoneurons in subjects with healthy teeth and gums and will illustrate the importance of keeping the periodontium healthy for developing strong and smooth masticatory forces. This knowledge can also allow us to treat jaw related disorders by approaches that bring back normal operation of the system. For example, this knowledge may help us design active dentures that replace the missing support.Read moreRead less