* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Running head: THIS IS A SHORT (50
Survey
Document related concepts
Neuropsychopharmacology wikipedia , lookup
Development of the nervous system wikipedia , lookup
Environmental enrichment wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Neural engineering wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Neuroanatomy wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Central pattern generator wikipedia , lookup
Transcranial direct-current stimulation wikipedia , lookup
Proprioception wikipedia , lookup
Embodied language processing wikipedia , lookup
Microneurography wikipedia , lookup
Transcript
Lumbosacral manipulation & MEP 1 “The effect of Lumbosacral Manipulation on Gastrocnemius Motor Evoked Potential’s using Transcranial Magnetic Stimulation.” Students: Claire Richardson (B.Sci.) Shaun Richardson (B.Sci.) Kymberley Sayers (B.Sci), Melanie Taylor (B.Sci), Nicholas Wittenberg (B.Sci) Supervisors Dr. Gary Fryer Dr. Alan Pearce Osteopathic Medicine Unit School of Biomedical & Health Sciences Victoria University June 2010 Submitted for consideration as a research proposal for the Master of Health Science (Osteopathy) minor thesis Lumbosacral manipulation & MEP TABLE OF CONTENTS Glossary of terms…………………………………………………………………………….....4 1. Introduction……………………………………………………..…………………………...9 2. Literature Review………………………………………………..………………………….11 2.1 Lumbosacral manipulation in osteopathy…………………………........................11 2.2 Theories for therapeutic mechanisms associated with HVLA……………………13 A) Studies involving spinal manipulation and H-Reflex B) Studies involving spinal manipulation reflex muscular activity 2.3 Effects of HVLA………………………………………………………………….15 A) Range of motion B) Hypoalgesia C) Other neurophysiological effects 2.4 Motor evoked potentials……………………………………………………………21 2.5 Summary…………………………………………………………………………...23 3. Aim………………………………………………………………..…………………………26 4. Methodology………………….………………………….…………………………………..27 4.1 Participants…………………………………………………………………………27 A) Inclusion Criteria B) Exclusion Criteria 4.2 Experimental Design………………………………………………………………28 4.3 Procedure………………………………………………………………………….28 A) Measurement of MEP 2 Lumbosacral manipulation & MEP B) Intervention i. HVLA ii. Control Group 4.4 Statistical Analysis…………………………………………………………………29 5. Ethics……………………………………………………..……………………………….....30 6. Timeline……………………………………….……………………………………………..32 7. Budget…………….……………………………………….…………………………….......33 8. References…………………………………………………………………………………...34 3 Lumbosacral manipulation & MEP GLOSSARY OF TERMS Afferent Fibre – a nerve fibre that carries impulses toward the central nervous system Alpha Motoneuron – lower motor neurons of the brainstem and spinal cord which innervate extrafusal muscle fibres of skeletal muscle and are directly responsible for initiating their contraction Analgesia – Absence of pain in response to stimulation which would normally be painful Axon hillocks – the anatomical part of a neuron that connects the cell body (the soma) to the axon Cavitation – the term used to describe the formation of gaseous bubbles or cavities within the synovial fluid of the joint, as a result of distraction that causes local reduction in pressure Central – see Central Nervous System Central Nervous System – pertaining to the brain, cranial nerves and spinal cord. It does not include peripheral nerves Corticospinal – pertaining to the corticospinal tracts, which are the descending motor pathways conveying motor signals from the brain to the periphery 4 Lumbosacral manipulation & MEP 5 Cerebral Cortex – The extensive outer layer of gray matter of the cerebral hemispheres, largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, reasoning, and memory Dendrite – a branching process off a cell which receives signals and information from other cells Dorsal horn – the posterior horn of grey matter of the spinal cord. It receives several types of sensory information from the body, including light touch, proprioception, and vibration Efferent Fibre– a nerve fibre that carries impulses away from the central nervous system Epicondylitis – inflammation of the muscles and soft tissues around an epicondyle Facilitated Segment – facilitated segment is a concept that is proposed to explain the behaviour of somatic dysfunction: an injured somatic or visceral structure produces a barrage of discordant afferent impulses into the dorsal horn of the spinal cord which "sensitises" that segment. It is proposed the spinal interneuron thresholds are lowered, allowing an exaggerated response to pathways synapsing at that level: increased pain perception, sympathetic outflow, and segmentally supplied muscle tone Lumbosacral manipulation & MEP Facilitation – the effect of a nerve impulse acting across a synapse, resulting in increase postsynaptic action potential of subsequent impulses in that nerve fibre or other convergent fibres H/Mmax ratio – The ratio of the. Maximum H-reflex to Maximum. M-wave High Velocity Low Amplitude (HVLA) – a forceful, high-velocity thrust that stretches a joint beyond its passive range of movement in order to increase its mobility. Manipulation is usually accompanied by an audible pop or click H-Reflex – the H-reflex is the electrical equivalent of the monosynaptic stretch reflex. It is elicited by selectively stimulating the Ia fibers of the posterior tibial or median nerve Hyperalgesia – increased sensitivity to painful stimuli Hypoalgesia – decreased sensitivity to painful stimuli Hypomobility – a decrease in the normal range of joint movement Meniscoid – fold of tissue within a joint structure Motoneuron Pool – all of the alpha motor neurons required to supply an entire muscle 6 Lumbosacral manipulation & MEP Motor Evoked Potential (MEP) – used to describe potentials obtained from muscles by the simulation of motor structures in the central nervous system Muscle spindle – sensory receptors situated within the muscle belly, which primarily detect changes in muscle length Neuron – a nerve cell. The basic unit of the nervous system, specialized for the transmission of electrical impulses Nociception – neurological detection of a painful stimulus Periaqueductal Gray (PAG) – the gray matter located around the cerebral aqueduct of the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour Radiolucent – in medicine; a part of a body or object which permits the passage of x-rays without leaving a shadow on the film. Soft tissues are radiolucent, bones are not Reflex – the body's automatic response to a trigger that involves nerve impulses being received from our sense organs, passed into the spinal cord, and a responding message being sent out straight away, without needing any input from the brain 7 Lumbosacral manipulation & MEP 8 Somatic Dysfunction – impaired or altered function of related components of the somatic (body framework) system: skeletal, arthroidal, and myofascial structures, and related vascular, lymphatic, and neural elements Spinal Manipulation – see HVLA Spinal Segment – a division of the spinal cord containing a bilateral pair of nerve roots Synapse – the functional membrane-to-membrane contact of the nerve cell with another nerve cell Transcranial Magnetic Stimulation (TMS) –is a non-invasive method of exiting neurons in the cerebral cortex. Weak electric currents are induced in the tissue by rapidly changing magnetic fields Lumbosacral manipulation & MEP 9 1. INTRODUCTION High velocity, low amplitude techniques (HVLA) are widely used by manual therapists and musculoskeletal practitioners, including Osteopaths, Physicians, Physiotherapists and Chiropractors. There have been many theories as to what effects this treatment technique has on various systems of the body, both locally and distally, as well as the effect on neurological processing and central nervous system excitability. (Dishman et al, 2002) This study aims to investigate the effect that HVLA techniques applied to the spine have on motor cortex excitability as measured by motor evoked potentials. There have been studies providing evidence that HVLA techniques produce an analgesic effect by activation of the descending pain inhibitory pathways of the spinal cord, as well as activation of Gate-control mechanisms in the dorsal horn of the spinal cord. (Pickar et al 2002, Melzack, R. et al, 1965) However, conflicting evidence regarding the neurophysiologic effects of HVLA and therefore muscle activity exists. Two studies have shown an increase in motor neuronal activity following spinal HVLA techniques, (Dishman et al 2002, Dishman et al 2008).Conversely, another study by the same author reported a decrease in motor neuronal activity (Dishman et al 2000). Both sets of results have theories as to how they may provide a resultant decrease in related musculature hypertonicity. It has been theorised that an increase in central excitability could decrease hypertonicity of related musculature by normalising the pain modulatory mechanisms of the central nervous system. (Dishman et al 2008) If however, HVLA decreases motor neuron excitability, it has been theorised that less noxious stimuli would be able to reach the affected segment. (Dishman et al 2002) More definitive research would obviously lend weight to one of these theories. Lumbosacral manipulation & MEP 10 Our study will use Transcranial Magnetic Stimulation (TMS) to produce Motor Evoked Potentials (MEP’s) in the gastrocnemius musculature, which we shall measure pre and post intervention (HVLA technique applied to the Lumbosacral junction.) MEP’s are a non-invasive method of measuring motor cortex excitability. The study is based upon previous research by Dishman et al 2002. We hope to provide clear results regarding the effect on central motor excitability as influenced by HVLA technique applied to the lumbosacral junction. Lumbosacral manipulation & MEP 11 2. LITERATURE REVIEW 2.1 Lumbosacral manipulation in osteopathy: Spinal manipulation, or High Velocity Low Amplitude (HVLA) technique, is a technique applied by chiropractors, physiotherapists, osteopaths and physicians. The technique “involves placing the joint (in this case spinal) in a locked position and applying a short, sharp thrust as precisely as possible to a single joint level” (Greenman 2003) There are many theories for the physiological mechanisms underlying how this technique may be of benefit to the patient, but these mechanisms are still largely speculative. (Dishman et al 2008). Authors of osteopathic texts claim that HVLA techniques, applied to various parts of the body, can aid to reduce “TART” diagnostic findings within the affected tissues. The TART diagnosis within the Osteopathic profession refers to a collection of clinical findings within a dysfunctional tissue: tenderness, asymmetry, altered range of motion and tissue texture change. These diagnostic findings are claimed to confirm the presence of a somatic dysfunction, a term relating to the impaired or altered function of the musculoskeletal system. (Licciardone JC, et al 2005). Gibbons and Tehan, 2006, have stated that HVLA techniques can aid in the treatment of clinical findings such as; hypomobility, motion restriction, joint fixation, acute joint locking, motion loss with somatic dysfunction, meniscoid entrapment, and adhesions. Studies have indicated that HVLA techniques may, by way of stretching joint capsular structures, ligamentous structures, discal structures and muscular structures, activate the diffuse descending pain inhibitory pathways, supporting the theory that this technique provides an analgesic effect. (Vicenzino B, ,et al 1998). Lumbosacral manipulation & MEP 12 Furthermore, HVLA techniques applied to the spine have been proven effective in the reduction of low back pain, (Koes, B., et al 1996) as well as being proven effective in decreasing the disability and pain levels of patients with chronic neck pain (Murphy, B et al 2009) There has also been research indicating that HVLA treatment of athletes with neck pain was potentially more effective than high dose analgesic medication. (Gunnar et al 2008). The literature has reported that HVLA techniques appear to affect not just the joints being manipulated, but the associated musculature, disc, ligamentous and tendinous structures. There have been studies undertaken which indicate the usefulness of HVLA techniques in reducing pain within the paraspinal musculature, as well as creating long lasting effects after doing so. (Shambaugh P. 1987, Zhu Y, Haldeman et 1993.) Also, HVLA has been hypothesised to reduce pain of a discal origin within the spine by transiently reducing the pressure-peak observed in the posterior annulus (J.Y. Maigne et al 2003). Authors have stated that the cavitation that occurs between the joint surfaces during administration of a HVLA technique increases the plasticity of the joint capsule, hence increasing joint motion. (J.Y. Maigne, et al 2003) This capsular stretching has also been attributed to the inhibition of paraspinal muscle spasm. (Bogduk N,et al 1985) There have been studies that have proven that continuous EMG activities of the adjacent multifidus muscle to the Lumbosacral junction have been diminished after having a HVLA technique applied to the Lumbo Sacral Junction. (Thabe H ;1986). In addition to the specific findings regarding pain and function of patients after administration of a HVLA technique, there is evidence that supports such reduction in pain and increase in Lumbosacral manipulation & MEP 13 function that patients were more likely to have improved psychological functioning and a reduction in absenteeism from work. (Gunnar et al, 2008) We know that the Lumbo-Sacral junction is where the nerve roots of the innervation to the gastrocnemius muscle originate, (Phillips L.H. 1991) and as such wish to investigate the effect that HVLA techniques have upon the MEP's measured within the muscle, facilitated at the segment. 2.2 Theories for therapeutic mechanisms associated with HVLA The monosynaptic Hoffmann Reflex (H-Reflex) is the electrically induced version of the spinal stretch reflex, also known as the myotatic reflex. Eliciting the H-reflex involves electrical stimulation of the Ia afferent fibres proximal to their origin in the muscle spindle, thereby bypassing the muscle spindle. The stimulus travels in the Ia afferent fibres through the motoneuron pool of the corresponding muscle to the efferent (motor) fibres. The H-reflex is an estimate of alpha motoneuron (aMN) excitability when presynaptic inhibition and intrinsic excitability of the aMNs remain constant. (Palmieri et al., 2004) A) Studies involving spinal manipulation and H-Reflex: An early study involving H-reflex changes following spinal manipulation was conducted by Dishman et al., 2000. The study investigated the effect of lumbosacral manipulation versus spinal mobilization on tibial nerve H-reflexes recorded from the gastrocnemius muscle. The authors found that there was a significant decrease in the H/Mmax ratio measured 10 seconds Lumbosacral manipulation & MEP 14 after the spinal manipulation, which returned to baseline 30 seconds after the manipulation. Dishman et al. published a paper in 2002 contrasting the different effects of cervical versus lumbar spinal manipulation on the tibial nerve H-reflex recorded from the gastrocnemius muscle. The authors found that the H/Mmax ratio was significantly depressed with respect to baseline values for 60 seconds after the L5/S1 spinal manipulative procedure; however, the there was no concomitant change after C5-6 spinal manipulation. This led them to conclude that SMT inhibition of motoneuron activity involves a local segmental response rather than an integrative central response. Another study on the effects of H-reflex changes following sacroiliac joint manipulation was conducted by Murphy et al., 1995. The study investigated H-reflex responses from the soleus muscle after ipsilateral sacroiliac joint manipulation. The authors found that H-reflex amplitude was significantly decreased in the ipsilateral leg (p < 0.001) post manipulation while there was no significant alteration following the sham intervention or in the contralateral leg. B) Studies involving spinal manipulation reflex muscular activity: A number of papers have demonstrated the existence of reflex muscular activity following spinal manipulation. An EMG study on reflex muscular responses to HVLA was published by (Herzog et al., 1999). The study demonstrated a consistent and systematic reflex response both in muscles local to the manipulated joint and also in more distant muscles. The estimated latency of the reflex response was 50ms. (Symons et al., 2000) conducted a similar experiment using an activator device to deliver the manipulation. More localized, mainly ipsilateral reflexes with a latency of 4ms were noted. An additional study on the effect of activator induced thrusts was Lumbosacral manipulation & MEP 15 conducted on low back pain patients by (Colloca and Keller, 2001). This paper also demonstrated reflex responses with a latency of 4ms and found that patients with the greatest degree of pain and disability had the largest amplitude of reflex response 2.3 Effects of HVLA: Spinal manipulation has been used for more than 2000 years (Evans, 2002). Manipulative treatments have been recorded since Hippocrates in 400BC who wrote of their value in treating spinal mal-alignment (Potter, McCarthy, & Oldham, 2005). Today spinal manipulation is used by chiropractors, osteopaths, physiotherapists and some medical practitioners (Potter, et al., 2005). Numerous theories have been proposed to explain the effects of spinal manipulation. A common trend in these theories is that changes in the normal anatomical, physiological or biomechanical dynamics of contiguous vertebrae can adversely affect function of the nervous system. Spinal manipulation is thought to correct these changes (Picker, 2002). Overall the goal off spinal manipulation is too restore maximal, pain-free movement of the musculoskeletal system (Greenman, 1989) A) Range of Motion: Current research indicates that the range of motion of a joint increases after cavitation (Brodeur, 1995). In a study by Fritz, Whitman & Childs (2005) subjects with LBP who were judged to have lumbar spine hypomobility experienced greater benefit from the manipulation The greater mobility caused by manipulation can easily be explained by the increase in joint volume as a result of the gas bubble formation within the joint (Brodeur, 1995). The change in Lumbosacral manipulation & MEP 16 joint volume associated with the crack must allow a greater range of motion; after cavitation the joint capsule is not restricted by the volume of synovial fluid (Brodeur, 1995). The synovial fluid offers little resistance to the force, and a temporary increase range of motion is given to the joint (Evans, 2002). Sandoz (Sandoz, 1976)performed a study looking at metacarpophalageal joint distractions, and showed that distractions causing cavitation increased the radiolucent joint space. This was associated with a 5-10deg increase in the range of movement of the joint once cavitaiton had occurred. Meal & Scott (1986) and Conway et al (1993) have since performed studies looking at the sounds from the metacarpophalageal joint distractions and compared them with the sounds from facet joint cavitations in the spine. By comparing the sound waves they proposed, giving the nature of the sound waves were similar in the finger distraction to the facet joint manipulations, that a similar event must occur in both joints. They inferred from this that facet joints also show an increase in joint space following HVLA (Conway, Herzog, Zhang, Hasler, & Ladly, 1993; Meal & Scott, 1986) Cramer et al (2000) were able to provide further evidence for an increase in joint space. By measuring the increase in joint space following HVLA using MRI, they were able to demonstrate that the average change in joint separation for the manipulation group was +1.2mm compared to the average change in the control group of 0.3mm (Cramer, Tuck, Krudsen, & Fonda, 2000).These results are consistent with the hypothesis that spinal manipulation cause a biomechanical separation of the facet joints within hypomobile joints (Potter, et al., 2005) B) Hypoalgesia: Lumbosacral manipulation & MEP 17 Biomechanical changes caused by the manipulation are thought to have physiological consequences by means of their effects on the inflow of sensory information to the central nervous system. By releasing trapped meniscoids, discal material or segmental adhesions, the mechanical input may ultimately reduce noiciceptive input from receptive nerve endings in innervated paraspinal tissues. (Picker, 2002) Similarly Bogduk & Jull (1985) identified that fibro-adipose meniscoids are structures capable of creating a painful situation and therefore reviewed the possible role of fibro-adipose meniscoids causing pain. They proposed that a HVLA manipulation, involving gapping of the zygoapophyseal joint, reduces the impaction and opens the joint, encouraging the mensicoid to return to its normal anatomical position in the joint cavity. This ceases the distension of the joint capsule, thus reducing pain. (Bogduk & Jull, 1985) Physiologically, spinal manipulation therapy is purported to relieve pain through modulation of noiciceptive input through a barrage of afferent input to the central nervous system resulting in pain reduction and improved perceived function for up to 6 months (Learman et al., 2009). A study by Cecchi et al compared short- and long-term effects of three treatments for chronic, non-specific low back pain: spinal manipulation, individual physiotherapy treatments and back school (group back exercises with patient information/education and ergonomic training aimed at optimizing functional recovery. Results showed that pain scores at one year after intervention remained significantly lower than baseline scores for the back school and spinal manipulation. In chronic non-specific low back pain, spinal manipulation provided more functional improvement and pain relief, and reduced drug intake than individual physiotherapy programs and back school. (Cecchi, Molino-Lova, Chiti, & Pasquini, 2010) Lumbosacral manipulation & MEP 18 The current study is the first to report that SMT specifically inhibits temporal summation in individuals with LBP. Additionally, this inhibition appears local, as it was observed only in the lower extremity and psychological factors were not strongly associated with resultant inhibition of temporal summation. These findings suggest that inhibition of temporal summation is a potential mechanism for pain relief following SMT for individuals with LBP (Bialosky, Bishop, Robinson, & Zeppieri, 2009). It has also been demonstrated that zygapophyseal HVLA manipulation causes not only a reduction of paraspinal hyperalgesia in subjects with symptoms, but also an increase in paraspinal pain thresholds to a noxious stimulation in subjects with no symptoms Therefore it seems more appropriate to describe one of the neurophysiologic effects of zygapophyseal HVLA manipulation as creating hypoalgesia (Evans, 2002). As a result, a link therefore could be postulated between the long term pain relief from spinal manipulation and the increase in paraspinal pain threshold creating hypoalgesia. C) Other neurophysiological effects HVLA has been reported to cause numerous neurophysiologic effects at both the spinal cord and cortical levels. One of the proposed central effects is called facilitation or sensitization. This refers to the increased excitability or responsiveness of dorsal horn neurons to an afferent input. An alteration between vertebral segments may produce a biomechanical overload leading to the alteration of signalling from mechanically or chemically sensitive neurons in paraspinal tissues. These changes in afferent input are believed to alter neural integration either by directly affecting Lumbosacral manipulation & MEP 19 reflex activity and/or by affecting central neural integration within motor and neuronal pools [Pickar]. Denslow et al were one of the first groups to investigate this phenomenon, and their findings suggested that motoneurons could be held in a facilitated state because of sensory bombardment from segmentally related dysfunctional musculature. It has been shown that central facilitation increases the receptive field of central neurons and allows innocuous mechanical stimuli access to central pain pathways [Woolf]. Essentially this means that sub-threshold stimuli may become painful as a result of increased central sensitization. As discussed in the other sections of this proposal, spinal manipulation is believed to be able to overcome this facilitation by making biomechanical changes to the joint [Pickar], and/or by creating a barrage of afferent inputs into the spinal cord from muscle spindle and small-diameter afferents, ultimately silencing motoneurons. [Korr]. Melzack and Wall’s [#] Gate Control Theory describes the dorsal horn of the spinal cord as having a gate-like mechanism which not only relays sensory messages but also modulates them. Noiciceptive afferents from small diameter Aγ and C fibres tend to open this gate, and nonnoiciceptive large diameter Aβ fibres (from joint capsule mechanoreceptor, secondary muscle spindle afferents, and coetaneous mechanoreceptors) tend to close the gate to the central transmission of pain. This modulation takes place in the lamina of the dorsal horn. Simplistically, Aβ afferents enter lamina II and V, stimulating an inhibitory interneuron in lamina II (which connects to lamina V); Aγ and C fibres enter lamina V. Consequently, the central transmission of pain is a balance between the influences of these opposing stimuli. [Potter, Kandel] HVLAT may Lumbosacral manipulation & MEP 20 modulate the pain gate mechanism in the dorsal horn by producing a barrage of non-noiciceptive input from large diameter myelinated Aβ afferents from muscle spindles and facet joint mechanoreceptors to inhibit noiciceptive C fibres [Besson & Chaouch]. Dishman et al recently published an article which questioned some of their own previous research findings. In this subsequent paper, the authors stated that the H-reflex technique is susceptible to the effects of pre-synaptic inhibition of the afferent arm of the reflex pathway. So, by using transcranial magnetic stimulation to directly measure the effect of corticospinal inputs on the alpha motor neuron pool, they were able to perform an experiment which showed a transient (20–60 s) increase in motor alpha neuron excitability post manipulation. This paper lends further support to the theory that spinal manipulation produces a brief activation of the motor alpha neuron leading to brief muscle contraction. Descending pathways also influence pain perception. Stimulation of the Periaqueductal gray produces analgesia via the descending PAG pathways[Morgan MM]. Stimulation of the dorsal PAG (dPAG) in the brain produces selective analgesia to mechano-nociception, whereas temperature nociception is modulated via the ventral PAG (vPAG). It is also known that sympatho-excitation results from stimulation of the dPAG, in contrast to sympatho-inhibition which occurs as a result of stimulating vPAG[Morgan MM]. Activation of the descending dPAG is a possible mechanism for the antinociceptive effects of spinal manipulation. Sterling et al measured changes in pain and sympathetic outflow by comparing a C5/6 HVLA to a sham intervention (manual contact but with no movement). The authors demonstrated HVLA produced mechanical hypoalgesia, measured by an increase in pain pressure threshold, and increased sympathetic outflow, measured by decreased blood flow, decreased skin temperature, and Lumbosacral manipulation & MEP 21 increased skin conductance. However, there was no alteration to thermal pain thresholds. Given such selective mechanical anti-nociception and sympathoexcitation, this supports the theory that the mechanism of effect is due to activation of the dPAG descending pain mechanism. Vincenzino et al conducted a similar experiment on subjects with epicondylitis and showed again that cervical spine HVLA lead to selective analgesia to mechanical stimulus and sympatho-excitation, adding further weight to the argument that spinal manipulation may influence the perception of pain by activation of the descending dPAG. This does not prove conclusively that there is definitely direct activation of dPAG, only that the effects of HVLA are give similar findings to what you would expect with stimulation of the dPAG, hence there is a plausible link between the two, and it is inferred that HVLA may lead to stimulation of the dPAG. 2.4 Motor Evoked Potentials: The term ‘motor evoked potentials’ (MEPs) is used to describe potentials obtained from muscles by the stimulation of motor structures in the central nervous system (Chiappa, 1997). These potentials can be caused by stimulation along any of the motor pathways, but the cerebral cortex and the cervical spinal cord are the most commonly stimulated areas. Direct electrical activation of the motor pathways using the cerebral cortex has been used in clinical experiments for many years. A study in 1980 by P. A. Merton and H. B. Morton used transcranial electrical stimulation (TES) to cause non-invasive stimulation of MEPs. This method was further refined in 1985 by Barker et al., with the introduction of transcranial magnetic stimulation (TMS). Although peripheral muscles and nerves were first investigated with TMS, studies nowadays often focus on stimulation of the cortex. Lumbosacral manipulation & MEP 22 TMS has been found to be a very effective method to measure MEPs. As stated by Dishman (2008) “…TMS allows for the recording of MEPs from virtually any muscle.” When using TMS to measure MEPs, there is electrical activation over the region being stimulated via an anode and a cathode at a distal site measuring the MEP response. When stimulating an area of cortex, different neural components of the precentral gyrus may become stimulated – the dendrites, the cell bodies or the axon hillocks. MEP generation depends on the activation of the axon hillocks. With magnetic stimulation,” an intense current in and external coil induces local depolarising electrical currents that flow through the neuron and axon hillock” (Daube, 2002). It is this depolarisation that initiates descending action potentials in the corticospinal pathways and cause an MEP to be produced. The size of the MEP obtained from muscle stimulation is a measure of the size or effectiveness of the corticospinal output caused by the stimulus, and also the excitability of the neurons in that pathway (MacDonell et al., 1991). An MEP reading consists of an initial D (direct) wave is followed by several I (indirect) waves, which come at periodic intervals (usually about 1 millisecond) or ‘latency period’, being the time between the MEP waves and the stimulation. Dwaves represent the “direct excitation of corticospinal tract neurons” (Jasvinder, 2009), while Iwaves reflect “indirect depolarization of the same axons via corticocortical connections” (Jasvinder, 2009). Larger MEPs may be produced with increased excitability of cortical and spinal neurons due to not only direct stimulation of these structures, but also stimulation of surrounding neurons (Capaday and Stein 1987; Butler et al, 1993). Motor neurons that contribute directly to the muscle activation may be unresponsive at the time of stimulation, but as found by Darling, et al.,(2006) “…for low level contractions one would only expect only a small percentage would be in this state because force is maintained by asynchronous activation of a Lumbosacral manipulation & MEP 23 number of motor units.” MEPs in muscles may be elicited by TMS with or without voluntary contraction of the muscle. However, as found by Rothwell et al.,(1991), Maertens de Noordhout et al., (1992), and Hauptman and Hummelsheim (1996), “voluntary preactivation is known to increase the magnitude of motor evoked potentials”. Although with increasing exercise levels the amplitude of MEPs decreases. This was found by Joaquinn, et al., (1993), where a “transient decrease in the amplitude of MEPs to TMS following a period of repetitive muscle activation to the point of subjective fatigue in healthy humans”. The findings from this study were supported by Giampietro, et al., (1995), in that decreases in MEP amplitude following repetitive exercises may indicate a level of central nervous system neurophysiological fatigue. The results from both of these studies also support the theory of this postexercise exhaustion to be due to a depletion of the acetylcholine that is immediately available. The major values of obtaining MEPs and carrying out MEP studies have been in measuring nervous system pathways inoperatively, and also clinically in conditions of the nervous system such as multiple sclerosis, where slowing of impulse conductions can be measured and monitored. In the case of this study the measuring of MEPs will help determine the effectiveness of a particular manual therapy technique, and what effects it does have at a neurophysiological level. 2.5 Summary: Spinal manipulation or high velocity, low amplitude (HVLA) techniques are widely used by manual therapists. This technique has been demonstrated to produce local and general analgesic effects, and may produce these effects through physiological mechanisms (stretching joint capsules, resetting neural pathways, etc.) as well as non-specific mechanisms, such as a Lumbosacral manipulation & MEP 24 psychological placebo effect. Osteopaths believe that the application of HVLA to dysfunctional areas of the body can reduce TART findings (tissue texture change, asymmetry, decreases in ranges of motion and tenderness), reduce pain levels and have effects more distal to the application site. Given that the lumbosacral level of the spinal cord provides innervations to the gastrocnemius muscle, manipulation of lumbosacral joints may help reduce signs of dysfunction in segmentally related tissues. Previous studies have examined the effects of HVLA at a neurophysiological level. One of the proposed theories of the mechanism of HVLA is facilitation or sensitisation, meaning that by the technique causes an increase in the excitability or responsiveness of the dorsal horn in the spinal cord, resulting in changes in reflex activity and/or central integration. Other studies have found that manipulation can cause mechanical hypoalgesia, resulting in increases in the pain pressure threshold and increased sympathetic outflow. These studies have looked at various muscular outputs including the H-reflex and muscle evoked potentials (MEPs) from HVLA techniques. The H-reflex is the electrically induced version of the spinal stretch reflex (monosynaptic), whilst MEPs are produced by stimulating higher order regions (the cerebral cortex) to produce depolarisation of descending motor pathways and an MEP to be elicited from a certain muscle. In 1985 a study by Barker et al., pioneered the use of transcranial magnetic stimulation (TMS), a non-invasive technique which used stimulation of the cortex to elicit action potentials through the axon hillocks of specific neurons in specific neural pathways. Since then TMS has been found to be a very effective means of stimulating MEPs, clinically aiding in measuring nervous system pathways inoperatively. Lumbosacral manipulation & MEP 25 In this study, TMS will be used to stimulate the descending motor pathways to the lower limb, namely to the gastrocnemuis muscle, and MEPs recorded. An MEP consists of 2 parts, an initial direct wave followed by several indirect waves. MEPs have been found to be elicited by TMS with or without voluntary contraction of that muscle; however voluntary preactivation has been found to increase the magnitude of the waves produced. The aim of this study is to determine whether high velocity, low amplitude (HVLA) techniques can alter the corticospinal excitability on the motorneurons innervating the gastrocnemius muscle using transcranial magnetic stimulation (TMS), as suggested by a previous study (ref Dishman). This study will build on the findings of previous studies and may clarify the neurological changes that occur following HVLA manipulation. Our study focuses on applying the technique to the Lumbo-Sacral junction to facillitate changes in the lower limbs, specifically the gastrocnemius muscle. Lumbosacral manipulation & MEP 26 3. AIMS The aim of this study is to determine whether high velocity, low amplitude (HVLA) techniques can alter the corticospinal excitability of the motorneurons innervating the gastrocnemius muscle using transcranial magnetic stimulation (TMS). Previous studies have investigated the effects of HVLA using TMS in the paraspinal muscles and the gastrocnemuis muscles, finding that HVLA has a transient increase in central motor excitability. This study aims to build on the results from these studies and to further investigate the effects of HVLA techniques at a neurophysiological level Lumbosacral manipulation & MEP 27 4. METHODS 4.1 Participants: Participants for this study will be drawn from the student population at Victoria University. Volunteers will be recruited via posters placed around the teaching clinics and university campuses at both the City Flinders and Footscray Park Campus. Volunteers will be invited to contact the principal researcher to indicate their interest to participate in the study and discuss what will be required of them. These volunteers will be sent Information to Participants sheets and will sign Consent forms if willing to participate. Based on an estimate of a large pre-post effect size (d = 0.97) in the only similar study (Dishman 2002) and analysis with ANOVA, 21 healthy participants will provide the study with 80% power. A) Inclusion criteria Healthy participants of either gender without current low back pain, aged between 18 and 50 years old. B) Exclusion criteria Participants will be excluded from this study if they are currently suffering from lower back pain. A neurological screening examination will be performed by one of the researchers to exclude subjects with radiculopathy or peripheral neuropathy. Participants will also be excluded if they exhibit any history signs that are contraindicative to HVLA.. 4.2 Experimental design: Lumbosacral manipulation & MEP 28 The study will be a controlled cross-over design where participants will be undergo both the control and experimental intervention, tested one week apart. The order of the treatment intervention will be randomised. 4.3 Procedure: A) Measurement of MEP Participants will be seated and a snugly fitting cap, with premarked sites at 1 cm spacing, will be placed over the participant’s head and positioned with reference to the nasion-inion and interaural lines. Sites near the estimated motor centre of the gastrocnemius muscle (2 - 4 cm anterior to the interaural line) will be first explored to determine the site at which the largest motor-evoked potential (MEP) can be obtained. Transcranial magnetic stimulation (TMS) will be delivered using a Magstim 2002 stimulator (Whitland, UK) with a 5 cm diameter, figure-ofeight coil which will be held tangential to the skull in an antero-posterior orientation. The coordinates on the cap will be recorded and this site will be used for further measurements. After determining the optimal stimulation site and individual motor threshold (defined as the lowest stimulation to evoke an MEP above 50 μV in 50% of MEPs), 10 MEP's (spaced 4 - 5 s apart) will be recorded at 20% above motor threshold as baseline values. Participants will then relocate to a treatment table and an intervention will be randomly allocated and performed. Immediately after the intervention, MEP's will be measured at 20 s intervals within the first 120 s to determine the acute time course of post manipulation effects on central motor pathways. MEP's will also recorded at 5 and 10 minutes after manipulation. Participants will return for a second session one week later and will receive the same procedures with the alternative intervention. Lumbosacral manipulation & MEP 29 B) Interventions i. HVLA A right sided L5-S1 side-posture HVLA manipulation will be administered. The patient is placed in a side-lying position, with hips in approximately 20 degrees of flexion. The lower left leg is left straight, with the upper right leg slightly flexed. The upper body is rotated to the right until the level of L5-S1. The clinician then manually contacts the tissues overlying the zygapophyseal joint, reinforcing both the lower and upper body rotation. Ensuring that the participant is relaxed and once tissue tension was maximised, a HVLA force is applied. The thrust is applied in the direction of the apophysial joint plane, commonly in a direction of a line along the long axis of the patient's right femur (Gibbons & Tehan, 2008). ii. Control group: The operator will assist the participant into a side posture; however no truncal torque will be applied and no manual contact will be made with the spine. 4.4 Statistical Analysis: Data will be collated using Microsoft Excel and analysed using SPSS version 18. Analysis of within and between group changes in MEP from baseline, immediately after intervention and 5 minutes after intervention will be performed using a split plot ANOVA (SPANOVA). Cohen’s d effect sizes will also be calculated on the pre-post data. The alpha level will be set at 0.05 Lumbosacral manipulation & MEP 30 5. ETHICS Before the study is conducted, an ethics document will be submitted to the Victorian University Human Research Ethics Committee. All participants in our study will be voluntarily participating and are free to withdraw at any stage. Similarly all personal information gathered from the patient will remain confidential and will only be viewed by researchers conducting the study. Possible ethical issues that could arise from our study are: Adverse effects to HVLA such as local pain and discomfort, headache, tiredness or fatigue, radiating pain or discomfort, parasthesia, dizziness, nausea, stiffness, hot skin or fainting (Gibbons & Tehan, 2006) Distress associated with manual therapy such as being undressed in front of researchers and having their hands placed on them whilst they perform the HVLA Psychological impact of the TMS procedure Side-effects from TMS Method of recruitment- whether it is coercive, and whether the patients will benefit from being in the study Ways we can minimize potential risks are: Patients will be neurologically screened before participating in the study, to rule out possible contraindications to HVLA All patients will have a private area to disrobe and appropriate gowns will be given for participants to wear. Towels will also be used to drape the patient adequately Patients will be given a consent form to sign Patients will have the right to withdraw from the study at any time Lumbosacral manipulation & MEP A qualified and experienced practitioner will be performing the HVLA and a practitioner with a doctorate in TMS will be administering and using the equipment How adverse events will be managed if they occur: A qualified first aid practitioner will be present A qualified Osteopathic practitioner able to assess and manage adverse reactions to HVLA will be present 31 A qualified psychologist will be available for counselling after the study Lumbosacral manipulation & MEP 6. TIMELINE Proposal Mar-10 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Dec-10 Jan-11 Feb-11 Mar-11 Apr-11 May-11 Jun-11 Jul-11 Aug-11 Sept-11 Ethics Testing Data Analysis Write up 32 Lumbosacral manipulation & MEP 6. BUDGET No budget will be required for this project. 33 Lumbosacral manipulation & MEP 34 5. REFERENCES Abercromby, A., Amonette, W., Layne, C., McFarlin, B., Hinman, M., & ., W. P. (2007). Variation in neuromuscular responses during acute whole-body vibration exercise. Medical Science: Sports Exercersie, 39, 1642–1650. Besson, J., & Chaouch, A. (1987). Peripheral and spinal mechanisms of nociception. Physiology Review, 67(1), 67-186. Bialosky, J., Bishop, M., Robinson, M., & Zeppieri, G. (2009). Spinal Manipulative Therapy has an Immediate Effect on Thermal Pain Sensitivity in People with Low Back Pain: A Randomised Control Trial. Physical Therapy, 89(12). Bogduk, N., & Jull, G. (1985). The theoretical pathology of acute locked back: a basis for manipulative therapy. Manual Medicine, 1, 78-82. Brodeur, R. (1995). The Audible Release Associated with Joint Manipulation. Journal of Manipulative and Physiological Therapeutics, 18(3). Cecchi, F., Molino-Lova, R., Chiti, M., & Pasquini, G. (2010). Spinal manipulation compared with back school and with individual delivered physiotherapy for the treatment of chronic low back pain: a ramdomised control trial with one-year follow-up. Clinical Rehabilitation, 24, 26-36. Chiappa, K. H. (1997). Evoked Potentials in Clinical Medicine (3rd ed.). Philadelphia, USA.: Lippincott-Raven Publishers. Colloca, C., & Keller, T. (2001). Electromyographic reflex responses to mechanical force, manually assisted spinal manipulative therapy. Spine, 26, 1117-1124. Lumbosacral manipulation & MEP 35 Conway, P. J., Herzog, W., Zhang, Y. T., Hasler, E. M., & Ladly, K. (1993). Forces required to cause cavitation during spinal manipulation of the thoracic spine. Clinical Biomechanics, 8, 210-214. Cramer, G. D., Tuck, N. R., Krudsen, J. T., & Fonda, S. D. (2000). Effects of side-posture positioning and side posture adjusting on the lumbar zygapophysial joints as evaluated by magnetic resonance imaging. Journal of Manipulative and Physiological Therapeutics, 23, 380-394. Darling, W. G., Wolf, S. F., & Butler, A. J. (2006). Variability of motor potentials evoked by transcranial magnetic stimulation depends on muscle activation. Experimental Brain Research, 174, 376-385. Daube, J. R. (2002). Clinical Neurophysiology (2nd ed.). New York, USA: Oxford University Press, Inc. Denslow, J., Korr, I., & Krems, A. (1947). Quantitative studies of chronic facilitation in human motoneuron pools. American Journal of Physiology, 150, 229-238. Dishman, J., Ball, K., & Burke, J. (2002). Central motor excitability changes after spinal manipulation: a transcranial magnetic stimulation study. Journal of Manipulative and Physiological Therapeutics, 25, 1-10. Dishman, J., & Bulbulian, R. (2000). Transient suppression of alpha motoneuron excitability following lumbosacral spinal manipulation. Spine, 25, 2519-2525. Dishman, J., Cunningham, B., & Burke, J. (2002). Comparison of tibial nerve H-reflex excitability after cervical and lumbar spine manipulation. Journal of Manipulative and Physiological Therapeutics, 25, 318-325. Lumbosacral manipulation & MEP 36 Evans, D. (2002). Mechanisms and Effects of Spinal High-Velocity, Low-Amplitude Thrust Manipulation: Previous Theories. Journal of Manipulative and Physiological Therapeutics, 25(4). Fritz, J., Whitman, J., & Childs, J. (2005). Lumbar Spine Segmental Mobility Assessment: An Examination of Validity for Determaining Intervention Stretegies in Patients with Low Back Pain. American Arcademy of Physical Medicine and Rehabilitation, 86. Gibbons, P., & Tehan, P. (2006). Manipulation of the Spine, Thorax and Pelvis: An Osteopathic Perspective (2 ed.): Churchill Livingston Elsevier. Greenman, P. E. (1989). Principles of Manual Medicine: Baltimore: Williams and Wilkins. Herzog, W., Scheele, D., & Conway, P. (1999). Electromyographic responses of back and limb muscles associated with spinal manipulative therapy. Spine, 146-152. Hurwitz, E., Aker, P., A Adams, W Meeker, & Shekelle, P. (1996). Manipulation and mobilization of the cervical spine. Spine, 21, 1746–1760. J Y Maigne, Vautravers, P., Bogduk, N., & Jull, G. (1985). The theoretical pathology of acute locked back: a basis for manipulative therapy. Manual Medicine, 1, 78-82. Jasvinder, C. (2009). Motor Evoked Potentials. Retrieved 23rd May, 2010, from http://emedicine.medscape.com/article/1139085-overview Joaquinn, P., Brasil-Neto, Alvaro Pascual-Leone, Josep Valls-Solé, Angel Cammarota, Leonardo G. Cohen, et al. (1993). Postexercise depression of motor evoked potentials: a measure of central nervous system fatigue. Experimental Brain Research, 93, 181-184. Kandel, E., Schwartz, J., & Jessell, T. (2000). Principles of Neural Science (4th ed.). London: McGraw-Hill. Lumbosacral manipulation & MEP 37 Koes, B., Assendelft, W., Heijden, G. V. D., & Bouter, L. (1996). Spinal manipulation for low back pain.An updated systematic review of randomized clinical trials. Spine, 21, 28602873. Korr, I. M. (1975). Proprioceptors and somatic dysfunction. Journal of American Osteopathic Association, 74, 638–650. Learman, K., Myers, J., Lephart, S., Sell, T., Kerns, J., & Cook, C. (2009). The Effects of Spinal Manipulation on Trunk Proprioception in Subjects with Chronic Low Back Pain During Symptom Remission. Journal of Manipulative and Physiological Therapeutics, 32, 118126. Macdonell, R., Shapiro, B., & Chiappa, K. (1991). Hemispheric threshold differences for motor evoked potentials produced by magnetic coil stimulation. Neurology, 41, 1441-1444. Meal, G. M., & Scott, R. A. (1986). Analysis of the joint crack by simultaneous recordings of sound and tension. Journal of Manipulative and Physiological Therapeutics, 9, 189-195. Melzack, R., & Wall, P. (1965). Pain mechanisms: a new theory. Science, 150, 971-979. Morgan, M. (1991). Differences in antinociception evoked from dorsal and ventral regions of the caudal periaqueductal gray matter. New York: Plenum. Murphy, B., Dawson, N., & Slack, J. (1995). Sacroiliac joint manipulation decreases the Hreflex. Clinical Neurophysioloogy, 35, 87-94. Palmieri, R., Ingersoll, C., & Hoffman, M. (2004). The Hoffmann reflex: methodologic considerations and applications for use in sports medicine and athletic training research. Journal of Athletic Training, 39(3), 268-277. Picker, J. (2002). Neurophysiological Effects of Spinal Manipulation. The Spine Journal 2, 357371. Lumbosacral manipulation & MEP 38 Potter, L., McCarthy, C., & Oldham, J. (2005). Physiological Effects of Spinal Manipulation: A Review of Proposed Theories. Physical Therapy Review, 10, 163-170. Sandoz, R. (1976). Some physical mechanisms and effects of spinal adjustment. Ann Swiss Chiropractic Association, 6, 91-141. Shambaugh, P. (1987). Changes in electrical activity in muscles resulting from chiropractic adjustment: a pilot study. Journal of Manipulative and Physiological Therapeutics, 10, 300-303. Sterling, M., Jull, G., & Wright, A. (2001). Cervical mobilisation: concurrent effects on pain, sympathetic nervous system activity and motor activity. Manual Therapy, 6, 72-81. Symons, B., Herzog, W., Leonard, T., & Nguyen, H. (2000). Reflex responses associated with activator treatment. Journal of Manipulative and Physiological Therapeutics, 23, 155159. Vicenzino, B., Collins, D., Benson, H., & Wright, A. (1998). An investigation of the interrelationship between manipulative therapy-induced hypoalgesia and sympathoexcitation. Journal of Manipulative and Physiological Therapeutics, 21, 448453. Vicenzino, B., Collins, D., & Wright, A. (1996). The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia. Pain, 68, 69-74. Vincenzino, B., Collins, D., & Wright, A. (1998). An investigation of the interrelationship between manipulative therapy-induced hypoalgesia and sympathoexcitation. Journal of Manipulative and Physiological Therapeutics, 21, 448-453. Lumbosacral manipulation & MEP Woolf, C. (1994). The dorsal horn: state-dependent sensory processing and the generation of pain (3rd ed.). Edinburgh: Churchill Livingstone. Zanette Giampietro, Bonato Claudio, Polo Alberto, Tinazzi Michele, Manganotti Paolo, & Antonio, F. (1995). Long-lasting depression of motor-evoked potentials to transcranial magnetic stimulation following exercise. Experimental Brain Research, 107, 80-86. Zhu, Y., Haldeman, S., Starr, A., Seffinger, M., & Su, S. H. (1993). Paraspinal muscle evoked cerebral potentials in patients with unilateral low back pain. Spine, 18, 1096-1102. 39