ESAT 3640 Therapeutic Modalities PAIN ESAT 3640 Therapeutic Modalities

What is Pain? International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms such as damage” http://www.iasp-pain.org/defsopen.html

Pain Composed of a variety of human discomforts Not a single entity Perception of pain can be subjectively modified by past experiences and expectations We try to change perception of pain

What is the Purpose of Pain? Warning system Something is wrong, provoking withdrawal response Can persist beyond its usefulness

Types of Pain Acute Chronic Referred Radiating

Tissue Sensitivity Order of sensitivity: 1 – Periosteum and joint capsule most sensitive 2 – Subchondral bone, tendons, and ligaments 3 – Muscle and cortical bone 4 – Synovium and articular cartilage

Sensory Receptors Activation of sense organs with therapeutic agents will decrease perception of pain 4 groups Mechanoreceptors Nociceptors Proprioceptors Thermoreceptors

Meissner’s Corpuscles Located near the surface at the dermal-epidermal junction Sensitive to light pressure Mechanoreceptor Produces impulse when stimulus is increasing or decreasing No impulse with sustained stimulus

Pacinian Corpuscles Deeper in the subcutaneous tissue Respond to deep pressure Mechanoreceptor Produces impulse when stimulus is increasing or decreasing No impulse with sustained stimulus

Merkel’s Corpuscles Located at the dermal–epidermal junction Touch receptors Sensitive to vertical pressure, not stretching Mechanoreceptor

Ruffini Corpuscles In skin sensitive to touch, tension, and heat In joint capsule and ligaments sensitive to change in position Mechanoreceptors Proprioceptors Thermoreceptors

Krause’s End Bulbs Located in skin React to decrease in temperature and touch Thermoreceptors Mechanoreceptors

Nociceptors Free nerve endings Sensitive to extreme mechanical, thermal, or chemical energy Respond to noxious stimuli PAIN Pretty much throughout the body

Muscle Spindles Bundle of specialized muscle fibers located in muscle Respond to tension and length when muscle is stretched or contracted Causes reflexive contraction of muscle Tendon tap Proprioceptors

Golgi Tendon Organs Musculotendinous junction Respond to length and tension changes in muscle Cause relaxation of muscle Proprioceptors

Accommodation Adaptation by the sensory receptors to various stimuli over an extended period of time Phasic vs. Tonic receptors Use of physical agents for extended period of time, may result in accommodation

Neural Transmission Afferent Efferent Nerve fibers that transmit impulses from the sensory receptors to the CNS Efferent Nerve fibers that transmit impulses from the CNS to the periphery Motor neurons

Simple Reflex Arc

Afferent System 1st order neurons 4 types of fibers Transmit impulses from sensory receptors to the dorsal horn of the spinal cord 4 types of fibers Alpha () Beta () Delta () C

Afferent System Continued 2nd order neurons Carry sensory information from dorsal horn to the brain Wide dynamic range or nociceptive specific 3rd order neurons Carry information to various brain centers for integration, interpretation, and action response

Synaptic Transmission Neurotransmitter – Passes information between neurons Neuroactive peptides can facilitate or inhibit synaptic activity Enkephalin Serotonin Norepinephrine -endorphine Dynorphin

Nociception Nociceptive neurons transmits pain signals Cell body located in the dorsal root ganglion Delta fibers = 25%, C fibers = 50% Once stimulated – substance P is released Size and conduction velocities different

Fast Pain Delta neurons Brief, well-localized, & well-matched to stimulus Originates from receptors in the skin

Slow pain C neurons Aching, throbbing, or burning Poorly localized Less specificity to stimulus Originate from both superficial and deep tissues

Afferent Pathways

Gate Control Theory Pain modulation due to sensory stimulation and resultant increase in the impulses in the  afferent fibers Stimulation of the substantia gelatinosa (SG) Stimulation of the SG by  fibers inhibit synaptic transmission in the large and small fibers

Ascending Gate Control Theory  and C fiber impulses inhibit SG, facilitating pain perception Use of physical agents stimulate large-diameter fibers creating analgesic response

Endogenous Opioid Analogue to the Ascending Gate Control Theory  fiber impulses trigger a release of enkephalin from neurons in the dorsal horn Inhibit synaptic transmission in the  and C fibers

Central Biasing Descending pain control Impulses from the thalamus and brain down the efferent fibers to the dorsal horn Impulses from the higher centers close the gate and block transmission of pain message at the dorsal horn Previous experience, emotional influences, sensory perception are factors which can influence transmission of pain

Endogenous Opioid Model of the Descending Pain Control Theory Stimulation of the periaqueductal grey region and raphe nucleus by ascending inputs activates descending mechanisms Stimulation of raphe nucleus sends impulses down the efferent fibers in the dorsal lateral tract Synapse with enkephalin interneurons Release of enkephalin

-Endorphin and Dynorphin Stimulation of small-diameter afferents stimulates the release of BEP & Dynorphin Prolonged stimulation of the small-diameter fibers is thought to trigger the release of BEP from the anterior pituitary gland BEP does not cross blood-brain barrier BEP probably release from area within brain

Pain Assessment Pain is difficult to evaluate and quantify Subjective nature Difficult to put into words

Pain Profiles Type of pain Quantify intensity of pain Effect of pain experience on the athlete’s level of function Assess psychosocial impact of pain

Pain Assessment Scales Visual analogue scales Pain charts McGill Pain Questionnaire Activity Pattern Indicators Pain Profile Numeric Pain Scale …Rate your pain on a scale from 1 to 10, with 10 being the worst pain you have every experienced or could imagine

Visual Analogue Scales

Pain Charts

McGill Pain Questionnaire