Chronic Pain

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage (1).

Further more is important to illustrate the scientific importance (2) of the understanding of neuronal mechanisms involved in nociception, the patients response-pain, and the resulting pain management. It helps validate what the practitioner is administering, in this case physical treatment-Chiropractic. Patients recognise  that they have received the appropriate diagnosis and treatment for their condition. Chiropractic emphasises the role of proper functioning of the nervous system to maintain proper health. Therefore it is of paramount importance that this report of our current understanding of the neurobiology of pain mechanisms, in terms of neurotransmitters, receptors and impulse transmission benefit Chiropractic treatment.

The transfer of synaptic input from nociceptors to specific laminae in the dorsal horn is highly topographically organized and activates particular subsets of second order projection neurons leading to activation of specific brain centres, to the sensitisation of acute pain as well as emotional cognitive and autonomic responses. Primary afferent neurons by virtue of their peripheral transduction specialisation, central termination site, or termination site or temporal characteristics, encode stimulus modality intensity, location and duration.

The mechanisms for neurotransmitters, receptor neuronal pathways, response has now been illustrated. Hence this now gives the clinician knowledge of a patients presenting signs and symptoms, aiding in more accurate diagnosis and appropriate treatment and ultimately correct pain management.

Its application in the neurobiology of pain can be related to Chiropractic . Noxious stimuli (3) come from small but abnormal degrees of movement in the zygapophyseal joints and disc. These abnormal movements presumably activate nociceptors in ligaments, periosteum and muscles. Electrophysiological (4) behavioural and clinical studies have confirmed that nociceptive activity in the dorsal horn is modulated in the substantia gelatinosa by input from joint mechanoreceptors, and A-beta afferents. Impulses travelling in larger myelinated mechanoreceptive fibres take precedence over smaller diameter nociceptive fibres and act to inhibit the transmission of nociceptive activity.

A lack of mechanoreceptive input (due to joint dysfunction) allows increased nociceptive nerve

transmission, which is responsible for pain syndromes, and nociceptive reflexes that can alter

musculoskeletal tone and affect the sympathetic nervous system. Manipulation initiates passive

joint movements, which result in mechanoreceptive stimulation, creating pre-synaptic inhibition of

nociceptive afferent activity thus diminishing or abolishing pain. Normal joint function can help

normalise mechanoreceptive and nociceptive input.

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