Spinal Manipulations

Spinal manipulations are commonly used throughout the world by osteopaths and chiropractors but how do they achieve a therapeutic benefit to patients?

There is little known about the physiological mechanism of this therapy and how it relieves pain. This blog set to explain what we currently believe is the mechanism that enables pain relief through spinal manipulations.

Originally the studies focused on the mechanical impacts of the manipulation, or the subluxation of the joint.

The Biomechanical effect of spinal manipulations focused on 4 areas:

1. Release of entrapped synovial folds

2. Restoration of buckled motion segments

3. Reduction in articular or periarticular adhesions

4. Normalisation of hypertonic muscles by reflexogenic effect

The relevance of these theories on patient outcomes is uncertain, and never consistently proved. The only theory with plausible explanation is reflexogenic effect, but this too lacks consistent evidence.

The inconsistencies of the evidence when assessing the biomechanical impacts of spinal adjustments suggests that other factors are at play.

This led us to our current point within the literature with studies focusing on neurophysiological mechanisms due to a cascade of neurochemical responses to the central and periphery nervous system released after a spinal adjustment. This includes, endorphins, enkephalins, oxytocin, neurotensin, cortisol, serotonin and dopamine

There is a complex relationship between periphery nervous system - where the stimulus or manipulation takes place- the central nervous system and the para spinal sensory afferents. The main function of the para spinal sensory afferents is to relay information to central nervous system for processing, integrating and, at times, responses of the motor pathways, from the periphery - skin, muscles and organs. They are located in the dorsal root ganglia alongside the spinal column.

The para spinal sensory afferents may be a key mechanism in enabling pain relief with spinal adjustments. Potentially due to...

Neuro muscular effects

The reflexogenic effect is centred around the pain-spasm-pain cycle. This argues that pain causes muscles hyperactivity (spasm), and muscle spasm produce pain, establishing a self perpetuating cycle. Spinal adjustments are said to disrupt this cycle by reducing muscle activity through the reflex pathways. It is suggested that mechanical stimuli applied during the manipulation on paraspinal tissue leads to muscle inhibition.

Hypoalgesic effects - enkephalins are the neurochemicals which reduces pain in the body

Based on the gate control theory of pain, by Malzack and Wall. This theory works on the premise that pain is a not a direct signal, it is regulated by a neural gate. The mechanical stimuli used in manipulations is proposed to alter the periphery sensory input from the paraspinal muscles, therefore influencing the gate closing mechanism. This is achieved by the large nerve fibres inhibiting the pain signals from moving through the gate. For example, you bang your head and instinctively rub it, the rubbing stimulates mechanorectors which stop the pain signals from reaching the brain. The physical stimulation from the spinal adjustment works in the same way.

The studies have moved from mechancial to the neurophysiological. The exact mechanism is still not fully understood and ongoing studies are required to combine with an improvement in technology to unlock this question.