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16 Articles in Volume 19, Issue #2
Analgesics of the Future: Inside the Potential of Glial Cell Modulators
APPs as Leaders in Pain Management
Cases in Urine Drug Monitoring Interpretation: How to Stay in Control
Complex Chronic Pain Disorders
Efficacy of Chiropractic Care for Back Pain: A Clinical Summary
Hydrodissection for the Treatment of Abdominal Pain Caused by Post-Operative Adhesions
Letters: The Word "Catastrophizing;" AIPM Ceases Operations; Patient Questions
Management of Severe Radiculopathy in a Pregnant Patient
Managing Pain in Adults with Intellectual Disabilities
Pain in the Courtroom: An Excerpt
Q&A with Howard L. Fields: How Patients’ Expectations May Control Pain
Special Report: CGRP Monoclonal Antibodies for Chronic Migraine
The Management of Chronic Overlapping Pain Conditions
Vibration for Chronic Pain
What are the dangers of loperamide abuse?
When Patient Education Fails to Improve Outcomes: A Low Back Pain Case

Vibration for Chronic Pain

The benefits of mechanical stimulation in managing chronic conditions: from a history of whole body stimulation to today's focal techniques.
Pages 60-63; 67
Page 1 of 3

Vibration, or the transmission of oscillatory mechanical stimulation, may be accomplished with auditory or ultrasonic waves, pulsed electromagnetic fields, electrical stimulation, shockwaves, or mechanical devices with motor-driven shaking platforms or eccentric flywheels. Perhaps because of an association between “good vibrations” and 1960s pop-psychology, there is an inverse relationship between an oscillatory mechanical therapy’s reimbursement and the therapy containing the actual “V” word. As research on whole body vibration (WBV) literature, and more recently focal vibration (FV) expands, the evidence supports each modality for a variety of chronic pain conditions, as reviewed herein.

History

Perhaps the first patients intentionally treated with vibration were those of neurologist Jean-Martin Charcot. After associating clinical improvement of his patients with Parkinson’s disease and prolonged train rides, he described in 1892 the creation of a similarly shaking chair – and similar clinical improvement.1 Although his student Georges Gilles de la Tourette created (and published) data on a vibrating helm for migraine, little else was done with therapeutic vibration for half a century. In 1949, Whedon created an oscillating bed with physiologic and metabolic improvement of patients with whole body casts.2

The association between vibration and pain relief developed in conjunction with an understanding of sensation itself. Pain transmission travels peripherally on fast Aβ fibers, joining in the substantia gelitinosa of the dorsal column with Aβ nerves transmitting mechanical information, and C-fibers transmitting cold and pressure information. Summary information is passed via interneurons to spinal fibers to the brain, with an interplay such that stronger signals in arriving to the dorsal horn inhibit weaker ones. After Melzack and Wall3 postulated that mechanical Aβ stimulation could reduce pain and physiologists tested WBV on animals for osteogenesis, full body plates to treat humans arrived. By the early 2000s, manufacturing was capable of small intense motors that could provide high-frequency vibration focally, and research on both WBV and FV have since grown exponentially.

An understanding of the mechanics and physiology may help to frame the sometimes contradictory literature, helping to predict when a patient may benefit from vibration. An understanding of vibration’s impact on mechanoreceptors, and the role of tension and intrinsic vibration frequency on anabolic cell behavior, help to illuminate vibration’s role in pain management.

(Source: Medical Technologies Limited UK)

Physiology

Of the four principal mechanoreceptors innervated by Aβ fibers, two likely account for most of the “gate control” pain-reducing effects. Fast-adapting, light-touch Meissner corpuscles detect frequencies between 20 and 40 Hz, while fast-reacting and long-acting deep Pacinian corpuscles begin sensing vibration at 65 Hz, with maximal sensitivity at 250 Hz.4 While WBV-induced longitudinal stretching of Aβ Ruffini bulbous corpuscles may cause additional “gate control” pain relief, it is more likely that the Ia and II afferents on the muscle spindles themselves centrally mediate pain relief with larger amplitude vibration. As both Ia afferents and Aβ afferents share the anatomical path to the substantia, a shared physiology of pain inhibition is posited.

A secondary benefit for patients with pain may emerge from mechanoreceptor’s role in balance. In the foot, for example, 70% of the mechanoreceptors are fast-adapting Meissner and Pacinian cells, but with three times the receptive fields of the hands. When these cells are anesthetized, balance is significantly reduced. Interestingly, the activation thresholds in the sole are also much higher; in other words, patients may not need to perceive the vibration to stimulate receptors and improve balance. Subthreshold vibration training and using vibration to amplify signal in the soles has been used to improve balance in patients with neuropathies, suggesting a modality of pain improvement through improved balance and kinesthetic awareness.5

All substances vibrate at an internal resonant frequency. Strike a string, steel beam, or taut band, and the frequency of vibration is intrinsic to the material, tension, and any surrounding compression lending integrity to the structure. This “tension integrity” in the body is provided by connective tissues. Vibration transmitted to skin stimulates mechanoreceptors and can descend to muscles. By transmission to limbs through weight bearing, vibration passes through bones, tendons, muscles, and the cells that make them up. Mechanical forces themselves can deform cells to open sodium channels, allowing ions to enter and leading to action potentials; integrins on cells recognize and respond to mechanical stressors.

Growth Stimulation & Balance Stabilization

Below a mechanical strain threshold, muscles atrophy and bone is resorbed. On a cellular level, stressors that exceed the minimum strain threshold prompt growth. Single whole body vibration sessions may increase overall oxygen uptake in tissues, thereby increasing microcirculation and blood flow. Over time, WBV works to decrease osteoclast activity, change gene expression of growth factors, and increase growth hormone expression.6 As a more macro example, orthopedists do not typically immobilize humerus fractures because the microtensions from active shoulder muscles remodel bone faster than casting. Vibration acts as a mechanical signal that exceeds the threshold strain level, increasing cellular anabolic (growth) activity.

In everyday life, cells and tissues undergo growth and remodeling with mechanical vibratory forces.7 Walking, for example, generates vibratory waves with a frequency between 10 to 20 Hz.8 When vibration exceeds the threshold for a growth response, typically due to higher amplitudes or excessive duration, the inability of tissues to respond with growth can cause damage. Rather than the increased microcirculation seen with low amplitudes of 0.3 g, the amplitudes of 1 to 2 N vasoconstrict.

Last updated on: March 4, 2019
Continue Reading:
New Device Combines Acupuncture With Four Other Technologies to Alleviate Pain
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