Q&A: Whole-Body Vibration and Cervical Degenerative Disc Disease

QUESTION: A 65-year-old obese male heavy-equipment operator, who drives bulldozers at a landfill, was seen for neck pain. Imaging studies revealed cervical facet arthropathy. Does whole-body vibration (WBV) cause or aggravate cervical disc degeneration?ANSWER: Causation analysis must be based on facts and scientific evidence. The AMA Guides to the Evaluation of Disease and Injury Causation provides guidance on causation analysis and apportionment. The second edition, published in 2014, provides the following guidance in Chapter 32, Effects of Whole-Body Vibration on the Spine:To create formidable proof to link WBV with a specific spinal disorder will require more research. The symptom of LBP is ubiquitous and can emanate from multiple diseases and disorders.This chapter from the AMA Guides to the Evaluation of Disease and Injury Causation focused on WBV and the low back rather than the neck (cervical spine). There is conflicting evidence in the medical literature regarding a causal relationship between WBV and neck pain. Studies have reported an association between WBV and neck pain.1–7 However, a study of forest machine drivers found no significant association between neck pain and high WBV exposure, although drivers with neck pain more often reported jolts while driving the vehicle as being uncomfortable.8A 2015 study analyzed the prevalence of neck pain by occupation with a cross-sectional dataset from the 2009 to 2012 National Health Interview Survey.9 It found that the proportion of workers in the United States with neck pain was 13.3%. In transporation and material handling occupations, the percentage was less, at 12.8%. Workers with the highest reports of neck pain had jobs in the military; health care support; arts, design, entertainment, sports, and media; community and social services; and personal care and service occupations.The question posed pertains not to neck pain but whether WBV causes or aggravates degeneration of cervical discs and/or facet joints. A search of PubMed revealed no results for WBV and cervical facet degeneration, facet joint degeneration, arthritis, or osteoarthritis. A search for WBV and cervical disc degeneration yielded only a single result.10 A 20-year prospective longitudinal study of degeneration in the cervical spine based on magnetic resonance imaging findings revealed the progression of degenerative changes in 95% of the subjects. However, there was no correlation between progressive degeneration and neck pain.11While studies have reported an association between WBV and neck pain, the development of pain may be dependent on the vibration frequency?4 and perhaps other factors, such as amplitude. In other words, not all WBV is detrimental, and some vibration profiles appear to be beneficial. WBV is used for neuromuscular training and treatment to supplement or substitute for conventional exercise to improve muscle strength, power, and flexibility.12–14 Causation of degenerative disc disease was reviewed in the July/August 2009 issue of the AMA Guides Newsletter.15 The primary cause of degenerative disc disease is genetics and aging.One must also be cautious about drawing conclusions from any study using an inherently subjective outcome measure such as pain. The Hawthorne Effect,16 also known as the observer-expectancy effect, is a type of reactivity in which people change some aspect of their behavior when aware they are being observed. For example, in a study on neck pain, subjects may be more likely to report cervicalgia whether due to hypervigilance, the demand effect (a desire to please the researchers by giving them the results they wanted to see), secondary gain (the tangible and/or intangible benefit[s] derived from being or being perceived as ill or injured), or other reason.Although studies suggest an association between WBV and neck pain, the paucity of information regarding vibration frequency in most studies, the prevalence of neck pain in the general population, the inherently subjective nature of pain, and the Hawthorne Effect raise concerns about drawing causal conclusions. There is insufficient evidence to conclude that WBV causes or aggravates cervical facet arthropathy. Further research would be helpful to understand which WBV profiles are beneficial or detrimenta.