An audiometric study of the effects of paraspinal stimulation on hearing acuity in human subjects understanding the Harv
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CHIROPRACTIC & MANUAL THERAPIES
RESEARCH
Open Access
An audiometric study of the effects of paraspinal stimulation on hearing acuity in human subjects – understanding the Harvey Lillard phenomenon Mark Demers, Zehra Gajic, Everett Gerretsen and Brian Budgell*
Abstract Background: The founder of chiropractic, Daniel David Palmer, constructed a model of causation of disease based on his seminal experience with a patient, Harvey Lillard, who lost his hearing at the instant of injuring his upper back, but had his hearing restored suddenly 17 years later after receiving spinal manipulation. Palmer’s model of disease causation, that of displaced vertebrae impinging on spinal nerves and thereby disrupting the innervation of dependent organs, was in fact incongruent with what was known at the time about human neuroanatomy and neurophysiology. The current study proposes and tests an alternative hypothesis: that increased afferent input from paraspinal muscles attenuates the central transmission of auditory information. Methods: Between September 13 and November 13, 2013, forty healthy young adults were recruited and randomly divided into two cohorts: one receiving successive trials of sham TENS, and the second receiving sham and then authentic TENS. During the administration of sham and authentic TENS to the upper thoracic spine, hearing acuity was measured to determine perception thresholds at the frequencies normally tested clinically. Results: In the first cohort, there were no differences in perception thresholds in the first and second trials of sham TENS, speaking to the reliability of the testing process. In the second cohort, there were no significant differences in perception thresholds during sham and authentic TENS. Conclusions: Within the constraints of the current study design, including demographic characteristics and TENS parameters, there was no evidence that innocuous afferent input to upper thoracic paraspinal muscles modulated thresholds of audibility. Keywords: (3–10) Audiometry, Hearing, Cochlear nucleus, Somatic stimulation, Muscle, Human
Background The founder of modern chiropractic, Daniel David Palmer, attributed his discovery of the underlying mechanisms of spinal manipulation to his clinical experience with two patients. The first of these was Harvey Lillard, a gentleman who reported sudden deafness coincident with an acute strain to his upper back. Palmer found a thoracic vertebra ‘racked’ from its normal position and reasoned that if he replaced the vertebra by spinal manipulation, the patient’s hearing would be restored [1]. As it turned out, he was correct in his clinical prediction. Palmer subsequently encountered a patient with * Correspondence: [email protected] Canadian Memorial Chiropractic College, 6100 Leslie St., Toronto, ON M2H 3 J1, Canada
some sort of cardiac problem and, coincidently, ‘displaced’ thoracic vertebrae. He reasoned that the displaced vertebrae were somehow impinging on the sympathetic nerves to the heart and thereby impairing cardiac function. He reported that res
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