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Direct measurement of the rhythmic motions of the human head identifies a third rhythm

PainSci » bibliography » Rasmussen et al 2021

PainSci notes on Rasmussen 2021:

This is a poorly written paper, obviously biased in favour of osteopathy, claiming to have dug an important signal out of very noisy data, identifying an unknown microscopic rhythm in skull movement that may or may not actually exist, but which in any case has no known physiological significance. But it does conveniently resemble something that Sutherland claims to have found by touch, so that was the take-home message of this paper: this extremely subtle signal, it might matter, and it might be what some old-timey quack claims to have felt almost a century ago.

Common issues and characteristics relevant to this paper: ?Scientific papers have many common characteristics, flaws, and limitations, and many of these are rarely or never acknowledged in the paper itself, or even by other reviewers. I have reviewed thousands of papers, and described many of these issues literally hundreds of times. Eventually I got sick of repeating myself, and so now I just refer to a list common characteristics, especially flaws. Not every single one of them applies perfectly to every paper, but if something is listed here, it is relevant in some way. Note that in the case of reviews, the issue may apply to the science being reviewed, and not the review itself.

  1. Mechanism masturbation (excessively wishful thinking about why/how treatments might work).
  2. A high (and possibly unacknowledged) risk of bias and its consequences (p-hacking, etc).
  3. An experimental design with many opportunities for p-hacking (often due to extra hardware, statistical analysis, or other complexities).

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

INTRODUCTION: Central to the osteopathic cranial field, and at the same time controversial, is the concept of a unique rhythmic movement believed to originate from a primary respiratory mechanism (PRM). Further, the PRM is reported to manifest as a cranial rhythmic impulse (CRI) on the living human skull. This study explores the rhythmic oscillations of the human head measured directly as physical movements. The aim is to investigate the existence of a third rhythm distinct from the head movements caused by respiratory breathing and arterial pulsing, in an objective and purely experimental study.

EXPERIMENTAL: In 50 healthy individuals, rhythmic oscillations of the head were measured in real-time for 42 min in a supine resting state without any intervention. A newly developed machine for tracking rhythmic movements was used for measurements.

RESULTS: In all individuals, a third rhythm was distinguished as separate from the arterial and respiratory rhythm at all times. The third rhythm was observed as a dynamic physiological phenomenon with a narrow range in resting healthy individuals with a mean of 6.16 cycles/minute (4.25-7.07). The significant contribution to the amplitude of the measured movements was the respiratory breathing and this third rhythm, whereas the contribution from the arterial pulsing were minor.

CONCLUSION: The present study demonstrates the existence, and normative range of a third physical rhythm detected on the human head. Having developed an objective approach to studying this third rhythm might form the future basis for clinical and physiological studies of craniosacral function and dysfunction.

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