Objective measurement of Cranial Rhythmic Impulse (CRI): visual analysis of an observational case series

One of the traditional principles of osteopathy is the presence of primary cranial movement, also defined as Cranial Rhythmic Impulse (CRI) in relevant literature. Though the presence of such movement is recognized by some and disputed by others, there is little evidence to support either stance. One of the main issues concerns the possibility of getting objective, simultaneous tracks of the physiological rhythms responsible for possible variations in size involving the skull and the whole body. The only data available in literature date back to old works which, according to the authors, only refer to sutural motion. Since osteopathic palpation of the cranium involves the perception of the physiology and/or pathology of all the tissues, earlier data may lead to a partial interpretation of tissue physiology. Our work is an attempt to provide a preliminary observation of the rhythmic oscillations of the skull size in physiological conditions, connecting them directly to the rhythmic oscillations of other physiological phenomena involving different body parts.

An observational case series of 20 young, healthy subjects seems to suggest that the rhythms existing in cranial tissues are the same as those existing in the circulatory and respiratory systems and show frequencies and amplitudes which are compatible with osteopathic perceptual skills.

Our visual analysis of the recorded tracks did not allow us to identify any rhythmic and constant autonomous oscillations of the peripheral tissues of the cranium that may be attributed to the CRI.

Our analysis seems to suggest that osteopathic palpation is able to detect the oscillations of physiological rhythms involving soft tissues. The presence of an intrinsic motility of the cranium, transmitted by sutural motion, did not emerge in our study; at least, it was not possible to identify a steady and autonomous peripheral CRI.