The palpated cranial rhythmic impulse (CRI): Its normative rate and examiner experience

Abstract

This retrospective review study aims to contribute data regarding the normal range of the palpated cranial rhythmic impulse (CRI) rate from a population of 734 healthy subjects, each determined by a different examiner. Experience levels ranged from 1 to 25 years training/practice in cranial osteopathy. This study reports an overall CRI rate range (mean ± SD) of 6.88 ± 4.45 cpm for all subjects (valid N = 727). The examiner population was subdivided into three groups based upon the level of examiner experience. The rates obtained from each subgroup, from least experienced to most experienced, are as follows: Level 1 (one year of experience), 7.39 ± 4.70; Level 2 (two years of experience), 6.46 ± 4.10; Level 3 (three-twenty five years of experience), 4.78 ± 2.57. Both group mean values of the reported palpated CRI rates and their standard deviations showed an inverse relationship with the level of examiner experience, i.e., as experience increases, the mean CRI rate and its deviation decreases. In the light of the findings of this study, the currently accepted range of the palpated CRI, 8–14 cycles/minute, should be reconsidered to be as low as 2–7 cycles/minute. Précis CRI rate means and ranges as assessed by experienced examiners are, respectively, lower and narrower.