Intraexaminer and interexaminer reliability for palpation of the cranial rhythmic impulse at the head and sacrum

Background: A range of health care practitioners use cranial techniques. Pa lpation of a cranial rhythmic impulse (CRI) is a fundamental clinical skill used in diagnosis and treatment with these techniques. There has been litt le research establishing the reliability of CRI rate palpation. Objective: This study aimed to establish the intraexaminer and interexamine r reliability of CRI rate palpation and to investigate the "core-link" hypo thesis of craniosacral interaction that is used to explain simultaneous mot ion at the cranium and sacrum. Design: Within-subjects, repeated-measures design. Subjects: Two registered osteopaths. both with postgraduate training in dia gnosis and treatment, using cranial techniques, palpated 11 normal healthy subjects. Methods: Examiners simultaneously palpated for the CRI at the head and the sacrum of each subject. Examiners indicated the "full flexion" phase of the CRI by activating silent foot switches that were interfaced with a compute r. Subject arousal was monitored using heart rate. Examiners were blind to each other's results and could not communicate during data collection. Results: Reliability was estimated from calculation of intraclass correlati on coefficients (2,1). Intrarater reliability for examiners at either the h ead or the sacrum was fair to good, significant intraclass correlation coef ficients ranging from +0.52 to +0.73. Interexaminer reliability for simulta neous palpation at the head and the sacrum was poor to nonexistent, ICCs ra nging from -0.09 to +0.31. There were significant differences between rates of CRI palpated simultaneous ly at the head and the sacrum. Conclusions: The results fail to support the construct validity of the "cor e-link" hypothesis as it is traditionally held by proponents of craniosacra l therapy and osteopathy in the cranial field.