Background: A range of health care practitioners use cranial techniques. Palpation of a cranial rhythmic impulse (CRI) is a fundamental clinical skill used in diagnosis and treatment with these techniques. There has been little research establishing the reliability of CRI rate palpation.
Objective: This study aimed to establish the intraexaminer and interexaminer reliability of CRI rate palpation and to investigate the "core-link" hypothesis of craniosacral interaction that is used to explain simultaneous motion at the cranium and sacrum.
Design: Within-subjects, repeated-measures design.
Subjects: Two registered osteopaths, both with postgraduate training in diagnosis 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 computer. 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 correlation coefficients (2,1). Intrarater reliability for examiners at either the head or the sacrum was fair to good, significant intraclass correlation coefficients ranging from +0.52 to +0.73. Interexaminer reliability for simultaneous palpation at the head and the sacrum was poor to nonexistent, ICCs ranging from -0.09 to +0.31. There were significant differences between rates of CRI palpated simultaneously at the head and the sacrum.
Conclusions: The results fail to support the construct validity of the "core-link" hypothesis as it is traditionally held by proponents of craniosacral therapy and osteopathy in the cranial field.