Objective: Compression of the fourth ventricle (CV-4) is a manual, noninvasive procedure that reportedly affects the cranial rhythmic impulse, a phenomenon recognized by practitioners of cranial manipulation, that is concomitant with low-frequency Traube-Hering (TH) oscillations in blood flow velocity. This study examines the CV-4 and its effect upon blood flow velocity.

Methods: Human subjects were paired with 28 individual physicians for application of the CV-4, and the duration of the application was recorded. Flowmetry records tracking the course of the procedure were obtained, 20 of which were useable for intergroup comparisons. Segments of these records (control, treatment, response) were Fourier-transformed; the Fourier-transformed spectra were subtracted from one another and the resultant difference-spectra compared.

Results: The mean CV-4 procedure length was 4.43 +/- 2.22 minutes. The mean frequency of the TH waveform visible in the blood flowmetry record was 7.10 +/- 2.07 cpm. The CV-4 procedure specifically affected the low-frequency oscillations in blood flow velocity. After application, the amplitude of the TH, 0.10 Hz, frequency wave increased (relative area units: control minus treatment [0.08010 units) compared with control minus response [-0.03358 units]; P = .011).

Conclusions: This study showed that CV-4 has an effect on the TH frequency component of blood flow velocity. The practitioners of cranial manipulation who participated in this study affected their subjects in a quantifiable manner with the application of the CV-4 procedure.