Abstract: To investigate the pathophysiology of syringomyelia, we developed a system to simultaneously record arterial, central venous, airway, cervical subarachnoid, and intrathecal pressures. In addition, our system recorded the electrocardiogram, and provided us with the means to analyze all pressures during individual and averaged cardiac cycles. During the study, flow magnetic resonance imaging and cardiac-gated ultrasound images were also used. To compare our pressure readings with these images we needed to account for the low frequency change in the recorded pressures resulting from normal respiration. We therefore wrote a program to derive mean pressure waves during the cardiac cycle that averaged-out the pressure effects of respiratory cycle. Simultaneous cerebrospinal pressure, hemodynamic pressure, and electrocardiogram were plotted. This allowed us to establish the simultaneous relationship of pressures, syrinx size, and cerebellar tonsil pulsation during the cardiac cycle. This system may prove valuable to other researchers investigating the interaction of multiple physiologic parameters during the cardiac cycle.