Meeting Abstract
Despite its clear clinical significance, the underlying flow dynamics of the CSF remain poorly understood. The study was intended to quantify some of the physiological features that contribute propulsive force to the CSF. Juvenile American alligators (Alligator mississippiensis) with a body length of approximately 180 cm were physically restrained on an inversion table. Using a cuffed tracheal tube the animal was connected to a mechanical ventilator and anesthetized with Isoflurane. Fluid pressure catheters were surgically implanted into the spinal and cranial subdural spaces. Surface EKG electrodes were placed on the ventral scalation on either side of the heart. The suboccipital muscles of the myodural bridge were surgically exposed on one side, implanted with bipolar EMG electrodes, and activated with a stimulating probe. In the first round of the experiment CSF pressure was recorded simultaneously with heart rate, ventilatory airflow, myodural bridge contraction, while the animal was exposed to varying gravitational gradients. FFT analysis of the pressure recordings was used to examine the relative contribution of the ventilatory movements and arterial pulsations. During the second round of the experiment ultrasonography was used to test for displacement of the dural sheath during contraction of the myodural bridge. During the third round of the experiment, artificial microspheres were introduced into the CSF and their pattern of movement studied using laser Doppler ultrasonography. All three rounds of the experiment provided support for the hypothesis that the myodural bridge functions as a CSF pump.
