STUDIES IN THE TREATMENT OF EXPERIMENTAL HYDROCEPHALUS

Abstract

Several types of ventricular-venous shunts were studied as a means of by-passing obstruction to the normal circulation of cere-brospinal fluid in hydrocephalic dogs. By use of small caliber, flexible plastic tubes, artificial shunts were created between the lateral ventricles and the venous system at the following points: intracranially (sagittal sinus); the intrathoracic veins (superior vena cava); and the superficial veins of the neck (facial, external maxillary and external jugular). The authors found that in hydrocephalic animals, ventricular pressure is ordinarily higher than the venous pressure in the sagittal sinus, and under controlled conditions of anesthesia and position, cerebrospinal fluid will flow from the lateral ventricle into the sagittal sinus. Under conditions of normal activity, this differential in hydrostatic pressure is obviated once the ventricle has been decompressed, so that the blood refluxes into the tubing connecting the ventricle to the sinus. When cerebrospinal fluid is diverted from the ventricular system into the superior vena cava, satisfactory decompression of the ventricle takes place within a few minutes. When the ventricular pressure has been reduced, however, clotting occurs in the connecting tube. The single valves in the superficial veins of the neck are not competent to prevent reflux of blood under conditions of normal venous pressure, therefore cerebrospinal fluid diverted into one of these veins will continue to flow satisfactorily only until the ventricular pressure falls below that of the venous pressure in the veins employed. It is felt, therefore, that unless an extremely sensitive but completely competent artificial valve can be devised and introduced between the cerebrospinal fluid pathways and the venous system in such a fashion as to permit only unidirectional flow of fluid no matter what the relative hydrostatic pressures may be, all attempts to achieve ventricular decompression by ventricular-venous shunts will fail and should not be submitted to clinical trial.