Chronic Measurements of Cerebrospinal-Fluid Pressure in the Dog

S T U D I E S of cerebrospinal-fluid pressure in the chronic experimental canine have been limited because of the lack of a simple, reliable method for carrying out this investigation. Various techniques for measuring cerebrospinal-fluid pressure in the dog have been described previously, 1,2,4,6 but none of these is suitable for the continuous or protracted study of cerebrospinal-fluid pressure. The chronic placement of a needle in the lumbar subarachnoid space or in the cisterna magna of the dog offers serious limitations. The lumbar spinal tap is difficult to perform because of the anatomical configuration of the dog's spinal column; 1 in addition, the bulk of the spinal cord fills most of the intradural space, thus only a very small amount of cerebrospinal fluid is present in the lumbar subarachnoid space. 5 After either lumbar or cisternal puncture the animal cannot be placed easily in the supine position without risking leakage around the needle or dislodgment of it at its point of entrance into the subarachnoid space, thereby compromising the accuracy of the recording. The poor support offered to the needle by the soft tissues of the neck (cisternal puncture) and lower back (lumbar puncture) would necessitate the limitation of the animal's freedom of ambulation in long-term experiments. Recently we have developed a simple method of cannulating the subarachnoid space and measuring cerebrospinal-fluid pressure in the dog by using an anterior approach in the neck.~ While this technique