Controlled Spinal Anesthesia

To relieve intractable pain, section of the anterolateral column of the spinal cord (Spiller-Frazier operation) has proved to be of practical clinical value. As all pain fibers enter the spinothalamic tract of the opposite side to terminate eventually in the thalamus, it is extremely important to determine at what point pain fibers from a certain area of the body finally join the anterolateral column on their way to the thalamus. It is recognized that these fibers travel not only in the peripheral nerves, but may follow divergent pathways along the arteries and find their way into the spinal cord at various levels. In order to determine the exact level at which all pain fibers have entered the spinothalamic tract from a given area, a clinical test has been devised. A method of obtaining a gradually ascending anesthesia of the spinal roots under accurate and constant control is necessary in order