A spinal anesthesia is given with a very small needle inserted in your lower back between two vertebrae. The main difference with an epidural is that the liquid is inserted directly in the spinal column, that the reaction is almost immediate, and that the necessary dose is very small. The medication for the spinal anesthesia is usually injected only once. Occasionally headaches may occur after a spinal anesthesia. If these headaches persist, they can be treated effectively.