Spinal anesthesia is a way to eliminate pain during certain procedures or surgeries by injecting medication into the spinal canal to interrupt nerve transmissions from the lower half of the body.
This procedure is commonly called "a spinal." It is usually used for procedures below the rib cage. It is an attractive alternative to general anesthesia for a person who needs a major operation but has medical complications that might make it difficult to tolerate or recover from general anesthesia.
A needle or special tube is inserted through the skin of the back until it enters a special sac that surrounds the spinal cord. Medication is then injected through the needle or tube. The medication blocks the impulses in the nerves that come from the spinal cord.
Spinal anesthesia is similar to but has certain differences from epidural anesthesia. With an epidural, the needle stops short of piercing the sac surrounding the spinal cord, and the the medication is injected just outside the sac.
A spinal requires a smaller volume of medication and works faster than an epidural, but is more likely to cause a headache or low blood pressure.
Medication for a spinal is usually given as a one-time injection with a special needle. However, sometimes, if a lengthy procedure is planned or if considerable pain after surgery is foreseen, the healthcare professional may place a tiny tube into the sac around the spinal cord in place of the needle, and leave it there as a port to inject more medication during and shortly after the surgery.
The medicine stops the sensation of pain and paralyzes the muscles, usually only below the rib cage. The amount of medication given and the location of the injection in the back are important. These factors can control where the numbness and paralysis are in the body.
The individual is generally awake during the procedure. A sedatives can be given if the person is anxious. During a spinal, people usually breathe on their own without needing an artificial breathing machine (ventilator). Oxygen levels in the blood, blood pressure, pulse, and other functions are carefully monitored during and after the procedure. Fluids are usually given through an intravenous line (IV) to prevent dehydration and low blood pressure.
Sabiston Textbook of Surgery, 1997, Sabiston et al.
Anesthesia, 1990, Miller et al.