Spinal analgesia, (or commonly called spinal anesthesia) is a form of regional anaesthesia involving injection of a local anaesthetic into the cerebrospinal fluid (CSF), generally through a long, fine needle.
There are hyperbaric, isobaric, hypobaric solutions of anesthetics to choose for the spinal anesthesia. Usually, the hyperbaric is chosen. Bupivacaine is the local anesthetic most commonly used, although lignocaine, ropivacaine, levobupivicaine and cinchocaine are also available. Regardless of the anaesthetic agent used, the desired effect is to block the transmission of nerve signals to and from the affected area. Sensory signals from the site are blocked, thereby eliminating pain, and motor signals to the area eliminate movement. In effect, the result is total numbness of the area and paralysis. This allows medical procedures to be performed with little or no sensation whatsoever to the person undergoing the procedure, and provides a still patient or area for the surgeon to work on. Some sedation is sometimes provided to help the patient relax and pass the time during the procedure, but with a successful spinal anesthetic the surgery can be performed with the patient wide awake. Spinal anesthetics are limited to procedures involving most structures below the upper abdomen, as to administer a spinal anesthetic higher may affect the ability to breathe by paralyzing the intercostal respiratory muscles, or even the diaphragm in extreme cases (called a "high spinal", or a "total spinal", with which consciousness is lost), as well as the body's ability to control the heart rate via the cardiac accelerator fibers.
Baricity refers to the density of a substance compared to the density of human cerebral spinal fluid. Baricity is used in anesthesia to determine the manner in which a particular drug will spread in the intrathecal space.
The first spinal analgesia was administered in 1885 by Leonard Corning (1855-1923), a neurologist in New York. He was experimenting with cocaine on the spinal nerves of a dog when he accidentally pierced the dura mater.
The first planned spinal anesthesia for surgery in man was administered by August Bier (1861-1949) on 16th August 1898, in Kiel, when he injected 3 ml of 0.5% cocaine solution into a 34 year old laborer. After using it on 6 patients, he and his assistant each injected cocaine into the other's spine. They recommended it for surgeries of legs, but gave it up due to the toxicity of cocaine.
During the procedure
- Spinal shock.
- Cauda equina injury.
- Failed spinal.
- Total spinal.
- Cardiac arrest.
- Broken needle.
- Post-dural puncture headache PDPH.
- Sixth cranial nerve palsy.
- Urinary retention.
- Corning J. L. N.Y. Med. J. 1885, 42, 483 (reprinted in ‘Classical File’, Survey of Anesthesiology 1960, 4, 332)
- Bier A. Deutsch. Zeit. f. Chir. 1899, 51, 361 (translated and reprinted in ‘Classical File’, Survey of Anesthesiology 1962, 6, 352)