Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Saddle anaesthesia is a loss of sensation (anesthesia) restricted to the area of the buttocks and perineum. It is frequently associated with cauda equina syndrome. Anesthesia, or anaesthesia, has traditionally meant the condition of having sensation (including the feeling of pain) blocked or temporarily taken away. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience. The word was coined by Oliver Wendell Holmes, Sr. in 1846. Another definition is a "reversible lack of awareness," whether this is a total lack of awareness or a lack of awareness of a part of the body such as a spinal anesthetic or another nerve block would cause. Anesthesia is a pharmacologically induced reversible state of amnesia, analgesia, loss of responsiveness, loss of skeletal muscle reflexes and decreased stress response.