Spread of extradural analgesia following caudal injection in children.

Sir,—I read with interest the paper by Schulte-Steinberg and Rahlfs (1977), as I did their earlier paper on this subject in 1970. As I have more experience in this subject now than in 1970 (700-800 caudal blocks in children aged 10 yr and less), I should like to say that I cannot see the relevance of this work to clinical practice. If a general anaesthetic is to be administered throughout surgery, why give a caudal block at all? I have found the principal advantages of caudal analgesia in children to be ease of administration, especially in very small children or for surgery in the prone position when general anaesthesia would require tracheal intubation, and the calm, pain-free emergence which allows analgesics to be given orally before pain has been felt. These advantages will be absent or modified considerably by concurrent general anaesthesia. I, who use unsupplemented caudal anaesthesia for my children, soon came to the conclusion that pinprick testing was clinically valueless (McGown, 1972). To test skin anaesthesia, I found it necessary to nip the skin with artery forceps (or, later, between the finger nails). After reading