What is a local anaesthetic infiltration?
Instead of depressing the functioning of the brain with a general anaesthetic, a local anaesthetic is temporarily depresses the functioning of the smaller nerves near the operative site. Due to the chemical composition, the injection of the local anaesthetic often hurts at the beginning, but once done, is able to provide many hours of complete painlessness to the area. Only certain types of operations can be done this way, typically small operations like superficial skin lesions.
What is a local anaesthetic block?
Similar to a local anaesthetic infiltration, but instead of injecting around the operative site, the injection occurs next to a nerve that eventually runs towards the operative site. By "deadening" this nerve before it reaches the operative site, this technique knocks out your ability to feel all the areas supplied by this nerve. An example is when the injection occurs around the base of your fingers (near the palm) and yet operating on your finger tip produces no pain.
Some operations can be done with a local anaesthetic block alone, because it can reliably produce complete pain relief.
Other operations, a local nerve block is used to supplement pain-relief medications, but is insufficient by itself to provide complete pain relief. This is because there are often multiple other nerves that supply the area that can't be reliably blocked out.
What about spinals or epidurals?
The principles behind a spinal block or an epidural block are the same as a local anaesthetic block - the difference being that instead of "deadening" a small nerve in a limb, a spinal/epidural (temporarily) deadens the entire spine below the level where the injection occurs. In high enough doses, this is able to provide complete pain relief adequate for any surgery below the chest.
Please click Spinals and Epidurals for further descriptions.