Spinal analgesia

Spinal analgesia is the suppression of pain and other sensation in a part of the body by injection of a analgesic drug or local anaesthetic into the space around the spinal cord. Two forms are commonly employed: epidural and subarachnoid routes. There is some confusion in the terminology - spinal analgesia is commonly taken to mean the subarachnoid route, and extradural is another term for epidural.

This technique is commonly used post-operatively and in complications of the third stage of labour.

Advantages:

• effective, with rapid onset
• minimal drug dose needed
• hypotension due to sympathetic blockade reduces the risk of haemorrhage
• muscular relaxation often permits surgery without disrupting spontaneous ventilation

Disadvantages:

• "one-shot" technique unless catheter infusion
• risk profound hypotension
• post-spinal headache in 15% of cases; does not occur with epidural analgesia
• very rarely, risk of meningeal infection