Researchers from the Royal United Hospital in Bath analysed the complications from over 700,000 spinals and epidurals performed in the UK.
They found that the estimated risk of permanent injury following a spinal anaesthetic or epidural - defined as symptoms lasting more than six months - was about one in 23,000 to one in 50,000, significantly lower than previously thought.
The researchers also found that the risk of being paralysed by one of these injections was two to three times rarer than of suffering any permanent harm.
The risk for women requiring pain relief for labour or Caesarean section was lower still, with the worst estimate of permanent harm being one in 80,000.
A similarly low risk was found in procedures performed for chronic pain and in children.
When an epidural was used for surgery, the risk was between one in 6,000 and one in 12,000. Although this is higher than the risks involved during childbirth, it is still considerabley lower than previous estimates, the researchers said.
Lead study author Tim Cook, consultant anaesthetist at Royal United Hospital, Bath, said the results were reassuring for patients but more still needs to be done.
‘Although complications related to epidurals are rare, the profession still needs to examine how and why these complications arise and make steps to reduce their frequency,’ he said.