Perioperative local anaesthesia for reducing pain following tonsillectomy

Pain relief after tonsillectomy is an important part of post-operative management. Sometimes local anaesthetics are administed to the tonsillar region, but their effectiveness in relieving pain has not been formally assessed.

To assess the effects of pre- and post-operative local anaesthesia for pain reduction following tonsillectomy.

Cochrane Controlled Trials Register, Medline, Embase and the Oxford Pain Database. Reference lists from identified publications, including those in non-English language publications, were scanned. Date of the most recent search was September 1998.

Randomised controlled trials of adults and/or children undergoing tonsillectomy alone with local anaesthetic (a) injected into the tonsillar region immediately prior to removal of the tonsils (b) injected into the tonsillar region after removal of the tonsils (c) sprayed or otherwise applied to the tonsillar region after removal of the tonsils Outcome measures included the reduction in demand for post-operative analgesia, both in terms of time elapsed to request for first analgesia and of the total amount of analgesia used.

All three reviewers extracted data independently and assessed trials for quality. Four authors were contacted to obtain information on either the method of randomisation or the type of intervention used.

Thirty trials were initially identified but only six trials met the inclusion criteria. These were all published in the English language literature between 1989 and 1997. Trials were excluded because procedures in addition to tonsillectomy were undertaken, inadequate randomisation techniques were used or because group sizes were inadequate. Of the six included studies, five involved local anaesthetic injection and one application of local anaesthetic spray. These studies used validated pain scores and measurement of supplemental analgesic intake for assessment of pain. However, some studies also included inappropriate, possibly post-hoc, outcome measures such as 'global pain scores' which may have resulted in bias. No included study showed a significant difference between intervention and control, other than for outcome measures which were felt to be inappropriate, such as the one mentioned above.

There is no evidence that the use of perioperative local anaesthetic in patients undergoing tonsillectomy improves post-operative pain control. The trials identified were of small size and several involved the perioperative co-administration of intravenous opiates which may have masked any beneficial effect of the local anaesthetic. Further randomised controlled trials are necessary.