title: The use of mandibular nerve block to predict safe anaesthetic induction in patients with acute trismus.
abstract: Acute trismus can be caused by pain, muscle spasm, swelling or mechanical obstruction. Unfortunately, the cause is not always obvious during pre-operative airway assessment. In this pilot study, we prospectively evaluated mandibular nerve block as a pre-operative tool to identify patients with reversible causes of trismus, namely pain or spasm, in order to allow safe anaesthetic induction. Six patients with unilateral fractured mandibles and trismus received a mandibular nerve block before induction of general anaesthesia. There was an increase in maximal inter-incisor gap after the blocks (median (range) distance: pre-block 16.5 (14-30) and post-block 34 (32-35) mm; p = 0.027), and no further improvement after induction of general anaesthesia (post-induction 37 (30-40) mm; p = 0.276 compared with post-block). There was an improvement in pain scores (p = 0.027), and no side-effects were detected. Pre-operative mandibular nerve blockade appears to reverse trismus caused by pain and muscle spasm, allowing the anaesthetist to decide whether awake intubation is genuinely indicated.
authors.affiliation: Royal Perth Hospital, Perth, Australia. Andrew.Heard@health.wa.gov.au
authors.forename: A M B
authors.initials: AM
authors.lastname: Heard
authors.forename: R J
authors.initials: RJ
authors.lastname: Green
authors.forename: D A
authors.initials: DA
authors.lastname: Lacquiere
authors.forename: P
authors.initials: P
authors.lastname: Sillifant
mesh_terms: D000208:Acute Disease; D000328:Adult; D000768:Anesthesia, General / Q000379:methods; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D008297:Male; D008337:Mandibular Fractures / Q000150:complications / Q000601:surgery*; D008340:Mandibular Nerve; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement / Q000379:methods; D010865:Pilot Projects; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D014313:Trismus / Q000209:etiology / Q000628:therapy*; D055815:Young Adult