Facial nerve palsy following intra-oral surgery performed with local anaesthesia.

The precise cause of Bell's palsy remains unclear. A variety of mechanisms have been linked to this palsy, including viral re-activation, demyelination, oedema, vasopasm and trauma. A link with dental treatment has been suggested previously, and a series of seven cases of facial nerve palsy following intra-oral surgery are reported. All of the patients had local anaesthetic solution containing adrenaline as the vasoconstrictor administered. There may be under-reporting of this association, as patients with facial nerve palsy are treated by specialists from several disciplines, not only maxillofacial surgeons. An association with local anaesthesia administered to permit dental treatment would have important medicolegal consequences, and perhaps go some way to explaining the pathophysiology of Bell's palsy.