Syndromes of a complex lesion of greater and lesser superficial petrosal nerves (paradoxical facial hyperaemia, salivation, lacrimation and mucus excretion).

After closed cranial trauma with paralysis of the facial nerve, a patient had a fracture into the petrosus apex with a bony bridge over the nerve, and a subdural haematoma, which were dealt with during an operation for nerve decompression. Examination of the patient 2.5 years later revealed the presence of the crocodile tears syndrome, mucus secretion and the salivary atropine paradox, i.e. severe hyperaemia of the paretic half of the face during intense salivation in response to atropine. Other patients who suffered similar trauma but had no operation demonstrated the same syndrome. The crocodile tears syndrome is considered to be a result of an ephaptic union of the central portion of the damaged lesser superficial petrosal nerve (SPN) with the peripheral portion of the greater SPN. The salivary atropine paradox is then due to the loss of the peripheral portion of the former nerve combined with denervation of the salivary parotid gland. Facial hyperaemia during intense salivation after atropine administration is explained as a result of the intensified release of vasoactive intestinal polypeptide from the gland, stimulated by atropine, into the blood circulation.