Neck tumour with syncope due to paroxysmal sympathetic withdrawal.

A patient with recurrent squamous carcinoma metastatic to the neck after radical neck dissection and high dose radiation therapy developed paroxysmal hypotensive episodes that were severe, spontaneous and characterised by suppressed sympathetic but not enhanced parasympathetic activity. Intravenous pressors were successful in treating acute episodes but neither drug therapy nor surgical neck exploration reliably prevented syncopal attacks. Glossopharyngeal and/or vagal nerve infiltration by tumour with episodic activation of the afferent limb of the baroreflex arc producing vasodilatation primarily due to sympathetic withdrawal is the likely mechanism of life threatening syncope in this patient.