Trigeminal nevralgia and Trigeminal-autonomic-cephalalgias: a continuum or simple co-existence?

Trigeminal neuralgia (TN) is a common unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve. Indeed, pain is commonly evoked by trivial stimuli, including washing, shaving, smoking, talking, or brushing the teeth and frequently occurs spontaneously (1). Cluster headache (CH), short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms, and paroxysmal hemicrania (PH) are classified as trigeminal-autonomic cephalalgias (TACs). These cephalalgias, according to International Classification of Headache Disorders, 2nd edn (ICHD-II) criteria, share the clinical features of headache accompanied by cranial parasympathetic autonomic features (1). These syndromes seem to be different and well-characterized. However, in recent years some cases have been described in which syndromes co-existed or switched from one type to another in the same patient. This event raised doubt that there could be some common mechanisms among them. We describe a patient who resurrects this problem. She first presented with TN, later developed SUNCT, and then manifested TN attacks, followed by CH, and finally SUNCT without TN attacks.