Cluster headache and SUNCT: similarities and differences

SUNCT is probably a distinct syndrome, although it shares some common features with cluster headache (CH): male sex preponderance, clustering of attacks, unilaterality of headache without sideshift, pain of non-pulsating type with its maximum in the periocular area, ipsilateral autonomic phenomena (e.g. conjunctival injection, lacrimation, rhinorrhea, increased forehead sweating), systemic blood pressure increment with heart rate decrement, blood flow velocity decrement in the middle cerebral artery, and hyperventilation. In spite of these similarities, SUNCT syndrome differs clearly from CH as regards a number of clinical variables, such as duration, intensity, frequency, and nocturnal preponderance of attacks. The two syndromes also differ markedly as regards precipitation of attacks, the usual age at onset, and efficacy of various treatment alternatives. Laboratory investigations have disclosed differences as regards presence or absence of Horner-like picture and possibily also the respiratory sinus arrhythmia pattern. All in all, these differences seem sufficiently ponderous to make it likely that SUNCT syndrome and CH differ essentially. SUNCT seems to be a “neuralgiform” headache, but different from trigeminal neuralgia.