IntroductionAutonomic disturbances in cluster headache (CH) are thought to result from parasympathetic stimulation [1] and from ocular sympathetic deficit [2] with expression of a Horner-like syndrome. Forehead sweating is though to be a consequence of a postganglionic lesion in sympathetic sudomotor fibres [3], with adaptive supersensitivity of the forehead sweat glands [4]. Facial flushing could result from a unilateral increase in extracranial blood flow, demonstrated during cluster attacks [5,6] as a consequence of trigeminal nociceptive activation [6,7].Principal component analysis is a data reduction method that explores correlations among the variables of a problem, producing a set of independent factors that resume the relation within the original variables -the principal components. We applied this deductive statistical method to the autonomic manifestations of a series of CH patients, trying to elucidate the relationships between these symptoms.
MethodsThe Cluster Headache Outpatient database of Santa Maria's Hospital in Lisbon was used to select ICHD-II [8] CH patients. All patients included in this database was observed by neurologists with experience in headache. Clinical data were analysed, including age at first consultation, gender, duration of illness, follow-up time, pattern (episodic/chronic), presence of autonomic symptoms and number and type of autonomic symptoms (mio-
Raquel Gil Gouveia Elsa Parreira Isabel Pavão MartinsAbstract The objective is to identify the pathogenesis of each autonomic manifestation in cluster headache (CH). Through a deductive statistics method (factor analysis) we analysed the type of autonomic symptoms reported by 157 CH patients. Three principal components were identified in the analysis: parasympathetic activation (lacrimation, conjunctival injection and rhinorrhoea), sympathetic defect (miosis and ptosis) and parasympathetic mediated effect (nasal congestion, eyelid oedema and forehead sweating). This work suggests that there are three different mechanisms underlying autonomic manifestations in CH.