[Cluster headache: its diagnosis, pathophysiology and treatment].

INTRODUCTION: Cluster headache (CH) is the most frequent subtype of trigeminal headache with autonomic symptoms (THAS); yet, despite its characteristic clinical profile it remains poorly understood and badly controlled.

AIMS: To identify the correct diagnostic criteria of CH and the respective differential diagnoses, as well as to gain an understanding of the pathophysiology of CH, its treatment and prognosis by means of a review of the literature.

DEVELOPMENT AND CONCLUSIONS: CH is a condition that is characterised by the presence of sharp, or extremely sharp, unilateral pain that is short-lasting and usually located in the retroocular and/or temporal region; it is also accompanied by ipsilateral autonomic symptoms (mainly conjunctival injection). CH can be differentiated from other THAS by the frequency with which it appears and the amount of time the pain lasts (the average is less than five attacks a day lasting from 30 minutes to 3 hours), as well as the response to treatment. A number of neuronal pathways are involved in the pathophysiology of CH. It has been suggested that the activation of the trigeminovascular and the parasympathetic systems, together with the dysfunction of the cranial sympathetic system, are involved in this condition. Moreover, there is evidence to support the role of functional and structural alterations in the hypothalamus. Treatment of CH is based on the proper pharmacological implementation of abortive, transitional and prophylactic therapies. Surgical interventions are recommended in patients with strictly unilateral pain in the ophthalmic division of the trigeminal nerve who are resistant to multiple therapies, and/or offer a poor response and/or contraindications to pharmacological treatment. Factors related to genetics, brain functioning or the environment, as well as the way the symptoms present (episodic or chronic), determine the prognosis of CH.