-Background: Hemodialysis (HD)-related headaches are a common complaint of patients undergoing this procedure. Objective: To determine the frequency and clinical characteristics of headache in patients undergoing HD and to discuss their diagnostic criteria. Method: The present study assessed, in a prospective manner, a series of patients consulting at a HD center in Aracaju, Sergipe, Brazil, from November 2007 to January 2008. Only patients with HD-related headaches without previous history of primary headache were diagnosed as isolated HD headache (HDH). Results: Headache was reported by 76.1% of the patients studied. Prior to beginning dialysis, 47.9% had migraine without aura, 6.7% migraine with aura, 0.6% hemiplegic migraine, 5% episodic tension-type headache, and 2.5% migraine and tension-type headache. HDH was diagnosed in 6.7% of the patients, the most prevalent features being diffuse or temporal region location, bilateral headache, throbbing nature, and moderate severity. Seven patients with headaches between the sessions were not classified. Conclusion: While the pathophysiology of HDH is unknown, to diagnose patients with HDH or other possible HD-related headaches remains a challenge.Key WOrDS: hemodialysis headache, end-stage renal, clinical description, diagnostic criteria. Caracterização clínica da cefaléia da diálise em pacientes renais crônicosResumo -Cefaléias relacionadas ao programa de hemodiálise é uma queixa comum. Objetivo: Determinar freqüência e características clínicas das cefaléias em pacientes em regime de hemodiálise e discutir critérios diagnósticos. Método: Foi feita uma avaliação clínica prospectiva de pacientes cefalêicos em um serviço de hemodiálise em Aracaju, Sergipe, Brasil, de novembro de 2007 a janeiro de 2008. Apenas pacientes sem antecedente de cefaléia primária receberam diagnóstico de cefaléia da diálise isolada. Resultados: Cefaléia esteve presente em 76,1% dos pacientes estudados. Como antecedente de cefaléia, 47,9% tinham migrânea sem aura, 6,7% migrânea com aura, 0,6% migrânea hemiplégica, 5,5% cefaléia tensional episódica, e 2,5% associação de migrânea e cefaléia tensional. A cefaléia da diálise isolada foi diagnosticada em 6,7% dos pacientes e as localizações difusas e temporais, cefaléia bilateral, pulsátil, e intensidade moderada foram as características mais prevalentes. Conclusão: enquanto a fisiopatologia da cefaléia da diálise for desconhecida, o diagnostico da cefaléia da diálise ou de outras possíveis cefaléias relacionadas à diálise permanecerá um desafio.PAlAvrAS-CHAve: cefaléia da diálise, insuficiência renal terminal, características clínicas, critérios diagnósticos.

Chronic migraine is recognized as a migraine complication and is characterized by frequency of attacks up to 15 days/ month for more than three months, in absence of painkiller abusive usage. Studies indicate that magnesium ion plays a role in migraine pathophysiology but, until now, they have never included only patients with chronic migraine as their population. Objective: To compare serum magnesium levels etween treated and non-treated chronic migraineurs. Methods: Twenty-two patients with chronic migraine were selected and divided in two groups (treated and non-treated), matched by sex and age, and submitted to serum dosage of magnesium ion for latter comparison. Result: The non-treated chronic migraineurs presented serum magnesium ion level within normal limits, but lower than those found in the treated group with a statistically significant difference. Conclusion: Similarly to other studies in the literature, this study stresses the importance of magnesium ion in the migraine pathophysiology, but studying only the chronic migraine patients.