Migraine pain is usually cyclic and may be evocated by inflammatory mediators released around the nerves and blood vessels. Acute migraine pain is more common in women than in men, and correlates with age. In this study, we report the development of an acute migraine attack in a young man (32 years old), which led to his admission to the emergency department. The positive functional brain changes recorded by electroencephalogram (EEG) during the migraine attack, and the non-contrast brain computed tomography scan showed the presence of an arachnoid cyst, which explained the acute migraine attack inducing a misdiagnosis. Using the case described herein, we aim to draw the attention of clinic/scientific communities toward the existence of brain infections in absence of the typical symptoms (e.g., fever and/or rigor nucalis). Considering this case, we propose that when a diagnosis is uncertain the invasive liquor test should be performed.