RESUMO
Arachnoid cysts are responsible for 1% of expansive lesions in the central nervous system. Usually, they do not cause neurologic symptoms unless they have expansion or hemorrhage. Intracystic bleeding is caused by trauma or may be spontaneous. There are few cases in the literature of spontaneous hemorrhage of arachnoid cysts. This 2-dimensional video (Video 1) demonstrates the case of a 6-year-old boy who presented with headache and diplopia. At the physical examination, he exhibited right sixth nerve palsy. The complementary examinations revealed a left middle fossa arachnoid cyst classified as Galassi 2. An urgent procedure was planned to fenestrate the cyst. Informed written consent was obtained from the patient's family. Due to the team experience, endoscope-controlled microsurgery was performed. The patient experienced remission of the headache and the diplopia. A CT scan was performed on the first postoperative day and revealed a lamina of acute blood at the subdural space. It was an asymptomatic thin lamina of blood; we opted to watch and follow. One month later, a control MRI revealed a left frontoparietal subdural hematoma. Despite being asymptomatic, the hematoma was determined to have significant mass effect; thus, it was evacuated by a parietal burr-hole. After 1 month, another MRI showed resolution of the frontoparietal hematoma and significant reduction in the arachnoid cyst. There are few cases described of spontaneous rupture of arachnoid cyst; beyond that, we would like to illustrate a step-by-step procedure that is not widely available as a video article.