Arachnoid Cyst: An Asymptomatic Exuberance

A 66-year-old man presented to the emergency department with sudden onset of dysarthria, left central facial palsy, and left hemihypesthesia involving the tongue. The patient was hemodynamically stable (blood pressure of 153/84 mmHg and heart rate of 80 bpm) and normoglycemic, without a history of trauma or toxic exposure. Assuming an acute stroke, the patient immediately underwent a brain CT scan that revealed a large left-sided fronto-parieto-temporal arachnoid cyst, with approximately 9.5 x 5.1 cm of maximum diameters (anteroposterior and transversal), compressing the brain parenchyma and the ventricular system, with a right deviation of the median structures by about 5 mm. The patient had a complete spontaneous resolution of the initial symptoms while in the emergency department. He declined admission to the ward for observation and further investigation, choosing to be discharged against medical advice. Lately, the patient represented to the ED with a new episode, this time with worsening symptoms, and consented to a cystoperitoneal shunt insertion. The procedure was well tolerated, and the patient has been asymptomatic since surgery.