Arachnoid cyst with complicating intracystic and subdural haemorrhage.

Intracranial arachnoid cysts are usually non-symptomatic. Intracystic and subdural haematomas induced by even minor head injury may turn an asymptomatic AC into a symptomatic one, necessitating surgical treatment. We present a case of a previous asymptomatic AC, spontaneously complicated with subdural hygroma and development of intracystic and subdural haematoma. Clinical follow-up and control CT regime of patients with AC are recommended.