: Resolution of an arachnoid cyst after minor head injury

초록

PURPOSE : Arachnoid cysts are intra-arachnoidal collections of cerebrospinal fluid. It is usually developmental anomalies. It is believed that most of asymptomatic arachnoid cysts do not change over long-term follow-up period although surgical management is required in symptomatic patients. The authors report an 11-year old boy whose arachnoid cyst almost disappeared after minor head injury. MATERIALS AND METHODS : A boy was admitted to a local hospital with a complaint of headache and mild confusion after traffic accident at the age of 8 years. He awoke from loss of consciousness for several minutes. Magnetic resonance imaging (MRI) of brain revealed a 40 x 40 mm sized arachnoid cyst in the right Sylvian area and very thin subdural hygroma in both frontotemporoparietal regions. There was no difference in amount of subdural hygroma between cerebral hemispheres and no midline shifting. He did not have follow up imaging study because he had no symptoms and neurological deficit after recovery from unconsciousness. He was referred to our department for the evaluation of minor head injury at 11 years of age. There was no remarkable abnormal finding on physical and laboratory examination at this time. MRI disclosed almost disappearance of the arachnoid cyst and no evidence of traumatic cerebral lesions. RESULTS : We presume the arachnoid cyst resolved almost completely after minor head injury although it is not clear whether the resolution of arachnoid cyst is directly related to the minor head injury or not. CONCLUSION : This case adds to the literature that the arachnoid cyst can resolve spontaneously or after head injury