Early onset of leptomeningeal cyst with severe brain herniation: report of two cases.

Leptomeningeal cyst as a rare complication of skull fracture in children is well documented. Most cases occur months or years after the original skull fracture, with characteristic roentgenogram findings. The authors report two cases of leptomeningeal cysts in children less than two years old. The association of hygroma, severe brain injury, increased ICP, and early development of leptomeningeal cyst are discussed. Both patients sustained parietal diastatic skull fracture and developed external brain herniation within 10 days after motor vehicle accidents. Clinically they presented with seizure, hemiparesis, and an enlarging subgaleal mass over the skull fracture. MRI demonstrated severe underlying brain contusion, hygroma around the fracture site, and brain herniation through the skull fracture. Surgical repair of dural laceration and cranioplasty produced good results. The development of hygroma and increased intracranial pressure might account for the early development of leptomeningeal cysts in these two cases.