Chronic subdural hematoma preceded by traumatic subdural hygroma.

Patients with traumatic subdural hygroma (SDG) are at an increased risk of developing chronic subdural hematoma (CSDH). However, the mechanism by which this occurs is still not fully understood. The purpose of this paper is to investigate the clinical characteristics and pathogenesis of CSDH, as well as the relationship between CSDH and SDG. We review the pertinent literature and retrospectively examine a series of cases in which CSDH had been preceded by SDG to understand the natural history and developmental mechanisms of these lesions. We discuss the cases of 24 patients in whom CSDH developed from traumatic SDG between 2001 and 2005. Headache was the most common symptom, and the mean Glasgow Coma Scale score was 14.1. Increases in SDG volume were observed in CT scans of 17 patients, and increased density and volume was observed in five patients. The mean interval between the two diseases was 57.6 days, and 13 patients developed new symptoms after the development of CSDH. The most common symptoms at that time were headache and hemiparesis. All patients underwent an operation, which resulted in good recovery in all but one case. The cycle of persistent SDG, rebleeding, coagulation and fibrinolysis contributes to the development of CSDH from SDG. It is important to understand the natural history of CSDH and carefully follow up patients with head injury, especially if it is associated with SDG, and the potential for the development of CSDH should be considered.