Role of traumatic subdural fluid collection in developing process of chronic subdural hematoma.

We investigated the role of traumatic subdural fluid collection in the genesis of chronic subdural hematoma (CSDH) in 43 consecutive patients with traumatic subdural fluid collection. Traumatic subdural fluid collection was found in 43 (6%) of 715 patients who underwent CT scans because of head injury. Twenty-four of the 43 patients were more than 65 years of age and this problem occurred in 30% of the 79 head-injured patients over 65 years of age. In 20 (Group 1) of the 43 patients CSDH subsequently developed. During the same period, 30 other patients were treated for CSDH. Twenty-four (Group 2) of these 30 patients had a history of head injury more than two weeks prior to the developing signs and symptoms and had hyper- or iso-dense hematomas on their first CT scan. It may have been that they too first had a traumatic subdural collection. Forty to sixty percent of the patients with asymptomatic traumatic subdural fluid collection may develop CSDH, and this may occur especially in the older patients. Careful observations after the head injury are particularly important in the aged because of the frequent occurrence of traumatic subdural fluid collection and the subsequent development of CSDH.