[Relationship of postoperative residual air and recurrence in chronic subdural hematoma].

The possibility exists that residual air after surgery is one cause of recurrence of chronic subdural hematoma. We have devised a new simple method which decreases postoperative residual air, using external drainage and an endoscope. First, we make endoscopic observations of the inner aspect of the hematoma cavity. Then, we insert external drainage apparatus into the most frontal area of the hematoma cavity, we regard this location as the most appropriate place to ensure most effective drainage. The present study included 37 chronic subdural hematomas in 32 patients who had been treated between January and December, 1999. Their ages ranged from 48 to 86 years old, with an average of 72 years. Insertion of external drainage in the most frontal area of the hematoma cavity was successfully achieved in 27 (73%, Group I) out of 37 cases and resulted in no recurrence. In the remaining 10 hematomas (27%, Group II), external drainage was not able to be inserted in the most frontal area, and four hematomas (40%) had recurrence (p < 0.01 vs Group I). Insertion in the most frontal area of the hematoma cavity decreases residual air after surgery, and may be effective for the prevention of recurrence of chronic subdural hematoma.