[The experience of severe complication in the surgical treatment of chronic subdural hematoma: the usefulness of the burr hole and continuous closed system drainage].

Seventy-four cases of chronic subdural hematoma were treated by burr hole with irrigation (31 cases), and burr hole and closed system drainage with slow decompression (43 cases). The postoperative changes of the clinical symptoms and CT findings in both groups were compared. Markwalder's clinical grading was used for evaluating the clinical symptoms. Preoperative grade distribution was as follows, 16 cases in grade 1, 12 cases in grade 2, 3 cases in grade 3 and no case in grade 4 in the irrigation group, and 22 cases in grade 1, 17 cases in grade 2, 3 cases in grade 3 and no case in grade 4 in the drainage group. There were two cases in the preoperative grade 2 which deteriorated after surgical decompression by burr hole with irrigation. One of them was considered due to brain swelling after abrupt decompression brought on by removal of the hematoma. This case was a 54-year-old male who lost consciousness during operation because of acute brain swelling. Severe neurological deficit such as speech disturbance and gait disturbance remained with him even three years after the operation. No case deteriorated in the drainage group. The postoperative improvement of the midline shift seen by CT scanning was of the same degree in both groups. Air accumulation in the subdural space was found in the irrigation group in all cases. However, it was found in only 5 cases in the drainage group. This study and available literature suggested that slow decompression should be carried out for all cases of chronic subdural hematoma, and we presented a closed system drainage as an example method.