Abstract
Two cases of chronic subdural hematoma after craniotomy, removal of the hematoma, dural plasty using lyophilized human cadaver dura mater, and external decompression for acute traumatic intracranial hematoma are reported. One of these was acute subdural hematoma and the other acute epidural hematoma. The pathophysiology of the chronic subdural hematoma in these two cases was considered to be: collection of a mixture of cerebrospinal fluid and blood in the subdural space caused by torn arachnoid at head injury or craniotomy, and unbalanced volume between the brain and subdural space caused by excessive dural plasty and intracranial hypotension due to external decompression. Opening and irrigation of the hematoma cavity were sufficient treatment at cranioplasty.