Rapid Spontaneous Resolution of Contralateral Lentiform Acute Subdural Hematoma After Burr Hole Trephination for Chronic Subdural Hematoma.

Although rare, acute subdural hematoma (ASDH) may occur after burr hole trephination (BHT) for chronic subdural hematoma (CSDH). It usually occurs in the hemisphere ipsilateral to the burr hole site and rarely in the hemisphere contralateral to the burr hole site. On computed tomography (CT), SDH is usually crescent-shaped and occasionally lentiform or biconvex, which can be misdiagnosed as epidural hematoma (EDH). In rare cases, ASDH may resolve spontaneously and rapidly. Here, we report a case of rapid spontaneous resolution of contralateral lentiform ASDH after BHT for CSDH in a patient with brain atrophy. A 55-year-old man developed left CSDH 2 months after traumatic brain injury. Left BHT was performed, and a lentiform hematoma, presumed to be EDH, was found in the right frontal region on the CT scan acquired immediately after BHT. On the CT scan acquired 12 hours later, the lentiform hematoma disappeared and spread along the hemisphere. It was presumed to be ASDH. To prevent contralateral ASDH after BHT, slow decompression and minimal gentle or no irrigation should be performed during BHT, particularly in patients with brain atrophy.