A hemicraniectomy is a surgical procedure in which part of the skull is temporarily removed to relieve pressure on the underlying brain. Hemicraniectomies are typically performed on patients experiencing severe brain injury, usually due to stroke or trauma. In these cases, the brain injury and swelling is so severe that it can lead to brain compression and brain death. As a result, a surgeon will remove the bone flap to help with brain swelling and increased intracranial pressure. After the patient heals, a cranioplasty will be performed to restore the bone flap to its original location.