Decompressive craniectomy
Decompressive craniectomy (crani- + -ectomy) is a neurosurgical procedure in which part of the skull is removed to allow a swelling or herniating brain room to expand without being squeezed. It is performed on victims of traumatic brain injury, stroke, Chiari malformation, and other conditions associated with raised intracranial pressure.
Source: Wikipedia — Decompressive craniectomy (CC BY-SA 4.0)