Cranial Defect

To compare the neurological recovery and complication rate of autogenous cranioplasty(CP) within 6 weeks after decompressive craniectomy (DC) with that of autogenous cranioplasty within 3\~6 months after DC.

Polyetheretherketone has become one of the most important material choices for cranioplasty surgery. It has been shown that conventional ultrasound can be performed through the polyetheretherketone material for the examination of brain tissue and ventricular morphology. Transcranial doppler ultrasound can obtain good images of cerebral hemodynamic parameters in patients through polyetheretherketone-covered temporal window. This trial is a clinical prospective observational study in which cases treated with polyetheretherketone cranioplasty, and transcranial doppler ultrasonography is performed preoperatively and 10 days postoperatively, and data were collected mainly including bilateral hemodynamic parameters of middle cerebral artery(MCA), terminal internal carotid artery(TICA), (anterior communicating artery)ACA, and posterior cerebral artery(PCA) (Vs, Vd, Vm, PI index, RI index) from temporal window.