The purpose of this prospective, multi-center randomized controlled trail is to compare the safety and efficacy of sequential surgery or staged surgery in patients with skull defect and hydrocephalus. The main observation will be the occurrence of complications such as postoperative infection, reoperation, shunt tube obstruction, hematoma, and subdural effusion. This will provide high-quality evidence for clinical selection of appropriate strategies.The concurrent surgery group needs to complete the VPS and CP in the same operation, and the sequence of the surgeries is determined based on the patient's condition and is recorded.However, the staged surgery group requires two surgeries, with an interval of 2 to 8 weeks and the operation order is determined by randomization.Within 1 week after surgery, participants should cooperate to monitor vital signs, assess neurological function ( such as GCS、GOS, etc.), conduct head CT examinations regularly to observe the postoperative intracranial condition, and record the occurrence of postoperative complications.Postoperative follow-up should last for at least 6 months.Outpatient or telephone follow-ups should be conducted at 1 week, 1 month, 3 months, and 6 months after the surgery.During each follow-up, a neurological function assessment and quality of life score (such as the SF-36 Health Survey) should be completed, and the occurrence of postoperative complications should be recorded.

Study Design and Setting This study is a prospective, multi-center randomized controlled trail and partly conducted in the First Affiliated Hospital of USTC in China.Patients especially who have following conditions:(1、having a history of prior CP or VPS. surgical.2、requiring bilateral CP.3、unsuitable for simulataneous surgery) will be recruited to the study.Before the operation, patients and their family member will be fully informed of the surgical risks.

Evaluation Endpoints Efficacy Endpoints:1. Neurological functional recovery: Assessed using the modified Rankin Scale (mRS) and Glasgow Coma Scale (GCS). Improvement is defined as a reduction in mRS score of ≥1 point or an increase in GCS score of ≥2 points at 12 months postoperatively.

2. Change in ventricular size: Postoperative cranial CT at 6 months showing a ≥20% reduction in the width of the lateral ventricular body compared to preoperative measurements.

Safety Endpoints1. Subdural effusion: Incidence of subdural fluid collection >1 cm in thickness with mass effect, as shown on CT scan at 1 month postoperatively.

2. Infection: Incidence of overall infection, central nervous system infection, cranioplasty site infection, and shunt infection.

3. Shunt obstruction: Incidence of shunt obstruction requiring surgical revision within 6 months postoperatively.

4. Hematoma: Incidence of epidural/subdural hematoma or intracranial hematoma requiring intervention.

5. Reoperation rate: Proportion of patients requiring secondary surgery due to complications within 1 year postoperatively.

Inclusion Criteria:

• 1.Patients who have undergone decompressive craniectomy (DC) for conditions such as Traumatic Brain Injury (TBI), Intracerebral Hemorrhage (ICH), Subarachnoid Hemorrhage (SAH), or Ischemic Stroke (IS), and present with a skull defect concurrent with hydrocephalus. Hydrocephalus must be confirmed by cranial CT/MRI and cerebrospinal fluid pressure measurement.

  2.A definitive diagnosis of hydrocephalus must meet the following criterion: presence of ventriculomegaly (Evans Index > 0.3), accompanied by either elevated intracranial pressure (or high bone flap pressure) OR clinical symptoms such as headache, vomiting, or impaired consciousness.

  3.Baseline characteristics: Age between 18 and 70 years, any gender, stable vital signs, and medically fit to tolerate surgery.

  4.Informed consent: The patient or their legal guardian must provide written informed consent.

Exclusion Criteria:

1. Patients with a history of prior cranioplasty (CP) or ventriculoperitoneal shunt (VPS) surgery (i.e., re-operation cases).
2. Patients requiring bilateral cranioplasty.
3. Patients deemed unsuitable for simultaneous surgery, such as those with excessively bulging or tense bone flaps that preclude safe cranioplasty.
4. Patients with severe organ failure, coagulation dysfunction, or other systemic conditions that render them unable to tolerate major surgery.
5. Patients with active intracranial infection, abdominal infection, or systemic infection during the acute phase.
6. Patients with a known allergy or hypersensitivity to the surgical materials used (e.g., PEEK implants, shunt components).
7. Pregnant or lactating women.
8. Patients unable or unwilling to comply with the required follow-up schedule. -