Background: Decompressive craniectomy (DC) is a crucial intervention for managing severe brain injury. The optimal timing for subsequent cranioplasty (CP) to maximize benefits and minimize complications is debated. This meta-analysis aims to synthesize current evidence to ascertain the impact of early versus delayed cranioplasty on neurological postoperative outcomes and complication rates.

Methods: An exhaustive literature search was conducted across PubMed, Scopus, and Embase up to January 2024, focusing on studies that addressed the timing of cranioplasty after craniectomy. The inclusion criteria were specifically designed to capture cross-sectional and retrospective studies, and case series of four or more adult patients, which directly examined the timing of cranioplasty. Studies not focused on timing, including those comparing materials, reporting techniques, or presenting cases with fewer than four patients, were excluded. Data extraction emphasized study design, patient demographics, timing intervals, and related outcomes, ensuring a rigorous quality assessment using the Newcastle-Ottawa Scale. Statistical analyses were aimed at evaluating study heterogeneity and synthesizing data regarding timing and its impact on outcomes.

Results: From the initial screening to the final selection, 7 studies with a total of 1009 patients were analyzed. The meta-analysis elucidates a significant association between the timing of cranioplasty and both neurological outcomes and complication rates. Notably, cranioplasty performed within 90 days post-craniectomy was linked to improved neurological recovery and reduced complication rates compared to delayed cranioplasty. Moreover, an ultra-early timing (within 30 days) was associated with lower infection rates but an increased risk of hydrocephalus, underscoring the complexity of timing decisions.

Conclusion: This meta-analysis provides compelling evidence that the timing of cranioplasty significantly influences neurological recovery and the incidence of postoperative complications. Early cranioplasty, preferably within 90 days of craniectomy, appears to offer advantages in terms of outcome and safety. However, the decision regarding timing should be carefully tailored to individual patient conditions, considering the nuanced balance between benefits and risks. Further high-quality, prospective studies are needed to refine these findings and support evidence-based clinical decision-making in cranioplasty timing.