# Outcomes of post-operative drain use after cranioplasty surgery – a systematic review and meta-analysis

## TL;DR

This study reviews whether using drains after cranioplasty surgery reduces complications, finding limited evidence of benefit due to inconsistent protocols.

## Contribution

The paper provides a systematic review and meta-analysis evaluating the effectiveness of post-cranioplasty drainage on complication rates.

## Key findings

- Post-cranioplasty drainage was associated with a lower complication rate (8.2%) compared to no drainage (21.7%).
- The pooled risk ratio for complications was 0.51, but the result was not statistically significant (p = 0.095).
- Heterogeneity in drainage protocols limits clear conclusions about their effectiveness.

## Abstract

Cranioplasty restores cranial integrity following decompressive craniectomy or skull trauma. Despite its reconstructive benefits, post-cranioplasty complication rates are high. Post-operative drainage has been proposed to mitigate these risks, yet its effectiveness remains uncertain. This study evaluates the impact of post-cranioplasty drain insertion on surgical outcomes.

A systematic literature search of MEDLINE, Embase, and Cochrane CENTRAL Library was conducted in accordance with PRISMA guidelines (PROSPEROID:CRD420251030365). Studies reporting cranioplasty outcomes with post-operative drainage were selected. Primary outcomes were complication rates, including infection, haemorrhage, and cerebrospinal fluid (CSF) leak.

Four studies met the inclusion criteria, comprising 522 patients (mean age 43.7 years) who underwent cranioplasty—282 with post-operative drainage and 240 without. Following decompressive craniectomy, the most common indications for cranioplasty were traumatic brain injury (196/514, 38.1%), vascular causes (187/514, 36.4%), and infection (25/514, 4.9%). All studies reported subgaleal drain use, with one study (25%) using epidural drains in an unspecified number of patients. The overall post-operative complication rate was 75/522 (14.4%), occurring in 23/282 drained patients (8.2%) and 52/240 (21.7%) undrained patients. A meta-analysis comparing post-operative complication rates across all studies between patients with and without post-cranioplasty drainage yielded a pooled risk ratio (RR) of 0.51 (95% CI: 0.21–1.24, p = 0.095).

The results suggest post-cranioplasty drainage does not significantly alter complication rates. However, heterogeneity in drainage protocols limits attribution of outcomes to specific modalities. Going forward, moderated prospective trials are needed to establish standardised post-cranioplasty drainage protocols.

The online version contains supplementary material available at 10.1007/s00701-025-06766-3.