Optimal timing of cerebrospinal fluid shunting in patients needing cranioplasty

Cranioplasty is performed to repair the cranium after injury or surgery. Cerebrospinal fluid shunts are commonly required to treat associated hydrocephalus. Single-stage shunt and cranioplasty surgery have been associated with increased risks compared with a staged approach. We aimed to assess whether the timing of cerebrospinal fluid (CSF) shunting (pre- or post-cranioplasty) affects complication rates.

We retrospectively identified all cranioplasty procedures conducted between 11/2017-12/2021 and 1/2004-3/2022 from the Cambridge and Oulu University Hospitals, respectively. The primary and secondary outcomes were implant removal and complications, respectively.

Four-hundred-and-thirty-three cranioplasties were performed in 379 patients. Sixty-eight (16 %) cranioplasties were performed in patients requiring a shunt. Forty-three (63 %) shunts were inserted before, three (4 %) during, and 22 (32 %) after cranioplasty. Overall complication rates excluding hydrocephalus were 47 % and 41 % among those shunted before and after cranioplasty, respectively (OR 0,74, 95 % CI 0,24-2,28). SSIs (26 % vs. 18 %) and CSF leaks (7 % vs. 0 %) were slightly more common among those shunted before cranioplasty compared to those shunted after cranioplasty, respectively, but rates of post-operative haematomas were similar (5 % vs. 5 %, respectively). Overall implant removal rates were statistically similar between patients with shunts cited pre-cranioplasty and those with shunts cited after cranioplasty (26 % vs. 32 %, respectively, OR 1,26, 95 % CI 0,44-3,55).

Although patients who underwent CSF shunting before cranioplasty had 6 % more complications than those who had been shunted after cranioplasty, those shunted after cranioplasty had 6 % more implant failures. Delaying CSF shunt insertion after cranioplasty should be preferable, not least because CSF absorption can improve on cranioplasty insertion. Single-stage surgery should be avoided.