Rapid antimicrobial-impregnated 3D-printed negative mould technique for PMMA cranioplasty in emergent management of syndrome of the trephined

Syndrome of the trephined is a rare but significant complication which can develop after large craniectomy, characterised by neurological deterioration that typically improves after cranioplasty. Advanced cases can lead to severe neurological impairment, such as impaired consciousness or respiratory failure, requiring urgent surgical intervention. Standard supply chains for custom implants, such as those fashioned from titanium or PEEK, often have prohibitively long turnaround times, unsuitable for emergency cases. The authors present a case of a patient experiencing recurrent apnoeic episodes as a manifestation of the syndrome of the trephined, who underwent an emergent, customised bi-frontal cranioplasty produced using in-house computer-aided design and 3D printing techniques. A 29-year-old patient who suffered a severe traumatic brain injury developed apnoeic episodes post-decompressive craniectomy. Imaging demonstrated significant sinking of the skin flap and distortion of the brainstem, suggestive of syndrome of the trephined. In order to expedite cranioplasty and mitigate the risk of further deterioration, an inlay PMMA graft was rapidly designed and fabricated on-site. The technique involved creation of a MED-610 acrylic positive model from pre-operative imaging, followed by a negative silicone mould, into which a vancomycin- and gentamicin-impregnated PMMA mixture was poured and allowed to cure. The graft was secured with plates and hitch sutures used to relieve brain slump. The production process took approximately 48 h at a fraction of the cost of commercially-available alternatives. The procedure had minimal complications. A favourable cosmetic outcome was achieved, and within days the patient’s apnoeic episodes resolved, allowing ventilation to be weaned. This case illustrates the potential for in-house CAD and 3D printing techniques to significantly reduce turnaround time for cranioplasty in urgent cases. Prefabrication of PMMA grafts reduces operative time and the risk of thermal injury and helps to achieve a good anatomical fit. Use of PMMA cement also allows incorporation of antimicrobial agents, possibly reducing the risk of surgical site infection and the risk of bone flap removal and recurrence of neurological deficits.