Background: Cranioplasty is important to cover defects following skull surgery and trauma for restoration of function and cosmoses. The objective of the study is to describe the author’s technical experience with the use of polymethyl methacrylate (PMMA) implant for cranioplasty to achieve the best results and avoid complications. Methods: The author describes the indications, locations and operative techniques of cranioplasty using polymethyl methacrylate (PMMA) implant for 75 patients. The implant was used to cover any small- or medium-sized (< 8 cm) cranial defect. Techniques have been done to facilitate reconstruction and to avoid complications to get excellent outcome. Results: This implant has been utilized in cases with excellent cosmetic results and no implant-related complications. Conclusions: Polymethyl methacrylate cranioplasty is a widely performed neurosurgical procedure with good cosmetic outcome and with little related implant complications when done in the proper time and proper techniques. Keywords: Cranioplasty, Polymethyl methacrylate, Skull defect Background has better compression and stress resistance than Cranioplasty is the surgical repair of a cranial bone hydroxyapatite; PMMA was shown to adhere to the dura defect, commonly, after a craniectomy or craniotomy for mater without reaction in the underlying tissue [4, 5]. cosmetic and protective effects . This commonly Several factors may influence the appearing of compli- happens when a decompressive craniectomy is needed cations: materials used, age and general conditions of for brain edema due to traumatic injury, ischemic or the patient and the experience of the surgeon on cranial haemorrhagic stroke, after the removal of cranio-dural reconstruction. Cranioplasty contraindications include tumors, depressed fractures or even after the correction infection, hydrocephalus and brain swelling . of skull malformations. This study aimed at achieving the best results and Many materials have been used to repair cranial avoiding complications by using polymethyl methacryl- defects. Ideal material used for cranioplasty would be (1) ate (PMMA) implant for cranioplasty. resistant to infections, (2) not conductive of heat or cold, (3) resistant to biomechanical processes, (4) malleable to Methods fit defects with complete closure and (5) inexpensive . This study was carried out on 75 patients, 46 males There was an evolution of materials from autologous and 29 females, ranging in age from 26 to 60 years grafts, allografts and xenografts to a broad spectrum of (mean = 33 years); posttraumatic cranioplasty was done at synthetic materials (metals and acrylics) used for cranio- least 1 year after trauma. The site of calvarial defect, indi- plasty over time . cations, possible problems encountered and the surgical Polymethyl methacrylate (PMMA) is a polymerized technique to solve these problems were studied. ester of acrylic acid discovered in 1939. PMMA is The inclusion criteria are as follows: strengthly comparable to the bone. Furthermore, PMMA Correspondence: firstname.lastname@example.org Neurosurgery Department, Assiut University Hospital, Assiut, Egypt © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Abd El-Ghani Egyptian Journal of Neurosurgery (2019) 33:7 Page 2 of 4 1. The study included patients with small- and Results medium-sized bone defects either post-traumatic or The indications for cranioplasty in the current study as a secondary procedure in some cranial surgeries. were mainly for reconstruction for bone defects after 2. After some craniotomies for brain tumors where craniotomies performed for benign brain tumors in 45 bone flaps were discarded due to their involvement cases. As well as, for bone defects after compound de- or due to craniectomy even with the existence of pressed skull fractures in 22 cases, five cases were done thick protective muscle mass to reduce the for replacement for symptomatic or complicated metal incidence of postoperative CSF leak . implants. Only one case needed cranioplasty to cover defect after cosmetically disfiguring bone implants, an- The exclusion criteria are as follows: other one for replacement of resorbing craniotomy bone flap and one for leptomeningeal cyst (Table 1). 1. Patients with hydrocephalus, infection and brain This study described that author has used PMMA to swelling cover suboccipital cranial bone defects in 37 cases, 30 2. Children below 4 years old, if there is an intact dura cases were parietal, 3 cases were operated upon for mater, (cranium can achieve self-closure)  temporal bone defect, two cases were for frontal bone defects and only one case was for occipital bone defect All patients were admitted and operated upon in the (Table 2). Neurosurgery Department of Assiut University Hospitals Table 3 clarifies the size of cranioplasty in relation to from January 2011 to January 2016. location. Suboccipital cranioplasty were operated upon Patients with post-traumatic bone defects, complicated 37 cases (49.3%) of medium-sized bone defect, parietal metal implant and cosmetically disfiguring bone im- cranioplasty was done in 22 cases (29.3%) of small size plants underwent 3D-CT scan of skull with measure- and 8 cases (10.7%) were of medium size. In frontal cra- ment of the defect dimensions. nioplasty, one case was small size and one was medium. The mean postoperative follow-up period was One case was small in temporal cranioplasty and 2 were 13 months with a range of 0 to 45 months. Judgment of medium size. The occipital case was medium-sized. Two the cosmetic results were evaluated by both patient cases were medium in fronto-tempro-parietal cranio- satisfaction and postoperative CT. plasty, and no cases were of larger than 8 cm. Excellent reconstruction was obtained in all cases with Materials and techniques of application no implant-related complications. The Cranioplastic kit used (Teknimed, Biomaterials Innovation, Gentafix 1 ®, France) is a biocompatible ma- Discussion terial that is composed of powder and liquid form of Cranioplasty is a commonly performed operation in the polymethyl methacrylate. The powder part consists of field of neurosurgery. The number of craniectomies and polymethyl methacrylate 84.3%, Benzoly peroxide 2.3%, the consequent reconstructive procedures has increased Barium sulphate 9.6% and Gentamicin sulphate corre- during the past decades. Methods of cranioplasty have sponding to 1 g base with 3.8% low viscosity. The liquid developed from using autogenous materials to alloplastic part consists of PMMA 84.4%, Butyl methacrylate 13.2%, materials; the most widely used being is PMMA alone or N-N dimethyl-p-toluidine 2.4% and Hydroquinone: in combination with titanium or wire mesh . In the 20 ppm. current study, the author did not use titanium or wire The whole powder and liquid were mixed and prepared mesh to reduce infection and cost. to obtain a homogenous mixture, the appropriate quantity There are many reports about cranioplasty in litera- of cement was mixed according to the size of the defect, tures such as case series, case-control study, cohort and the final hardening phase takes place in situ. The mixture was carefully mixed so as to minimize the Table 1 Indications for cranioplasty entrapment of air bubbles and then was left alone. Take Indication Number the cement in gloved hands and knead it until it no longer Compound depressed skull fractures 22 adheres to the fingers; insertion in situ can be performed Craniotomies performed for benign tumors 45 after lying down gel foam over the dura. The impact was Complicated metal implant 5 inserted and held firmly in place until the cement had been set hard. Any excess cement is removed before hard- Cosmetically disfiguring bone implants 1 ening. Continuous irrigation with saline is advisable. Replacement of resorbing craniotomy bone flap 1 Hardening time in normal environmental conditions is Leptomeningeal cyst 1 10 min. Fixation of the implant was not performed either Total 75 by titanium screw nor titanium miniplates. Abd El-Ghani Egyptian Journal of Neurosurgery (2019) 33:7 Page 3 of 4 Table 2 Location of reconstruction cranioplasty that the PMMA implant offers a safe, cosmetically alter- native to standard cranioplastic implants. Location Number However, the use of PMMA may be associated with Frontal 2 potential complications including an exothermic reac- Parietal 30 tion produced during the curing process which may Temporal 3 result in local burn and tissue damage; the author advo- Occipital 1 cates the use of wet gel foam underneath the PMMA Suboccipital 37 together with continuous irrigation with saline to lower Fronto-tempro-parietal 2 the temperature. The main challenge in the procedure is not in fresh Total 75 cases such as those after craniotomy for tumors, but it is for cases with trauma or those with thin-scarred scalp. studies, clinical trials and complications data. Major To overcome this problem, the author recommends topics on cranioplasty are such as complications, surgi- planning the scalp incision away from the thin-scarred cal timing, surgical technique, free flap preservation scalp whenever possible. Flap shape needs to be tailored methods, new materials and cost-effectiveness . to patient’s anatomy considering scalp blood supply, es- Few studies provided surgical basis and techniques pecially in cases where vascularization may be already that optimize results and reduce complications [3, 9]. In compromised. In general, it is definitely better to raise a this study, the author describes 75 cases of cranioplasty larger flap . Ensure good contouring of the implant. using PMMA with different indications, sites and sizes Avoid any prominence whether from the implant or as shown in Tables 1, 2 and 3. from the surrounding craniotomy. Try to preserve a The indications for cranioplasty in this study include pericranial flap to form a layer over the implant, this the following: the size of the defect should be larger than pericranial coverage provides good vasculature for over- the size of trephine opening (unless in a cosmetically vis- lying scalp and consequent good wound healing. If good ible location, i.e. forehead), lacks complete covering by implant contour without prominence is achieved, try not thick protective overlying muscle masses, and full thick- to mobilize it; the best one is the first one. Maintain ness scalp covers the area of the cranial defect. good homeostasis. Avoid tight head wrapping to main- Cranial bone defects that occurred after compound tain good blood flow in the scalp and also avoid very wounds, or where the operative site was infected, are loose wrapping to minimize haematoma collection. not indicated for cranioplastic repair until at least 1 year Piitulainen et al.  performed cranioplasties with has elapsed since compounding or last evidence of PMMA bone cement, and 5 out of 11 cases had compli- wound infection. cated implant; 3 patients presented with surgical site infec- In the current study, the policy has been to perform tion, and 2 patients presented with displaced alloplast. immediate cranioplasty for benign cerebral tumor re- “Bone cement reaction” caused by toxicity of methyl meth- movals where bone flap is discarded (i.e. meningiomas), acrylate monomers and exothermic polymerization reaction or craniectomy is used (i.e. suboccipital craniectomy) was one cause for reduced survival of the alloplast. without complications. In the present study, the implant has been used for Conclusions coverage of small- and medium-sized (< 8 cm) cranial Polymethyl methacrylate cranioplasty is a widely per- defects in various locations. This experience suggests formed neurosurgical procedure with good cosmetic outcome and with little related implant complications when done in the proper time and proper techniques. Table 3 Size of reconstructive cranioplasty Abbreviations CSF: Cerebrospinal fluid; PMMA: Polymethyl methacrylate Location Number and size Small (< 4 cm) Medium (4–8 cm) Acknowledgements I would like to express my deep appreciation and sincere gratitude to Prof. Frontal 1 1 Dr. Ahmed Ibrahim Alghriany, Prof. of Neurosurgery, Faculty of Medicine- Parietal 22 8 Assiut University for his kind supervision, valuable advice, perfect guidance and continuous encouragement. Temporal 1 2 Occipital 0 1 Funding The research has not been funded by Assiut Faculty of Medicine Research Suboccipital 0 37 Grant Office. Fronto-tempro-parietal 0 2 Availability of data and materials Total 75 From the corresponding author. Abd El-Ghani Egyptian Journal of Neurosurgery (2019) 33:7 Page 4 of 4 Authors’ contributions The author contributed to the protocol development, manuscript writing and editing, data collection and data management. The author read and approved the final manuscript. Ethics approval and consent to participate This work had the approval from Assiut Medical School Ethical Review Board. Informed consent was taken from all individuals who participated in the study. Competing interests The author declares that he has no competing interests. Publisher’sNote Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Received: 1 October 2017 Accepted: 27 February 2018 References 1. Sanan A, Haines SJ. Repairing holes in the head: a history of cranioplasty. Neurosurgery. 1997;40(3):588–603. 2. Shah AM, Jung H, Skirboll S. 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Egyptian Journal of Neurosurgery
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Published: Jun 1, 2018