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LETTER TO EDITOR
Year : 2017  |  Volume : 65  |  Issue : 3  |  Page : 660-663

Cost effective, technically simpler, and aesthetically promising cranioplasty in developing countries


1 Department of Neurosurgery, Christian Medical College and Hospital, Vellore, Tamil Nadu, India
2 Department of Dental Surgery, Christian Medical College and Hospital, Vellore, Tamil Nadu, India

Date of Web Publication9-May-2017

Correspondence Address:
Krishna Prabhu
Department of Neurological Sciences, Christian Medical College, Vellore - 632 004, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/neuroindia.NI_210_16

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How to cite this article:
Baldia M, Sharma SA, Prabhu K, Koshy S. Cost effective, technically simpler, and aesthetically promising cranioplasty in developing countries. Neurol India 2017;65:660-3

How to cite this URL:
Baldia M, Sharma SA, Prabhu K, Koshy S. Cost effective, technically simpler, and aesthetically promising cranioplasty in developing countries. Neurol India [serial online] 2017 [cited 2022 Sep 26];65:660-3. Available from: https://www.neurologyindia.com/text.asp?2017/65/3/660/205907


Sir,

Cranioplasty is defined as the surgical repair of acquired defects or congenital deformities of the vault of the cranium. Cranioplasty provides mechanical protection, better cosmesis, and improves neurological impairment that may be present secondary to changes in brain metabolism and cerebral blood flow.[1],[2],[3] The various materials used for cranioplasty are methylmethacrylate, hydroxyapatite, titanium, polyethylene, and allogenic and autologous bone, of which polymethylmethacrylate (PMMA) and titanium are most commonly used.[4] With the introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) techniques and three-dimensional (3D) printers, the fabrication of PMMA prostheses by hand has reduced.[5] However, in situ ations where three-dimensional (3D) printing techniques are unavailable or unaffordable, prefabrication of large PMMA prostheses is still possible using the modified flasking technique, which is highlighted in our article. This technique gives a good prosthesis fit equal to that of a computer-designed prosthesis.

We report five cases wherein 2 patients had a bone flap and the other three did not. The patients in whom the bone flap was available, a direct impression and flasking technique was done, and the patients in whom there was no bone, a negative impression and flasking technique of the skull was done.

Case 1

A 48-year old male patient was referred from another hospital 1 year after a decompressive craniectomy for severe head injury. He had remained in a vegetative state after the first and second surgeries with a Glasgow Coma Scale (GCS) score of 6T/15 (E4M2VT) and had spasticity in all four limbs. A right ventriculoperitoneal shunt had already been placed at another centre for the management of hydrocephalus. On examination, there was a large frontotemperoparietal craniectomy defect with the sunken scalp flap [Figure 1]. Magnetic resonance imaging (MRI) of the brain showed a mass effect on the left frontal horn and third ventricle with effacement of cortical sulci. There was a midline shift of 20 mm towards the right side [Figure 2]. The shunt tube was in situ in the right frontal horn.
Figure 1: Side view of the patient showing the cranial defect

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Figure 2: Preoperative MRI showing the cranial defect

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The original bone flap was examined and the actual bony defect was calculated by placing it on the patient's craniectomy defect. The bone flap was disinfected in the autoclave and the anterior and posterior borders were marked with a permanent marker. The borders of the bone flap were then relined directly on the skull defect using rubber base addition (silicone putty impression material) [Figure 3]. The excess putty was removed and the relined bone flap was rechecked for accurate fitting. Minor adjustments were done till satisfactory adaptation was achieved.
Figure 3: Relining/molding the borders of the original bone flap

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The relined bone flap was coated with a thin layer of petroleum jelly on both the dorsal and ventral sides. A handmade flask was made to make the impression and fabricate the prosthesis. The concave part of the bone flap was immersed in plaster of Paris (POP), and was used as a solid base for flasking as well as an impression material. Three metal pellets were semi-immersed in the POP and used as a stopper and guide to open and close the handmade flask [Figure 4]. The convex part of the bone flap was covered with alginate over which dental stone was used as a base for alginate [Figure 5]. After the setting of the dental stone and alginate, the handmade flask was opened, and the impression of the convexity of the bone was seen on the alginate. The original bone flap was removed from the flask and a mixture of cold cure clear acrylic (polymethylmethacrylate; PMMA) was poured into the flask cavity and closed with the three metal pellets as reference points [Figure 6]. This was kept for 2 hours for complete polymerization, after which the prosthesis was removed from the flask. The prosthesis was considered to be satisfactory as fine details of the cranial suture lines and even the grooves of the middle meningeal arteries were visible. Multiple 2-mm holes were made on the prostheses to allow the seepage of extradural fluid out into the subgaleal space. The prosthesis was then trimmed and polished.
Figure 4: Impression and handmade flasking of the bone flap showing POP as the base and impression material

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Figure 5: Flasking impression of the bone taken with the three metal pellets.

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Figure 6: Acrylic prosthesis

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In the cases (2, 3, and 4) where the bone flap was not available, we took the negative impression from the skull defect with the help of POP and wax. The prosthesis was fabricated using the negative impression with the similar steps mentioned above. After sterilizing the PMMA prosthesis by gas sterilization, it was fixed in situ with silk sutures [Figure 7].
Figure 7: Intraoperative image showing prosthesis fixation with silk sutures

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The postoperative computed tomography (CT) scan of the brain showed the expanded brain on the left side along with the expansion of the left frontal horn of the lateral and third ventricles with a decrease in midline shift [Figure 8]a and [Figure 8]b. The prosthesis had a good alignment with the skull bone. The convexity of the skull contour on the side of the cranioplasty was the same as that of the opposite side. The patient and his family were satisfied with the aesthetic results of the procedure. At follow-up after 5 months, the patient showed symptomatic improvement in terms of his GCS 8 tracheostomised (T)/15(E4VTM4). The neurological and cosmetic outcome of all the cases are summarized in [Table 1].
Figure 8: (a and b) Postoperative CT scan showing the good adaptation of cranioplasty prosthesis to the defect and the decrease in midline shift to 10.5 mm

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Table 1: Summary of the cranioplasty cases

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The ideal implant material should be biocompatible, inert, provide mechanical strength, be resistant to heat, radiolucent, nonmagnetic, light-weight, easy to shape and apply, and inexpensive.[6] Today, both titanium and PMMA are widely used alloplastic materials.[7] However, titanium is more expensive and harder to fabricate than PMMA. PMMA has the advantage of being inert, radiolucent, nonmagnetic, requiring a simple fabrication technique, is relatively inexpensive, and has better mechanical properties.[8],[9]

PMMA prosthesis can be fabricated preoperatively using the original bone flap impression or can be molded intraoperatively using the rough dimensions of the defect. The prefabrication technique is simpler and has the advantage of reduced operative time, blood loss, and infection rate. In addition, the aesthetic result is superior compared to that obtained when an intraoperative moulding is performed. In this case, the prosthesis was fabricated by hand POP flasking. We modified the procedure by the use of POP as an impression material, which gave us the fine details of the bone flap. Instead of a large-sized metal flask, which is ideal, POP was used as a solid base with three metal pellets as a reference for opening and closing the handmade flask. However, the large sized metal flask is not freely available everywhere. In this technique, the handmade flasking showed a good dimensional accuracy. For fixing the acrylic prosthesis, we used silk sutures to ensure cost-effectiveness of the construct instead of using titanium bioplates.

The best cost effective material for cranioplasty is PMMA. However, the material has to be used carefully because of its few unwanted physical properties. The disadvantages of PMMA material are:

  • Exothermic reaction: The PMMA during the setting period generates a temperature of 100°C as its boiling point is 100°C. Even though it raises the epidural temperature up to 64°C, it does not cause any damage to the brain as the meninges dissipate the heat by their extensive vascular supply [10]
  • Change in mechanical properties of the material: During the exothermic reaction, air bubbles form, which coalesce and cause shrinkage of the flap.[10],[11] This directly affects the strength of the material. The strength of the material also depends on the mixture ratio of the polymer and monomer
  • Osteointegration: PMMA material can neither be integrated with bone nor vascularized
  • Infection: The PMMA can give rise to infection due to formation of a biofilm.[12],[13] The bacteria commonly habitat beneath the biofilm, which acts as a protective barrier against the antibiotics. The reported infection rate in various long-term studies was 9.2–19%.[11]


The technique described in this article ideally requires the original bone flap for a good cosmetic outcome. The limitation of the procedure is that the fit may not be precise, if additional bone was bitten off during the craniectomy. However, even if the bone flap is not available, one can create a negative impression and fabricate the flap.

The modified flasking technique is a good option for cranioplasty in situ ations where 3D printers are not available or cannot be used due to the high cost involved. Acrylic cranioplasty flaps, which provide good mechanical protection, cosmesis, and improved functioning are a cost-effective and simple alternative for centres that lack advanced facilities. The background knowledge of its properties and usage must, however, be kept in mind. We need to advocate this technique because it is a feasible option even in rural centres, and results in better cosmetic and neurologic outcomes with fewer complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Isago T, Nozaki M, Kikuchi Y, Honda T, Nakazawa H. Sinking skin flap syndrome: A case of improved cerebral blood flow after cranioplasty. Ann Plast Surg 2004;53:288-92.  Back to cited text no. 1
[PUBMED]    
2.
Kuo JR, Wang CC, Chio CC, Cheng TJ. Neurological improvement after cranioplasty – Analysis by transcranial Doppler ultrasonography. J Clin Neurosci 2004;11:486-9.  Back to cited text no. 2
    
3.
Winkler PA, Stummer W, Linke R, Krishnan KG, Tatsch K. Influence of cranioplasty on postural blood flow regulation, cerebrovascular reserve capacity and cerebral glucose metabolism. J Neurosurg 2000;93:53-61.  Back to cited text no. 3
    
4.
Aydin S, Kucukyuruk B, Abuzayed B, Aydin S, Sanus GZ. Cranioplasty: Review of materials and techniques. J Neurosci Rural Pract 2011;2:162-7.  Back to cited text no. 4
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Dean D, Min KJ, Bond A. Computer aided design of large format-prefabricated cranial plates. J Craniofac Surg 2003;14:819-32.  Back to cited text no. 5
    
6.
Caro-Osorio E, De la Garza-Ramos R, Martínez-Sánchez SR, Olazarán-Salinas F. Cranioplasty with polymethylmethacrylate prostheses fabricated by hand using original bone flaps: Technical note and surgical outcomes. Surg Neurol Int 2013;4:136.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Marchac D, Greensmith A. long term experience with methylmethacrylate cranioplasty in craniofacial surgery. J Plast Reconst Aesthet Surg 2008;61:744-53.  Back to cited text no. 7
    
8.
Sahoo N, Roy ID, Desai AP, Gupta V. Comparative evaluation of autogenous calvarial bone graft and alloplastic materials for secondary reconstruction of cranial defects. J Craniofacial Surg 2010;21:79-82.  Back to cited text no. 8
    
9.
Moreira – Gonzalez A, Jackson IT, Miyawaki T, Barakat K, Dinick V. Clinical outcome in cranioplasty: Critical review in long term follow up. J Craniofac Surg 2003;14:144-53.  Back to cited text no. 9
    
10.
Mason, Thomas O., Barry S. Rose, and Joseph H. Goodman. Gas bubbles in polymethylmethacrylate cranioplasty simulating abscesses: CT appearance. Am J Neuroradiol 1986;7:829-31.  Back to cited text no. 10
    
11.
Jaberi J, Gambrell K, Tiwana P, Madden C, Finn R. Long-term clinical outcome analysis of poly-methyl-methacrylate cranioplasty for large skull defects. J Oral Maxillofac Surg 2013;71:e81-8.  Back to cited text no. 11
    
12.
Peethambaran AK, Gopal VV, Valsalamony J. Four-quadrant osteoplastic decompressive craniotomy: A novel technique for refractory intracranial hypertension-A pilot study. Neurol India 2015;63:895-902  Back to cited text no. 12
    
13.
Gristina AG, Costerton JW. Bacterial adherence to biomaterials and tissue. The significance of its role in clinical sepsis. J Bone Joint Surg Am 1985;67:264-73.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1]

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