The use of frozen autogenous bone flaps in delayed cranioplasty revisited

OBJECTIVE: To reevaluate the use of frozen autogenous bone flaps for patients undergoing delayed cranioplasty. METHODS: In the past 12 years, 49 patients have undergone delayed cranioplasty using frozen autogenous bone flaps. Bone flaps removed during the initial operation were sealed in three sterilized vinyl bags and stored at -35 degrees C (n = 37) or -84 degrees C (n = 12) for 4 to 168 days (mean, 50.6 d). The bone flaps were thawed at room temperature and replaced in their original positions. After cranioplasty, we monitored resorption of the bone flaps with computed tomography and evaluated the clinical and aesthetic results. Follow-up periods ranged from 14 to 147 months (mean, 59.2 mo). RESULTS: For 47 patients (95.9%), there were no complications during the follow-up period; there was slight thinning of the bone flap in some cases, but clinical and aesthetic results were highly satisfactory. Resorption was observed for a 12-year-old boy who had undergone cranioplasty, using two pieces of bone flap, 66 days after the initial operation. A 14-year-old boy with a cerebral contusion experienced a bone flap infection. Both patients underwent a second cranioplasty procedure, with ceramic plates. CONCLUSION: The clinical and aesthetic results of delayed cranioplasty using frozen autogenous bone flaps were satisfactory. The most important factor for success was excellent contiguity between the flap and the bone edge.     

Preservation of bone flaps in patients with postcraniotomy infections

OBJECT: Management of postcraniotomy wound infections has traditionally consisted of operative debridement and removal of devitalized bone flaps followed by delayed cranioplasty. The authors report the highly favorable results of a prospective study in which postcraniotomy wound infections were managed with surgical debridement to preserve the bone flaps and avoid cranioplasty. METHODS: Since 1990, 13 patients with postcraniotomy wound infections have been prospectively treated with open surgical debridement and replacement of the bone flap. All patients received a full course of systemic antibiotic agents based on the determination of the bacterial culture and antibiotic sensitivity. Notable risk factors for infection included prior craniotomies, radiotherapy, and skull base procedures. The mean long-term follow-up period was 35 +/- 20 months. In all five patients who underwent craniotomies without complications, bone flap preservation was possible with full resolution of the infection and without the need for additional surgery. Among the eight patients with risk factors, bone preservation was possible in six patients, although two required minor wound revisions (without bone flap removal). Both patients who underwent craniofacial procedures required an additional procedure in which the bone flap was removed for recurrent infection (one after 2 months and the other after 29 months). CONCLUSIONS: In patients with uncomplicated postcraniotomy infections, simple operative debridement is sufficient and it is not necessary to discard the bone flaps and perform cranioplasties. Even patients with risk factors such as prior surgery or radiotherapy can usually be treated using this strategy. Patients who undergo craniofacial surgeries involving the nasal sinuses are at higher risk and may require bone flap removal.     

灭活自体颅骨回植钛铆钉固定的临床应用

目的 总结灭活自体颅骨回植以钛铆钉固定进行颅骨修补术的临床应用经验。方法 2000年3月至2003年12月对21例急性颅脑损伤等去骨瓣减压或颅骨本身受肿瘤侵蚀的患者，行自体颅骨普通冰箱冰冻保存后煮沸消毒，早期回植或受肿瘤侵蚀的骨瓣灭活后一期回植，以钛铆钉固定，随访观察修复效果。结果 所有病例伤口均一期愈合，无并发症发生，随访6个月至2年半，X射线片及CT显示回植骨瓣边缘吸收未超出钛铆钉固定范围，头颅外观及牢度良好，肿瘤无复发。结论 灭活自体颅骨回植进行颅骨修补术，方法简单、实用，利用钛铆钉固定可有效防止因回植骨瓣边缘吸收而导致的牢度下降。     

A systematic review and meta-analysis of factors involved in bone flap resorption after decompressive craniectomy

Decompressive craniectomy (DC) is effective in controlling increasing intracranial pressure determined by a wide range of conditions, mainly traumatic brain injury (TBI) and stroke, and the subsequent cranioplasty (CP) displays potential therapeutic benefit in terms of overall neurological function. While autologous bone flap (ABF) harvested at the time of DC is the ideal material for skull defect reconstruction, it carries several risks. Aseptic bone flap resorption (BFR) is one of the most common complications, often leading to surgical failure. The aim of our study was to systematically review the literature and carry out a meta-analysis of possible factors involved in BFR in patients undergoing ABF cranioplasty after DC. A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. Different medical databases (PubMed, Embase, and Scopus) were screened for eligible scientific reports until April 30th 2021. The following data were collected for meta-analysis to assess their role in BFR: sex, age, the interval time between DC and CP, the presence of systemic factors, the etiology determining the DC, CP surgical time, CP features, VP shunt placement, CP infection. Studies including pediatric patients or with less than 50 patients were excluded. Fifteen studies were included. There was a statistically significant increased incidence of BFR in patients with CPF?>?2 compared to patients with CPF?≤?2 (54.50% and 22.76% respectively, p?=?0.010). TBI was a significantly more frequent etiology in the BFR group compared to patients without BFR (61.95% and 47.58% respectively, p?<?0.001). Finally, patients with BFR were significantly younger than patients without BFR (39.12?±?15.36 years and 47.31?±?14.78 years, respectively, p?<?0.001). The funnel plots were largely symmetrical for all the studied factors. Bone flap fragmentation, TBI etiology, and young age significantly increase the risk of bone resorption. Further studies are needed to strengthen our results and to clarify if, in those cases, a synthetic implant for primary CP should be recommended.

     

Bone flap storage following craniectomy: a survey of practices in major Australian neurosurgical centres

Introduction: The resurgence of decompressive craniectomy surgeries for management of intracranial hypertension has led to a parallel increase in cranioplasty procedures for subsequent reconstruction of the resultant extensive skull defects. Most commonly, cranioplasties are performed using the patients' own cryopreserved skull flaps. Currently, there are no standardized guidelines for freeze‐storage of bone flaps either nationally or internationally. In this initial study, the authors surveyed major neurosurgical centres throughout Australia to document current clinical practices. Methodology: Twenty‐five neurosurgical centres affiliated with major public, teaching hospitals in all Australian states were included in the current survey study. A standardized survey guide incorporating standardized questions was used for data collection either by phone interviews and/or electronic (email) communication. Details regarding bone flap preparation following craniectomy, temperature and duration of freeze‐storage, infection control/micro‐contamination detection protocols, pre‐implantation procedures were specifically recorded. Results: Cranioplasty using cyropreserved autogenous bone flaps remains the most common (96%) mode of skull defect reconstruction in major neurosurgical centres throughout Australia. Following the initial craniotomy, the harvested skull flaps were most frequently (88%) double‐ or triple‐bagged under dry, sterile conditions. In 16% of hospitals, skull flaps were irrigated either with antibiotic mixed‐saline or Betadine prior to cryopreservation. Skull biopsies or swabs were obtained from the skull flaps for micro‐contamination studies in accordance with departmental protocol in 68% of hospitals surveyed. Subsequently, the bone flaps were cryopreserved at wide ranging temperatures between ?18°C to ?83°C, for variable time intervals (6 months to ‘until patient deceased’). Twelve neurosurgical centres (48%) elected for bone flap storage to be undertaken at the local bone bank. In the remainder (52%) of the hospitals, bone flaps were cryopreserved in locally maintained freezers. Prior to re‐implantation of the skull flaps at subsequent cranioplasty surgeries, six (24%) of the neurosurgical centres had specific thawing procedures involving immersion of the frozen bone flaps in Ringer's solution and/or Betadine. Further pre‐implantation bacteriological cultures from bone biopsies or swabs were obtained only in three (12%) hospitals. Conclusions: This study has documented highly varied skull flap cryopreservation and storage practices in neurosurgical centres throughout Australia. These differences may contribute to relatively high complication rates of infection and bone resorption reported in the literature. The results of the current study argue for the further need of high quality clinical and basic science research, which aims to characterize the effect of current skull flap management practices and freeze‐storage conditions on the biological and biomechanical properties of skull bone.     

Ethylene oxide gas sterilization: a simple technique for storing explanted skull bone. Technical note

The authors evaluated the effectiveness of a simple technique using ethylene oxide (EtO) gas sterilization and room temperature storage of autologous bone grafts for reconstructive cranioplasty following decompressive craniectomy. The authors retrospectively analyzed data in 103 consecutive patients who underwent cranioplasty following decompressive craniectomy for any cause at the University of Illinois at Chicago between 1999 and 2005. Patients with a pre-existing intracranial infection prior to craniectomy or lost to follow-up before reconstruction were excluded. Autologous bone grafts were cleansed of soft tissue, hermetically sealed in sterilization pouches for EtO gas sterilization, and stored at room temperature until reconstructive cranioplasty was performed. Cranioplasties were performed an average of 4 months after decompressive craniectomy, and the follow-up after reconstruction averaged 14 months. Excellent aesthetic and functional results after single-stage reconstruction were achieved in 95 patients (92.2%) as confirmed on computed tomography. An infection of the bone flap occurred in eight patients (7.8%), and the skull defects were eventually reconstructed using polymethylmethacrylate with satisfactory results. The mean preservation interval was 3.8 months in patients with uninfected flaps and 6.4 months in those with infected flaps (p = 0.02). A preservation time beyond 10 months was associated with a significantly increased risk of flap infection postcranioplasty (odds ratio [OR] 10.8, p = 0.02). Additionally, patients who had undergone multiple craniotomies demonstrated a trend toward increased infection rates (OR 3.0, p = 0.13). Data in this analysis support the effectiveness of this method, which can be performed at any institution that provides EtO gas sterilization services. The findings also suggest that bone flaps preserved beyond 10 months using this technique should be discarded or resterilized prior to reconstruction.     

Composite skull and dura defect reconstruction using combined latissimus dorsi musculocutaneous and serratus anterior muscle‐rib free flap coupled with vascularized galea transfer: A case report

Recalcitrant epidural abscess following cranioplasty is a complicated problem, which becomes even more trying when large span of dura and skull bone are being replaced by alloplastic materials. A 22‐year‐old male underwent right fronto‐temporo‐parietal craniectomy and duroplasty with artificial dura graft after traumatic brain injury. Epidural abscesses recurred after cranioplasty with autologous bone graft as well as with a methyl methacrylate bone plate. The massive defects of both the dura and skull bone (15 × 9 cm) caused by radical debridement were reconstructed successfully with a combined free latissimus dorsi and serratus anterior myo‐osseous flap transfer plus galea flap transposition. Proper contour and adequate stability of the construct were maintained during 2‐year follow up without episodes of relapsing infection. © 2010 Wiley‐Liss, Inc. Microsurgery, 2010.     

Histopathology of subcutaneously preserved autologous bone flap after decompressive craniectomy: a prospective study

Background

Limited reports are available regarding the viability of subcutaneously preserved autologous bone flaps after decompressive craniectomy. The present study was undertaken to evaluate the histopathological changes in these autologous bone flaps.

Methods

Between January 2011 and July 2012, 50 patients were prospectively studied at the time of cranioplasty. Bone flap retrieved from the abdominal wall was subjected to histopathological examination to look for mononuclear cell infiltration into the Haversian system, presence of osteocytes, osteoblastic activity, angiogenesis and new bone formation. Microbiological culture of bone specimens was also done.

Results

Of the 50 patients, there were 40 cases of trauma, 6 of aneurysmal bleed, 2 of tumor, and a single case of intracerebral hemorrhage and middle cerebral artery infarct, respectively. Mean age of the patients was 35.8 years (range, 10–64 years). Histopathological examination revealed the presence of osteocytes in 86 %, which indicates the viability of bone flaps. Osteoblastic activity was noted in 38 % and angiogenesis in 14 % of bone flaps, respectively. New bone formation was found in 6 %, and all had underlying osteoblastic activity. No significant correlation was found between the presence of osteocytes, osteoblasts, angiogenesis and duration of preservation of bone flaps. Acinetobacter species were cultured in a single patient. However, there was no evidence of clinical infection.

Conclusions

Subcutaneously preserved bone flap in the anterior abdominal wall remains viable and retains its osteogenic potential, and it is a simple, cost-effective option for storage of bone flaps during decompressive craniotomy. It has a negligible infection rate.     

Salvage of infected craniotomy bone flaps with the wash-in, wash-out indwelling antibiotic irrigation system. Technical note and case series of 12 patients

OBJECT: When complicated by infection, craniotomy bone flaps are commonly removed, discarded, and delayed cranioplasty is performed. This treatment paradigm is costly, carries the risks associated with additional surgery, and may cause cosmetic deformities. The authors present their experience with an indwelling antibiotic irrigation system used for the sterilization and salvage of infected bone flaps as an alternative to their removal and replacement. METHODS: The authors retrospectively reviewed the medical records for 12 patients with bone flap infections following craniotomy who received treatment with the wash-in, wash-out indwelling antibiotic irrigation system. Infected flaps were removed and scrubbed with povidone-iodine solution and soaked in 1.5% hydrogen peroxide while the wound was debrided. The bone flaps were returned to the skull and the irrigation system was installed. Antibiotic medication was infused through the system for a mean of 5 days. Intravenous antibiotic therapy was continued for 2 weeks and oral antibiotics for 3 months postoperatively. Wound checks were performed at clinic follow-up visits, and there was a mean follow-up period of 13 months. Eleven of the 12 patients who had undergone placement of the bone flap irrigation system experienced complete resolution of the infection. In five patients there was involvement of the nasal sinus cavities, and in four there was a history of radiation treatment. In the one patient whose infection recurred, there was both involvement of the nasal sinuses and a history of extensive radiation treatment. CONCLUSIONS: Infected bone flaps can be salvaged, thus avoiding the cost, risk, and possible disfigurement associated with flap removal and delayed cranioplasty. Although prior radiation treatment and involvement of the nasal sinuses may interfere with wound healing and clearance of the infection, these factors should not preclude the use of irrigation with antibiotic agents for bone flap salvage.     

Intraoperative template-molded bone flap reconstruction for patient-specific cranioplasty

Cranioplasty is a common neurosurgical procedure. Free-hand molding of polymethyl methacrylate (PMMA) cement into complex three-dimensional shapes is often time-consuming and may result in disappointing cosmetic outcomes. Computer-assisted patient-specific implants address these disadvantages but are associated with long production times and high costs. In this study, we evaluated the clinical, radiological, and cosmetic outcomes of a time-saving and inexpensive intraoperative method to mold custom-made implants for immediate single-stage or delayed cranioplasty. Data were collected from patients in whom cranioplasty became necessary after removal of bone flaps affected by intracranial infection, tumor invasion, or trauma. A PMMA replica was cast between a negative form of the patient's own bone flap and the original bone flap with exactly the same shape, thickness, and dimensions. Clinical and radiological follow-up was performed 2?months post-surgery. Patient satisfaction (Odom criteria) and cosmesis (visual analogue scale for cosmesis) were evaluated 1 to 3?years after cranioplasty. Twenty-seven patients underwent intraoperative template-molded patient-specific cranioplasty with PMMA. The indications for cranioplasty included bone flap infection (56%, n?=?15), calvarian tumor resection (37%, n?=?10), and defect after trauma (7%, n?=?2). The mean duration of the molding procedure was 19?±?7?min. Excellent radiological implant alignment was achieved in 94% of the cases. All (n?=?23) but one patient rated the cosmetic outcome (mean 1.4?years after cranioplasty) as excellent (70%, n?=?16) or good (26%, n?=?6). Intraoperative cast-molded reconstructive cranioplasty is a feasible, accurate, fast, and cost-efficient technique that results in excellent cosmetic outcomes, even with large and complex skull defects.     

Use of hinge craniotomy for cerebral decompression. Technical note

Decompressive craniectomy to relieve cerebral edema and intracranial hypertension due to traumatic brain injury is a generally accepted practice; however, the procedure remains controversial because of its uncertain effects on outcome, specific complications such as the syndrome of the sinking skin flap, and the need for subsequent cranioplasty. The authors developed a novel craniotomy technique using titanium bone plates in a hinged fashion, which maintains cerebral protection while reducing postoperative complications and eliminating subsequent cranioplasty procedures. The authors conducted a retrospective review of data obtained in all consecutive patients who had undergone posttraumatic cerebral decompression craniotomy using the hinge technique at a Level I trauma facility between 1990 and 2004. Twenty-five patients, most of whom were male (88%) and Caucasian (88%) with a mean age of 38.2 +/- 16.1 years, underwent the hinge craniotomy. The in-hospital mortality rate was 48%, and good cerebral decompression was achieved. None of the patients required surgery for flap replacement. Long-term follow-up data showed that one patient required subsequent cranioplasty due to infection and one patient presented with cranial deformities. None of the patients presented with bone resorption or sinking flap syndrome. The hinge technique effectively prevents procedure-related morbidity and the need for subsequent surgical bone replacement otherwise introduced by traditional decompressive craniectomy. A randomized controlled trial is required to substantiate these findings.     

Management of a large skull defect utilizing a vascularized free omental transfer

A patient who underwent prior cranial surgery and radiation therapy and had the loss of his bone and skin flaps is presented. Basal cell carcinoma of a skin graft, placed on the dura mater and osteomyelitis of the surrounding cranium subsequently occurred. This problem of infection, neoplasia, cerebral protection, coverage, and cosmesis was managed successfully with a complex repair. The repair utilized autogenous fascia lata for the replacement of dura mater, rib and iliac crest bone for an autogenous cranioplasty, a free vascularized omental transfer for soft tissue bulk overlying the cranioplasty, and an autogenous split thickness skin graft over the omentum for coverage. Subsequent partial resorption of the autogenous cranioplasty necessitated the placement of a methyl methacrylate cranioplasty.     

Microbial contamination assessment of cryostored autogenous cranial bone flaps: should bone biopsies or swabs be performed?

Background

Autogenous cranioplasty infection requiring bone flap removal is under-recognised as a major complication causing significant morbidity. Microbial contamination of stored bone flaps may be a significant contributing factor. Current infection control practices and storage procedures vary. It is not known whether ‘superficial’ swabs or bone cultures provide a more accurate assessment.

Method

Twenty-five skull flaps that were cryo-stored for more than 6 months were studied. Two swab samples (superficial and deep) and a bone biopsy sample were taken from each skull flap sample and cultured. Half blood agar and half chocolate agar plates were inoculated with the swabs for anaerobic and aerobic cultures respectively. The bone biopsy samples were cultured in brain-heart broth and subcultured similar to the swabs for 5 days.

Results

Incidence of microbial contamination was 20 % in the bone flaps studied. One swab culture and five bone biopsy cultures were positive for bacterial growth, all of which contained Propionibacterium acnes (p?=?0.014). Positive cultures were from bone flaps stored less than 18 months, whereas no growth was obtained from bone flaps that were stored longer (p?=?0.014).

Conclusions

Bone biopsy culture is a more sensitive technique of assessing microbial contamination of cryo-stored autogenous bone flaps than swab cultures. The clinical implications of in vitro demonstration of microbial contamination require further study.     

Cranioplasty with autologous cryopreserved bone after decompressive craniectomy. Complications and risk factors for developing surgical site infection

Background

Renewed interest has developed in decompressive craniectomy, and improved survival is shown when this treatment is used after malignant middle cerebral artery infarction. The aim of this study was to investigate the frequency and possible risk factors for developing surgical site infection (SSI) after delayed cranioplasty using autologous, cryopreserved bone.

Methods

This retrospective study included 74 consecutive patients treated with decompressive craniectomy during the time period May 1998 to October 2010 for various non-traumatic conditions causing increased intracranial pressure due to brain swelling. Complications were registered and patient data was analyzed in a search for predictive factors.

Results

Fifty out of the 74 patients (67.6 %) survived and underwent delayed cranioplasty. Of these, 47 were eligible for analysis. Six patients (12.8 %) developed SSI following the replacement of autologous cryopreserved bone, whereas bone resorption occurred in two patients (4.3 %). No factors predicted a statistically significant rate of SSI, however, prolonged procedural time and cardiovascular comorbidity tended to increase the risk of SSI.

Conclusions

SSI and bone flap resorption are the most frequent complications associated with the reimplantation of autologous cryopreserved bone after decompressive craniectomy. Prolonged procedural time and cardiovascular comorbidity tend to increase the risk of SSI.     

Bone flap salvage in acute surgical site infection after craniotomy for tumor resection

Craniotomy surgical site infections are an inherent risk and dreaded complication for the elective brain tumor patient. Sequelae can include delays in resumption in adjuvant treatments for multiple surgeries if staged cranioplasty is pursued. Here, the authors review their experience in operative debridement of surgical site infections with single-stage reimplantation of the salvaged craniotomy bone flap. A prospectively maintained database of a single surgeon’s neuro-oncology patients from 2009 to 2017 (JRF) was queried to identify 11 patients with surgical site infection after craniotomy for tumor resection. All patients underwent a protocol of aggressive operative debridement including drilling the bone edges and intraoperative flap sterilization with single-stage reimplantation, followed by tailored-antibiotic therapy. Ten of the 11 patients with frankly contaminated bone flaps from surgical site infection were able to be salvaged in a single-stage procedure. Five of these patients underwent adjuvant chemotherapy and/or radiation without secondary complication. There was one treatment failure in a delayed fashion which required additional surgery for craniectomy; however, this occurred after adjuvant treatment was administered. Surgical debridement and bone flap salvage is safe and cost-effective in managing acute surgical site infections after craniotomy for tumors. Additionally, this practice is likely beneficial in expediting the resumption of cancer therapy.     

手术治疗胫腓骨骨折术后骨外露的疗效探讨

目的探讨手术处理胫腓骨骨折术后骨外露的疗效。方法21例骨外露患者,其中7例单纯皮肤坏死并软组织感染,予清创及筋膜皮瓣转移处理;皮肤感染、坏死并骨髓炎但无明显死骨及死腔者9例,行彻底清创后,骨面钻多个小孔,予筋膜皮瓣转移,闭式冲洗引流;有明显骨质破坏的骨髓炎患者5例,伴内固定物松动,螺丝钉腔感染明显,拆除内固定,改外固定支架,行病灶清除,带神经血管的小腿内、外侧筋膜皮瓣及骨膜转移,闭式冲洗引流。结果2例转移皮瓣边缘部分坏死,经换药后愈合,其余皮瓣均成活。18例获随访,平均10.5(6~12)个月,原有骨坏死的骨髓炎患者骨折均愈合,平均愈合时间5.3(3.5~7)个月。结论再次清创、筋膜皮瓣转移术是治疗胫腓骨骨折术后骨外露的有效措施,对骨髓炎患者应行闭式冲洗引流。     

股前外侧脂肪筋膜瓣经和血管吻合游离移植修复面部凹陷畸形

目的 探讨应用股前外侧脂肪筋膜瓣经血管吻合游离移植修复面部凹陷畸形的手术方法及临床效果.方法 1996年10月至2007年1月,根据面部凹陷的范围及深度,应用相应大小和厚度的股前外侧脂肪筋膜瓣游离移植修复32例面部凹陷畸形,其中8例伴有骨骼缺损的患者同期行Medpor骨膜下植入修复骨骼缺损.结果 修复32例面部凹陷畸形共应用33块股前外侧脂肪筋膜瓣,单侧应用31例,双侧应用1例.股前外侧脂肪筋膜瓣的大小为12 cm×8 cm～20 cm×11 cm(平均16.5 cm×10.5 cm).30块股前外侧脂肪筋膜瓣完全存活,另3块于术后半年内出现了边缘的吸收.32例中有23例经一期修复即获得满意效果,其余9例于术后半年行二期修整,其中6例因面部臃肿行脂肪抽吸修薄术矫正,另3例因周边吸收行自体脂肪移植术修复.术后随访6个月至2年半,所有患者面部凹陷畸形均得到显著改善,双侧面部接近对称.供区切口一期愈合,瘢痕隐蔽,未出现功能障碍.结论 股前外侧脂肪筋膜瓣町利用的面积大,可修剪成合适厚度用于三维重建,解剖较恒定、切取安全等,必要时可辅以骨骼支架的重建,能使面部凹陷得到较满意的修复.     

Cryopreservation of autogeneous bone flap in cranial surgical practice: what is the future? A grade B and evidence level 4 meta-analytic study

AIM: Autogenous bone flap adequately preserved can be used successfully for repair of iatrogenic cranial bone defects because of its biological and economic advantages. The commonly used techniques of bone preservation are freezing at temperature ranging from -16 to -40 inverted exclamation mark C or subcutaneous pocketing. METHODS: We searched on NLM database querying as subject headings "cranioplasty and autologous bone" and found 7 papers meeting our criteria. For every series we considered the frequency of bone resorption and infection and performed statistical analysis by means of contingency tables carrying out for the chi2 test according to Pearson and considering to be statistically significant p(chi2) <0.05 values. RESULTS: Compared series presented no statistically significant difference with regard to frequency of the complications (chi2=6.43 for critical value of 11.07 (k-1=5) (P>0.25) and chi2=5.48 for critical value of 7.81 (k-1=3) (P>0.10) respectively for infection and resorption. CONCLUSION: Although we did not find any significative difference among the frequencies of the complications of the series, it is our opinion that freezing the bone flap is preferable to abdominal pocketing because it needs no double surgical abdominal time and the bone flap frozen is stronger to mechanical loading than fresh flap. Cryopreservation of autologous bone flap should be the standard technique of preservation for delayed cranioplasty but a multicentric prospective trial is advisable to obtain in short time statistically significant results focusing better on the rate of marginal resorption of the bone flap using new cryoprotectant solutions.     

Autologous Vascularized Dural Wrapping for Temporalis Muscle Preservation and Reconstruction After Decompressive Craniectomy: Report of Twenty-five Cases

Temporalis muscle reconstruction is a necessary step during frontotemporal cranioplasty ensuing decompressive craniectomy (DC). During this procedure, scarring between the temporalis muscle and the dural layer may lead to complicated muscle dissection, which carries an increased risk of dura and muscle damage. At time of DC, temporalis muscle wrapping by an autologous vascularized dural flap can later on facilitate dissection and rebuilding during the subsequent cranioplasty. In a span of 2 years, we performed 57 DCs for different etiologies. In 30 cases, the temporalis muscle was isolated by wrapping its inner surface using the autologous dura. At cranioplasty, the muscle could easily be dissected from the duraplasty. The inner surface was easily freed from the autologous dural envelope, and reconstruction achieved in an almost physiological position. Follow-up examinations were held at regular intervals to disclose signs of temporalis muscle depletion. Twenty-five patients survived to undergo cranioplasty. Muscle dissection could always be performed with no injury to the dural layer. No complications related to temporalis muscle wrapping were recorded. Face asymmetry developed in four cases but it was always with bone resorption. None of the patients with a good neurological recovery reported functional or aesthetic complaints. In our experience, temporalis muscle wrapping by vascularized autologous dura proved to be effective in preserving its bulk and reducing its adhesion to duraplasty, thereby improving muscle dissection and reconstruction during cranioplasty. Functional and aesthetic results were satisfying, except in cases of bone resorption.