Anterior Cranial Base Defects Research Articles

Multilayer Anterior Skull Base Reconstruction with Cortical Rib Bone Graft: Preliminary Experience

During the past decades, different methods have been described for anterior skull base reconstruction. Regarding larger skull base defects, few investigators have described the use of bone grafts to foster support and prevent frontal lobe sagging, herniation, or falling. The aim of this study is to describe the use of a rib bone graft, which could be an option in these cases due to its rigidity and dimensions. We retrospectively collected preoperative, intraoperative, and postoperative data at the last follow-up of 10 patients who underwent multilayer anterior skull base reconstruction, including rib bone graft, for large anterior cranial base defects at 2 tertiary care academic hospitals. Eight patients underwent endoscopic craniectomy for sinonasal malignancies, and the other two underwent transnasal endoscopic surgery for congenital meningoencephalocele. Anterior skull base defects measured on average 3.8 cm ± 0.9 SD antero-posteriorly (range 2.5-5 cm) and 2.3 ± 0.9 SD latero-laterally (range 0.9-4 cm). Multilayer reconstruction was performed in all cases, including a rib bone graft positioned as intracranial extradural layer. No patient experienced thoracic complications during the postoperative period. No side effects related to the bone graft or meningoencephalocele occurrence were reported after a mean follow-up of 8.0 ± 6.3 months. The use of a cortical rib bone graft could be a safe and effective option in skull base reconstruction when managing large defects after cancer removal.

Vascularized Pericranial Flap for Endonasal Anterior Skull Base Reconstruction.

Introduction As the limits of advanced skull base malignancies that can be managed through an endoscopic endonasal approach continue to be expanded, the resultant anterior skull base defects are of increasing size and complexity. In the absence of nasoseptal or turbinate flaps, the vascularized pericranial flap has been employed at our institution with excellent results. Objective The study aimed to review the outcomes of patients who underwent endonasal anterior craniofacial resection with anterior skull base reconstruction using a vascularized pericranial flap. Design Retrospective chart review of patients treated by the University of California - San Francisco minimally invasive skull base service from the years 2011 to 2017. Average duration of follow-up was 16.4 months. Setting This study was conducted at Academic tertiary referral center. Participants A total of nine patients with advanced anterior cranial base malignancies were identified who were treated with a minimally invasive, endoscopic anterior craniofacial resection from the years 2011 to 2017. Due to the nature of the resection in these patients, nasoseptal flaps and inferior/middle turbinate flaps were unavailable or insufficient for anterior skull base defect repair. Each patient underwent reconstruction of the anterior cranial base defect using an anteriorly based pericranial flap harvested by bicoronal incision, and tunneled anteriorly to the nasal cavity through a frontoethmoidal incision.

Transcription factor Foxc1 is involved in anterior part of cranial base formation.

The cranial base is a structure mainly formed through endochondral ossification and integrated into the craniofacial complex, which acts as an underlying platform for the developing brain. Foxc1 is an indispensable regulator during intramembranous and endochondral ossification. In this study, we found that the spontaneous loss of Foxc1 function in a mouse (congenital hydrocephalous), Foxc1ch/ch , demonstrated the anterior cranial base defects, including unossified presphenoid and lack of middle part of the basisphenoid bone. Hypoplastic presphenoid primordial cartilage (basal portion of the trabecular cartilage [bTB]) and a lack of the middle part of basisphenoid primordial cartilage (the hypophyseal cartilage) were consistently observed at earlier developmental stage. Foxc1 was expressed robustly and ubiquitously in undifferentiated mesenchyme of the cranial base-forming area in E11.0 wild-type fetuses. Once chondrogenesis commenced, the expression was downregulated and later limited to the perichondrium. Detection of transcripts of Collagen type2 A1 (Col2a1) revealed that both bTB and the anterior part of the hypophyseal cartilage developing anterior to the persistent epithelial stalk of the anterior lobe of the pituitary gland were suppressed in the Foxc1ch/ch . Proliferation activity of chondrocyte precursor cells was higher in the Foxc1ch/ch . Loss of Foxc1 function only in the neural crest cell lineage (Wnt1-cre;Foxc1ch/flox ) showed ossification of the posterior part of the hypophyseal cartilage derived from the mesoderm. These findings suggest that Foxc1 is an important regulator to further chondrogenesis and initiate the ossification of the presphenoid and basisphenoid bones.

Titanium Plate as Reconstructive Adjunct for Large Anterior Cranial Base Defect

Background: Extensive resection of tumors involving the anterior skull base warrants complex reconstruction. In cases with extensive destruction of the posterior frontal table, reconstruction can be particularly challenging. The reach of the pedicled nasoseptal flaps is often limited at this location. In addition, underlay grafts can be dislodged due to the physiologic pulsations of the brain. We present a brief technical report utilizing titanium plating for successful salvage of a failed layered reconstruction.

Pedicled flaps in endoscopic skull base reconstruction: review of current techniques.

To discuss the current applications and indications for the use of pedicled flaps in the reconstruction of endoscopic skull base defects. Current trends in endoscopic skull base surgery include the use of vascularized pedicled flaps rather than free tissue grafts (autograft or allograft) for the repair of anterior cranial base defects. In particular, recent evidence-based algorithms for skull base reconstruction suggest that use of pedicled flaps for clival defects and high-flow cerebrospinal fluid (CSF) leaks may reduce the incidence of postoperative CSF leaks. The primary workhorse continues to be the nasoseptal flap (NSF); however, other options exist in cases wherein this flap is unavailable because of prior sacrifice or unable to reach the area of interest (e.g., defects adjacent to the frontal recess). Adoption of vascularized pedicled flaps over the last decade, particularly the recently popularized NSF, has greatly reduced complications associated with endoscopic skull base surgery. The need for vascularized flap reconstruction is governed primarily by defect size and location, and by the presence of a high-flow CSF leak. Additional vascularized flaps can be used in conjunction with the NSF, or as an alternative when the NSF is unfavorable or unavailable.

Endonasal Endoscopic Release of a Delayed Tension Pneumocephalus After Craniofacial Resection of a Tumor of the Anterior Skull Base

Tension pneumocephalus is a rare complication that can occur after craniofacial resection of lesions of the anterior skull base. Early diagnosis is important to avoid potential serious neurologic deficits, including death. It has been associated with the perioperative placement of a lumbar drainage and with esthesioneuroblastoma. Therapy consists of evacuation of the intracranial air as well as conservative measures. Here we report a case of a patient with an ethmoidal esthesioneuroblastoma who underwent a traditional microsurgical craniofacial resection and developed a delayed epidural tension pneumocephalus. This was treated by performing an incision in the pericranial flap covering the anterior cranial base defect using an endonasal endoscopic approach. To our knowledge, this particular treatment technique has not been reported before in this context.

OP158: The perforator-based rectus abdominis transplant: New reconstructive advantages from an old friend

Purpose To describe three advantages of the perforator-based rectus abdominis transplant: a long pedicle that reduces the need for vein grafts, moldable fat ideal for custom-designed flaps, and volume for constrained spaces. Material and methods Eleven patients underwent reconstruction with the perforator-based rectus abdominis transplant from May 2011 to July 2012. Indications for reconstruction were tumor ablation in nine patients and osteoradionecrosis in two patients. There were seven oral cavity defects, two maxilla defects, one anterior cranial base defect, and one orbital defect. Six patients had prior neck dissection and one had prior chemoradiation. Results The success rate of transplantation was 91%; one patient had a flap failure. Mean pedicle length was 14.5 cm. No vein grafts were utilized, and in four patients (36%) with defects distant from the neck and/or vessel-poor necks the pedicle length directly avoided the need for vein grafting. In all 11 patients, at least one reconstructive advantage was achieved. In six patients (55%), at least two advantages were achieved. In three patients (27%), all three advantages were accomplished. Conclusions The perforator-based rectus abdominis transplant provides at least three major reconstructive advantages for patients who require complex head and neck reconstruction.

PP150: Evaluation of reconstructive techniques for anterior skull base defects following tumor ablation

Purpose Reconstruction of craniomaxillofacial cancer defects is challenging when tumors extend to the skull base. Nowadays vascularized flaps are the option of choice. Free flaps have the added benefit of access to more cephalad defects without constraints of rotational arc as with pedicled flaps. We compared various flaps used to reconstruct anterior skull base defects after resection of malignant tumors. Materials and methods We identified 14 free or pedicled flaps done to reconstruct anterior cranial base defects. We performed a retrospective analysis to compare patient demographics, tumor histology, surgical technique, and complications among the various flaps. We also compared patients’ quality of life by conducting a telephone survey. Results All patients had stage 3 or 4 squamous cell carcinoma, most originating in the paranasal sinuses extending to the anterior skull base. There were six radial forearm free flaps, three anterolateral thigh flaps, four latissimus dorsi free flaps and one pedicled supraclavicular flap. Complications included three mesh exposures following radiation treatment, one wound infection, and two flap dehiscences after XRT. Both dehiscences occurred with RFFF and both were redone with TDAP flaps. There were no csf leaks or donor site morbidities. There were no complaints of functional deficits with feeding or speech impairments. Some patients reported visual disturbance after orbital exenteration, however they adjusted to this. Conclusions Vascularized flaps provide reliable and durable reconstructive options for anterior skull base defects following resection of malignant neoplasms of the craniofacial region. Free flaps such as RFFF, ALT, and TDAP are well suited for these defects. They have a low risk of complications and low donor site morbidity, while offering good functional and esthetic outcomes.

Cerebrospinal fluid volume replacement following large endoscopic anterior cranial base resection

Large endoscopic skull-base resections often result in extensive postoperative pneumocephalus secondary to copious evacuation of cerebrospinal fluid (CSF) during the procedures. Replacing CSF lost during craniotomy with saline is a common technique in neurosurgery, but is difficult after extensive transnasal resection of the anterior cranial base because direct transnasal CSF augmentation will escape until the skull base reconstruction is sealed. The present study evaluated the effectiveness of intraoperative CSF volume replacement via lumbar drains on improving postoperative outcomes. Ten large endoscopic anterior skull-base resections (>2.5 cm) were performed from 2008 to 2011. Sellar, parasellar, and transplanum resections were excluded. Etiologies included esthesioneuroblastoma (2), squamous cell carcinoma (2), intracranial dermoid (2), adenocarcinoma (1), adenoid cystic carcinoma (1), melanoma (1), and meningioma (1). Six patients were administered preservative-free normal saline via lumbar drain during skull-base reconstruction. Data collected included volume of postoperative pneumocephalus, intravenous pain medicine requirements 24 hours after surgery, and length of hospital stay. Volume of pneumocephalus (4.78 cm vs 12.8 cm(3) , p = 0.04) and length of hospital stay (2.17 days vs 8.5 days, p = 0.03) were significantly decreased in the normal saline volume replacement group. Average intravenous pain medication requirements were reduced in the first 24 hours postoperatively (8 mg morphine vs 14 mg morphine, p = 0.25), but did not reach statistical significance. Evacuation of intracranial air by transthecal administration of saline during reconstruction of large anterior cranial base defects was an effective technique to decrease postoperative pneumocephalus and length of hospital stay. Further evaluation is warranted.

Inactivation of Six2 in mouse identifies a novel genetic mechanism controlling development and growth of the cranial base

The cranial base is essential for integrated craniofacial development and growth. It develops as a cartilaginous template that is replaced by bone through the process of endochondral ossification. Here, we describe a novel and specific role for the homeoprotein Six2 in the growth and elongation of the cranial base. Six2-null newborn mice display premature fusion of the bones in the cranial base. Chondrocyte differentiation is abnormal in the Six2-null cranial base, with reduced proliferation and increased terminal differentiation. Gain-of-function experiments indicate that Six2 promotes cartilage development and growth in other body areas and appears therefore to control general regulators of chondrocyte differentiation. Our data indicate that the main factors restricting Six2 function to the cranial base are tissue-specific transcription of the gene and compensatory effects of other Six family members. The comparable expression during human embryogenesis and the high protein conservation from mouse to human implicate SIX2 loss-of-function as a potential congenital cause of anterior cranial base defects in humans.

Minimally invasive endoscopic pericranial flap: A new method for endonasal skull base reconstruction

One of the major challenges of cranial base surgery is reconstruction of the dural defect. Following a craniofacial resection, the standard reconstructive technique is direct suture repair of the dural defect with a fascial graft and rotation of an anteriorly based pericranial scalp flap to cover the dura. The introduction of endoscopic techniques and an endonasal approach to the ventral skull base has created new challenges for reconstruction. The nasoseptal flap has become the workhorse for vascularized endoscopic skull base reconstruction; however at times, the septal mucosal flap may be unavailable for reconstruction. This can be due to prior surgical resection or involvement of the nasal septum by sinonasal cancer. We have developed a minimally invasive endoscopic pericranial flap for endoscopic skull base reconstruction. The use of a pericranial scalp flap for reconstruction during endonasal skull base surgery using minimally invasive techniques has not been previously reported. We performed cadaveric studies to illustrate feasibility of an endoscopic pericranial flap for endonasal skull base reconstruction, then applied this novel technique to an elderly patient after endonasal skull base and dural resection of an esthesioneuroblastoma. The technical report of the minimally invasive pericranial flap is outlined and the advantages and limitations during endonasal skull base reconstruction are discussed. The patient had excellent healing of her skull base and had no evidence of any postoperative cerebrospinal fluid leak. The minimally invasive endoscopic pericranial flap provides another option for endonasal reconstruction of cranial base defects. There is minimal donor site morbidity, and it provides a large flap that can cover the entire ventral skull base. The issues of intranasal tissue tumor involvement and the need for radiotherapy make the endoscopic pericranial flap an ideal reconstruction for anterior cranial base defects resulting from endonasal sinonasal and skull base cancer resections.

Use of a pedicled galeopericranial flap for the reconstruction of anterior cranial base defect

目的 探讨带蒂帽状腱膜骨膜瓣在颅前底肿瘤术后颅底缺损重建中的应用价值.方法 对21例经额颅内入路手术或颅面联合手术前颅底肿瘤患者采用帽状腱膜骨膜瓣重建颅底缺损,不带游离皮肤、骨片、钛网,修复最大缺损3 cm×5 cm.结果 术后全部病例临床症状改善,1例术后第4天出现脑脊液漏,自然恢复,无手术死亡、脑膜脑膨出、颅内感染及其他严重并发症.随访1年至11年,存活1年以上者18例,3年以上者11例,5年以上者7例.死亡8例.1、3、5年生存率分别为18/21(85.7%)、11/17(64.7%)、7/13例(53.8%).结论 带蒂帽状腱膜骨膜瓣具有柔软、血供好、强度大等优点,可以有效分隔颅腔和鼻腔,是一种安全、简便、有效的前颅底重建方法,可用于较大颅底缺损的重建。

Three-layer reconstruction for large defects of the anterior skull base.

To evaluate and discuss a three-layer rigid reconstruction technique for large anterior skull base defects. Prospective, nonrandomized, non-blinded. Tertiary teaching medical center. Twenty consecutive patients underwent craniofacial resection for a variety of pathology. All patients had large anterior cranial base defects involving the cribriform plate, fovea ethmoidalis, and medial portion of the roof of the orbit at least on one side. A few patients had more extensive defects involving both roof of the orbits, planum sphenoidale, and bones of the upper third of the face. The defects were reconstructed with a three-layer technique. A watertight seal was obtained with a pericranial flap separating the neurocranium from the viscerocranium. Rigid support was provided by bone grafts fixed to a titanium mesh, anchored laterally to the orbital roofs. All patients had a computed tomography scan of the skull on the first or second postoperative day. Patients were observed for immediate and long-term postoperative complications after such reconstruction. Postoperative computed tomography scans showed small pneumocephalus in all patients. It resolved spontaneously and did not produce neurologic deficits in any patient. There was no cerebrospinal fluid leak, hematoma, or infection. On long-term follow-up, exposures of bone graft or mesh, brain herniation, or transmission of brain pulsation to the eyes were not observed in any patient. Three-layer reconstruction using bone grafts, titanium mesh, and pericranial flap provides an alternative technique for repair of large anterior cranial base defects. It is safe and effective, and provides rigid protection to the brain.

Use of titanium mesh for reconstruction of large anterior cranial base defects.

The authors evaluated the role of titanium mesh used in combination with vascularized pericranium to provide rigid support during reconstruction of anterior skull base defects. Thirteen patients with large anterior skull base defects caused by tumor invasion or traumatic injury involving the cribriform plate, orbital roof, and planum sphenoidale were included in the study. The reconstruction technique involved placement of titanium mesh between two layers of continuous vascularized pericranium. Surgical glue and routine lumbar cerebrospinal fluid (CSF) drainage were not used in any patient. At a mean postoperative follow-up time of 22 months (range 8-39 months), none of the patients had developed infection or meningocele. Postoperative CSF rhinorrhea occurred in two patients with extensive dural defects, which resolved with temporary lumbar drainage. Use of titanium mesh and a two-layer vascularized pericranial graft is a safe, reproducible, and feasible method for reconstructing the anterior skull base. Patients with large dural defects may need temporary CSF diversion to avoid postoperative fistula formation.