Surgical technique for repair of complex anterior skull base defects

Transorbital Microsurgery: An Anatomical Description of a Minimally Invasive Corridor to the Anterior Cranial Fossa and Paramedian Structures

Objectives  Transorbital neuroendoscopic surgery (TONES) has ignited interest in the transorbital access corridor, increasing its use for single and multi-portal skull base interventions. However, the crowding of a small corridor and two-dimensional viewing restrict this access portal. Design  Cadaveric qualitative study to assess the feasibility of transorbital microsurgery (TMS). Setting  Anatomical dissection steps and instrumentation were recorded for homogeneous methodology. Participants  Six cadaveric specimens were systematically dissected using TMS to the anterior cranial fossa and paramedian structures. Main Outcome Measures  Anatomical parameters of the TMS craniectomy were established, and the visible and accessible neuroanatomy was highlighted. Results  A superior lid crease incision achieved essential orbital rim exposure and preseptal dissection. The orbital roof craniectomy is defined by three boundaries: (1) frontozygomatic suture to the frontosphenoid suture, (2) frontal sinus and cribriform plate, and (3) frontal sinus and orbital rim. The mean (standard deviation) craniectomy was 440 mm 2 (78 mm 2 ). Exposing the ipsilateral optic nerve and internal carotid artery obviated the need for frontal lobe retraction to identify the A1-M1 bifurcation as well as near-complete visualization of the M1 artery. Conclusion  TMS is a feasible corridor for intracranial access. Mobilization of orbital contents is imperative for maximal intracranial access and protection of the globe. TMS enables access to the frontal lobe base, ipsilateral optic nerve, and most of the ipsilateral anterior circulation. This cosmetically satisfactory approach causes minimal destruction of the anterior skull base with satisfactory exposure of the anterior cranial fossa floor without sinus invasion.

Dural reconstruction with or without a bone graft of paranasal and anterior skullbase malignancies: Retrospective single-center analysis of 11 cases and review of literature

Introduction

The reconstruction of frontobasal defects following oncologic resections of paranasal and anterior skull base (ASB) malignancies remains challenging. Ineffective reconstruction could lead to cerebrospinal fluid leak, meningitis, and tension pneumocephalus.

Research question

Aim of this investigation was to analyse postoperative complication rates with or without bone graft for anterior skull base reconstruction.

Material and methods

In this retrospective study, we included patients following resection of paranasal and/or anterior skull base malignancies between October 2013 and December 2022. Complications were analysed with regards to the type of skull base reconstruction.

Results

Eleven patients were identified (2 female, 9 male, age (median, SD) 64 ± 14.1 years (range 38-81). There were nine cases of paranasal sinus and nasal cavity carcinomas and two cases of olfactory neuroblastomas. Overall survival was 22.5 ± 28 months (range: 5-78), progression free survival was 17.0 ± 20.3 months (range: 11-78). Bone skull base reconstruction using a split graft was performed in three cases. Postoperative complications requiring surgical intervention were seen in 33% (one tension pneumocephalus) of cases in the bone reconstruction group and 50% (three patients with cerebrospinal fluid leak, one infection) in the non-bone reconstruction group.

Discussion and conclusion

The structural reinforcement of structural bone chip grafting might provide additional support of the ASB and prevent CSF leakage or encephalocele. Especially in large (>10 cm2) bone defects of advanced sinonasal malignancies extending into the middle cranial fossa, the full armamentarium of reconstruction possibilities should be considered.

Our Experience in Trans Nasal Endoscopic Repair of Anterior Skull Base Defects Reinforced with Multiple Layers of Graft Materials

Aims: To determine the best technique to repair anterior skull base defects using various grafts. Materials & Methods: This Ambi-directional cohort study was carried out at a tertiary care hospital from May 2019 to October 2021. A total of 17 patients who underwent Endoscopic Repair of Anterior Skull Base Defects using various grafts were included in the study. Detailed history and clinical evaluation followed by Diagnostic Nasal Endoscopy, Biochemical and Radiological investigations were done for all patients with postoperative follow-up for at least 6 months. Results: Most common site of anterior skull base defect in our study group was the posterior wall of the sphenoid sinus. Various graft materials used in our study were fascia lata, thigh fat, Hadad flap, Septal cartilage, nasal septal bone chip, septal mucosal free flap, surgicel and fibrin glue. The most commonly used sequence of graft materials used is the fat(underlay) - fascia lata - fat(overlay). Various complications that occurred were nasal bleeding, residual CSF leak, localized collection of pus in the Septal region, cerebral oedema and Alar trauma. Conclusions: The success of Anterior skull base defect repair depends on watertight Dural closure with multiple layers of grafts to prevent postoperative CSF leak. Although dependent on the Surgeon's preference, usually the sequence of an underlay fat - fascia lata - overlay fat followed by glue/gel foam/Hadad flap works well. Even after discharging the patient, regular follow-up and evaluation ensure that the graft is in situ and there is no CSF leak or other complication.

Outcomes and Utility of Intracranial Free Tissue Transfer

OBJECTIVE

Complications associated with intracranial vault compromise can be neurologically and systemically devastating. Primary and secondary repair of these deficits require an air and watertight barrier between the intracranial and extracranial environments. This study evaluated the outcomes and utility of using intracranial free tissue transfer as both primary and salvage surgical repair of reconstruction.

METHODS

A retrospective review was performed of all subjects who underwent intracranial free tissue transfer as primary or salvage repair.

RESULTS

A total of 13 intracranial free tissue transfers were performed on 11 subjects: osteocutaneous radial forearm free flaps (n = 6), partial myofascial rectus abdominis flaps (n = 5), temporoparietal fascia flap (n = 1), and serratus anterior myofascial flap (n = 1). Primary reconstruction was performed on 4 subjects with the remaining being salvage repair. Indications for surgery included neoplasm (n = 6 of 11), ballistic trauma (n = 3 of 11), motor vehicle accident (n = 1 of 11), and infection (n = 1 of 11). Three subjects required additional surgical repair for CSF leak and pneumocephalus, with 2 subjects requiring an additional free tissue transfer at a different site.

CONCLUSION

In our experience, free tissue transfer is an effective primary and salvage surgical technique in the reconstruction of complex intracranial problems.

Basal encephalocele: surgical strategy and functional outcomes in the Tokyo experience

OBJECTIVE

The basal encephalocele (BEC) is the rarest form of encephalocele, with an incidence of about 1/35,000 live births. The incidence of its subtype, sphenoidal BEC, is even lower at about 1/700,000 live births. The aim of this study was to propose the optimal surgical approach to repairing BEC, with special attention to the reconstruction of the skull base bone defect.

METHODS

Fourteen consecutive pediatric patients with BEC who underwent surgical repair between March 2004 and March 2020 (10 boys and 4 girls, age 25 days to 7 years, median age 4 months) were enrolled. The follow-up period of the surviving patients ranged from 53 to192 months (mean 119.8 months). The patient demographics, BEC subtypes, preoperative clinical condition, radiographic findings, surgical procedures, and postoperative course were retrospectively analyzed.

RESULTS

There were 4, 8, and 2 cases of sphenoidal BEC, sphenoethmoidal BEC, and ethmoidal BEC, respectively. The size of the bone defect was small in 3 patients, medium in 7, and large in 4 patients. All the patients with sphenoethmoidal and ethmoidal BEC showed associated congenital anomalies other than cleft palate. In total, 25 operations were performed. Two patients underwent multiple operations, whereas the remaining 9 patients received only 1 operation. The transoral transpalatal approach was the initial procedure used in all 14 patients. The transfrontobasal approach was applied as an additional procedure in 2 patients and as part of a 1-stage combined operation in 2 patients. Autograft bone alone was used for skull base reconstruction in 17 early operations. A titanium mesh/plate was used in the remaining 8 operations without any perioperative complications. All BECs were successfully repaired. Three patients died during the clinical course due to causes unrelated to their surgery. All but one of the surviving patients started growth hormone replacement therapy before school age.

CONCLUSIONS

Based on the authors' limited experience, the key to successful BEC repair involves circumferential dissection of the BEC and a firm reconstruction of the skull base bone defect with a titanium plate/mesh. The transoral transpalatal approach is a promising, reliable procedure that may be used in the initial operation. When a cleft palate is absent, transnasal endoscopic repair is recommended. The transfrontobasal approach should be reserved for cases with a huge BEC and other anomalies. Long-term prognosis is apparently favorable in survivors.

Pericranial Flap Anterior Skull Base Reconstruction With Gelfoam Intradural Compression

Anterior cranial base reconstruction is occasionally necessary following severe trauma. Several methods for reconstruction have been described and some authors have described their experiences regarding the use of a pericranial flap for anterior skull base reconstruction after trauma. A 26-year-old woman was admitted to our department with multiple facial bone fractures identified using facial bone computed tomography. Plastic surgeons performed surgery under general anesthesia for the patient's nasal bone fractures. On the seventh day after admission, the patient's brain computed tomography showed an abscess in the frontal lobe. Antibiotic treatment was started, but the lesion deteriorated. Anterior skull base reconstruction was then performed using a pericranial flap with gelfoam compression. No complications, including leakage of cerebrospinal fluid, cerebral hemorrhage, necrosis of the pericranial flap, or frontal lobe herniation, were observed 1 year following surgery. In our case, the authors performed a simple and effective treatment with reconstruction using pericranial flap and gelfoam compression without complications. This technique is useful for reconstructing defects in the base of the frontal bone resulting from various causes, as well as for fracture of the anterior skull base following trauma.

Dural Closure in Confined Spaces of the Skull Base with Nonpenetrating Titanium Clips

BACKGROUND

Dural repair in areas with limited operative maneuverability has long been a challenge in skull base surgery. Without adequate dural closure, postoperative complications, including cerebrospinal fluid (CSF) leak and infection, can occur.

OBJECTIVE

To show a novel method by which nonpenetrating, nonmagnetic titanium microclips can be used to repair dural defects in areas with limited operative access along the skull base.

METHODS

We reviewed 53 consecutive surgical patients in whom a dural repair technique utilizing titanium microclips was performed from 2013 to 2016 at our institution. The repairs primarily involved difficult-to-reach dural defects in which primary suturing was difficult or impractical. A detailed surgical technique is described in 3 selected cases involving the anterior, middle, and posterior fossae, respectively. An additional 5 cases are provided in more limited detail to demonstrate clip artifact on postoperative imaging. Rates of postoperative CSF leak and other complications are reported.

RESULTS

The microclip technique was performed successfully in 53 patients. The most common pathology in this cohort was skull base meningioma (32/53). Additional surgical indications included traumatic dural lacerations (9/53), nonmeningioma tumors (8/53), and other pathologies (4/53). The clip artifact present on postoperative imaging was minor and did not interfere with imaging interpretation. CSF leak occurred postoperatively in 3 (6%) patients. No obvious complications attributable to microclip usage were encountered.

CONCLUSION

In our experience, intracranial dural closure with nonpenetrating, nonmagnetic titanium microclips is a feasible adjunct to traditional methods of dural repair.

A Method for Combining Thin and Thick Malleable Titanium Mesh in the Repair of Cranial Defects

Introduction: Cranial defects following the removal of tumor involved bone require repair and reconstruction for brain protection and cosmesis. A variety of autologous bone substrates and synthetic materials can be employed, alone or in combination. In this article, we describe the use of dual thin and thick titanium mesh, connected together using plate hardware, to repair a right frontotemporal sphenoidal bone defect following resection of a hyperostosing sphenoid wing meningioma.

Methods: Reconstruction of the pterion was done with a dual mesh cranioplasty. After replacement of the native orbitozygomatic and frontotemporal bone pieces, a piece of thinner mesh was molded to the pterional defect connecting the two bone pieces and re-creating the concave shape of the pterion below the superior temporal line. The circular area of the bony defect overlying the frontal and temporal lobes was supplemented by cutting and molding an additional piece of thicker mesh which was secured to the thinner mesh with burr hole cover sectors using rescue screws.

Results: A 30-year-old woman presented with painless proptosis and was found to have a hyperostosing right sphenoid wing meningioma. The patient underwent a frontotemporal orbitozygomatic craniotomy for tumor resection and extensive bony osteotomy. Repair and reconstruction of the cranial defect in the region were accomplished at the time of open operation using two thicknesses of mesh connected one to another with titanium plate pieces and rescue screws. The patient underwent gross total resection of the meningioma and near total resection of the soft tissue and bony components (Simpson Grade II). The external cosmetic results following the orbital-cranial reconstruction with the dual mesh technique was deemed “very good” by the surgeon and patient. Postoperative CT imaging demonstrated symmetric re-approximation of the shape of the pterion as compared to the opposite side.

Conclusions: We present a method for connecting two titanium mesh sheets with available hardware to improve the strength in compression while maintaining the ability to mold thinner sheets as necessary for the best cosmetic results. This method is an option for coverage of bony defects in the region of the pterion for young, physically active patients providing them with additional mesh cranioplasty strength.