Endoscopic Endonasal Transcribriform Approach Research Articles

Simple and safe resection of the crista galli.

A critical procedure in the transcribriform approach is the resection of the crista galli. However, the standard technique for crista galli resection has several disadvantages. We reviewed the cases of patients with olfactory neuroblastomas who underwent an endoscopic endonasal transcribriform approach using a newly developed technique for crista galli resection. We performed a cadaveric study to measure the superior accessibility limits using the proposed method. We included 38 patients with olfactory neuroblastomas in this study. The tumor invaded the posterior crista galli in four patients. The anterior end of the crista galli was not invaded by the tumor. Our cadaveric study showed that the dura was approachable to the point that was 7.4 ± 1.3 mm superior and 23.2 ± 7.2 mm lateral to the foramen cecum following crista galli removal. By resecting the crista galli in advance, manipulation of the superior dura became feasible.

Limitations of the endoscopic endonasal transcribriform approach

The endoscopic endonasal transcribriform approach (EETA) has become a useful strategy in the treatment of various anterior skull base pathologies, including meningoencephaloceles, olfactory groove meningiomas, schwannomas, esthesioneuroblastomas, and other sinonasal malignancies. However, not all pathologies are optimally treated through this approach due to tumor size, extent of the lesion, vascular involvement, and the presence of intact olfaction. One must be prepared to use a transcranial approach if the EETA is not favorable. In some patients, a combined approach (transcranial-EETA) may be needed in appropriate cases. Therefore, patient selection is paramount for achieving a successful result with avoidance of complications. For certain tumors, the limitations of the EETA may result in lower rates of gross-total resection, higher rates of cerebrospinal fluid leakage, postoperative impairment of olfaction, and higher complication rates. In this paper, we discuss the limitations of the EETA when considering approach selection to treat anterior skull base lesions.

Relaxing Sphenoidal Slit Incision to Extend the Anterior and Posterior Reach of Pedicled Nasoseptal Flaps During Endoscopic Skull Base Reconstruction of Transcribriform Defects: Technical Note and Results in 20 Patients.

Reconstruction of large anterior skull base (ASB) defects after an endoscopic endonasal transcribriform approach (EEA-TC) remains a challenge despite the advent of the vascularized pedicled nasoseptal flap (PNSF). We describe a relaxing PNSF slit incision that extends the anterior and posterior reach of the PNSF to maximize tensionless flap coverage of transcribriform ASB defects. A retrospective chart review was conducted on 20 consecutive patients who underwent endoscopic endonasal transcribriform approach and subsequent PNSF reconstruction with a relaxing slit incision. At the time of endoscopic ASB reconstruction, the PNSF is rotated into position so that the anterior margin of the flap is situated at the posterior table of the frontal sinus. A relaxing slit incision is made across the sphenoidal segment of the PNSF, which is the segment of flap that bridges across the sphenoid sinus once the flap is rotated into position. The anterior reach of the flap is increased to adequately cover the posterior table of the frontal sinus, and the redundant sphenoidal flap is rotated posteriorly to make contact to the bony planum sphenoidale. No patients developed postoperative cerebrospinal fluid leaks (0%). The ASB repair was monitored via postoperative outpatient nasal endoscopy at various time points, which demonstrated excellent mucosalization of the ASB with a mean follow-up of 19.2 months (range: 4.1-36.2 months). Our simple relaxing slit incision in the sphenoidal portion of the PNSF allows for maximal tensionless coverage of extensive transcribriform defects by increasing the anterior and posterior reach of the flap.

Intracranial Anatomic Landmarks for Endoscopic Endonasal Transcribriform Approach to Anterior Skull Base.

To help surgeons locating anatomic landmarks when performing endoscopic endonasal transcribriform approach to anterior skull base. High-resolution axial computed tomography (CT) images at thickness of 0.6 mm, and reconstructed 0.41-mm thick gapless sagittal and coronal CT images were taken from 123 subjects. Using mimics software, first located elementary points and line: nasal spine, midpoint of posterior hard palate and the line between them; then located measured points right/left posterior and anterior points; measured distances between measured points and from measured points to nasal spine and angles between lines connecting measured points to nasal spine and the basic line. The distances from nasal spine to right/left posterior and anterior points of anterior skull base are 68.67 ± 6.04 and 61.71 ± 5.09 mm, corresponding angles are 45.89 ± 4.20° and 72.07 ± 4.06°, respectively. The width and length of defect of anterior skull base are 24.45 ± 2.62 and 31.03 ± 4.96 mm; its area ranges from 373.75 ± 94.08 to 800.91 ± 195.07 mm. The study provides information about anterior skull base anatomic landmarks, which can help surgeons to locate them and avoid relative complications during endoscopic endonasal transcribriform approach to anterior skull base. The measurements can be used as surgical indicators to investigate the landmarks.

Phantosmia and Dysgeusia following Endoscopic Transcribriform Approaches to Olfactory Groove Meningiomas.

The endoscopic, endonasal transcribriform approach (EETA) is an important technique used to directly access the anterior skull base and is increasingly being used in the management of olfactory groove meningiomas (OGMs). As this approach requires removal of the cribriform plate and olfactory epithelium en route to the tumor, patients are anosmic postoperatively. Here, we report the development of phantosmia and dysgeusia in two patients who underwent EETAs for OGMs, which has not yet been reported in the literature. We hypothesize that phantosmia and dysgeusia may result from aberrant neuronal signals or misinterpretation centrally from the remaining distal portions of the olfactory and taste pathways. Since EETAs are newer than traditional open craniotomy-based techniques, reporting these outcomes will be important to appropriately counsel patients preoperatively.

Endoscopic Endonasal Transcribriform Approach for Anterior Skull Base Lesions Involving the Cribriform Plate: Indications, Techniques, and Results in 24 Patients

Endoscopic Endonasal Transcribriform Approach for Anterior Skull Base Lesions Involving the Cribriform Plate: Indications, Techniques, and Results in 24 Patients

Endoscopic endonasal resection of sinonasal and anterior skull base schwannomas

Sinonasal and anterior skull base (ASB) schwannomas are rare entities. The majority of these lesions are found within the sinonasal tract, although some have intracranial extension via invasion of the ASB. Often, these tumors can be confused for other entities, especially olfactory groove meningiomas and esthesioneuroblastomas in the olfactory groove region, and juvenile nasopharyngeal angiofibromas in the infratemporal fossa. We present a single institutional series of four patients with sinonasal and ASB schwannomas that were resected purely via an endoscopic endonasal approach. A retrospective chart review was performed to identify individuals with sinonasal and/or ASB schwannomas. Demographic data, presenting symptoms, imaging, treatment, and follow-up were recorded. Two male and two female patients were included in this study. The average age was 53.5years (range, 21 to 71). The most common presenting symptoms were facial pain and hyposmia. All tumors were treated with endoscopic endonasal resection. One patient had intradural intracranial extension and required an extended endoscopic endonasal transcribriform approach with ASB resection, while another case involving the infratemporal fossa was treated with an extended endoscopic endonasal transpterygoid approach to this region. There were no major complications at an average follow-up of 9months (range, 0 to 16). Sinonasal and ASB schwannomas are rare entities, with often nondescript symptoms and can often mimic other types of skull base tumors. Total resection via a purely endoscopic endonasal approach can be considered for these rare neoplasms.

Assessment of frontal lobe sagging after endoscopic endonasal transcribriform resection of anterior skull base tumors: Is rigid structural reconstruction of the cranial base defect necessary?

The endoscopic endonasal transcribriform approach (EETA) is a viable alternative option for resection of selected anterior skull base (ASB) tumors. However, this technique results in the creation of large cribriform defects. Some have reported the use of a rigid substitute for ASB reconstruction to prevent postoperative frontal lobe sagging. We evaluate the degree of frontal lobe sagging using our triple-layer technique [fascia lata, acellular dermal allograft, and pedicled nasoseptal flap (PNSF)] without the use of rigid structural reconstruction for large cribriform defects. Retrospective analysis. Nine patients underwent an EETA for resection of large ASB tumors from August 2010 to November 2011. The degree of frontal lobe displacement after EETA, defined as the ASB position, was calculated based on the most inferior position of the frontal lobe relative to the nasion-sellar line defined on preoperative and postoperative imaging. A positive value signified upward displacement, and a negative value represented inferior displacement of the frontal lobe. The average cribriform defect size was 9.3 cm(2) (range, 5.0-13.8 cm(2) ). The average distance of postoperative frontal lobe displacement was 0.2 mm (range, -3.9 to 2.9 mm) without any cases of significant brain sagging. The mean follow-up period was 10.1 months (range, 4-19 months). There were no postoperative CSF leaks. Rigid structural repair may not be necessary for ASB defect repair after endoscopic endonasal resection of the cribriform plate. Our technique for multilayer cranial base reconstruction appears to be satisfactory in preventing delayed frontal lobe sagging.

Triple‐layer reconstruction technique for large cribriform defects after endoscopic endonasal resection of anterior skull base tumors

Endoscopic endonasal transcribriform (EET) resection of anterior skull base (ASB) tumors results in large defects that may extend the entirety of the cribriform plate. Endoscopic repair of these cribriform defects can often be challenging. We describe our reconstruction technique for large ASB defects after EET resection of ASB tumors. This triple-layer technique is comprised of autologous fascia lata, acellular dermal allograft, and a vascularized pedicled nasoseptal flap (PNSF). The technique is described and postoperative cerebrospinal fluid (CSF) leak rate is evaluated. Retrospective review over a 2-year period identified 10 patients who underwent a purely EET approach for resection of ASB tumors. Patients who underwent combined cranionasal approaches and those treated for ASB encephaloceles were excluded from this study. After tumor resection, patients underwent triple-layer reconstruction using autologous fascia lata inlay, acellular dermal allograft inlay/overlay, followed by a PNSF to reconstruct the cribriform defect. No postoperative lumbar drainage was used. The average cribriform defect size was 9.1 (range, 5.0-13.8) cm(2) . All 10 patients underwent successful reconstruction with a postoperative CSF leak rate of 0% without the use of postoperative lumbar drainage. The mean follow-up period was 7.4 (range, 2-17) months. The mean age was 45.8 (range, 15-81) years with 30% of the patients being females. The triple-layer reconstruction technique is effective in reconstructing large ASB defects after endoscopic resection of the cribriform plate. We feel that the use of postoperative lumbar drainage is not necessary when using this repair technique.

Endoscopic Endonasal Transcribriform Approach for Anterior Skull Base Tumors Involving the Cribriform Plate: Indications, Techniques, and Results in 13 Patients

Introduction: Tumors involving the anterior skull base have traditionally been treated with a transcranial or craniofacial approach. The endoscopic endonasal transcribriform approach (EEA-TC) is an extracranial approach that provides direct visualization and exposure of the ventral anterior skull base without brain retraction or manipulation of neurovascular structures. In this study, we reviewed our experience with EEA-TC for surgical removal of anterior skull base tumors.

Expanded endoscopic endonasal transcribriform approach for resection of anterior skull base olfactory schwannoma.

Anterior skull base (ASB) schwannomas are extremely rare and can often mimic other pathologies involving the ASB such as olfactory groove meningiomas, hemangiopericytomas, esthesioneuroblastomas, and other malignant ASB tumors. The mainstay of treatment for these lesions is gross-total resection. Traditionally, resection for tumors in this location is performed through a bifrontal transbasal approach that can involve some degree of brain retraction or manipulation for tumor exposure. With the recent advances in endoscopic skull base surgery, various ASB tumors can be resected successfully using an expanded endoscopic endonasal transcribriform approach through a "keyhole craniectomy" in the ventral skull base. This approach represents the most direct route to the anterior cranial base without any brain retraction. Tumor involving the paranasal sinuses, medial orbits, and cribriform plate can be readily resected. In this video atlas report, the authors demonstrate their step-by-step techniques for resection of an ASB olfactory schwannoma using a purely endoscopic endonasal transcribriform approach. They describe and illustrate the operative nuances and surgical pearls to safely and efficiently perform the approach, tumor resection, and multilayered reconstruction of the cranial base defect. The video can be found here: http://youtu.be/NLtOGfKWC6U .

Surgical nuances for removal of olfactory groove meningiomas using the endoscopic endonasal transcribriform approach

Olfactory groove meningiomas represent 10% of intracranial meningiomas and arise in the midline of the anterior cranial fossa along the dura of the cribriform plate and planum sphenoidale. Hyperostosis of the adjacent underlying bone is common, and further extension into ethmoid sinuses and nasal cavity can occur in 15%-25% of cases. Radical tumor resection including the involved dural attachment and underlying hyperostotic bone offers the best chance of a Simpson Grade I resection to minimize recurrence. Incomplete removal of involved hyperostotic bone can result in tumor recurrence at the cribriform plate with extension into the paranasal sinuses. Resection has traditionally been performed using a bifrontal or pterional approach, both of which require some degree of brain retraction or manipulation to expose the tumor. The endoscopic endonasal transcribriform approach offers the most direct and immediate exposure to the tumor without brain retraction and manipulation of neurovascular structures. An endonasal "keyhole craniectomy" is performed in the ventral skull base directly over the basal dural attachment, extending from the posterior wall of the frontal sinus to the planum sphenoidale and tuberculum sellae in the anteroposterior plane, and from one medial orbit to the other in the coronal plane. Excellent panoramic visualization of the keyhole skull base defect can be obtained with a 30° endoscope after performing a modified Lothrop procedure. Because the dural attachment is adjacent to the paranasal sinuses, early devascularization and total Simpson Grade I removal of the tumor including the dural attachment and underlying hyperostotic bone can be achieved in properly selected patients. This approach is also very suitable for meningiomas that have recurred or extended into the paranasal sinuses. Extracapsular, extraarachnoid dissection of the tumor from the frontal lobes and neurovascular structures can be performed using conventional bimanual microsurgical techniques. In this report, we review the surgical technique and describe our operative nuances for removal of olfactory groove meningiomas, including recurrent tumors with extension into the nasal cavity, using a purely endoscopic endonasal transcribriform approach. In addition, we discuss the advantages, limitations, patient selection, and complications of this approach. We specifically highlight our technique for multilayer reconstruction of large anterior skull base dural defects using fascia lata and acellular dermal allograft supplemented by bilateral vascularized pedicled nasoseptal flaps. Three new cases of endoscopically resected olfactory groove meningiomas are also presented.