Midline Anterior Skull Base Research Articles

The Pterional Port in Dual-Port Endoscopy: A 2D and 3D Cadaveric Study.

Objective We propose a novel dual-port endonasal and pterional endoscopic approach targeting midline lesions of the anterior cranial fossa with lateral extension beyond the optic nerve. Methods Ten dual-port approaches were performed on five cadaveric heads. All specimens underwent an endoscopic transtuberculum/transplanum approach followed by placement of a pterional port. The endonasal port was combined with an endoscopic extradural pterional keyhole craniectomy. The pterional port was placed at the intersection of the sphenoparietal and coronal sutures. The extradural space was explored using two-dimensional and three-dimensional endoscopes. Results The superolateral access provided by the pterional port may improve the ability to achieve a gross total resection of tumors with lateral extensions. The complete opening of the optic canal achieved through the dual-port approach may enable resection of the intracanalicular portion of a tumor, a crucial step in improvement of visual function and reduction of tumor recurrence. Conclusion The pterional port may enhance control of midline anterior skull base lesions with lateral extension beyond the optic nerve and optic canal. Dual-port endoscopy maintains minimally invasiveness and dramatically increases the working limits and control of anatomical structures well beyond what is attainable through single-port neuroendoscopy.

Transglabellar approach for resection of anterior midline skull base meningiomas: technical note

We describe our experience of minimally invasive approach of the anterior skull base through the transglabellar approach. The technical details of the transglabellar approach are described in this article as we have been using it for the past 3 years. After an inter-eyebrow skin incision, the scalp is elevated allowing the creation of a 3-cm bone flap in the frontal sinus, which gives direct access to the anterior midline skull base. Removal of the tumour is carried out without brain retraction. The closure requires obstruction of nasofrontal ducts and sinus mucosa removal. We operated on 24 patients using this approach. The tumour was completely removed in every case. We reported one case of meningitis and three cerebrospinal fluid leaks. Every patient was satisfied with the aesthetic results. The transglabellar approach is a reasonably easy and efficient way to resect anterior midline skull base meningiomas.

The anterior interhemispheric approach - a safe and effective approach to anterior skull base lesions

Many approaches to the anterior skull base have been reported. Frequently used are the pterional, the unilateral or bilateral frontobasal, the supraorbital and the frontolateral approach. Recently, endoscopic transnasal approaches have become more popular. The benefits of each approach has to be weighted against its complications and limitations. The aim of this study was to investigate if the anterior interhemispheric approach (AIA) could be a safe and effective alternative approach to tumorous and non-tumorous lesions of the anterior skull base. We screened the operative records of all patients with an anterior skull base lesion undergoing transcranial surgery. We have used the AIA in 61 patients. These were exclusively patients with either olfactory groove meningioma (OGM) (n = 43), ethmoidal dural arteriovenous fistula (dAVF) ( n = 6) or frontobasal fractures of the anterior midline with cerebrospinal fluid (CSF) leakage ( n = 12). Patient records were evaluated concerning accessibility of the lesion, realization of surgical aims (complete tumor removal, dAVF obliteration, closure of the dural tear), and approach related complications. The use of the AIA exclusively in OGMs, ethmoidal dAVFs and midline frontobasal fractures indicated that we considered lateralized frontobasal lesions not suitable to be treated successfully. If restricted to these three pathologies, the AIA is highly effective and safe. The surgical aim (complete tumor removal, complete dAVF occlusion, no rhinorrhea) was achieved in all patients. The complication rate was 11.5 % (wound infection (n = 2; 3.2 %), contusion of the genu of the corpus callosum, subdural hygroma, epileptic seizure, anosmia and asymptomatic bleed into the tumor cavity (n = 1 each). Only the contusion of the corpus callosum was directly related to the approach (1.6 %). Olfaction, if present before surgery, was preserved in all patients, except one (1.6 %). The AIA is an effective and a safe approach to tumorous, vascular and traumatic pathologies of the midline anterior skull base. This approach should be part of the armamentarium of skull base surgeons.

Surgical management of midline anterior skull base meningiomas: experience of 30 cases.

Midline anterior skull base meningiomas include olfactory groove meningiomas (OGMs), Tuberculum Sellae meningiomas (TSMs), and planum sphenoidale meningiomas (PSMs). The main surgical challenge in treating these lesions is to excise the tumor totally without causing mortality or morbidity. Studying the clinical patterns and the surgical outcomes of these lesions. Thirty cases of midline anterior skull base lesions were included in our study. Patients were operated upon by four routes: (i) unilateral subfrontal, (ii) bilateral subfrontal, (iii) frontotemporal approach, and (iv) bifrontal basal interhemispheric. Extent of resection was classified according to the Simpson grading system. The functional outcome of the patients was assessed by comparing the preoperative and the postoperative neurological examination, as well as the Karnofsky performance scale. We had 14 OGMs (46.7%), 9 TSMs (30%), and 7 PSMs (23.3%). The most commonly utilized approach was the subfrontal approach (unilateral or bilateral) in 80% of the cases, followed by the pterional approach in 16.6% of the cases. Total removal was achieved in 86.7% of the cases; subtotal excision was achieved in 13.3% of the cases. 41.2% of our cases showed postoperative clinical improvement. We had two mortalities in our study, representing 6.7%. We did not detect any tumor recurrences in our follow up. The median preoperative Karnofsky scale was 85, while the median postoperative Karnofsky scale was 90. Midline anterior skull base lesions are becoming amenable for total surgical excision with minimal morbidities and mortalities. Most preferred surgical routes are the subfrontal and the pterional approaches.

The lion's mane sign: surgical results using the bilateral fronto-orbito-nasal approach in large and giant anterior skull base meningiomas

Concerns about extreme peritumoral edema and its ensuing surgical and perioperative complications led the authors to use the bilateral fronto-orbito-nasal approach to remove midline anterior skull base meningiomas that were larger than 4 cm. The authors hypothesize that extreme vasogenic edema exemplified by finger-like hyperintensities extending into the bifrontal white matter and external capsule and/or the extreme capsule, coined the lion's mane sign (LMS), would help identify patients with a challenging postoperative course. They hypothesize that the LMS would better predict symptomatic postoperative cerebral edema than the edema index (EI). This is an observational case series of 9 patients. The authors noted the grade, pathology, tumor volume, EI, and the presence or absence of the LMS in all tumors. They used the intensive unit care (ICU) length of stay as a nonspecific measure reflecting postoperative symptomatic cerebral edema. Comparisons of edema-related postoperative complications and the EI were made between patients with and without an LMS. Bifrontal hyperintensities, extending into at least three-eighths of the length of the external capsules on T2-weighted MRI, seen in 4 of 9 patients, portended a longer postoperative ICU stay. The presence of an LMS better predicted postoperative complications related to cerebral edema than tumor grade, pathology, volume, or EI. The LMS predicts an increased duration of stay in the ICU after a bilateral fronto-orbito-nasal approach for resection of large and giant anterior skull base meningiomas. Furthermore, the LMS better predicted increased length of stay in the ICU than did the EI.

Treatment outcomes after surgical resection of midline anterior skull base meningiomas at a single center

Meningiomas of the midline anterior skull base (ASB) typically grow around the optic chiasm. These tumors can displace or adhere to the optic apparatus, resulting in visual abnormalities. For this reason, in most studies of surgically resected meningiomas, only surgical and visual outcomes have been evaluated. However, in this study, we assessed overall clinical outcomes and the effects of different surgical approaches on outcomes. Clinical data for 126 patients who were treated surgically for midline ASB meningiomas between 1994 and 2009 were collected and reviewed retrospectively. The mean follow-up duration was 39months (range: 0.5–146months). Most procedures were performed via a pterional approach and did not require an aggressive skull base approach. Clinical outcomes were evaluated using our own criteria, and potential predictive factors for visual and clinical outcomes were tested statistically. The tumor control rate was 83% (105/126). Immediate postoperative visual status and optic canal involvement were correlated with visual outcome. Of the patients who ultimately had improved visual status, only six were originally categorized as having severe visual impairment (all were only able to count fingers). In terms of clinical outcome, 41 patients were classified as “excellent”, 32 as “good”, 29 as “fair”, and 20 as “poor”. A symptom duration of less than six months, less severe preoperative visual symptoms of the affected eye, and the extent of resection were all correlated with improved clinical outcome. Involvement of the optic canal, adherence of the tumor to the optic nerve, and major arterial encasement by the tumor were associated with poor clinical outcome. We recommend that in patients with unilateral severe visual impairment, the focus should be on improving visual function in the contralateral eye. Preoperative and postoperative evaluation of several variables allows for the prediction of clinical and visual outcomes.

What Is the Best Approach to Resect an Anterior Midline Skull Base Meningioma in 2011? Microsurgical Transcranial, Endonasal Endoscopic, or Minimal Access Cranial?

What Is the Best Approach to Resect an Anterior Midline Skull Base Meningioma in 2011? Microsurgical Transcranial, Endonasal Endoscopic, or Minimal Access Cranial?

Transconjunctival Approach to the Anterior Skull Base

Introduction: Traditional craniofacial approaches to the midline anterior cranial base are associated with risks (i.e., loss of olfaction) that, while tolerated for malignancies, could be avoided for benign and less extensive pathologies. The orbit could serve as a direct, minimally invasive conduit to select lesions through a cosmetically hidden incision–the precaruncular transconjunctival incision. Typically used for intraorbital pathology, we employed this incision to access the midline anterior skull base and aspects laterally not accessible endonasally.

Combined Transorbital-Endonasal Approach to the Anterior Skull Base

Introduction: Traditional craniofacial approaches to the midline anterior skull base are associated with risks (i.e., loss of olfaction) that, while tolerated for malignancies, could be avoided for benign/less extensive pathology. Keyhole craniotomies are based anterolaterally where view of the midline skull base is hindered by the orbital roof. The orbit could serve as a direct conduit to access select lesions; combined with an endonasal approach, this could allow circumferential exposure of the anterior cranial fossa.

Endoscopic transnasal resection of anterior cranial fossa meningiomas

The extended transnasal approach, a recent surgical advancements for the ventral skull base, allows excellent midline access to and visibility of the anterior cranial fossa, which was previously thought to be approachable only via a transcranial route. The extended transnasal approach allows early decompression of the optic canals, obviates the need for brain retraction, and reduces neurovascular manipulation. Between 2004 and 2007, 11 consecutive patients underwent transnasal resection of anterior cranial fossa meningiomas--4 olfactory groove (OGM) and 7 tuberculum sellae (TSM) meningiomas. Age at surgery, sex, symptoms, and imaging studies were reviewed. Tumor size and tumor extension were estimated, and the anteroposterior, vertical, and horizontal diameters were measred on MR images. Medical records, surgical complications, and outcomes of the patients were collected. A gross-total removal of the lesion was achieved in 10 patients (91%), and in 1 patient with a TSM only a near-total (> 90%) resection was possible. Four patients with preoperative visual function defect had a complete recovery, whereas 3 patients experienced a transient worsening of vision, fully recovered within few days. In 3 patients (2 with TSMs and 1 with an OGM), a postoperative CSF leak occurred, requiring a endoscopic surgery for skull base defect repair. Another patient (a case involving a TSM) developed transient diabetes insipidus. The operative time ranged from 6 to 10 hours in the OGM group and from 4.5 to 9 hours in the TSM group. The mean duration of the hospital stay was 13.5 and 10 days in the OGM and TSM groups, respectively. Six patients (3 with OGMs and 3 with TSMs) required a blood transfusion. Surgery-related death occurred in 1 patient with TSM, in whom the tumor was successfully removed. The technique offers a minimally invasive route to the midline anterior skull base, allowing the surgeon to avoid using brain retraction and reducing manipulation of the large vessels and optic apparatus; hastens postoperative recovery; and improves patient compliance. Further assessment and refinement are required, particularly because of the potential risk of CSF leakage. Other studies and longer follow-up periods are necessary to ascertain the benefits of the technique.

Endoscopic endonasal approach to the ethmoidal planum: anatomic study

The endoscopic endonasal technique is currently used by otolaryngologists for the management of different extradural lesions located below the ethmoidal planum. The cooperation between ENTs and neurosurgeons has recently pushed the use of such approach also in the removal of some intradural lesions, which has promoted the interest for an anatomic study to identify the anatomical landmarks and the dangerous points during the endoscopic approach to this area. In six fresh cadaver heads, unilateral and bilateral measurements between the main landmarks of the approach were performed by means of an endoscopic endonasal approach. A wide exposure of the midline anterior skull base was realized. The maximum of lateral extension was obtained between the two medial orbital walls, at the middle of the cribriform plate (mean distance 25,33 mm), while the mean distance between the anterior and posterior ethmoidal arteries at the level of the lamina papyracea was 16 mm. The endoscopic endonasal route can be considered a minimally invasive technique to approach the ethmoidal planum. It requires adequate anatomical knowledge and endoscopic skill for its realization. Due to the wide window realizable through this corridor, it could be considered in selected cases for the removal of intradural lesions such as meningiomas or estesioneuroblastomas.

Low complication rates of cranial and craniofacial approaches to midline anterior skull base lesions.

Surgery is a cornerstone of treatment for a wide variety of neoplastic, congenital, traumatic, and inflammatory lesions involving the midline anterior skull base and may result in a significant anterior skull base defect requiring reconstruction. This study is a retrospective analysis of the reconstruction techniques and complications seen in a series of 58 consecutive patients with midline anterior skull base pathology treated with craniotomy or a craniofacial approach. The complication rates in this series are compared with other retrospective series and specific techniques that may reduce complications are then discussed. This is a retrospective analysis of 58 consecutive patients who had surgery for a midline anterior skull base lesion between January 1994 and July 2003. Data were collected regarding pathology, surgical approach, reconstruction technique, and complications. Twenty-nine patients underwent surgery for a meningioma (50%). The remainder had frontoethmoidal cancer, mucoceles/invasive nasal polyps, encephalocele, esthesioneuroblastoma, anterior falx dermoid cyst with a nasal sinus tract, or invasive pituitary adenoma. In most patients, a low and narrow two-piece biorbitofrontal craniotomy was used. When possible, the dura was repaired before entering the nasal cavity. Thirteen patients experienced a complication (22%). There was one case of postoperative cerebrospinal fluid (CSF) leak (2%), one case of meningitis (2%), two cases of bone flap infection (3%), and two cases of symptomatic pneumocephalus (3%). There were no deaths, no reoperations for CSF leak, and no patient had a new permanent neurologic deficit other than anosmia. Transcranial approaches for midline anterior skull base lesions can be performed safely with a low incidence of postoperative CSF leak, meningitis, bone flap infection, and symptomatic pneumocephalus. Our results, particularly with regard to CSF leakage, compare favorably with other retrospective series.

Proposed Classification for the Transbasal Approach and Its Modifications

The transbasal approach offers extradural exposure of the anterior midline skull base transcranially. It can be used to treat a variety of conditions, including trauma, craniofacial deformity, and tumors. This approach has been modified to enhance basal access. This article reviews the principle differences among modifications to the transbasal approach and introduces a new classification scheme. The rationale is to offer a uniform nomenclature to facilitate discussion of these approaches, their indications, and related issues.

Expanded endonasal approach: the rostrocaudal axis. Part II. Posterior clinoids to the foramen magnum

Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. Recently, however, the standard endonasal approach has been expanded to provide access to other parasellar lesions. With the addition of the endoscope, this expansion has significant potential for the resection of skull base lesions. The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the clivus and cervicomedullary junction are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The caudal portion of the midline anterior skull base and the cervicomedullary junction is divided into modules of approach: the middle third of the clivus, its lower third, and the cervicomedullary junction. Case illustrations of successful resections of lesions via each module of the approach are presented and discussed. Endoscopic expanded endonasal approaches to caudally located midline anterior skull base and cervicomedullary lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.