Pneumosinus dilatans in anterior skull base meningiomas

Surgical Implications and Radiologic Classification for the Upward Bulging of the Planum Sphenoidale in Patients With Anterior Skull Base Meningiomas Involving the Tuberculum Sellae Area

OBJECTIVE

To investigate the surgical implications and morphologic type of upward bulging of the planum sphenoidale (PS) in anterior skull base meningiomas involving the tuberculum sellae area.

METHODS

Between January 2014 and June 2021, 96 patients with anterior skull base meningiomas underwent surgery at the Sanbo Brain Hospital of Capital Medical University. A total of 96 patients with nonintracranial space-occupying lesions were selected as the control group. The height of upward bulging of the PS was measured and classified. The authors performed univariate and multivariate analyses to evaluate the rate and effects of upward bulging of the PS.

RESULTS

The PS upward bulging rate was 23.00% versus 66.70% (P<0.001) between the control and meningioma groups. Multiple linear regression showed that it was correlated with the tumor midsagittal anteroposterior length (P=0.025) and the midsagittal height diameter (P=0.012). According to the height of PS upward bulging, it was divided into types 1, 2, and 3. The tumor gross-total resection rates were 96.9%, 92.3%, and 76.0%, respectively (P=0.042).

CONCLUSIONS

Anterior skull base meningiomas involving the tuberculum sellae area can cause PS upward bulging, which lowers the tumor resection rate and should be considered while determining the treatment approach.

Bilateral Visual Loss Caused by Pneumosinus Dilatans: Idiopathic Cases are not Always Reversible

Purpose

To report a rare case of primary pneumosinus dilatans (PSD) and to specify the cardinal imaging findings associated with this condition.

Methods

A 20-year-old patient presented with bilateral profound visual loss as a result of primary PSD. A detailed review of clinical findings and presumed pathophysiological basis of vision loss was performed.

Results

Other than undiagnosed primary hypothyroidism, no other abnormalities were found. With the diagnosis of PSD, the patient underwent optic nerve decompression through transnasal sphenoidotomy. However, after nine months of follow-up, no improvement in the patient's vision was attained.

Conclusion

Unlike previous reports of favorable visual results after sphenoidotomy and bilateral decompression of the optic nerves, vision recovery was not achieved in this case.

Pneumosinus dilatans of the sphenoid and visual loss: when should the optic nerve be decompressed?

Pneumosinus dilatans of the sphenoid sinus is a rare disorder which can be responsible for visual impairment and blindness. We present the case of an adolescent female who experienced progressive decrease in right-eye vision over 2 years. CT scan of the head showed an extensive pneumatization of the sphenoid bone extending to the lesser wing of the sphenoid and to the anterior clinoid process on the right side. MRI revealed right nerve atrophy in the optic canal and in the posterior part of the orbit. A surgical decompression of the right optic canal was performed via an intradural fronto-pterional approach. Postoperatively, her vision worsened, and at 3 years the patient was able to count fingers at 2.5 m. Our case and literature review of symptomatic sphenoidal pneumosinus dilatans confirmed that visual prognosis in such cases depended on the preoperative visual status. Early surgical decompression should be proposed whenever possible, before signs of severe visual disorders and optic atrophy.

Endoscopic technology and repair techniques

In this chapter, we describe advances in endoscopic endonasal surgery that have impacted skull base meningioma surgery. After reviewing the technical innovations in endoscopy, we describe the advances as they relate to each surgical step. We discuss preoperative planning and approach and the utility of neuronavigation and neuromonitoring. We then discuss endoscopic instrumentation, technology for tumor debulking (ultrasonic aspirators, radiofrequency ablators, suction debriders), and hemostatic agents as they relate to tumor resection and hemostasis. In the end, we discuss techniques of skull base reconstruction and closure (nasoseptal flap, gasket seal and bilayer button).

Enlargement of Frontal Sinus, Case Report

INTRODUCTION

Frontal sinus enlargement has been classified into hypersinus, pneumosinus dilatans and pneumocele.

CASE REPORT

A young male presented with aesthetic concerns regarding his forehead swelling. The patient had no functional disturbances. Radiographic assessment proved expansion of the frontal sinus with extreme thinning of the frontal bone.

DISCUSSION

The causes of frontal sinus expansion have been listed along with a proposed management plan for each type. If blockage is suspected, functional endoscopic sinus surgery can alleviate the blockage. Open surgery is indicated when the element presents as an aesthetic concern. Obliteration of the sinus is indicated with NF obstruction. And reshaping of the anterior table is the mainstay to correct the enlargement.

CONCLUSION

Frontal sinus enlargement regardless of the cause can be tackled using well known principles. We believe that every plastic surgeon should have a basic understanding of frontal sinus enlargement and its management.

LEVEL OF EVIDENCE V

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[Variability and age-related features of the anatomy of the midline structures of the anterior skull base]

The article presents the literature data on the structural variability and age-related features of the midline anatomical structures of the anterior skull base (frontal sinus, ethmoid bone, anterior parasellar region, and medial orbital wall). This is the area of surgical interests of neurosurgeons and rhinosurgeons. The study objective is to analyze the literature data on the individual variability and age-related anatomy of these structures. The work is illustrated with original images from the authors' personal archive. The individual anatomical features of eloquent structures in the surgical area (structures within the surgical corridor, key anatomical landmarks, optic tract, internal carotid and ethmoidal arteries, etc.) should be considered in planning surgery in patients of all age groups because they can limit the view and the amount of safe manipulations or increase the risk of complications. The presented data may be useful for neurosurgeons and otolaryngologists whose surgical interests are focused on the midline structures of the anterior skull base.

The Role of Conservative Management in Pneumosinus Dilatans Frontalis With Minimal Bony Deformity

The authors describe the conservative management of 2 rare patients of uncomplicated pneumosinus dilatans of the frontal sinus with minimal bossing of the forehead. Regular nasal hygiene in combination with topical corticosteroids was administered with following complete resolution symptoms.

Complex Frontal Pneumosinus Dilatans Associated with Meningioma: A Report of Two Cases and Associated Literature Review

Introduction  Pneumosinus dilatans (PSD) is a rare phenomenon involving the expansion of the paranasal sinuses, without bony destruction or a mass. Previously documented cases have demonstrated simple expansion of a solitary air cell. We present two unique cases of PSD in the presence of meningioma, in which complex new cells developed within the frontal sinus. One of the two patients developed associated sinus disease.

Case 1  A 28-year-old man presented with facial pain. A computed tomography scan showed an abnormally enlarged, septated right frontal sinus, not present on childhood scans. He underwent a modified endoscopic Lothrop approach to divide the septations, and his symptoms resolved.

Case 2  A 72-year-old woman presented with a 3-month history of headaches. Scans revealed a left frontal meningioma and multiple enlarged, dilated left frontal air cells. She had no clinical sinusitis and therefore was managed conservatively.

Conclusions  PSD has been widely documented in association with fibrous dysplasia and meningioma. The most prevalent theory of the mechanism of PSD is of obstruction of the sinus ostium causing sinus expansion through a “ball-valve” effect. Our cases, which demonstrate septated PSD, suggest a more complex process involving local mediators and highlight the need to consider underlying meningioma in pneumosinus dilatans.

Endonasal Operative Corridor Expansion by Sphenoidal Pneumosinus Dilatans in Tuberculum Sellae Meningiomas

BACKGROUND

A retrospective cohort study of patients with tuberculum sellae meningioma (TSM)-associated sphenoidal pneumosinus dilatans (PSD) over a recent epoch was evaluated using a propensity-matched morphometric analysis.

METHODS

A total of 38 patients with TSM and sphenoidal PSD were identified and matched by age and sex to 32 patients without tumors (controls).

RESULTS

Overall, no significant difference between test and control groups was noted in sphenoid sinus size or other parameters; however, significantly greater mean distances from the posterior margin of the planum sphenoidale to the diaphragma sella (0.76 ± 0.23 vs. 1.03 ± 0.27, respectively; P = 0.0001) and angle between the planum sphenoidale to anterior face of sella turcica (113.41 ± 10.58 vs. 123.21 ± 12.55, respectively; P = 0.001) were seen in patients with TSM and PSD, suggestive of a selective expansion of the tuberculum sellae region. TSM/sphenoid sinus morphologies were divided into 3 types (A, B, and C) based on the extent of tumor and sinus morphology. There was progressive increase in tumor volume and anteroposterior sinus diameter from sphenoidal PSD types A-C, which influenced selection of surgical approach.

CONCLUSIONS

This study suggests that TSM-associated sphenoidal PSD leads to more selective splaying of the tuberculum sellae region rather than cumulative increase in sinus volume. This may lead to operative corridor expansion for endonasal access to TSM associated with sphenoidal PSD. A radiologic classification scheme for sphenoidal PSD associated with TSM is suggested that may aid surgical decision-making.

Sellar and Parasellar Imaging

The skull base is a complex anatomical region that harbors many important neurovascular structures in a relatively confined space. The pathology that can develop at this site is varied, and many disease processes may present with similar clinical and neuroimaging findings. While computed tomography maintains a role in the evaluation of many entities and can, for instance, delineate osseous erosion with great detail and characterize calcified tumor matrices, magnetic resonance imaging (MRI) is the mainstay in the neuroimaging assessment of most pathology occurring at the skull base. Various MRI sequences have proven to be robust tools for tissue characterization and can provide information on the presence of lipids, paramagnetic and diamagnetic elements, and tumor cellularity, among others. In addition, currently available MRI techniques are able to generate high spatial resolution images that allow visualization of cranial nerves and their involvement by adjacent pathology. The information obtained from such examinations may aid in the distinction of these disease processes and in the accurate delineation of their extent prior to biopsy or treatment planning.

Surgical Correction of an Extensive Skull Base Defect as a Result of Pneumocele

Pneumocele is a condition involving the pathologic expansion of paranasal sinuses with corresponding bony erosion of the skull base. Extensive pneumocele can lead to pneumocephalus, especially in patients with long-term cerebrospinal fluid shunts. Here, the authors present a case of pneumocele in an adult with a history of congenital hydrocephalus managed with a ventriculoperitoneal shunt. The patient underwent reconstruction of a posterior table defect with a pericranial flap followed by frontal sinus obliteration with abdominal fat.

Surgical implications of frontoethmoidal pneumosinus dilatans-associated proptosis caused by meningioma

Pneumosinus dilatans (PSD) involves paranasal sinus enlargement without radiologic evidence of localized bone destruction, hyperostosis, or mucous membrane thickening. We discuss the surgical implications of PSD-associated proptosis in patients with anterior skull-base meningioma. A 20-year-old man with proptosis, hypoglobus, and lateral globe displacement had WHO grade I anterior skull-base and orbital meningiomas. Aggressive resection using anterior/medial orbitotomy and an anterior interhemispheric skull-base approach achieved Simpson grade I resection. Postoperatively, his symptoms improved, with no recurrence at 2-year follow-up. Although PSD-associated proptosis is relatively uncommon, it carries important clinical implications in surgical management of skull-base and orbital meningiomas.

Sphenoidal pneumosinus dilatans due to anterior skull base meningiomas - CT and MRI aspects: Report of two new cases and literature review

We report on two patients disclosing a pneumosinus dilatans (PSD) and an anterior skull base meningioma. Our findings, together with those from the pertinent literature, support the thought that this infrequent anomaly of paranasal sinuses is a useful clue to suspect a concomitant meningioma. Moreover, hypotheses concerning the pathophysiology of PSD are discussed.

Advances in computed tomography evaluation of skull base diseases

Introduction Computed tomography (CT) is a key component in the evaluation of skull base diseases. With its ability to clearly delineate the osseous anatomy, CT can provide not only important tips to diagnosis but also key information for surgical planning.

Objectives The purpose of this article is to describe some of the main CT imaging features that contribute to the diagnosis of skull base tumors, review recent knowledge related to bony manifestations of these conditions, and summarize recent technological advances in CT that contribute to image quality and improved diagnosis.

Data Synthesis Recent advances in CT technology allow fine-detailed evaluation of the bony anatomy using submillimetric sections. Dual-energy CT material decomposition capabilities allow clear separation between contrast material, bone, and soft tissues with many clinical applications in the skull base. Dual-energy technology has also the ability to decrease image degradation from metallic hardwares using some techniques that can result in similar or even decreased radiation to patients.

Conclusions CT is very useful in the evaluation of skull base diseases, and recent technological advances can increase disease conspicuity resulting in improved diagnostic capabilities and enhanced surgical planning.

Brain stones revisited-between a rock and a hard place

OBJECTIVES AND METHODS

Large intracranial calcifications are occasionally encountered in routine computed tomography (CT) scans of the brain. These calcifications, also known as "brain stones", can be classified according to location and aetiology. Combining imaging findings with relevant clinical history and physical examination can help narrow down the differential diagnosis and may allow confident diagnosis in certain situations.

RESULTS

This article provides a pictorial review illustrating various clinical entities resulting in brain stones.

DISCUSSION

Based on location, brain stones can be classified as extra- or intra-axial. Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. Intra-axial brain stones can further be classified according to aetiology, namely neoplastic, vascular, infectious, congenital and endocrine/metabolic. Imaging findings combined with essential clinical information can help in narrowing the differential diagnosis, determining disease state and evaluating effect of therapy.

TEACHING POINTS

• Based on location, brain stones can be either extra- or intra-axial. • Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. • Intra-axial aetiologies include neoplastic, vascular, infectious, congenital and endocrine/metabolic. • CT scan is the mainstay in identifying and characterising brain stones. • Certain MRI sequences (gradient echo T2* and susceptibility-weighted imaging) are considered adjunctive.