Tumors of the meninges

Visual loss due to optic chiasm and retrochiasmal visual pathway lesions

PURPOSE OF REVIEW

Building on the anatomic and diagnostic approaches presented elsewhere in this issue of CONTINUUM, this article presents important differential considerations for chiasmal and retrochiasmal vision loss, useful strategies for confirming the underlying etiology, principles of their natural history, and, where appropriate, treatment strategies.

RECENT FINDINGS

Although a wide variety of pathologic processes can affect the optic chiasm and retrochiasmal visual pathways, those commonly seen in neurologic practice are comparatively fewer in number. This article updates current understanding of vision loss localizing to the optic chiasm, including pituitary adenoma, sellar meningiomas, and aneurysms. Important causes of retrochiasmal vision loss, including stroke and posterior reversible encephalopathy syndrome, are also presented.

SUMMARY

The optic chiasm and retrochiasmal visual pathways are susceptible to various forms of injury, with resultant patterns of vision loss that can be precisely localized on the basis of clinical and neuroimaging findings. Accurate localization, in association with other clinical features, allows for consideration of relevant differential diagnoses, which can be confirmed through the judicious application of appropriate diagnostic studies. Accurate localization, diagnosis, and robust clinical surveillance are essential to the effective management and treatment of these causes of vision loss.

Clinical features of sellar and suprasellar meningiomas

Meningiomas account for about 1% of sellar masses. Although they can mimic pituitary adenomas, they are more vascularized and invasive. To gain insights that would enhance our ability to establish a pre-surgical diagnosis of meningioma, we performed a retrospective study of these tumors. Query of the surgical pathology database identified 1,516 meningiomas operated at out institution between January 2000 and May 2012. Cases were matched to the radiology database to identify a strictly defined sellar and/or suprasellar location. We identified 57 meningiomas. F:M ratio was 6:1. The mean age was 52 years (median 50, range 30-78). The most common symptoms were visual disturbance (58%), headache (16%) and incidental finding (12%). The mean duration of symptoms was 13 months. Hyperprolactinemia was found in 36%, with mean value of 51.6 ng/ml (median 41.8, range 22.5-132). Mean maximal diameter was 2.9 cm (median 2.7, range 0.9-6.8), and most tumors enhanced homogeneously on MRI after gadolinium. A "dural tail" sign was reported in a third. The radiologist reported "likely meningioma" in 65%, "possible meningioma" in 8.7%, and pituitary adenoma in 11%. After surgery, visual disturbances improved in most patients (80%) but headache only in 7%. Post-operative complications at 1 and 3 months occurred 38.6 and 33.3% respectively. There was no mortality. Sellar/suprasellar meningiomas represent 4% of all meningiomas, and have a particularly high female predominance. The diagnosis is suggested by the radiologist in approximately 2/3 of the cases. An improved method to differentiate preoperatively these tumors from adenomas would be desirable.

Meningeal and choroid plexus cells--novel drug targets for CNS disorders

The meninges and choroid plexus perform many functions in the developing and adult human central nervous system (CNS) and are composed of a number of different cell types. In this article I focus on meningeal and choroid plexus cells as targets for the development of drugs to treat a range of traumatic, ischemic and chronic brain disorders. Meningeal cells are involved in cortical development (and their dysfunction may be involved in cortical dysplasia), fibrotic scar formation after traumatic brain injuries (TBI), brain inflammation following infections, and neurodegenerative disorders such as Multiple Sclerosis (MS) and Alzheimer's disease (AD) and other brain disorders. The choroid plexus regulates the composition of the cerebrospinal fluid (CSF) as well as brain entry of inflammatory cells under basal conditions and after injuries. The meninges and choroid plexus also link peripheral inflammation (occurring in the metabolic syndrome and after infections) to CNS inflammation which may contribute to the development and progression of a range of CNS neurological and psychiatric disorders. They respond to cytokines generated systemically and secrete cytokines and chemokines that have powerful effects on the brain. The meninges may also provide a stem cell niche in the adult brain which could be harnessed for brain repair. Targeting meningeal and choroid plexus cells with therapeutic agents may provide novel therapies for a range of human brain disorders.

Pneumosinus dilatans in anterior skull base meningiomas

INTRODUCTION

Skull base meningiomas are often missed on non-contrast CT or MR examinations due to their close proximity to bone and low lesion to brain contrast. The purpose of this study is to illustrate that pneumosinus dilatans can be an indicator of anterior skull base meningiomas.

METHODS

A retrospective search of the radiology information system and picture archiving and computing system database was performed. Search terms were "meningioma" in association with "pneumosinus dilatans." Medical records and imaging studies were reviewed independently by two experienced neuroradiologists and were read in consensus. We recorded the patient age at the time of discovery of the meningioma, main presenting symptom(s), location of the tumor, and imaging characteristics. We also performed a comparative literature search for pneumosinus dilatans and its association with meningiomas.

RESULTS

Ten patients (six women; four men) were identified in whom a meningioma of the anterior skull base was associated with a pneumosinus dilatans. Three patients had multiple meningiomas, so a total of 14 intracranial tumors were identified. Mean age at discovery was 59 years with an age range of ± 20years. All meningiomas were diagnosed by MRI and/or CT.

CONCLUSION

Pneumosinus dilatans can be a helpful sign to indicate the presence of a meningioma of the anterior skull base.

Dural lesions mimicking meningiomas: A pictorial essay

The purpose of this essay was to illustrate the radiological and pathological findings in a wide spectrum of dural lesions mimicking meningiomas. Familiarity with and knowledge of these findings will narrow the differential diagnosis and provide guidance for patient management. In this pictorial review, we describe the following entities: Solitary fibrous tumors, hemangiopericytoma, gliosarcoma, leiomyosarcoma, dural metastases, Hodgkin’s disease, plasmocytoma, Rosai-Dorfman disease, neurosarcoidosis, melanocytic neoplasms and plasma cell granuloma.