INTRODUCTIONPrimary optic nerve sheath meningiomas (ONSMs) are the most common primary tumours of the optic nerve sheath. The diagnosis and management of ONSMs have changed dramatically in the last decade. In this review article, we discuss the latest information regarding these issues.

MATERIALS AND METHODSReferences for this manuscript were obtained by searching the database PubMed using the phrase "optic nerve sheath meningioma". Approximately 150 articles were identified and reviewed. These articles served as reference sources for other articles, books and chapters on the subject. The results were combined with our personal experience, which includes over 100 cases of ONSMs that have been observed or treated with one or more of the modalities described below.

RESULTSThe diagnosis of ONSM can be suspected in most cases from clinical findings and supported by the results of neuroimaging, obviating tissue biopsy in the majority of cases. Management depends on several factors. Observation may be appropriate in patients with mild or no visual deficit or in whom visual loss is not progressing, whereas stereotactic fractionated radiation therapy has been documented to improve or stabilise vision in progressive or advanced cases. Attempts at excision of ONSMs are associated with a high risk of blindness and should be reserved for the rare case of an anteriorly located, primarily exophytic tumour with focal involvement of the dural sheath. Rare patients with acute visual deterioration may benefit from optic nerve sheath fenestration.

CONCLUSIONThe majority of ONSMs can be suspected on clinical grounds and diagnosed with readily available non-invasive neuroimaging. Stereotactic fractionated radiotherapy is currently the treatment of choice for ONSMs that require therapy.

Humans ; Meningioma ; diagnosis ; therapy ; Optic Nerve Neoplasms ; diagnosis ; therapy

INTRODUCTIONRadiation-induced optic neuropathy (RON) is an infrequent but devastating consequence of radiation exposure to the visual pathways, usually following months to years after the treatment of paranasal or intracranial tumours. Hyperbaric oxygen (HBO) therapy is one of several therapies that have been tried for this condition. The purpose of this review is to describe the clinical characteristics of RON, the rationale for the use of HBO in this condition, and the available clinical data on its safety and efficacy.

METHODSMEDLINE searches were performed on radiation optic neuropathy, hyperbaric oxygen therapy, and similar terms, and selected references were reviewed. The results were combined with the experience at our own institution.

RESULTSRON typically follows a fulminant course with characteristic symptoms, examination findings, and imaging. The threshold for prior radiation exposure depends upon the delivery system used and patient characteristics. Therapy with anticoagulants or steroids has been unsuccessful. While there are case reports in the literature of successful treatment with HBO, therapy with HBO has to be initiated soon after the onset of vision loss, and even then yields variable results at best.

CONCLUSIONSThere is still no consistently successful treatment for RON. HBO may be attempted in selected cases, but the prognosis for preservation of vision remains grim.

Humans ; Hyperbaric Oxygenation ; Optic Nerve Diseases ; therapy ; Radiation Injuries ; therapy