Review of controversies in management of non-benign meningioma.

Meningiomas are one of the most common brain tumors. World Health Organisation (WHO) Grade II and Grade III meningiomas are grouped together as non-benign meningioma (NBM). There are several controversies surrounding NBM management, including the significance of extent of resection and the efficacy of post-operative radiation and drug treatment. We reviewed the literature to develop recommendations for management of NBM. The questions we sought to answer were: Does gross total resection (GTR) improve patient outcome? Is radiation therapy (RT) warranted after complete or after incomplete resection of NBM? What drug therapies have been proven to improve outcome in patients with NBM? We found that GTR improves outcome in WHO Grade II meningioma, and should be attempted whenever considered safe. GTR correlates less closely to outcome in Grade III meningioma compared to subtotal resection (STR). Extreme measures to completely resect Grade III meningioma are not warranted. RT following GTR of Grade II meningioma does not improve patient outcome, and may be reserved for recurrence. RT improves outcome following STR of Grade II meningioma. RT improves outcome after resection of Grade III meningioma. No drug therapy has been shown to improve outcome in NBM. This review elucidates recommendations for some of the controversies involving NBM.

Is a wake-up call in order? Review of the evidence for awake craniotomy.

Awake craniotomy (AC) has been used in increasing frequency in the past few decades. It has mainly been used for resection of intrinsic tumors, but also, rarely, for other pathologies. The vast majority of reports specific to one pathology, however, have focused on resection of low grade glioma in the awake setting. Tumors in eloquent areas have mainly been resected when the patient is awake for the purpose of preservation of function. Motor function is the most documented, and most successfully preserved function. Other functions are harder to localize with direct electrical stimulation (DES), and thus more difficult to preserve. The success rate of DES localization correlates to the rate of function preservation. The effect of AC on extent of resection is inconsistent in the literature. Other functions, such as sensory and visuospatial recognition, have been protected during AC, but this is best performed in large, referral centers that have experience with the procedure. Other benefits to AC, such as cost-effectiveness and reduction in patient pain and anxiety, have also been reported.

Assessment of Optic Pathway Structure and Function in Patients With Compression of the Optic Chiasm: A Correlation With Optical Coherence Tomography.

PURPOSE: The purpose of this study was to investigate correlations between retinal fiber thickness measured by optical coherence tomography (OCT) and anterograde functional and structural differences in the optic pathway of patients with compression of the optic chiasm. Our hypothesis was that loss of visual acuity caused by chronic compressive pathologies may lead to an irreversible decline in vision because of permanent neurodegeneration of the optic radiations and visual cortex. METHODS: Quantitative OCT, functional magnetic resonance imaging (MRI) and diffusion tensor MRI measurements were made in 17 patients being surgically treated for chiasmal compression. RESULTS: In our study we found that surgically irreversible visual field defects and reduced retinal nerve fiber layer thickness were significantly associated with lower fractional diffusion anisotropy and higher diffusivities in optic radiations and less functional MRI activation in the visual cortex. CONCLUSIONS: Damage to the retinal nerve fiber layer is associated with downstream structural and functional degradation of the optic pathway. This may be related to trans-synaptic degeneration and the fact that these factors are important potential imaging biomarkers for predicting visual recovery after surgical decompression.