Meningiomas
Meningiomas are a common variety of intracranial tumor. They may arise anywhere within the central nervous system and are typically slow growing benign tumors. The presenting symptoms of meningiomas are largely related to their location and size. Meningiomas arising from the sphenoid wing are particularly prone to present with visual symptoms due to the close proximity to the optic apparatus. A variety of authors have attempted to create grading systems that can be used to identify predictive factors related to outcomes and provide prognostic information. While no one grading system is universally agreed upon, there are multiple presenting factors that hold prognostic significance with regard to clinical visual outcomes. These factors include: preoperative visual loss, duration of visual loss, preoperative condition of the optic disc, tumor size, invasion of the optic canal, extension into the cavernous sinus, and peritumoral edema on preoperative imaging. The presence of hydrocephalus, while not directly related to meningomas, is also a possible negative prognostic factor for visual outcomes due to damage to the optic nerves from increased intracranial pressure.
The size and location of meningiomas can be associated with significant cognitive, language and executive dysfunction. This is particularly true of those tumors causing mass effect and/or cerebral edema of the dominant, left, temporal and frontal lobes. Hydrocephalus is also independently associated with impairment of cognitive and executive skills.
Visual outcomes involving meningiomas of the visual apparatus
Multiple factors are associated with negative visual outcomes involving meningiomas of the visual apparatus. These factors include preoperative visual loss, preoperative optic disc edema, tumor size (greater than 30 cc volume) and associated cerebral edema. Hydrocephalus at presentation also factors in as it is associated with elevated intracranial pressure and independently can result in damage to the optic nerves. Involvement of the optic canal is another negative prognostic factor for visual outcomes.
The combination of the meningioma location, size, mass effect, and the associated cerebral edema and hydrocephalus all impact on higher neurologic functions. In particular, an impacted dominant temporal and frontal lobes would be expected to result in decreased executive function (planning, attention to details), language and memory. Such effects will highly likely result in an inability to clearly perceive, prioritize, and follow through with physician’s recommendations.
Meningioma medical expert witness specialties include neurosurgery, neurology, anesthesiology, neurotology/otology, ophthalmology, neuro ophthalmology, neuropsychology, and emergency medicine.