Approach

The definitive method for the diagnosis of meningioma is with clinical history and physical exam followed by magnetic resonance imaging (MRI) with and without gadolinium-contrast enhancement.[43][44][45] Increasingly, meningiomas are identified incidentally when imaging the neuro-axis for unrelated reasons.

History and physical exam

A thorough history should be undertaken in all patients with a suspected primary brain tumor. Signs and symptoms of meningiomas are generally nonspecific but may include:[46]

  • Headache

  • Focal cranial nerve deficit

  • Seizure

  • Cognitive deficit

  • Weakness

  • Vertigo/dizziness

  • Ataxia/gait changes

  • Pain/sensory changes

  • Proptosis

  • Syncope.

New onset headache, cranial nerve deficit, and seizure are among the most common findings, occurring in up to 37%, 31%, and 17% of patients with meningioma, respectively; this symptom history should prompt an imaging evaluation of the patient for a potential brain tumor, especially with advancing age.[46][47] The history should also establish risk factors for meningioma including: exposure to radiation or exogenous hormones, history of breast cancer, and genetic predisposition (i.e., family history of brain tumor or neurofibromatosis 2).[6][25][26][29][34][35]

Both a general exam and a detailed neurologic exam should be undertaken. Specific neurologic deficits, such as cranial nerve, motor, or sensory deficits, should be evaluated and recorded, including the specific spinal level where deficits are localized to, as this will then direct level-specific imaging. Some cranial nerve deficits may require formal evaluation by a specialist for clinically accurate documentation.

Imaging

The diagnostic study of choice is MRI brain or spine with and without gadolinium enhancement.[43][44][45] Radiographic findings of brain MRI that support a diagnosis of meningioma include: dural-based mass, homogeneously contrast-enhancing tumor, dural tail, and cerebrospinal fluid cleft.[43] Around half of all meningiomas are found at the skull base (anterior, middle, or posterior cranial fossa), with around 40% occurring at the convexity, falx, or parasagittal regions.[46] Between 7% to 12% of all meningiomas occur at spinal sites.[48][Figure caption and citation for the preceding image starts]: Sagittal image (left) demonstrates large extra-axial mass isointense with brain. After contrast administration, the lesion avidly enhances, as shown in the coronal image (center left) and axial image (center right). Note the extensive edema surrounding the tumor on the T2 axial image (right)From the personal library of Dr William T. Couldwell; used with permission [Citation ends].com.bmj.content.model.Caption@1defa2c3

Computed tomography (CT) is indicated if concern exists about any bone involvement (e.g., loss of vision caused by hyperostosis around the optic nerve or involvement of the 8th cranial nerve) or if MRI is contraindicated (e.g., in patients with certain types of pacemakers or shrapnel/metal in their body). CT may add complementary information demonstrating hyperostosis associated with the tumor or calcifications, which may be present in a significant percentage of patients. Calcification within a meningioma usually indicates a slower-growing tumor.[49]

Cerebral angiography, although performed commonly in the past, is used less frequently for diagnosis in the era of contemporary MRI.[50] Occasionally, cerebral angiography will be performed to demonstrate the predominant arterial input to the tumor.[44] It is also essential in surgical planning when the patency of major venous sinuses is in question.

Positron emission tomography (PET)/CT can be used to detect the somatostatin analogs DOTA-D-Phe1-Tyr3-octreotate (DOTATATE) or DOTA-D-Phe1-Tyr3-octreotide (DOTATOC) that are labeled with a radionuclide such as gallium-68, copper-64, or yttrium-90. Although not yet standard clinical practice, somatostatin receptor PET/CT can help confirm the diagnosis, or distinguish residual or recurrent tumors from postoperative scarring.[43][50][51] It may also be useful in radiation planning to delineate the target volume.[44][52][53]

Laboratory

There are no specific laboratory tests required to confirm a diagnosis of meningioma, or for preoperative planning, other than to confirm normal electrolytes and coagulation.

Where diagnosis is uncertain based on radiographic findings alone, surgical resection may be considered.[43] Meningiomas have a wide range of appearances on histopathological analysis of the surgically resected tumor. The mitotic index may indicate a faster-growing tumor. There are significant differences in mitotic indices among tumor grades. The vast majority of meningiomas stain for epithelial membrane antigen (EMA) and somatostatin receptor 2A (SSTR2A), and vimentin positivity is found in all meningiomas. Diagnostic ultrastructural features include copious vimentin filaments, complex interdigitating cell processes, and desmosomal intercellular junctions.[54]

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