21A. Meningiomas

Meningiomas are tumours which arise from the arachnoid layer cells. 90% occur in the skull, 10% in the spine. They’re very slowly growing, very benign tumours, but because they grow in a closed space, they can increase the intracranial pressure or apply pressure to the brain. However, many are asymptomatic and only discovered incidentally.

They account for 1/3 of all primary CNS tumours. They mostly occur in elderly.

Clinical features

Meningiomas can cause headaches and focal neurological deficits. In addition to these symptoms, location-specific symptoms can occur. Here are the most common locations and their specific symptoms:

• Convex brain surface – seizures
• Falx cerebri and parasagittal area – personality changes, contralateral weakness
• Sphenoid wing – visual defects, loss of sensation in face
• Olfactory groove – anosmia, visual defects
• Suprasellar – visual defects
• Posterior cranial fossa – cerebellar symptoms
• Spinal cord – back pain, lumboischialgia

The convex brain surface location is the most common.

Diagnosis and evaluation

Unlike other brain tumours, meningiomas are usually never biopsied because they have such a characteristic appearance on neuroimaging that it’s not necessary for diagnosis. MRI with contrast shows a round, sharply demarcated, extra-axial lesion with a “dural tail” and strong contrast enhancement.

Treatment

Asymptomatic cases can be managed with active surveillance with follow-up MRI to look for growth.

In symptomatic cases, surgical removal or gamma knife may be required. The tumour and the surgical scar may cause symptomatic seizures, so many times patients require lifelong antiepileptics.