Meningiomas

Meningiomas are the second most common primary brain tumors, accounting for approximately 20% of all intracranial tumors. They arise from the arachnoid cap cells of the meninges and are usually slow-growing and benign (WHO Grade 1), although atypical (Grade 2) and anaplastic (Grade 3) variants occur. The most common sites include the cerebral convexity, parasagittal region, and sphenoid ridge. Clinical manifestations depend on the tumor size, location, and associated mass effect. Early diagnosis and appropriate surgical management are essential to prevent permanent neurological deficits and improve long-term outcomes.

Epidemiology

Meningiomas are among the most frequently diagnosed primary intracranial tumors in adults. They occur more commonly in females than males and are most frequently diagnosed between the fifth and seventh decades of life. Most meningiomas are benign, while atypical and malignant forms account for a smaller proportion but have higher recurrence rates.

Risk factors

Risk factors for meningioma include:

• Increasing age

• Female sex

• Exposure to ionizing radiation

• Neurofibromatosis type 2 (NF2)

• Family history of meningioma

• Previous cranial irradiation

• Hormonal influences

Pathophysiology

Meningiomas originate from arachnoid cap cells of the meninges. They grow slowly and compress adjacent brain tissue rather than invading it in most cases. Tumor growth may result in increased intracranial pressure, cerebral edema, compression of cranial nerves, seizures, and focal neurological deficits depending on the anatomical location. Histologically, they are classified into WHO Grade 1 (benign), Grade 2 (atypical), and Grade 3 (anaplastic/malignant), with increasing aggressiveness and recurrence risk.

Clinical presentation

Patients commonly present with slowly progressive neurological symptoms resulting from tumor growth and compression of adjacent brain structures. The presentation depends on the tumor location and degree of cerebral edema.

Symptoms

• Chronic headache

• Adult-onset seizures

• Loss of vision

• Progressive focal neurological deficits

• Cognitive or personality changes

• Weakness or numbness of limbs

• Difficulty with speech

• Hearing impairment or tinnitus (depending on tumor location)

• Symptoms of raised intracranial pressure, including nausea and vomiting in large tumors

Clinical signs

• Papilloedema

• Cranial nerve deficits

• Visual field defects

• Motor weakness

• Sensory deficits

• Hyperreflexia

• Ataxia

• Cognitive impairment

• Focal neurological deficits corresponding to the tumor location

Differential diagnosis

• Glioma

• Brain metastases

• Pituitary adenoma

• Vestibular schwannoma

• Primary central nervous system lymphoma

• Dural metastasis

• Intracranial abscess

• Chronic subdural hematoma

• Arteriovenous malformation

Diagnostic criteria

The diagnosis of meningioma is based on compatible clinical features together with characteristic neuroimaging findings and histopathological confirmation following surgical resection or biopsy.

Diagnosis is supported by:

• Clinical features suggestive of an intracranial mass.

• CT or MRI demonstrating an extra-axial, dural-based lesion consistent with meningioma.

• Histopathological confirmation and WHO grading where tissue is available.

Investigations

• Full blood picture (FBP)

• Serum electrolytes

• CT scan of the brain

• CT angiography or MR angiography

• Histopathological examination

• MRI of the brain with contrast where available for better assessment of tumor extent and surgical planning

Management

Management depends on tumor size, location, symptoms, WHO grade, patient age, and surgical fitness.

Initial management includes:

• Assess airway, breathing, and circulation in critically ill patients.

• Evaluate neurological status and signs of raised intracranial pressure.

• Control seizures when present.

• Reduce cerebral edema before definitive treatment when indicated.

• Plan definitive treatment based on imaging findings and multidisciplinary neurosurgical assessment.

Non-pharmacological treatment

Surgical management

• Intracranial meningiomas are best managed with total excision following the principle of maximum safe excision.

• Surgical resection should follow the Simpson grading principles for intracranial meningiomas.

• Subtotal resection is associated with inferior outcomes and higher tumor regrowth rates.

• Histopathological examination should be performed on all resected specimens.

Radiotherapy

• Radiotherapy is indicated for unresectable tumors.

• Radiotherapy is recommended following postoperative incomplete resection of WHO Grade 1 tumors.

• Radiotherapy is recommended for all WHO Grade 2 and Grade 3 tumors.

• Operative findings together with postoperative CT or MRI should guide radiotherapy planning.

Pharmacological treatment

For seizure control:

• Anticonvulsants should be administered in patients presenting with seizures.

For cerebral edema:

• Dexamethasone should be administered to reduce brain edema.

Management according to underlying cause

Symptomatic meningioma

• Maximum safe surgical excision is the preferred treatment whenever feasible.

Unresectable tumor

• Radiotherapy should be offered as definitive treatment.

Incomplete surgical resection

• Consider postoperative radiotherapy, particularly for WHO Grade 1 tumors with residual disease.

WHO Grade 2 or Grade 3 meningioma

• Surgical resection followed by adjuvant radiotherapy is recommended.

Small asymptomatic tumors

• Observation with periodic neuroimaging may be appropriate, particularly in elderly patients or those with significant comorbidities.

Referral

Refer all patients with suspected or confirmed meningioma to a neurosurgical service.

Urgent referral is indicated for patients with:

• Rapidly progressive neurological deficits

• Features of raised intracranial pressure

• Recurrent or uncontrolled seizures

• Visual deterioration

• Altered level of consciousness

• Large tumors causing significant mass effect

• Suspected malignant meningioma

Complications

• Increased intracranial pressure

• Brain edema

• Persistent seizures

• Permanent neurological deficits

• Visual impairment

• Tumor recurrence

• Hydrocephalus

• Postoperative complications including infection, hemorrhage, and cerebrospinal fluid leak

• Malignant transformation (rare)

Prognosis

The prognosis depends on the WHO tumor grade, extent of surgical resection, tumor location, patient age, and recurrence. Benign WHO Grade 1 meningiomas generally have an excellent prognosis following complete surgical excision, whereas Grade 2 and Grade 3 tumors have higher recurrence rates and require closer follow-up and adjuvant radiotherapy.

Prevention

There are no established measures for preventing meningioma. Avoidance of unnecessary exposure to ionizing radiation may reduce risk. Early evaluation of persistent headaches, adult-onset seizures, or progressive focal neurological deficits facilitates timely diagnosis and treatment.