Intracranial Tumors, Primary

Essentials of Diagnosis

• Personality changes, intellectual decline, emotional lability

• Seizures, headaches, nausea

• Increased intracranial pressure in some patients

• Neuroradiologic evidence of space-occupying lesion

General Considerations

• About one-third of all primary intracranial neoplasms (Table 24–4) are meningiomas; a quarter are gliomas

• The remainder are

  • Pituitary adenomas

  • Neurofibromas

  • Other tumors

• Certain tumors (eg, neurofibromas, hemangioblastomas, and retinoblastomas) have a familial basis

• May lead to a generalized disturbance of cerebral function and symptoms of increased intracranial pressure

Demographics

• Tumors may occur at any age, but some gliomas are age-specific (Table 24–4)

Symptoms and Signs

HERNIATION SYMPTOMS

• Temporal lobe uncus herniation with compression of the third cranial nerve, midbrain, and posterior cerebral artery

  • Ipsilateral pupillary dilation

  • Followed by stupor, coma, decerebrate posturing, and respiratory arrest

• Cerebellar tonsillar displacement causing medullary compression, apnea, circulatory collapse, and death

FOCAL DEFICITS

• Frontal lobe lesions

  • Progressive intellectual decline, slowing of mental activity, personality changes, and contralateral grasp reflexes

  • Expressive aphasia if the posterior part of the left inferior frontal gyrus is involved

  • Anosmia secondary to pressure on the olfactory nerve

  • Precentral lesions may cause focal motor seizures or contralateral pyramidal deficits

• Temporal lobe lesions

  • Seizures with olfactory or gustatory hallucinations, motor automatisms, and impairment of external awareness without actual loss of consciousness

  • Depersonalization, emotional changes, behavioral disturbances, sensations of déjà vu or jamais vu

  • Micropsia or macropsia (objects appear smaller or larger than they are), visual field defects (crossed upper quadrantanopia), and auditory illusions or hallucinations

  • Left-sided lesions may lead to dysnomia and receptive aphasia, while right-sided involvement may disturb the perception of musical notes and melodies

• Parietal lobe lesions

  • May cause sensory seizures

  • Contralateral disturbances of sensation, sensory loss or inattention (cortical in type and involves postural sensibility and tactile discrimination, so that the appreciation of shape, size, weight, and texture is impaired)

  • Objects placed in the hand may not be recognized (astereognosis)

  • Extensive lesions may produce contralateral hyperpathia and spontaneous pain (thalamic syndrome)

  • Optic radiation involvement leads to a contralateral homonymous field defect that sometimes consists solely of lower quadrantanopia

  • Left angular gyrus lesions cause Gerstmann syndrome (alexia, agraphia, acalculia, right-left confusion, and finger agnosia), whereas involvement of the left submarginal gyrus causes ideational apraxia

  • Anosognosia (denial, neglect, or rejection of a paralyzed limb) is seen in patients with lesions of the nondominant (right) hemisphere

  • Constructional apraxia and dressing apraxia may also occur with right-sided lesions

• Occipital lobe lesions

  • Crossed homonymous hemianopia or a partial field defect

  • Left-sided or bilateral lesions may cause visual agnosia; irritative lesions on either side can cause unformed visual hallucinations

  • Bilateral occipital lobe involvement causes cortical blindness with preservation of pupillary responses to light and lack of awareness of the defect by the patient

  • Loss of color perception, prosopagnosia (inability to identify a familiar face), simultagnosia (inability to integrate and interpret a composite scene as opposed to its individual elements), and Balint syndrome (failure to turn the eyes to a particular point in space, despite preservation of spontaneous and reflex eye movements), denial of blindness or a field defect (Anton syndrome)

• Brainstem and cerebellar lesions

  • Brainstem lesions lead to cranial nerve palsies, ataxia, incoordination, nystagmus, and pyramidal and sensory deficits in the limbs

  • Intrinsic brainstem tumors, such as gliomas, cause an increase in intracranial pressure, usually late

  • Marked ataxia of the trunk if the vermis cerebelli is involved

  • Ipsilateral appendicular deficits (ataxia, incoordination and hypotonia of the limbs) if the cerebellar hemispheres are affected

• False localizing signs

  • Neurologic signs other than by direct compression or infiltration, leading to errors of clinical localization

  • Include third or sixth nerve palsy and bilateral extensor plantar responses produced by herniation syndromes, and an extensor plantar response occurring ipsilateral to a hemispheric tumor because the opposite cerebral peduncle is compressed against the tentorium

Differential Diagnosis

• Metastatic intracranial tumors

  • Cerebral metastases

  • Leptomeningeal metastases (carcinomatous meningitis)

• Intracranial mass lesions in AIDS patients

Imaging Studies

• MRI with gadolinium

  • Preferred method to detect the lesion and to define its location, shape, and size; the extent to which normal anatomy is distorted; and the degree of any associated cerebral edema or mass effect

  • Best for tumors in the posterior fossa

• CT scanning with radiocontrast enhancement is less helpful than MRI for small lesions or tumors in posterior fossa

• Characteristic appearance of meningiomas on MRI or CT scanning is virtually diagnostic

• Additional MRI sequences that may be helpful in differentiating gliomas from other intracranial pathology include

  • Perfusion imaging

  • Magnetic resonance spectroscopy

  • Diffusion weighted imaging

• Arteriography is largely reserved for presurgical embolization of highly vascular tumors

Diagnostic Procedures

• Biopsy is necessary for definitive diagnosis when glial neoplasms are suspected

• Lumbar puncture is rarely necessary

  • Findings are seldom diagnostic

  • Herniation is a risk

• However, lumbar puncture should be considered when intracranial germ cell tumors are suspected

  • If it can be performed safely, CSF should be tested

    • Cytology

    • Determination of alpha-fetoprotein and beta-human chorionic gonadotropin

  • Tumor markers should be examined in serum

Medications

• Temozolomide is commonly used for gliomas

• Lomustine plus temozolomide

  • Improved median survival from 31 to 48 months in a randomized controlled trial in patients with glioblastoma with methylated methylguanine-DNA methyltransferase (MGMT) promoter

  • The addition of low-intensity 200 kHz frequency alternating electric fields, delivered extracranially at least 18 hours daily, improves progression-free survival by 2.7 months and median survival by 4.9 months compared to temozolomide alone in glioblastoma

• Corticosteroids help reduce cerebral edema and are usually started before surgery

• Herniation is treated with intravenous dexamethasone (10–20 mg as a bolus, followed by 4 mg every 6 hours) and intravenous mannitol (20% solution given in a dose of 1.5 g/kg over about 30 min)

• Anticonvulsants in standard doses (Table 24–2); however, they are not indicated as prophylaxis in patients with no history of seizures

• Bevacizumab is approved in the United States but not in Europe for use in recurrent high-grade glioma

Surgery

• Complete surgical removal if the tumor is extra-axial (eg, meningioma, acoustic neuroma) or is not in a critical or inaccessible region of the brain (eg, cerebellar hemangioblastoma)

• Surgery may be diagnostic and may relieve intracranial pressure symptoms even if the neoplasm cannot be completely removed

• Simple surgical shunting procedures help in cases with obstructive hydrocephalus

Therapeutic Procedures

• Treatment depends on the type and site of the tumor (Table 24–4) and the condition of the patient

• Palliative care is important for patients who deteriorate despite treatment

• With malignant gliomas, radiation therapy increases median survival rates regardless of preceding surgery; chemotherapy provides additional benefit

• Indications for irradiation for other primary intracranial neoplasms depend on tumor type and accessibility and the feasibility of complete surgical removal

Follow-Up

• Serial annual imaging can be used to monitor patients with benign tumors, especially meningiomas discovered incidentally

Complications

• Long-term neurocognitive deficits resulting from radiation therapy

• For those patients with difficult to treat symptoms or those needing help with advance care planning, specialty palliative care consultation is appropriate

When to Refer

• All patients should be referred to neurologists or neuro-oncologists

When to Admit

• All patients with increased intracranial pressure

• All patients requiring biopsy, surgical treatment, or shunting procedures