An estimated 66,290 new primary tumours of the central nervous system (CNS) will be diagnosed in the United States in 2012, of which approximately one third will be malignant.
An estimated 4200 new childhood (ages 0 to 19 years) primary benign and malignant CNS tumours will be diagnosed in 2012. Brain tumours are the second most common malignancy among children, second only to leukaemias.
Radiation exposure is the best-established risk factor for brain tumours. Hereditary syndromes including neurofibromatosis type 1 and 2, tuberous sclerosis, von Hippel–Lindau, and Li-Fraumeni are associated with higher risk of brain tumours.
Taking all age groups into account, histologic types of CNS tumours include meningiomas (35%), glioblastomas (16%), other astrocytomas (7%), tumours of cranial and paraspinal nerves ( 9%), tumours of the sellar region (14%), oligodendrogliomas (2%), ependymomas (2%), and embryonal tumours including medulloblastomas (1%).
Among children 14 years or younger, histologic tumour types include pilocytic astrocytomas (17%), glioblastomas (3%), other astrocytomas (9%), ependymomas (6%), oligodendrogliomas (1%), embryonal tumours including medulloblastomas (15%), craniopharyngiomas (4%), and germ cell tumours (4%).
Most brain tumours are supratentorial; notable exceptions include brainstem gliomas, cerebellar pilocytic astrocytomas, medulloblastomas, and ependymomas that involve the posterior fossa.
Glioblastoma (World Health Organization grade IV astrocytoma) and brainstem gliomas in children carry the poorest prognosis. Pilocytic astrocytomas carry the best prognosis.
General signs and symptoms from mass effect, increased intracranial pressure, edema, or shift or destruction of surrounding brain tissue may include changes in personality and cognitive function, headaches, nausea, vomiting, seizures, and papilledema.
Focal signs and symptoms may include focal seizures, visual changes, speech abnormalities, gait abnormalities, and cranial nerve deficits.
Posterior fossa tumours often compress the fourth ventricle, causing hydrocephalus, and frequently manifest with ataxia and intractable nausea and vomiting.
Brainstem gliomas often manifest with a combination of cranial nerve palsies and “long tract” signs such as hemianesthesia or hemiparesis coupled with ataxia in cases with cerebellar involvement.
Pineal region tumours (germ cell tumours, pineocytomas, and pineoblastomas, as well as gliomas of this region) may compress the aqueduct of Sylvius, causing hydrocephalus. Compression of the pretectal area produces Parinaud syndrome, with paralysis of upgaze, ptosis, and loss of pupillary light reflexes, along with retraction-convergence nystagmus.
For most brain tumours, tissue diagnosis is required (an exception may be selected brainstem gliomas).
Treatment for brain tumours is highly dependent on histologic type. For many tumours (e.g., gliomas, meningiomas, primitive neuroectodermal tumours [PNETs], and ependymomas), maximal surgical resection that is safely feasible is the primary treatment.
For some tumours (e.g., glioblastomas, PNETs, and germ cell tumours), radiation therapy is an essential adjunct treatment after surgery.
For some tumours (e.g., acoustic neuromas and glomus tumours), either irradiation or surgery can offer successful control; the decision between the two is based on assessment of adverse effects.
Chemotherapy is assuming an increasingly important role in the management of many brain tumours (e.g., glioblastomas, germ cell tumours, anaplastic oligodendrogliomas, PNETs, and CNS lymphomas).
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