Signs and Symptoms of Gliomas
Brain Tumors Arising from Glial Cells May Mimic Other Conditions
Feb 6, 2009
Gliomas are tumors that arise from the glial cells of the brain. Although they do not conduct impulses like neurons do, glial cells perform a variety of critical supportive functions within the nervous system.
Several types of glial cells are present in the human brain. Signs, symptoms, and prognoses associated with glial cell tumors vary with the cell type and the location of the tumor.
Types of Glial Cells in the Human Brain
- Astrocytes: these star-shaped cells provide a network of physical support and isolation for neurons. Via phagocytosis, they clean up debris within the brain and provide nourishment and a healthy chemical environment for the neurons.
- Oligodendrocytes: these are globular cells that reach out with numerous arms, like those of an octopus, to wrap nearby axons (the “electric cable” network of the brain) with myelin. Myelin insulates individual axons and improves the efficiency of impulse conduction.
- Microglia: these small glial cells are representatives of the immune system; they help to prevent the invasion of microorganisms.
In general, death from brain tumors results from local tumor growth and compression or invasion of nearby structures. Even benign brain tumors—when not treated early—can cause significant neurological impairment or even death.
Gliomas are classified according to their underlying cell type, their location within the brain, and their degree of malignancy (invasiveness).
Types of Gliomas and Their Classification
Oligodendrogliomas: among the most benign gliomas, they occur most frequently in the cerebral cortex, particularly the frontal lobes
Astrocytomas: classified in ascending order of malignancy (low-grade or anaplastic astrocytomas most often develop in younger persons; they can change character and evolve into higher-grade glioblastomas):
- Grade 1 or 2 (low-grade)
- Grade 3 (anaplastic astrocytomas)
- Grade 4 (glioblastomas, including glioblastoma multiforme, the most common malignant brain tumor)
Medulloblastomas: malignant tumors that probably arise from undifferentiated cells. They occur primarily in children—more often in boys—and they can spread through the brain via the cerebrospinal fluid.
Ependymomas: uncommon tumors that arise from glial cells lining the fluid-filled ventricles of the brain. Ependymomas can spread to the spinal cord via cerebrospinal fluid. Classification is based on microscopic appearance:
- Grade 1 (sub-ependymoma; slow-growing)
- Grade 2 (ependymoma [low-grade])
- Grade 3 (anaplastic or malignant ependymoma)
Medulloblastomas and ependymomas frequently obstruct the flow of cerebrospinal fluid through the brain, causing hydrocephalus and increased intracranial pressure.
Signs and Symptoms of Gliomas
Many signs and symptoms from brain tumors result from increased pressure within the rigid skull, which does not allow the brain to expand significantly as a tumor grows. Other symptoms are secondary to effects upon nearby structures and inflammation associated with malignant invasion.
- Headache (often worse upon awakening from deep sleep) is the most common symptom. Vomiting may accompany headache
- Deterioration in mental status (lethargy, personality changes, combative or aggressive behavior, impaired cognition, etc.)
- Memory loss
- Generalized or focal seizures (new onset)
- Impairment of motion or sensation in a body region; often unilateral
- Difficulty walking
- Hearing loss
- Visual field defects or loss of vision
- Vertigo
- Acquired inability to smell
- Tremor
- Nystagmus
- Urinary urgency or incontinence
- Difficulty speaking or understanding what others are saying
- Excessive thirst or appetite
- Inappropriate denial of illness, injury or bodily defects
- Visual hallucinations
Many signs and symptoms of gliomas mimic other medical or psychiatric entities. Neurological symptoms that cannot be readily explained (e.g., ataxia from alcohol use or hallucinations secondary to substance abuse) must be promptly investigated.
References and Resources:
The Merck Manual, 18th Edition 2006:1916-21
Cancer in the Nervous System (2nd edition). Levin. Oxford University Press, 2002
Chandana S, et al. Primary brain tumors in adults.Am Fam Physician 2008;77(10):1423-1430
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