What are the types of brain lesions?
There are many types of brain lesions. The brain can be affected by a host of potential injuries that can decrease its function. The type of lesion depends upon the type of insult that the brain receives.
Aging: Some lesions occur as a result of aging with loss of brain cells as they naturally age and die. If enough cells die, atrophy can occur and brain function decreases. This may present with symptoms of loss of memory, poor judgment, loss of insight and general loss of mental agility.
Genetic: Lesions related to a person's genetic makeup, such as people with neurofibromatosis.
Vascular: Loss of brain cells also occurs with stroke. With ischemic strokes (CVA) blood supply to an area of the brain is lost, brain cells die and the part of the body they control loses its function.
Bleeding: Strokes can also be hemorrhagic, where bleeding occurs in part of the brain, again damaging brain cells and causing loss of function. Uncontrolled high blood pressure, AV malformations, and brain aneurysms are some causes of bleeding in the brain.
Trauma: Bleeding in the brain may be caused by trauma and a blow to the head. Bleeding may occur within brain tissue or in the spaces surrounding the brain. Epidural and subdural hematomas describ blood clots that form in the spaces between the meninges or tissues that line the brain and spinal cord. As the clot expands, pressure increases within the skull and compresses the brain.
Acceleration/deceleration injury: Sometimes trauma can affect the brain with no evidence of bleeding on CT scan. Acceleration deceleration injuries can cause significant damage to brain tissue and connections causing microscopic swelling. Shaken baby syndrome is a good example of acceleration/deceleration type injury, where the brain bounces against the inner lining of the skull.
Infection and inflammation: Infectious agents resulting in diseases such as meningitis, brain abscesses or encephalitis
Tumors: Tumors are types of brain lesions and may be benign (meningiomas are the most common) or malignant like glioblastoma multiforme. Tumors in the brain may also be metastatic, spreading from cancers that arise primarily from another organ. Symptoms occur depending upon the location and size of the tumor.
Immune: Immunologic causes may also affect the brain, for example diseases like multiple sclerosis.
Plaques: Some investigators suggest that abnormal deposits of material that form plaques may be a type of disease that causes damage and eventual brain cell death in diseases like Alzheimer's disease.
Toxins: Toxins may affect brain function and may be produced within the body or may be ingested. The most common ingested poison is alcohol, though other chemicals can adversely affect the brain. Individuals can develop encephalopathy due to a variety of chemicals and substances that build up in the blood stream. Ammonia levels rise in patients with liver failure while patients with kidney failure can become uremic.
Multiple types: The type of lesion depends upon its cause and symptoms depend upon its location and amount of brain irritation or damage that has occurred. Some brain lesions types may occur from more than one cause, such as Alzheimer's disease that may be related to plaque formation, brain cell death, and possibly genetics. Research is ongoing and is likely to provide better insights into these various brain lesion types.