Often, a brain lesion has a characteristic appearance that will help your doctor determine its cause. Sometimes the cause of the abnormal-appearing area cannot be diagnosed by the image alone, and additional or follow-up tests may be necessary.

Among the known possible causes of brain lesions are:

1. Brain aneurysm (a bulge in an artery in your brain)
2. Brain AVM (arteriovenous malformation) — an abnormal formation of brain blood vessels
3. Brain tumor (both cancerous and noncancerous)
4. Encephalitis (brain inflammation)
5. Epilepsy
6. Hydrocephalus (a congenital brain abnormality)
7. Multiple sclerosis
8. Stroke
9. Traumatic brain injury

While brain trauma of any sort may result in a concussion as well as a brain lesion, concussions and brain lesions are not the same thing. Concussions more often occur without ever causing any changes on the CT or MRI and are diagnosed by symptoms rather than imaging tests.

• Definition
• When to see a doctor

Jan. 11, 2018