Why an MRI and EEG?

Lyn's MRI and EEG both came back as "normal". However, something is going on in her brain. You don't forget how to manage a bodily function without something changing. So, that got me to wondering about these tests and why they're used in the diagnostic process.

When a doctor asks for a patient who is showing signs of dementia to undergo an MRI, the doctor is looking to see if something in the brain is causing the symptoms. The MRI can show if there is a brain tumor, head trauma, evidence of a stroke or a problem with the blood flow in the brain. The MRI is looking at the structure of the brain. A normal MRI would indicate that there is no tumor, no Lewy bodies or other abnormal clusters of protein, there is no bleeding and no apparent signs of stroke. It would also mean that there's no damage to the structures of the brain.

To me, this is the interesting part with Lyn's MRI. When Lyn was in high school, she had a year of seizures and had an MRI at that time. The neurologist pointed out the areas of her left frontal and temporal lobes where the majority of her brain damage was found. If there was damage in those lobes 20+ years ago, I would expect the damage to be evident in the MRI which was just done. As a result, I would not have expected a result of "normal."

When a doctor asks for a patient who is showing signs of dementia to undergo an EEG, the doctor is again looking to see if the cause of the symptoms can be determined by the test. The EEG looks at the function of the brain by monitoring its electrical activity. The brain functions could be interrupted if there is a brain tumor, a change in the blood flow, head injury or other causes of symptoms similar to those looked for by the MRI. A normal EEG will show regular brain waves from both sides of the brain. Spikes in the EEG indicate that the brain is experiencing a change in its activity.

So, both tests potentially allow us to see what could cause the dementia symptoms. They may not always give us a definitive answer however.

Additional Information Sources:
WebMd - EEG
Whole Brain Atlas
BrainInjury.Com - Understanding Diagnostic Tests


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