Epilepsy surgery and functional MRI

fmri

BrainMRI3planes

Epilepsy surgery is an option for patients with intractable partial onset seizures that are not controlled by oral medications.  Epilepsy monitoring is used to localize the seizure focus, often a lesion or abnormal area of brain located in the temporal lobe.  That part of the brain is then carefully removed to prevent future seizures:

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A patient with a brain abnormality in the R temporal lobe (top) undergoes brain surgery to remove that area of brain and prevent future seizures.

Epilepsy surgery is very effective and yet still underutilized for treating seizures.

Left temporal lobe resections are more risky that right-sided cases, because the left hemisphere controls language functions in most (even left handed) patients.  Surgeons have to be very careful planning seizure surgery on the left side to be sure that they do not damage brain critical for speech and language and leave the patient with aphasia.

That’s where functional magnetic resonance imaging (fMRI) comes in.  fMRI goes beyond the conventional imaging of brain structure, and can actually localize regional brain functions by detecting changes in regional blood flow in response actual or imagined activity.

fMRI is increasingly being used to evaluate candidates for epilepsy surgery by identifying important functional regions within the brain, including unpredictable patterns of functional reorganization, to prevent unexpected post-operative deficits.  Click here for a link to a paper with illustrative cases.

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Brain Scans Predict Criminal Behaviour

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Recent research shows that brain scans can predict whether convicted felons are likely to engage in criminal behavior in the future,.

The study involved 100 male prisoners who underwent a functional MRI scan just before they were released.

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During the scan they were shown letters flashing on to a TV screen, either an X (84% of time) or a K (16% of the time).  They were told to press a button within 1 second when the letter X appeared, but do nothing if the letter K appeared.

Because the X appeared most of the time, they would have to stop themselves from pushing the button when the K appeared.  In other words, this was a test of impulsivity.

The investigators analyzed brain activity in the the prisoners’ anterior cingulate cortex (ACC), an area located at the front of the brain that is responsible for making decisions, while they performed this task.

ACC

The subjects who made more errors on the task had lower activity in the ACC, suggesting an inclination to act upon impulses without thinking.

After being released from prison, the men were followed up for four years.

Interestingly, the men who had lower levels of ACC activity were re-arrested 2.6 times more for all crimes and 4.3 times more for nonviolent crimes.

A potential neurocognitive biomarker for persistent antisocial behavior?

Click here to find out more.