Posts Tagged ‘chronic traumatic encephalapathy’

Mild Traumatic Brain Imagery (mTBI)

September 22, 2019

This post is based on an important book by Scott D. Slotnick titled “Cognitive Neuroscience of Memory.” Remember to consult the website
to see the anatomical information referred to in this post.

Patients with mTBI do not have any brain abnormalities, as measured using structural neuroimaging methods such as anatomic MRI. The diagnosis of mTBI includes loss of consciousness for less than 30 minutes and post-traumatic amnesia for less than 24 hours. Patients with mTBI can have attention and memory deficits, but these typically resolve within a few weeks.

The performance between mTBI patients and control participants did not differ on the memory task they were performing, but the mTBI patients had a greater extent and magnitude of fMRI activity in the dorsolateral prefrontal cortex and the parietal cortex than control participants.

Fifteen mTBI patients with concussions due to sports-related injuries were tested 2 days, 2 weeks, and 2 months after the injury. Only one of the 15 patients still had symptoms 2 months after the injury. Consistent with the previous research, there were no differences in the performance of the memory task between the patients and the control participants, but there was greater fMRI activity in the mTBI patients than the control participants within the dorsolateral prefrontal cortex at all three time points and within the parietal cortex at the first two time points. This greater fMRI activity 2 months after injury is concerning because they indicate there are differences in brain processing even after behavioral symptoms have been resolved. So there can be persistent brain disruptions even though there are no behavioral symptoms or brain abnormalities observable with anatomic neuroimaging methods.

Dr. Slotnick writes, “As mTBI patients may be more sensitive to repeated head trauma, it is arguable that they should not be allowed to continue participating in impact sports until their fMRI activity returns to normal.

There is also evidence that the magnitude of fMRI activity decreases in mTBI imagery with more severe or repeated head injuries. One working memory fMRI study had mTBI patients with more severe sports-related head injuries. These not-so-mild mTBI patients were tested 1 to 14 months after the most recent head injury. The large majority of participants had multiple previous concussions, and 15 of the 16 participants had persistent symptoms. As before, behavioral measures did not differ on the memory tasks between the mTBI patients and the control subjects. There was greater activity in the dorsolateral prefrontal cortex for the control participants than in mTBI patients, in direct opposition to the previous findings for less severe mTBI patients. Additionally, participants with greater post-concussive symptoms had a smaller magnitude and extent of firm activity within the dorsolateral prefrontal cortex during visual working memory blocks. The same pattern of fMRI results was obtained in a subsequent study that employed the identical visual working memory task and a similar group of not-so-mild mTBI participants. It is important to realized that repeated mTBI and sub-concussive head injuries ( due to boxing or football, for example) can lead to chronic traumatic encephalopathy (CTE).

There are eleven previous posts addressing chronic traumatic encephalopathy.