Saturday, July 29, 2017

Prophetic Diagnosis

Using MRI to detect brain damage that leads to temporal lobe epilepsy.

Magnetic resonance imaging has been an amazing and flexible technology. It has been tailored to varying chemical targets and environments, so that both chemical and anatomical details can be visualized. A recent paper (review) deployed tractology, which uses MRI to trace water diffusion in lengthy neurons and related cells, to vizualize detailed brain organization.

They were looking for traces of damage or change that could predict or correlate with epilepsy. Their model was mice, whom they injected with kainate in their hippocampi. Kainate over-excites and rapidly kills neurons, and this particular injection is known to induce temporal lobe epilepsy, a syndrome that can be brought on by genetics or trauma in humans, and is known to cause not only seizures, but also other problems such as memory loss, depression, personality changes, and hyper-religiosity. Whether the mice start propounding new religions is naturally unknown.

Time course after injecting damaging chemicals into the hippocampus of mice, and then tracing the growth of new glia oriented cross-wise (green, in box) versus the native neural tracts.

What they did find is that they can track damage in the mice quite easily, and this brain damage takes the form, in part, of new tracts of (glial) cells that grow cross-wise versus the native neural pathways. This helps to rationalize what may be causing the epilepsy, and was supported by finding similarly deranged tracts of glia in the brains of humans suffering from temporal lobe epilepsy and hippocampal sclerosis, which is the main physiological finding associated with such epilepsy, especially forms that can not be treated by drugs. And the severity of the lesion, which in the mouse system is traceable from very early times, prior to the onset of epilepsy, correlates in both systems with the severity of the eventual epilepsy.
Our study demonstrates for the first time that the extent of epileptogenesis-associated tissue alterations in the hippocampus directly mirrors the ensuing severity of intractable mTLE [mesial temporal lobe epilepsy].
This may provide and early way to check out brain damage that may lead to this syndrome, though what to do about it is a separate question, typically answered in these cases by surgically removing the mis-grown scar tissue that was studied here.

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