BrainScan filter

June 18, 2007 2:46 PM

Is it possible to tell the difference between an old, long-standing injury and a more recent injury to the brain on a brain scan? Would a particular type of brain scan (fMRI as opposed to CAT scan) be better able to reveal the difference between the two? This question would be pertinent to the Peter Braunstein case: earlier in the news coverage, they showed Braunstein's brain scan on television, because the defense claims that the decreased activity shown in the frontal region is consistent with schizophrenia. However, I understand Braunstein hit his head while in custody, and I'm thinking that could cause a similar result on the brain scan. I'm also wondering, could a brain scan show whether he got dropped on his head when he was a baby and/or all three possible conditions and when, approximately, they developed?
posted by bunky to health & fitness (2 comments total)

IANAD/IANAneuroscientist. But, my very basic understanding is that, depending on the type, older trauma can get worked around (although the region itself will never recover, if the neurons died), while newer trauma is quite a bit more functionally destructive. I suppose if you matched up fMRI data for a couple of common processes using the affected region, & looked to see how well the 'bad' brain had learned to deal with it, that'd give some indication of the length of time.

I'd also expect it would be relatively easy for someone to tell the difference between damage caused by blunt trauma or scizhophrenia from any type of MRI (or perhaps even an angiogram), but perhaps not.
posted by devilsbrigade at 2:56 PM on June 18, 2007

"Consistent with" or "compatible with" is a way doctors have of providing other doctors with useful information without committing themselves to ironclad statements that could be used in court. Sure, the abnormalities you mention are seen in some cases of schizophrenia. That makes them "compatible with" schizophrenia. A normal brain scan is also "compatible with" schizophrenia. The presence of a brain tumor or an old or new brain injury may also be "compatible with" schizophrenia.

However, as I think about it, I cannot think of a single finding that could be seen on any kind of brain scan that I would characterize as "incompatible with" schizophrenia. Does this answer your question?

For the purpose of deciding whether someone has schizophrenia, what you want is a finding that is "diagnostic of" or "pathognomonic of" schizophrenia. There are no brain scans or blood tests or any other technology-based tests for schizophrenia. This is because of the way schizophrenia is defined: it is defined as a clinical diagnosis rendered by a psychiatrist after reviewing all the data.

As it happens, there aren't even any brain scan findings that could be said to have a 'halfway decent correlation' with the clinical diagnosis of schizophrenia. (My favorite of the ones that, on rigorous analysis, don't turn out to have a decent correlation with the clinical diagnosis is the cavum septum pellucidum, which as it turns out is simply a marker for mild frontally-predominant atrophy, itself a nonspecific finding.)

A similar state of affairs with respect to the question of "capacity" exists. Capacity - the ability to be legally held responsible for one's actions - cannot be detected by a brain scan. It's generally determined by doctors too, but in cases where it's in dispute a judge is often called on to render a final opinion. The question of whether a person has capacity or not is absolutely identical with the question of whether the court decides that a person has capacity.

The judge may look at the brain scan; more likely he'll consult a doctor to get the interpretation of the brain scan. Judges may not know MRI's but they know the difference between 'diagnostic of' and 'consistent with' and they generally tend to rule accordingly.

To answer your other questions, once a static (completed) brain injury is more than a few weeks old, it's hard to date it accurately using MRI. If it was a bloody injury or you know what it looked like when it was acute, you may have a little bit more to work with - but if you know what it looked like when it was acute, I can't see a need to use some other means to date it.

I can think of a few exceptions with regard to congenital injuries that happen very early in uterine life and that have a consistently unique appearance, but they're not of much forensic interest.
posted by ikkyu2 at 10:00 PM on June 20, 2007