Hi Samuel,

I think there are several possible explanations:

1. Because self-awareness is usually linked to prefrontal areas of the brain researchers choose this clinical population since brain pathology in TBI most often includes injuries of frontal lobes (hemorrhages, bruises, contusions, shearing etc.). On the other hand, lesions in stroke are most often located in the teritory of MCA. Strokes in prefrontal areas are rare, although hemorrhage from ACoA aneurysm leads to similar (dysexecutive) symptoms.

2. Of course it doesn't mean that unawareness cannot be seen in patients after MCA stroke. In fact most (or even all in acute phase) patients with neglect have limited awareness, just as you mentioned in your question. However, it is extremely difficult to design a research on patients with severe aphasia who most certainly have deficits in self-awareness as well. In case of UNS, in turn, researchers usually focus on the most prominent disorders which is space perception difficulties (although improvement of awareness is ALWAYS one of the goals in rehabilitation).

3. Age matters. However it sounds. It's much more likely that a 30-year-old working man has no history of pre-injury cognitive (and meta-cognitive) problems than a 80-year-old (approximate mean age of stroke patients) retired individual with stroke.

4. Some anosognosic symptoms after stroke withdraw quite early - during first hours or days. Take Anton's syndrome for example. I have never seen it lasting for more than a week or two.

Hope it helps a bit,

Marcin

Hi Samuel,

I think there are several possible explanations:

1. Because self-awareness is usually linked to prefrontal areas of the brain researchers choose this clinical population since brain pathology in TBI most often includes injuries of frontal lobes (hemorrhages, bruises, contusions, shearing etc.). On the other hand, lesions in stroke are most often located in the teritory of MCA. Strokes in prefrontal areas are rare, although hemorrhage from ACoA aneurysm leads to similar (dysexecutive) symptoms.

2. Of course it doesn't mean that unawareness cannot be seen in patients after MCA stroke. In fact most (or even all in acute phase) patients with neglect have limited awareness, just as you mentioned in your question. However, it is extremely difficult to design a research on patients with severe aphasia who most certainly have deficits in self-awareness as well. In case of UNS, in turn, researchers usually focus on the most prominent disorders which is space perception difficulties (although improvement of awareness is ALWAYS one of the goals in rehabilitation).

3. Age matters. However it sounds. It's much more likely that a 30-year-old working man has no history of pre-injury cognitive (and meta-cognitive) problems than a 80-year-old (approximate mean age of stroke patients) retired individual with stroke.

4. Some anosognosic symptoms after stroke withdraw quite early - during first hours or days. Take Anton's syndrome for example. I have never seen it lasting for more than a week or two.

Hope it helps a bit,

Marcin

Dear Samuel,

To emphasize Marcin's most illuminating reply, I have had several ACA stroke patients with behavioural dysfunction. More often than not, executive functions were one of the most affected elements. One particular ACM bleeding patient that I've had showed severe loss of exterocepsis as well as propriocepsis. These observations may have different clinical explanations, though.

To accumulate a sizeable population for research, it is easier to divert to TBI patients. I would however be most interested to read more about interventional studies regarding stroke patients with loss of self-awareness and metacognition.

Yours truly,

Rik

Dear Marcin,

Dear Rik,

Thank you for your answers and for sharing your precious experience which enables me to keep working on this topic with even more hindsight.

Best regards,

Samuel