Saturday, February 14, 2015

Hemianopsia (visual field cut) after stroke: The Neuroplastic model

Note: There are two free resources for retraining vision after stroke. Both are on the right hand column of this site (à). Click on "Vision Problems? Click Here!" and/or "Tx for hemianopia and spatial neglect".

Sometimes survivors "neglect" their bad side. Survivors who have neglect don't pay attention (don't see or even recognize as their own) the "bad" side. In fact, it can be so bad that they don't even look at the "bad side" half of the world.
There are a ton of terms for this phenomenon. Unilateral neglect is the most common. Other terms are... 
  • unilateral spatial agnosia 
  • unilateral visual neglect 
  • hemi-inattention
  • hemi-imperception

This inattention may be caused by visual deficits on the neglected side— a problem of the eyes and eyesight. The problem with eyesight that cuts off half the world is called hemianopsia. Or it may be a matter that the brain is not processing information coming from that side, including vision. Or it could be both of those (vision and a brain problem) together. 

Unilateral neglect and the brain
What do we pay attention to? There's lots of stuff in this great big world so we make choices about what we attend to. But someone with unilateral neglect can't/won't pay attention to their "bad" side.  




The "neuroplastic model of stroke recovery" was a term I coined based on the observation that, no matter what deficits are left the survivor there are groups of researchers trying to develop "brain rewiring" treatments to reverse those deficits.
The neuroplastic model for Unilateral neglect becomes really clear if you look at it as more of a "won't" issue and less of a "can't" issue. If a survivor won't, it suggest that they could. Because if they won't then maybe their perspective can be changed so they will. So reducing inattention can be helped by paying more attention. 
With unilateral neglect inattention to the affected side is bad for obvious reasons. But Inattention is also bad, because, as this book points out: Inattention results in confusion, and confusion increases inattention. So what can be done? How do you get someone or yourself, to attend; to pay attention? 

Therapists contend that you should approach and do everything on the affected side so that the stroke survivor attends this affected side. However, it's a good idea to start off on the good side, otherwise, you may not know if the survivor is even paying attention to what you're trying to communicate with them. For instance the survivor may not understand instructions, context, spacial issues, etc. So do all the early teaching stuff on the good side.

To start with, survivors can be encouraged to turn their head towards the neglected side. Eventually, the survivor should be encouraged not to turn their head, but to move their eyes towards the neglected side.
It happens more often with people where the left side of their body is the "bad side." This may have something to do with the fact that we tend to be "right eye dominant." That is just in the normal course of human events, the right eye is the one that we more trust, and use.

Using tactile stimulation can help survivors be aware of the neglected side. You can use touch on the affected side, or rough cloth, a vibrator, etc.

It's a good idea for survivors to understand that they have neglected side. If it's a vision problem, be aware that you have vision loss on that side. Examples in the room around them can be used. You might say how many chairs in this room, and the survivor would only count half of them as they would neglect half the room, and therefore have the chairs.

Don't deny...

Nerdy take:

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