Left Neglect vs. Field Cut

It is possible for multiple distinct symptoms of an acquired brain injury to present in remarkably similar fashions.  For instance, a brain-injured survivor’s failure to take medication could be due to a memory deficit leading that survivor to simply forget his or her medication or it could be due to an attention deficit leading the survivor to be too distracted to take the medication in question.  In each case the medication was missed, but for acutely separate reasons.  A similar issue comes to light in observation of post-injury visual deficits.  Did a survivor fail to notice information to his or her left due to left neglect or due to a field cut?

Let’s start off with outlining precisely what a field cut is, as it is the simpler of the two to understand.  Under the effects of a field cut, the survivor has actually permanently lost the ability to perceive a portion of the field of vision.  That area of the field formerly available has now been “cut” away.  Due to his or her injury, the survivor is now in effect partially blind.  In medical terms, this loss of vision is often called “hemianopsia.”  So a survivor contending with a field cut has had actual visual loss  in his or her left visual field and thereby misses seeing information on his or her left side.

Left neglect is an attention issue which often manifests in the visual attention domain.  It is associated with an injury to the right side of the brain.  With left neglect, the brain fails to pay attention to information to the left side of the survivor.  If you ask a survivor with left neglect to turn his or her head all the way to the right, he or she will generally turn until the chin reaches the right shoulder.  However if you ask the same survivor to turn to the left, he or she may only bring the chin half-way to the the left shoulder despite fully understanding the request and giving a best effort to fulfill it.  It is almost as if the survivor’s brain is saying, “the left side of the world does not exist.”  The survivor’s eyesight can be perfectly intact, yet his or her brain is ignoring information generated from the left side.  This ignoring is not voluntary; as far as the survivor is consciously aware, he or she did look all the way to the left even though an outside observer can clearly see that the survivor did not make it all the way over.  Again, though it appears functionally as if the survivor has lost vision, the underlying issue is one of attention.

In the case of a field cut, most survivors do reasonably well after becoming sufficiently aware of their field cuts.  They will after enough practice naturally turn and make that extra effort to look for the information in their blind spots.  For a survivor with left neglect, improvement requires not just awareness but also daily repetition of scanning exercises and consistent use of visual aids.  As example, a survivor with left neglect may practice scanning techniques by slowly looking for information on a piece of paper being sure to start all the way on the left of that page before scanning across.  It can also be helpful to put a brightly colored highlighter mark on the paper to identify the far left of the page.  Sadly, in some cases a survivor will suffer from both left neglect and a field cut.  This combination can of course make successful functioning especially difficult, but with appropriate dedication and determined effort most any such goal gains entrance into the realm of the attainable.

I hope this clarifies the differences between left neglect and a field cut.  Please leave me a comment below with any questions, thoughts or ideas!

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