September 16, 2012

Sight without seeing: Bálint's syndrome

Scientific literature is, to say the least, pretty dull.

It's rife with redundant phrases, confusing methodologies, and tiny graphs. Reading page after page of long words in small font is better than any over-the-counter sleep aid out there for getting the job done.

Occasionally, the rare gem will come along just when you least expect it, providing a readable (dare I say—enjoyable) account of the latest research.

So begins a paper published this past week in Neurology:

"It was a quiet Thursday afternoon when 'A.S.', a 68-year-old woman from a suburb of Chicago, awakened from a nap to the realization that something was terribly wrong."

What?! What's wrong! Must...keep...reading...

As the article continues, we learn how A.S. and another patient, J.D., adjust to their lives before and after their diagnoses of Bálint's syndrome.

A.S. couldn't find doors or cabinets in her house. She had difficulty naming familiar household objects, and she was unable to read a book or the numbers on her phone.

Armed with an ophthalmologist's' note declaring 20/20 vision with glasses, the next step was to visit a neurologist.

J.D.'s first experience with the disorder came at a much less opportune time. The 66-year-old "robust and active man" was driving to his son's house for Thanksgiving when he began to swerve. During dinner, J.D. held the spoon upside-down.

Loyola University of Chicago neurologist Murray Flaster, a co-author of the paper, explains: "If you ask somebody if you see a glass or a toothbrush, they'll say 'yes'. Then if you ask them to pick it up, they can't.

"There's nothing wrong with their movement or their eyes. They just can't easily understand how to reach the glass."

This strange affliction is known as Bálint's syndrome, named for the Hungarian neurologist Rezsö Bálint who first described it in 1907. Individuals with this disorder are unable to coordinate their physical movements in response to what they perceive visually.

Typically, visual information reaches our brains via the optic nerve, terminating in the primary visual cortex located in the occipital lobe (shown in light purple). In a parallel pathway, the shapes, colors, contexts, and dimensions of what we're seeing are analyzed by our parietal lobe (pink) and other regions known as "association areas."

(No, your brain isn't really multi-colored!)

Bálint's syndrome, however, is caused by a stroke or other injury that damages these association areas, creating a disconnect between the processes of seeing an object and understanding its context. 

Although rare, the disorder can be devastating. According to J.D.'s wife, "He never once cried before, but now he cries often." There are no cures nor therapy, and patients cope by adapting.

To brush her teeth, A.S. puts the toothpaste directly into her mouth before scrubbing by trial and error. Her family has placed yellow tape around the doors of the house to help her find them. She gets her news via radio, and was "enthusiastic" to learn that she could read her beloved books by tape.

Indeed, this Neurology piece proved to be enjoyable, informative, and brought forth much-needed awareness to this unusual condition. As A.S. wants readers of the paper to know, "If more people know about it, they won't have to go through what I've gone through."

But now I must sadly return to my large red binder of "to-read" papers, with Wikipedia close at hand to translate.

Photos courtesy United Health One and Dr. Ross.

Jason Cuomo, MA, Murray Flaster, MD, & José Biller, MD (2012). Right Brain: A descriptive account of two patients' experience with and adaptations to Bálint syndrome Neurology, 79 (11) DOI: 10.1212/WNL.0b013e3182698d28

1 comment:

  1. This might lend support to those who support a dual-stream pathway of perception. As Milner and Goodale might put it, A.S., and J.D. are both experiencing deficits in their unconscious vision-for-action. That is, the ventral stream provides conscious representations which allow us to decide that one object is a toothbrush and another is a cup, and the dorsal stream provides unconscious representations of spatial distance, location, movement, and other aspects important for visuo-motor function. And it seems these patients are experiencing difficulties with the latter.


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