One street sign pointing left reads "S. Marco Rialto", below it another street sign reading "S. Marco Rialto" points to the right.

Is post-stroke delirium related to compromised right-brain function?

One street sign pointing left reads "S. Marco Rialto", below it another street sign reading "S. Marco Rialto" points to the right.

Ever felt lost in a foreign place?

Have you ever felt confused? Perhaps, you were visiting another country where everyone around you spoke a different language? You’ve lost your way to your hotel and didn’t know how to ask for directions?  This situation can be unnerving to the most level-headed person. Yet, this is but a glimpse of what it must feel like to someone with delirium. Delirium is an acute state of confusion, described as a sudden decline in attention, cognitive function, and arousal. Like the scenario of being lost in an unfamiliar place, delirium can induce disorientation. It also produces perceptual distortions, disorganized thinking, and even hallucinations.
A young woman trying to take a picture of a wild bear just outside her hospital room; a mother crying because she thought her daughter had passed away, when the daughter just stepped outside the door, a patient unsure of where she is and who the people around her are. These individuals have one thing in common, delirium.  They are also participants in a Kessler Foundation study investigating the brain systems disrupted in delirium after stroke.  This study was designed to help us understand why some patients make a successful post-stroke recovery and why others develop delirium and face longer hospital stays, worse physical and cognitive function, and even increased chance of mortality. If clinicians know more about what’s causing the acute brain dysfunction in delirium, they may be able to intervene in just the right moment to prevent or to treat this syndrome.
Older, white male wearing glasses in foreground being examined by female asian physician behind him

Risk for stroke and delirium both increase with age.

Perhaps, not so surprisingly, delirium is associated with another post-stroke syndrome, called spatial neglect.  Spatial neglect is characterized by a disruption of attention and spatial cognition. Spatial cognition enables individuals to acquire and organize knowledge about their environments and to utilize this knowledge for action planning. Stroke survivors with spatial neglect do not act upon or notice things on the side of space contra-lateral to their stroke lesion.  Those with spatial neglect seem to be especially prone to developing delirium: the more severe the spatial neglect – the more delirium symptoms they have. This finding, reported at the World Congress for Neurorehabilitation meeting in 2016, suggests that the brain systems for arousal, attention, and spatial orientation may play a critical role in post-stroke delirium, as we know they do in spatial neglect.
The right side of the brain attributes salience, coordinates and shifts attention to events in space, and initiates spatial action preparation. The right brain is, thus, dominant for spatial attention and action.  Studies of stroke patients indicate that delirium, like spatial neglect, may develop more frequently after right- than left-sided lesions.  Could a disruption in the right-dominant brain networks for spatial attention and orientation be responsible for post-stroke delirium? Researchers in the Kessler Foundation Stroke Rehabilitation Research Program are collecting behavior and brain data to test this theory, which could open doors for new attentional-behavioral therapies and physiological diagnostic tools and treatments, for example, non-invasive brain stimulation. The promising future of delirium research stands to resolve the confusion about the patients’ state of confusion.
Author note: This post was contributed by Olga Boukrina, Research Scientist in Stroke Rehabilitation at the Kessler Foundation.

For additional resources on delirium, please see our Resources page.

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