Patient A.D., a physical fit senior woman, suffered a bleeding stroke, attributed to Cerebral Amyloid Angiopathy, in her left occipital lobe. (This is where visual information is processed.) As a result, she lost vision in the right half of each eye, a condition called Homonymous Hemianopia.
Hallucinations of Giant Flowers and People. While recovering at Stanford University Hospital, she began to notice frequent hallucinations. Often, they were of very large or even giant flowers, and sometimes even giant people. In one instance, she reported seeing a large group of soldiers wearing brightly colored eastern European dress uniforms who marched in front of her. Since these images were mainly pleasant ones, she did not initially experience much discomfort. Her neurologist described the images as an example of the Charles Bonnet syndrome, and suggested that they were the result of the brain needing to substitute for the imagery that was missing from the one half of her visual field.
A few days later during inpatient rehabilitation at a different medical facility, the hallucinations continued. But there were differences. In one case, she was looking for her glasses, and she saw a tiny hallucination of eye glasses on her hospital bed.
Some Images Begin to Be Distressing. She first began to be distressed by the hallucinations on the way home from an inpatient rehabilitation facility because, instead of trees, she saw what appeared to be giant buildings along the road home. She also saw a hallucination of a nonexistent cross street that seemed to go up toward the sky at a steep angle. She also had the impression that there was a steep and extremely dangerous cliff along the edge of the road. She wondered why there was no guardrail along the road to protect cars from the extreme danger represented by her hallucinations. In at least one case, she saw a car—that did not really exist–arriving from a cross street.
Inability to Recognize her Own Neighborhood. The most serious consequence of these new hallucinations was that they made it impossible for her to recognize where she actually lived. When she arrived home, she did not recognize it or the neighboring houses. In fact, she wondered what would happen if she were to be lost. She would not even be able to get home by herself or even accurately describe to someone where she was.
At this point, the hallucinations had become such a concern that she stated that she would be satisfied with the loss of one-half of her visual field and be able to adapt to it if only the hallucinations would go away.
Final Recovery. Eventually, by repeated driving on the same streets, she began to recognize certain building as being familiar and they would no longer stimulate hallucinations. Still, many trees along the Stanford University campus continued to generate images of giant buildings for a long time. Her doctors had predicted that the hallucinations would not last more than six months, but they actually lasted several months longer. One year after her stroke, she has fully recovered, rarely sees any hallucinations at all, and they are no longer a source of concern.
Related Reading. Professor Oliver Sachs, a neurologist at New York University Medical School, has published an interesting book on hallucinations, which have many different causes. https://www.nytimes.com/2012/11/27/books/hallucinations-by-oliver-sacks.html