Charles Bonnet Syndrome

May 17, 2017

By Trevor Shewfelt, Artist in Residence at the Dauphin Clinic Pharmacy

"I can't believe this tree has little branch hooks up my nose!" At least the nasal probing distracted me from my position teetering on a ladder. One Saturday, Eric and I had bought a ring style frisbee. I always thought they were cool, because they fly really far. On the Sunday, as I was trying to attach an odometer to my bike, Eric rode up to the house. He asked if he could use the pole grabber we have for changing high light bulbs in the garage. Eric and his friends had gotten the new ring frisbee stuck in a tree. I said sure. I thought at least he was solving his own problems. A while later, I took my bike with new odometer out for a spin and checked on Eric. The boys were on the edge of the field beside Barker School. Eric was using the pole grabber as a giant hockey stick and whacking a half deflated soccer ball. I told him to stop breaking the pole grabber and asked where the frisbee ring was. He pointed way up into a pine tree, well beyond the reach of the pole grabber. I told him it was bedtime in 15 minutes, that it looked like the frisbee ring was lost, and to collect his stuff and get home soon. He did come home in 15 minutes, but with no pole grabber. When I asked where it was, he said it was in the tree too.

I had never thought Eric would get a light bulb grabbing pole stuck in a tree. I also had never thought of visual hallucinations that occurred when someone's sight gets worse. I had a request to write an article about Charles Bonnet Syndrome. Honestly, I had no idea what Charles Bonnet Syndrome was, but I suppose that was the point of the request. The person who asked me to write the article said many health care professionals had never heard of Charles Bonnet Syndrome before.

Charles Bonnet Syndrome (CBS) can happen in people who are blind or visually impaired. People with CBS have problems with their eyes, but their brains produce visual hallucinations. CBS visual hallucinations have been reported in virtually every medical problem that causes vision loss. The list includes age-related macular degeneration, glaucoma, diabetic retinopathy, and stroke. Interestingly, CBS has never been reported in people with congenital blindness. That is people who have been blind from birth.

The most commonly held theory for Charles Bonnet Syndrome goes like this. Visual signals no longer go into the part of the brain that processes vison. This lack of input into the vision sections of the brain somehow causes the vision sections of the brain to start firing spontaneously. This spontaneous firing of the vision parts of the brain is then interpreted as something that is really there. These hallucinations of CBS are sometimes called release hallucinations. These release hallucinations can be simple images like lines, light flashes or geometric shapes. Or they can be complex images of people, animals or whole scenes. There are no sounds or senses of touch with these hallucinations. The content of the hallucinations of Charles Bonnet Syndrome doesn't usually have an emotional impact or personal meaning to the patient. The patient almost always know the hallucinations are unreal. However, a significant number of CBS patients are distressed by the hallucinations.

Because Charles Bonnet Syndrome is not a well known condition, it is often misdiagnosed as psychosis or early dementia. As dementia and vision loss both increase in frequency in as we age, it is easy to misinterpret a patient who starts seeing things that aren't there as having dementia instead of looking for other causes. Like everything else in life, the diagnosis of Charles Bonnet Syndrome isn't necessarily easy. When a patient with reduced vision has hallucinations, the doctor has to rule out the many, many other possible causes of the hallucinations. These can include migraine aura, epileptic seizures, dementia (especially caused by Lewy bodies and Parkinson's disease), medications, alcohol withdrawal, and other psychiatric conditions.

How is Charles Bonnet Syndrome treated? In a small number of patients, we can improve their vision. For example, if someone has cataract surgery and their vision improves, often the hallucinations improve. But most of the time there is no treatment. Some patients are reassured knowing their hallucinations are just because the vision part of their brain is misfiring. Some patients are able to temporarily suppress the hallucinations by closing their eyes or looking away. If the hallucinations are troubling to the patient sometimes we can try a low dose of an antipsychotic, an Alzheimer's medication, an antidepressant or an antiseizure medication. There aren't any studies to back up the use of these medications in CBS, but they have been useful in some patients some of the time.

After a few unkind words to Eric about losing the pole grabber, we all jumped in the minivan. Doris, Emily, Sheldon the dog, Eric, a ladder, an extendable squeegee for outside windows and I all arrived at the edge of the Barker School field. I was grudgingly impressed by two things. One: the parking lot that the ring frisbee was thrown from was a really long way from the pine tree it was stuck in. Two: Eric has gotten three separate pieces of the pole grabber and the half deflated soccer ball all stuck high up in the poplar tree beside the frisbee's perch. I'm not fond of heights, so wobbling on top of a ladder trying to knock things out of a tree with a squeegee isn't my idea of a good time. But at least it had hook branches up my nose to distract me. I eventually got the soccer ball, and the three bits of the destroyed grabbing pole down. But I couldn't get near the frisbee ring. The good news was that we caused such a spectacle, the neighbors started coming out. Garry Roloff came over with an 18 foot extendable yard stick. Garry recognized how uncomfortable I was on the ladder, so he went up. Garry is taller than me, so I'll guess his height at 6'3". His feet were about my chin height while I was holding the ladder, let's call that 5 feet off the ground. Let's assume his arms reach two feet above his head, plus the 18 foot long yard stick. So, let's say the frisbee ring was 31 feet off the ground. And it was stuck in the branches really well. It took Garry several tries to pull it out. Eric, I think you should hand this in this incident as a math estimation project to your teacher. You could call it, "How I figured out that the pine trees on the edge of the Barker School field are more than 31 feet tall."

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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Charles Bonnet Syndrome - CNIB -


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