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Visual hallucinations anyone? Also called release hallucinations

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  • Visual hallucinations anyone? Also called release hallucinations

    Author:Victoria S Pelak, MDSection Editor:Paul W Brazis, MDDeputy Editor:Janet L Wilterdink, MD

    The Charles Bonnet syndrome refers to symptoms of visual hallucinations that occur in patients with visual acuity loss or visual field loss. These are often called release hallucinations, reflecting the most widely accepted theory of their pathogenesis.
    Underlying conditions of vision loss associated with the Charles Bonnet syndrome affect the eye, optic nerve, or brain and include a diverse set of pathologies, such as macular degeneration and stroke. While often not functionally disabling, the hallucinations can be distressing to patients and negatively impact quality of life [1]. Published case reports suggest that the syndrome is not well recognized by clinicians and may often be misdiagnosed as psychosis or early dementia [2,3].

    The pathophysiology, causes, clinical features, diagnosis, and treatment of the Charles Bonnet syndrome will be reviewed here. Other causes and the overall approach to visual hallucinations are discussed separately. (See "Approach to the patient with visual hallucinations".)


    The Charles Bonnet syndrome (CBS) may be more common than is generally appreciated. Visual hallucinations are often unreported by patients because they fear that they represent psychiatric disease [1,4,5]. When this symptom is specifically solicited in older patients with impaired vision, 11 to 15 percent admit to having visual hallucinations [1,5-11]. The reported prevalence was even higher, 39 percent, in one survey of patients diagnosed with macular disease [12]. These surveys also reveal that most patients had failed to report these symptoms to their physician or to family members. One study found that only 12 percent of patients attending a retinal clinic were aware of the condition [13].
    Release hallucinations have been reported in all age groups, including children [8,14]. However, most patients with CBS are elderly; in large case series, the mean age is between 70 and 85 years [4,8,15,16]. This probably reflects the mean age at which the most common underlying conditions causing vision loss are seen. Some investigators, but not others, have found that advanced age is a risk factor for release hallucinations within their study population [6,11,17].

  • #2
    Oliver Sacks wrote a whole book about this. People in sensory deprivation get them, too. It's kind of a response to not enough stimulation - brain doesn't like to be bored.


    • #3
      That's right

      I read a lot of Sachs......I remember him talking about such things.
      I have always had a lot of what I call visual oddities with my course of MS. Here on my farm it always could be an animal flying by so it took me a while to figure out what is happening.

      I will keep exploring the literature and figure out a way to ignore what is before my eyes!


      • #4
        I haven't had hallucinations but I do get "phosphenes" in my almost completely blind left eye, it comes as little sparkly dots of light all over field of vision, almost like light reflecting off of snow. Usually doesn't last long, not painful or anything, just really distracting. I think it's linked to Uthoff's as well as I tend to get it when overheated, or during a hot bath or shower.
        Callenge life before life challenges you - from inside collar of my "Bike Off More Than You Chew" bike jersey


        • #5
          Oooh. Take hot shower, see fireworks!
          The book, incidentally, is "Hallucinations," by Oliver Sacks. In paperback, or used, available on Amazon. (Also, and better, as an audiobook.)