Visual hallucinations in psychosis
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Visual hallucinations in psychosis are hallucinations accompanied by delusions.[1]
Presentation
Visual hallucinations in psychoses are reported to have physical properties similar to real perceptions. They are often life-sized, detailed, and solid, and are projected into the external world. They typically appear anchored in external space, just beyond the reach of individuals, or further away. They can have three-dimensional shapes, with depth and shadows, and distinct edges. They can be colorful or in black and white and can be static or have movement.[2][3][4][5][6][7][8]
Simple vs. complex
Visual hallucinations may be simple, or non-formed visual hallucinations, or complex, or formed visual hallucinations.
Simple visual hallucinations without structure are known as
Sometimes, hallucinations are 'Lilliputian', i.e., patients experience visual hallucinations where there are miniature people, often undertaking unusual actions. Lilliputian hallucinations may be accompanied by wonder, rather than terror.[13][14]
Content
The frequency of hallucinations varies widely from rare to frequent, as does duration (seconds to minutes). The content of hallucinations varies as well. Complex (formed) visual hallucinations are more common than Simple (non-formed) visual hallucinations.
Causes
Two neurotransmitters are particularly important in visual hallucinations – serotonin and acetylcholine. They are concentrated in the visual thalamic nuclei and visual cortex.[13]
The similarity of visual hallucinations that stem from diverse conditions suggest a common pathway for visual hallucinations. Three pathophysiologic mechanisms are thought to explain this.
The first mechanism has to do with cortical centers responsible for visual processing. Irritation of visual association cortices (Brodmann's areas 18 and 19) cause complex visual hallucinations.[12][15]
The second mechanism is
Prevalence
[9] The DSM-V lists visual hallucinations as a primary diagnostic criterion for several psychotic disorders, including schizophrenia and schizoaffective disorder.[1][10][16] Visual hallucinations can occur as a symptom of the above psychotic disorders in 24% to 72% of patients at some point in the course of their illness.[2][17][11]
References
- ^ a b American Psychiatric Association (2013). The Diagnostic and Statistical Manual Revision V (DSM-V).
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- ^ a b Block, Michael N. (March 2012). "An overview of visual hallucinations: patients who experience hallucinations secondary to a host of underlying conditions often will look to you for guidance, reassurance and treatment". Review of Optometry. 149 (3): 82–90.
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- ^ a b Ali, Shahid; Patel, Milapkumar; Avenido, Jaymie; Bailey, Rahn K.; Jabeen, Shagufta; Riley, Wayne J. (November 2011). "Hallucinations: Common features and causes". Current Psychiatry. 10 (11): 22–29.
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