Disorders of perception


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Disorders of perception

  1. 1. Mental status examination• Thought o Stream o Form o Possession o Content o Continuity• Perception• Mood and Affect• Insight 1
  2. 2. Disorders of Perception
  3. 3. • Sensory distortions – There is a constant real perceptual object, which is perceived in a distorted way• Sensory deceptions – new perception occurs that may or may not be in response to an external stimulus
  4. 4. • Sensory distortions• Changes in perception due to changes in the intensity, quality of the stimulus or spatial form
  5. 5. • Changes in intensity• Hyperaesthesia - due to intense emotions or lowering of physiological threshold.• Eg- anxiety, depression, alcohol withdrawal,LSD , hypomanic may see colours as bright intense• Hypoacusis- delirium, threshold for sensations is raised
  6. 6. • Changes in quality• Mainly visual perceptions are affected• Caused by toxic substances• Xanthopsia, chloropsia, erythropsia• Derealisation – everything appears strange and unreal• Mania- appears perfect and beautiful
  7. 7. • Changes in Spatial form ( Dysmegalopsia)• Changes in perceived shape of an object• Micropsia: Lilliputian hallucinations• Macropsia• Dysmegalopsia – retinal disease, accomodation and convergence disorders, TL or parietal lesions• Rarely seen in schizophrenia
  8. 8. • Distortions of experience of time• Physical and personal time• Personal time – decided by the personal judgment of the passage of time• This is effected in Psychiatric disorders
  9. 9. Sensory deceptions• Illusions• Hallucinations• Illusions• Misinterpretation of stimuli arising from an external object• Visual illusions are most common
  10. 10. • Illusions can occur in normal, Delirium• Not in themselves indicative of pathology
  11. 11. Hallucinations• ‘Perception without an object’• Jaspers- “ a false perception which is not a sensory distortion or misinterpretation , but which occurs at the same time as real perceptions”• Come from ‘within’ but reacts to them as if they were true perceptions.• Objective space
  12. 12. True perceptions Mental images• Substantial • Incomplete• Objective space • Not clearly delineated• Clearly delineated • Dependent on will• Constant • Subjective space• Independent of will • Inconstant• Sensory elements are full • Have to be recreated and fresh
  13. 13. • Pseudo hallucinations Mental image though clear and vivid , lack the substantiality of perceptions, seen in full consciousness, known to be not real perceptions and located in subjective space• InsightPresence of PH do not indicate pathology
  14. 14. Causes of hallucinations
  15. 15. Hallucinations of individual senses
  16. 16. Hallucinatory syndromes
  18. 18. • Disorders of Content• Disorders of Possession• Disorders of Stream• Disorders of Continuity• Disorders of Form
  19. 19. Disorders of Content
  20. 20. Delusion• A delusion is a false unshakeable idea or belief which is out keeping with the patient’s educational , cultural and social background. It is held with extraordinary conviction and subjective certainty.
  21. 21. Case Vignette• Christina , a 44 year old woman, was arrested after harassing a local television newscaster with telephone calls and letters asserting that he had fathered, then absconded with her child. She denied any wish to harm him but steadfastly pursued him with demands that he give her “visitation rights” to “their” child. She said she understood that he would be unable to marry her, or even to outwardly acknowledge his love for her, because of his delicate public position.• There was no indication that the newscaster had ever had a relationship with Chris, although evidence from her files and from her apartment indicated that her fantasized relationship with him had existed for several years. There was no indication of hallucinations, disturbance of affect, significant Mood Disorder, or organic illness, and the woman had never been treated for a psychiatric disorder.
  22. 22. • English word “ delude” means - to mock, to cheat, defrauding etc• The decision to call a belief as a DELUSION is not made by the person holding the belief , but by an external observer.
  23. 23. • The person who is holding the delusion holds the belief with the same conviction as he holds his other non delusional belief about himself .
  24. 24. • Jaspers regarded delusion as a perverted view of reality, incorrigibly held so giving delusion 3 componentsC.They are held with unusual convictionD.They are not amenable to logicE. The absurdity or erroneousness of their content is manifest to other people.
  25. 25. Primary delusions• Delusion is not occurring in response to another psychopathology• “ apophany”• New meaning arises in connection with some other psychological event• Arises ‘ de novo
  26. 26. • Core feature of a primary or autochthonous delusion is that it is ultimately “ Ununderstandable” - Jaspers• Eg: a female patient with schizophrenia believes that men enter her flat anesthetize her and gang rape her every night.
  27. 27. Secondary delusions• Arising from some other morbid experience• Are Understandable• Systematization• Completely systematized delusion- there is one basic delusion and the remainder of the system is logically built on this error
  28. 28. Content of delusions
  29. 29. Delusional misidentification• The capgras syndrome– familiar person is been replaced by stranger• Syndrome of Fregoli- stranger is familiar
  30. 30. Overvalued ideas• Thought that ,because of the associated feeling tone ,takes precedence over other ideas and maintains this precedence permanently for a long period of time.• Less fixed and have some degree of basis in reality• Can occur in normal individuals also
  31. 31. • Overvalued idea is an acceptable, comprehensible idea pursued by the patient beyond the bounds of reason.• It becomes so dominant that all other ideas are secondary and relate to it.• This term was introduced by Wernicke ( 1906)
  32. 32. Disorders of Possession
  33. 33. obsessions• A thought that persists and dominates an individuals thinking despite that individual’s awareness that the thought is either entirely without a purpose or else has persisted and dominated their thinking beyond the point of relevance.
  34. 34. • It is a thought, idea, imagery or impulse which is repetitive , intrusive, irrational, recognised as ones own thought and ego dystonic.• Compulsions- are repetitive ritualistic motor or cognitive acts which are used to control anxiety secondary to obsessions
  35. 35. • Contamination obsessions• Aggressive obsessions• Pathological doubts• Sexual obsessions• Blasphemic obsessions• Obsessive ruminations• miscellenaeous
  36. 36. Thought alienation• Thoughts are under the control of an outside agency• Others are participating in their thinking
  37. 37. DISORDERS OF CONTINUITY• Perseveration: mental operations persist beyond the point at which they are relevant progress of thinking, found in organic disorders• Thought Block: sudden arrest of the train of thought, leaving a “blank”- Terrifying experience, highly indicative of schizophrenia