Disorders of perception,dr deepthi,ks hegde medical academy,2013
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Disorders of perception,dr deepthi,ks hegde medical academy,2013 Disorders of perception,dr deepthi,ks hegde medical academy,2013 Presentation Transcript

  • Dr Deepthi V H
  •  Sensation : is the first stage in receiving information from outside the self.  Perception : occurs when a stimulus has undergone processing according to its form, color, motion.  The subject is able to recognize that an object is in his field of vision- sensation intact  He is unable to recognize what the object or its function is - impaired perception
  •  Constant real perceptual object in a distorted way…………sensory distortion.  New perception that may or may not be in response to an external stimulus………..sensory deception.
  •  Sensory distortions….a) Visual perception b) Auditory perception c) Splitting of perception  Sensory deceptions …a) Illusions b) Hallucinations c) Pseudohallucinations.
  •  Disturbance of the mental state with/without organic brain pathology  Involve any elementary aspects of perception like uniqueness , size , shape, colour ,location,motion or general quality.  Significance ,,,,? Perceived object is correctly recognized and identified yet there is a deviation from its customary appearance.
  • Changes in spatial form Metamorphopsia  Alteration in the customary shape of perceived object.  Dysmegalopsia  Retinal disease,disorders of accomodation and convergence,temporal & parietal lobe lesions  Rare association with schizophrenia.  May occur in poisoning with atropine or hyoscine.
  •  Macropsia : size of perception is large.  Micropsia : size of perception is small.  Hemimicropsia : apparent reduction in one hemi field of vision – temporal lobe epilepsy  Palinopsia : recurrence or prolongation of visual phenomenon beyond the customary limits of appearance of the real event eg: “cat noticed in the street one day kept appearing at various times and situation over the next few days”  Paraprosopia :when metamorphopsia affect faces.
  • Changes in intensity  Visual hyperasthesia: increased intensity of colour  Acrometopsia :complete absence of colour -unilateral/bilateral occipital lesions (lingual, fusiform gyri)  Dyschromatopsia : perversion of colour perception -unilateral posterior lesions
  •  Spatial location Telopsia : subjects appearing far away Pelopsia : subjects appearing nearer. Alloaesthesia :when the perceived object is in a different position Akinetopsia: unable to perceive the motion of the object. seen in B/L posterior cortical damage. Eg: ‘ she had difficulty in pouring tea into a cup because the fluid appeared to be frozen’.
  • Changes in quality  Colouring of yellow- xanthopsia,green-chloropsia & red- erythropsia. -poisoning with digitalis  Derealization : everything appears unreal and strange. Eg: a factory worker sees a grass hopper and becomes disturbed and excited at the site of this very strange and unknown animal.
  •  Uniqueness of perception Palinacousis : persistance of sounds that are heard  Intensity of perception Hyperacusis : increased sensitivity to noise. Anxiety & depressive disorders, migraine, hangover from alcohol. Hypoacusis: threshold for noise is raised Delirium, depression & attention-deficit disorder.
  •  Unable to form the usual, assumed links between two or more perceptions.  Rare phenomenon  Described sometimes with organic states & also with schizophrenia Eg: a patient watching television experienced a feeling of competition between the visual and auditory perceptions
  • Physical and personal Personal: Determined by personal judgement of passage of time. Influence of mood: happy-time flies, sad-slow Affected by psychiatric disorder Severe depression- time passes slowly Mania- time speeds by
  •  Illusions : Misinterpretations of stimuli arising from an external object  Hallucinations :Perception without an adequate external stimulus.
  •  Completion illusions: depends on inattention for their occurrence. ‘ _ook’ misread as ‘Book’ though the faded letter was ‘L’  Affect illusions: arise in context of particular mood state. Delirious person may perceive the innocent gestures as threatening.  Pareidolia: vivid illusions without patients effort. Subject sees vivid pictures in fire or in clouds without any conscious effort.
  •  A perception without an object (Esquirol 1817).  A false perception which is not a sensory distortion or a misinterpretation ,but which occurs at the same time as real perceptions(Jaspers ,1962).  A hallucination is an exteroceptive or interoceptive percept that does not correspond to an actual object (smythies ,1956).
  •  A hallucination is a perception without an object or the appearance of an individual thing in the world without any corresponding material event (cutting 1997).  According to Slade (1976) ,3 criteria are essential (a) percept like experience in the absence of external stimuli, (b) percept like experience that has the full force and impact of a real perception (c ) percept like experience that is unwilled ,occurs spontaneously and cannot be readily controlled by the percipient.
  •  Intense emotions.  Disorders of sense organs  Sensory deprivation  Disorders of central nervous system.
  •  Auditory hallucinations  elementary & unformed- bells, whistling, machinery or rattles.  Completely organized as hallucinatory voices schizophrenia  May also occur in chronic alcoholic hallucinosis or affective psychosis occasionally
  •  Visual hallucination  Elementary- in the form of flashes of light  Partly organized- patterns  Completely organized-visions of people, objects or animals  Occipital lobe tumours  Post-concussional state  Metabolic disturbances-hepatic failure  Alzheimer’s disease, senile dementia
  •  Charles Bonnet’s syndrome( phantom images)- Individuals experience complex visual hallucinations in association with impaired vision without any psychopathology or disturbance of consciousness  More common in elderly  Associated with central & peripheral reduction in vision  Importance in differential diagnosis.
  •  Delirium tremens  Alcohol withdrawal syndrome characterized by gross changes in perception, mood and conscious state.  Pareidolic or affective illusions are often prodromal.  Lilliputian hallucinations-seeing tiny people or objects. accompanied by pleasure & amusement.
  •  Superficial : Affecting skin sensation  Thermic - heat and cold (‘my feet on fire’)  Haptic - of touch (‘a dead hand touched me’)  Hygric – a perception of fluid (‘ I can feel a water level in my chest’)
  •  Kinaesthetic hallucinations : The patient feels that his limbs are being bent or twisted or his muscles squeezed.  Schizophrenia  Withdrawal state from benzodiazepine or alcohol intoxication. Eg: ‘I thought my life was outside my feet and made them vibrate’
  •  Olfactory hallucination: schizophrenia , epilepsy.  Hallucination of smell which may or may not be unpleasant.  Eg : people are pumping anaesthetic gas into the house which the patient alone can smell.
  • Gustatory hallucinations: schizophrenia, depression, temporal lobe epilepsy, psychotropic drugs- lithium or disulfiram. Eg: In schizophrenia and depression the flavour of food may disappear alltogether or become unpleasant.
  •  Autoscopy (phantom mirror image) : subjects see an image of themselves in external space viewed from within their own physical body.  Negative autoscopy : for instance, the patient looks in the mirror and sees no image at all.  Extracampine hallucination (concrete awareness): experienced outside the limits of the sensory field, outside the visual field or beyond the range of audibility Eg:‘ I keep on hearing them talking about my disease down in the post office’ (half a mile away)
  •  Hypnogogic hallucination: perceptions that occur while going to sleep.  Hypnopompic hallucination: perceptions that occur on waking. May be visual, auditory or tactile Occur in many people in good health Described with narcolepsy, cataplexy and sleep paralysis. Toxic states- glue sniffing , acute fever , post infective depressive states.
  • Eg - ‘a feeling of someone pushing him over the bed’ or ‘seeing a man coming across the bedroom’
  •  Functional hallucination : External stimulus is necessary to provoke hallucination but the stimulus is experienced as well as the hallucination Eg : ‘ A schizophrenic patient heard hallucinatory voices only when water was running through the pipes’.  Reflex hallucination : A stimulus in one sensory modality producing a hallucination in another. Eg : ‘ I can feel you writing in my stomach’
  •  SIMS’ Symptoms in the mind psychopathology, fourth edition.  Fish’s clinical psychopathology, third edition.
  • Thank you