disorders of perception (1).pptx

7/27/2019 disorders of perception (1).pptx

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DISORDERSOFPERCEPTION

Presenter : Dr. Imon Paul

Chairperson : Dr. Shyam Sunder


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PERCEPTION

Interpretation of what we take in through our

senses

Requires sensation information to be taken in

from outside world

Eliminating the irrelevant

Associating what is seen with other relevant data to

form a percept


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ABNORMALPERCEPTION

Sensory distortions

Changes in intensity

Changes in quality

Changes in spatial formConstant real

perceptual object

percieved in distorted

way

False perceptions/

sensory deceptions

Illusions

Hallucinations Pseudo-hallucinations

New perception which

may/may not be in

response to externalstimulus


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SENSORYDISTORTIONS - INTENSITY

Hyperasthesia

Intense emotions

Lowering of

physiological threshold Neurotics and

hypochondriacal

personalities

Hypoasthesia

anxious preoccupation

delirium (rise in

threshold)


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QUALITY

Mainly visual distortions

Usually due to toxic substances, some

antihelminthics

Xanthopsia- caffeinism Chloropsia - digitalis toxicity

Erythropsia- preretinal and vitreous haemorrhage


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SPATIALFORM/ DYSMEGALOPSIA

Micropsia

Macropsia Metamorphopsia- Retinal diseases- Disorders of accomodation and convergence

- Temporal lobe lesions

- Delirium, degenerative brain diseases affecting visual

association cortex- Atropine/hyoscine poisoning

Porropsia- retreat of objects without change in size


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SENSORY DECEPTIONS

Illusions

Hallucinations


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SENSORY

DECEPTIONS


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ILLUSIONS

Misinterpretation of stimuli arising from an external

object

Stimuli from a perceived object are combined with a

mental image to produce a false perception

transformations of perceptions coming about by a

mixing of the reproduced perceptions of the

subjects fantasy with natural perceptions

(Hagen)


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TYPES

Completion

depend on inattention for occurrence

Incomplete perception meaningless of itself isfilled in by a process of extrapolation from

previous experience to produce significance


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Affect

combination of heightened emotion and

misperception

Can be understood in context of prevailing moodstate

A child waking up in the middle of the night

scared in the dim light , mistakes the towel

hanging on the wall for a person


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Pareidolic

- are created out of sensory percepts by an

admixture with imagination.

- Images seen from shapes- the percept takes on a full and detailed appearance

- becomes more intricate with attention


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Fantastic illusions

Person sees extraordinary modifications of his

environment eg. Looking into a mirror and seeing

head of a pig instead of own head.


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D/D

Intellectual misinterpretation

Functional hallucination


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HALLUCINATIONS

A perception without an object

(Esquirol)

A false perception, that is not a sensory distortion ormisinterpretation but which occurs in the same time

as a real perception

(Jaspers)


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Three criteria are essential for hallucination:

1. Percept like experience in the absence of a

stimulus

2.

Has the full force and impact of a real perception3. Which is unwilled, occurs spontaneously, cannot

be readily controlled by the recipient

(Slade)


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CAUSES

Emotional states

Suggestion

Sensory deprivation

CNS disorders


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CLASSIFICATION

Sensory Modality: Visual, Auditory, Olfactory,

Gustatory, and Kinesthetic.

Form: Elementary and Formed.

Precipitating circumstance: Functional, reflex,

hypnagogic, and hypnopompic.

Degree of attenuation of reality: True

hallucination, pseudo-hallucination and Imagery


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AUDITORYHALLUCINATIONS

May be

elementary noises

partly organized music

completely organized voices Imperative

Seen in schizophrenia, affective psychoses, chronic

alcoholic hallucinosis

content could be commanding, critical, abusive


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Schniderian first rank symptoms:

- hearing ones thoughts being spoken aloud

( Gedankenlautverden)

- voices speaking about patient in third person- voices in form of running commentary


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VISUALHALLUCINATIONS

Types:

Simple - colored lights

Partly organized - geometric shapes

Completely organized - scenes, humans, animals

Seen in organic brain conditions like occipital or

temporal lobe lesions, dementing illnesses, sensory

deprivation, eye pathology, hallucinogens


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Delirium tremens seeing rats, mice, squirrels,

spiders, insects, lilliputian etc

Scenic hallucinations epilepsy, oneiroid states

visions of fire, religious scenes etc

Combined auditory visual hallucinations in

temporal lobe epilepsy

Very uncommon in schizophrenia


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OLFACTORYHALLUCINATIONS

occur in schizophrenia, temporal lobe epilepsy

(commonly aura) and some other organic states.

The smell may or may not be pleasant but usually

has a special and personal significance

For eg- people putting poisonous gas/ anaesthetic

into the house

sometimes relating to oneself I smell repulsive


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A delusion in which a patient believes himself to

smell malodorously without an accompanying

olfactory hallucination is common in schizophrenia.


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GUSTATORYHALLUCINATIONS

Can occur in schizophrenia (odd tastes in food,

food is being poisoned, etc.)

Difficult to establish whether these are clear

hallucinations at times

Can also occur in temporal lobe epilepsy


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HALLUCINATIONSOFBODILYSENSATIONS

May be superficial, kinaestheticorvisceral

superf ic ial :

Thermic

Haptic a dead hand touched me Hygric a perception of fluid

all my blood has dropped into my legs


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Kinaesthetic:

- of muscle or joint sense

- perception of limbs being twisted or muscles being

squeezed.

- in schizophrenia, organic states, withdrawal states

from BZDs or alcohol

Visceral: sensations referred to internal organs,

common in schizophrenia


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Formication/ cocaine bugs

Internal delusional zoopathy :

- eg: sensation of a wasp wandering inside the body

External delusional zoopathy:- sensation of an animal crawling about on the body


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PSEUDO-HALLUCINATIONS

A type of mental image which although clear andvivid,

- lack the substantiality of perceptions,

- are seen in full consciousness,

- located in subjective space.(Jaspers)

Difference between real and pseudo-hallucinationsdepends on the absence or presence of insight.

(Hare)


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True Perception

- Substantial

- Objective Space

- Clearly delineated

- Constant

- Independent of will

- Sensory elements: Full& Fresh

Mental Image /Fantasy

- Incomplete

- Subjective space

- Not clearly delineated

- Inconstant

- Dependent on will

- Have to be recreated

(Jaspers)


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PSEUDO-HALLUCINATIONS

Similarities to True

perception

- Clear & Vivid

- In full consciousness

- Involuntary

Similarities to Mental

Image / Fantasy

- Type of Mental Image

- Lack the substantiality

- Not a real perception

- Subjective Space


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Perception=Hallucinati

on

Pseudohall

ucination

Imagery

Experience Concrete, tangible,

objective, real

Inner eye Pictorial subjective

Location Outer obj. space Inner subjective

Definition Definite, complete Indefinite, incomplete

Vividness Full, fresh, bright Dim, neutral

Constancy retained evanescent

Independence Cannot dismiss/recall at

will

Voluntary creation

Insight Quality of perception Quality of idea

Bhv. relevance relevant Not relevant

Sensory

modality

Another modality Not possible

Existence independent dependent


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SPECIFIC/NAMEDHALLUCINATIONS

Functional hallucinations:

- occurs only in the presence of an external stimulus

in the same modality, but is perceived separately

(eg. hearing voices only when a fan is switched on,

though the sound of the fan is perceivedseparately)

- both perceptions are distinct and real


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Synesthesia:

- is the stimulation of one sensory modality eliciting a

perception in a different sensory modality, as in

seeing a sound.

- associated with toxic states,

- considered the classic perceptual disturbance of

LSD intoxication


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Reflex hallucinations:

- a morbid variety of synaesthesia in which a

stimulus in one modality (eg. Hearing someone

laugh) produces a sensation in another modality

(eg. a pain in the chest)

Extracampine hallucinations: hallucinations

experienced outside the limits of sensory field

Imperative: voices giving commands


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Autoscopy : experience of seeing oneself and

knowing that it is oneself

Negative autoscopy :looking in the mirror and

seeing no image at all.

Internal autoscopy: seeing ones internal organs


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Experiential:hallucinations of past memories

(visual and auditory) in temporal lobe epilepsy

Hypnagogic / hypnopompic: occurring as subject

is falling asleep or waking up; generally a normal

phenomenon

Cenesthetic:bizarre visceral hallucinations in

schizophreniasemen travelling up my vertebral

column to brain where its laid out in sheets"


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Lilliputian hallucinations:visual hallucinations of

small figures / animals (i.e. with micropsia), usually

perceived as pleasant

Charles Bonnet syndrome: visual hallucinations

of human / animal figures in elderly patients with

eye disease, in the absence of other

psychopathology


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Phantom limb: perception of sensation from a limb

that has been amputated (or, more rarely)has been

denervated

- Occurs in about 95 percent of amputees

- does not necessarily correspond to previous image

of the limb


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EVALUATINGHALLUCINATIONS

Schizophrenia: usually distinct and continuousvoices, often in the third person, male or female,delusional elaborations

Depression: rarer (about 10-20% in psychotic

depression), intermittent, disjointed voices Organic states: usually less well formed,

elementary, simple voices (but depends on site oflesion


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Alcoholic hallucinosis: auditory hallucinations,derogatory or threatening

Delirium tremens: visual hallucinations (usuallysmall animals, insects)

Epilepsy: all modalities may occur in temporal lobeepilepsy

Dementia: visual and auditory hallucinations,simple or partly organized


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Hallucinatory syndromes

Confusional

Self reference

Verbal Fantastic


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DESCRIBINGHALLUCINATIONS

Modality : Auditory

Level of consciousness

From Outside or Inside

Known / Unknown peoples voices Content - Pleasant / Unpleasant

Intermittent / continuous / running commentary type


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Directly to the patient or talking among themselves

Commanding / Non-commanding

Controllable or not Insight

Acting out behaviour


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THANKYOU

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disorders of perception (1).pptx