HALLUCINATIONS

27thAug2013

• Sensory distortions • Hyperacusis

• hyperaesthesia

• Sensory deceptions• Illusion

• hallucination

DISORDERS OF PERCEPTION

DEFINITION

• False sensory perceptions

• occurring in the absence of any relevant external stimulation

• of the sensory modality involved.

_(kaplan & saddocks synopsis of psychiatry)

• Esquirol (1817) _ a perception without an object.

• Smythies(1956)_a hallucination is an exteroceptive or interoceptive percept which doesn’t correspond to an actual object.

• Slade(1976)_ 3 criteria are essential for an operational definition.

• Percept like experience in the absence of an external stimulus.

• Percept like experience which has the full force and impact of a real perception.

• Percept like experience which is unwilled ,occurs spontaneously and cannot be readily controlled by the percipient.

CLASSIFICATIONParameter Types

Depending on sensory modality Auditory,visual,olfactory,gustatory,tactile, vestibular, deep sensations.

Depending on complexity Simple : single sense modality Complex: Multiple sensory modality involved.

Depending on organisation Unformed: sparks of light, noisesFormed: voices accusing the patient.

Depending on reality value True hallucinations have reality valueFalse hallucination pt. is aware of the unreality of his perception.

Special types of hallucinations Hypnagogic,hypnopompic,functional,extracampine,scenic etc.

AUDITORY HALLUCINATIONS

• Elementary and unformed as ‘ noises,bells,whispers’ _ occur in organic states.

• Partially organised as ‘music’ or completely organised as ‘voices’ in schizophrenia.

• Hallucinatory voices also occur in organic states such as delirium or dementia.

• Imperative hallucination: Are hallucinatory voices giving instructions to the patient ,who may or may not act upon them.

• 3rd person hallucination: giving running commentary about the patient to a 2ND person.

• Audible thoughts: ( thought echo or thought sonorisation) Patient can hear his own thoughts as real perception.

VISUAL HALLUCINATIONS

• Elementary_ flashes of light

• Partialy organised_ patterns

• Completely organised_ visions of people,objects,or animals.

Lilliputian hallucination

Visual hallucination with micropsia.

usually seen in delirium tremens.

CHARLES BONNET SYNDROME:

• Presents with visual hallucinations in the absence of any psychopathology or brain disease.

• Victims are usually old age persons with visual loss.

• No other psychotic symptoms and aware about the unreality of the perceptions.

OLFACTORY HALLUCINATIONS

• Occur in

• schizophrenia,

• organic states and

• depressive psychosis.

• Combines with the persecutory delusions in schizophrenia.

• Temporal lobe epilepsy: seizures + olfactory hallucinations.

GUSTATORY HALLUCINATIONS

• Seen in schizophrenia as well as acute organic states.

• In schizophrenic patients it always mix with the delusional explanations.

Tactile hallucinationsFormication:cocaine psychosis. _insects crawling over

his body

_along with delusion of persecution cocaine bug

SIMS CLASSIFICATION

• Superficial: thermic, haptic, hygric, paraesthetic.

• kinaesthetic: affects the muscles and joints. Feels that their limbs are being twisted,pulled or moved. Seen in schizophrenia.

• Visceral: patients complaints of visceral pain and deep sensations.

DELUSIONAL ZOOPATHY

• Animal crawling inside his body.

• Alcoholic hallucinosis

Auditary hallucinations, during relative abstinence, asso. with long standing alcohol misuse.

• Organic hallucinosis

Presents with 20-30% of patients with dementia especially of the alzheimer type .usually auditory or visual.

HALLUCINATORY SYNDROMES

SPECIAL TYPES:

• Hypnagogic and hypnapompic hallucinations:

• Functional hallucinations.

• Reflex hallucinations.

• Extra campine hallucinations.

• Panoramic hallucinations/scenic hallucinations.

Somatic hallucinations

Phantom limb phenomenon:

Sexual hallucinations:

AUTOSCOPY

NEGATIVE AUTOSCOPY

PSEUDO HALLUCINATIONS

• False perceptions which the patient recognises as unreal in contrast to true hallucinations where the patient recognises as real.

• Not pathognomonic of any mental illness.

HALLUCINATIONS MEMORY IMAGES

Occures in external space in front of the subject

Occur inside the mind in the mind space-inner subjective space

Clearly defined Incomplete and ill defined. Only individual details are prominent.

The subject has a sense of reality Subjects know that they are product of his imagination.

Remain constant and unchanged Fade off over time like memory

Occure independent of the subject’s will

Can be produced and altered voluntarily.

ELICITATION

• The full phenomenology of hallucination should be explored.

• Auditory hallucinations _ content

• _ volume

• _ clarity

• _ circumstances

• Visual hallucinations _ content

• _ intensity

• _ situations

• _ response•

THEORETICAL APPROACHES

• As a first approach to studying the mechanism of hallucinations, psychologically normal individuals with hallucinations due to lesions have been studied, and the lesion was generally found to be in the brain pathway of the sensory modality of the hallucination.

• For example, the complex visual hallucinations seen in Charles Bonnet syndrome are most often caused by damage to the visual system such as macular degeneration or lesions in the visual pathway.

NEUROIMAGING

• Hallucinations in patients with schizophrenia have been studied with respect to changes in central nervous system structure, function and connectivity. The most consistent finding of structural neuroimaging studies of patients with auditory hallucinations is reduced grey matter volume in the superior temporal gyrus, including the primary auditory cortex.

• One study also reported volume reduction in the dorsolateral prefrontal cortex.

• Functional activation studies of actively hallucinating participants have reported increased activity in language areas and in the primary auditory cortex, strongly implicating the superior and middle temporal gyri

• In summarizing current knowledge on neuroimaging of hallucinations, Allen and colleagues have proposed a model for auditory hallucinations in which there is overactivity in the primary and secondary auditory cortices in the superior temporal gyrus and altered connectivity with language processing areas in the inferior frontal cortex. The model also includes weakened control of these systems by anterior cingulate, prefrontal, premotor and cerebellar cortices. Basically, it appears that neuroimaging data have confirmed the expectation that hallucinations involve altered activity in the neural circuits known to be involved in normal audition and language and their control. However, the major question of how this altered activity arises is still unanswered !!...

REFERENCES:

• Kaplan and sadock’s synopsis of psychiatry (10th ed.)

• Fish’s clinical psychopathology(3rd edition)

• Sims symptoms in the mind.

• Concise textbook Psychiatry, VMD Namboodiri(3rd ed.)

THANK YOU…