3. DEFINITION
• False sensory perceptions
• occurring in the absence of any relevant external stimulation
• of the sensory modality involved.
_(kaplan & saddocks synopsis of psychiatry)
4. • 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.
5. • 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.
6. CLASSIFICATION
Parameter 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, noises
Formed: voices accusing the patient.
Depending on reality value True hallucinations have reality value
False hallucination pt. is aware of the
unreality of his perception.
Special types of hallucinations Hypnagogic,hypnopompic,functional,extraca
mpine,scenic etc.
7. 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.
8. • 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.
9. VISUAL HALLUCINATIONS
• Elementary_ flashes of light
• Partialy organised_ patterns
• Completely organised_ visions of
people,objects,or animals.
11. 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.
12. OLFACTORY HALLUCINATIONS
• Occur in
• schizophrenia,
• organic states and
• depressive psychosis.
• Combines with the persecutory delusions in schizophrenia.
• Temporal lobe epilepsy: seizures + olfactory hallucinations.
13. GUSTATORY HALLUCINATIONS
• Seen in schizophrenia as well as acute organic states.
• In schizophrenic patients it always mix with the delusional
explanations.
15. 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.
17. HALLUCINATORY SYNDROMES
• 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.
18. SPECIAL TYPES:
• Hypnagogic and hypnapompic hallucinations:
• Functional hallucinations.
• Reflex hallucinations.
• Extra campine hallucinations.
• Panoramic hallucinations/scenic hallucinations.
22. 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.
23. 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.
24. ELICITATION
• The full phenomenology of hallucination should be explored.
• Auditory hallucinations _ content
• _ volume
• _ clarity
• _ circumstances
• Visual hallucinations _ content
• _ intensity
• _ situations
• _ response
•
25. 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.
26. 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.
27. • 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
28. • 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 !!...
29. 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.)
