SYMPTOMS AND SIGNS IN PSYCHIATRY - 2

8.       Disorders of Perception:

o  Sensory Distortions: Hyperaesthesia -> Sounds appears louder, Colours brighter and Pain unbearable; Hypoaesthesia –> they are all diminished.

o Sensory Deceptions: Illusion-> misperceptions of external stimuli; Hallucination -> false perceptions which occur in the absence of corresponding sensory stimuli.

o       Perceptual Disturbances of time and space.

o       Perceptual Disturbances of Body Image.

Varieties of   Hallucinations:

• Depends on sensory modalities: Auditory (e.g. voices), Visual (e.g. flashes of light) Olfactory (e.g. smell), Gustatory (e.g. taste) Tactile (e.g. insect crawling sensation on the skin), Vestibular (e.g. flying in space).

• Depends on complexity: Simple: Single sense modality (e.g. tap on the door). Complex: Multiple sensory Modalities (e.g. Hallucination of a wild fire. When visual (tongues of flame), auditory (crackling wood) and olfactory (smoke) sense modalities are involved.

• Depends on organization: Unformed (sparks of light, noises), Formed (Voices accusing the patient)

• Depends on reality value: True hallucinations have reality value. Pseudo-hallucinations are those where the patient is aware of the unreality of his perceptions.

• Special types of hallucinations:

o    Hypnagogic and Hypnopompic Hallucinations: are usually visual but may occur in other sensory modalities also (e.g. hearing the patient’s own name being called).

o    Functional Hallucinations: Hallucination accompanies a provoking stimulus and both are perceived at the same time (e.g. water tickling from a leaking tap is hearing along with voices of the patient’s neighbour cursing him).

o  Synacsthesia (reflex hallucinations): Stimulation in one sensory modality produces sensations pertaining to another (e.g. when the light flashes, the patient gets a tingling sensation.

o    Extracampine Hallucinations: They are hallucinations experienced outside the limits of one’s sensory fields. (eg hearing voices of people who are talking several kilometers away; seeing through the back of one’s head.

o    Scenic (panoramic) Hallucinations: Hallucinations are vivid, continuous and complex as if one sees a movie.

(to be conted...)