(I) Hallucinosis (Hallucinatory Syndromes):
Hallucinosis are disorders in which there are persistent hallucinations in any sensory modality in the absence of other psychotic features.
1. Alcoholic Hallucinosis:
Hallucinations (most commonly auditory) occur during periods of relative abstinence. Sensorium is clear & hallucinations rarely persist longer than 1 week. Alcoholic hallucinosis is usually associated with long term alcohol use.
2. Organic Hallucinosis:
These are seen in 20-30% of patients with dementia, especially of the Alzheimer type. Auditory/ visual hallucination are common. Patient may be disoriented to time, place or person.
(II) Functional Hallucinations:
Functional hallucination requires the presence of another real sensation. These can not occur without the stimulus.
For example: Voices coming from the running tap and from the chirruping of the birds.
(III) Reflex Hallucinations:
Reflex hallucinations are a morbid form of synaesthesia. In this, a stimulus in one sensory organ produces a hallucination in another.
For example, felling pain in head (somatic hallucination) on hearing a sneeze (the stimulus).
(IV) Extracampine Hallucinations:
Extracampine hallucinations are hallucinations that are outside the limits of the sensory field.
For example, hearing voices from Canada while the patient is in India.
(V) Autoscopy (Phantom Mirror-Image):
In Autoscopy, Patient visualizes or experiences a hallucinatory image of his double.
These hallucinations are more common in acute and sub-acute delirious states, but can also occur in schizophrenia.
Negative autoscopy: Some patients suffering from organic states look in the mirror and see no image. This is known as negative autoscopy.
(VI) Hypnagogic and Hypnopompic Hallucinations:
Hypnagogic hallucinations are hallucinations that occur during the transitions between wakefulness and deep sleep.
Hypnopompic hallucinations are hallucinations that occur in the morning while waking up.
The importance of hypnagogic and hypnopompic phenomena is to recognise that they are not indicative of any psychopathology even though they are true hallucinatory experiences.
(VII) Organic Hallucinations:
- Charles Bonnet syndrome consists of visual hallucinations in the absence of any other psycho- pathology, although impaired vision is present.
- Phantom limb is the most common organic somatic hallucination of psychiatric origin. In this case the patient feels that a limb that has been removed or amputated is still present in the body.