What term refers to sensory perceptions that occur in the absence of an external stimulus?

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Learning outcomes

By the end of this CAL you will be able to:

• Describe the general purpose and component parts of the Mental State Examination (MSE), specifically patients’ perception and mood.
• Evaluate patients’ perception and mood in their mental state and use appropriate terminology to describe abnormalities.

Acknowledgments:

Thank you to Neelom Sharma, Alexandra Pittock, Meroe Grove, Maia Forrester and Mercedes Smith for their major contributions to the content of this module.

Introduction Part 1 of 11

Hope you got on well with the last session!

Let’s just quickly recap over it one last time before we move on…

The next two domains we’re going to learn about are perception and mood.

Perception Part 2 of 11

Perception can be considered as processed sensation. In other words, it is the meaning we give to sensory input, based on current context, past (learned) experiences, current emotional state etc.

Abnormal perceptual experiences form part of the clinical picture of many mental disorders. Equally, the range of normal perceptual experience is very wide.

For the MSE, we’re going to split perception into ‘perception of the world’ and ‘perception of the self’.

Hallucinations Part 3 of 11

Hallucinations are perceptions occurring in the absence of an external physical stimulus, which have the following important characteristics:

• To the patient, the nature of a hallucination is exactly the same as a normal sensory experience – i.e. it appears real. Therefore, patients often have little insight into their abnormal experience.

• They are experienced as external sensations from any one of the five sensory modalities and should be distinguished from ideas, thoughts, images or fantasies which originate in the patient’s own mind

• They occur without an external stimulus and are not mere distortions of an existing physical stimulus (as in illusions).

Auditory Hallucinations Part 4 of 11

These are hallucinations of the hearing modality, and are the most common in psychiatry.

Auditory hallucinations are split into elementary and complex hallucinations.

• Elementary hallucinations are simple sounds e.g. whirring, buzzing, whistling or single words.
• Complex hallucinations occur as spoken phrases, sentences or even dialogue that are sub-classified into first, second, and third person.

First person auditory illusions (i.e. audible thoughts): patients hear their own thoughts spoken out loud as they think them.

Second person auditory hallucinations: patients hear a voice, or voices, talking directly to them. Second person hallucinations can be persecutory, highly critical, complimentary or issue commands to the patient (command hallucination). These kind of hallucinations can often be mood-congruent i.e. a patient with low mood will more often experience hallucinations of a persecutory or critical nature, and similarly a patient with an elevated mood will more often experience hallucinations of a complimentary nature.

Third person auditory hallucinations: patients hear a voice or voices speaking about them, referring to them in the third person. This may take the form of two or more voices arguing or discussing the patient among themselves; or one or more voices giving a running commentary on the patient’s thoughts or actions.

Other Hallucinations Part 5 of 11

Visual Hallucinations:

These are hallucinations of the visual modality. They occur most commonly in organic brain disturbances (e.g. delirium, occipital lobe tumours, epilepsy, dementia) and in the context of psychoactive substance use.

Somatic Hallucinations

These are hallucinations of bodily sensation and include superficial, visceral and kinaesthetic hallucinations.

Superficial hallucinations describe sensations on or just below the skin. They may be:

• Thermal: false perceptions of heat or cold
• Hygric: false perception of fluid e.g. ‘I can feel water sloshing in my brain’
• Tactile: experience of the skin being touched, pricked or pinched

Visceral hallucinations describe false perceptions of the internal organs.

Patients may be distressed by deep sensations of their organs throbbing, stretching, distending or vibrating.

Kinaesthetic hallucinations are false perceptions of joint or muscle sense.
Patients may describe their limbs vibrating or being twisted. The fleeting but distressing sensation of free falling just as one is about to fall asleep is an example that most people have experienced.

Olfactory and Gustatory Hallucinations

These are false perceptions of smell and taste, respectively. They commonly occur together because the two senses are closely related.

Illusion Part 6 of 11

Illusions are misperceptions of real external stimuli, e.g. in a dark room, dressing gown hanging on a bedroom wall is perceived as a person.

Illusions often occur in healthy people and are usually associated with inattention or strong emotion.

Completion illusions rely on our brain’s tendency to ‘fill in’ presumed missing parts of an object to produce a meaningful percept and are the basis for many types of optical illusions.

Affect illusions occur at time of heightened emotion

Pareidolic illusions are meaningful percepts produced when experiencing a poorly defined stimulus

Quick Summary on Perception Part 7 of 11

If patients admit to problems with perception, it is important to ascertain:

• Whether the abnormal perceptions are hallucinations, illusions, or intrusive thoughts
• If it is a hallucination – from which sensory modality the hallucinations appear to arise (i.e. are they auditory, visual, olfactory, gustatory or somatic hallucinations)
• If it is an auditory hallucinations – elementary or complex?
  • If complex, are they experiences in the first person (audible thoughts, thought echo), second person (critical, persecutory, complimentary or command hallucinations) or third person (voices arguing or discussing the patient, or giving a running commentary).

It is also important to note whether patients seem to be responding to hallucinations during the interview, as evidenced by them laughing inappropriately as though they are sharing a private joke, or suddenly tilting their head as though listening, or quizzically looking at hallucinatory objects around the room.

As with describing thought disorder, when reporting disorders of perception should be described by classifying the type of false perception e.g. first person auditory hallucinations or depersonalisation, followed by a quote (if possible) of what they said that made you arrive to this deduction.

Also note that the MSE should only report symptoms and signs that are present at the time of the examination, thus if the patient says that they’ve been hearing voices an hour ago but are not hearing them at the time of the examination, then that would be reported in the history, and the MSE report would be negative for any abnormal perception.

Finally, make sure you give your own objective assessment of any perceptual disturbance – e.g. do they appear distracted? do they appear to be responding to unseen stimuli? – as sometimes a patient cannot (or will not) disclose any abnormal experiences.

Mood Part 8 of 11

When we document mood in the MSE we split it up into two different parts: mood and affect.

Mood is the patient’s sustained, subjectively experienced emotional state over a period of time.

Affect is the emotional state prevailing at the time of the examination

To use a meteorological analogy: affect is the weather, whereas mood is the climate.

Mood is assessed by asking patients how they are feeling, thus a patient’s mood might be: depressed, elated, anxious, guilty, frightened, angry etc. or euthymic (i.e. is a normal non-depressed, reasonably positive mood).

Mood is reported in two ways…

Subjectively – i.e. what the patient says they are feeling – best to note this down in their own words

You also want to explore the degree to which they experience this, any variability, and any overt emotionality (e.g. tearfulness)

Objectively – i.e. what your impression of their mood is during the interview, e.g. her mood was subjectively ‘rock bottom’ and objectively low.

Also note how congruent the objective mood seems to be with the other aspects of the mental state and their circumstances, including any discrepancy between what the patient describes and how they appear.

As part of the objective judgement of mood, the clinician should also note the presence or absence of ‘biological’ symptoms – i.e. changes to sleep, appetite (and, if present, degree of weight loss), concentration and libido, and note whether there is any diurnal variation of mood.

Affect Part 9 of 11

Affect is a component of feeling that is short-term, reactive to internal or external circumstances and rapidly changeable.

Variations in affect, from happiness to sadness, irritability to enthusiasm, anxiety, rage and jealousy, are all within everyone’s normal experience.

Affect is assessed by observing patients’ posture, facial expression, emotional reactivity and speech (e.g. smiling at a joke, or crying at a sad memory).

There are a few components to consider when assessing affect…

The appropriateness or congruity of the observed affect to the patient’s subjectively reported mood (e.g. a woman with schizophrenia who reports feeling suicidal with a happy facial expression would be described as having an incongruous affect).

The range of affect or range of emotional expressivity. In this sense the affect may be:

• Within normal range (euthymic) or higher (elated)
• Reactive or flat

The stability of their affect throughout the interview

NB: If a patient’s mood is low always screen for suicidal thoughts, thoughts of self-harm, or thoughts of
harming to others. If any of these do come up, remember that it is important to do a risk assessment in
order to ensure the safety of your patient and the people around them.

Questions Part 10 of 11

Now watch this video and make a note of the patient’s perception and mood, then click the button at the end to compare your answer

Summary Part 11 of 11

Feedback

What is the perception in the absence of external stimulus?

What effect of drugs does a false sensory perception without an external stimuli refer to?

What is a false sensory perception?

What are the types of hallucinations?