Download Causes, diagnosis and treatment of visceral hallucinations

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Visceral hallucinations
Causes, diagnosis and treatment of
visceral hallucinations
Natarajan Kathirvel MBBS MD, MRCPsych, Ann Mortimer BSc, MMedSc, MD, FRCPsych
Visceral hallucinations are unpleasant sensations that appear to arise from internal
organs, and can occur in both psychiatric and neurological disorders. Here, Dr Kathirvel
and Professor Mortimer discuss the differential diagnosis, pathophysiology and
treatment of visceral hallucinations.
H
allucinations of bodily sensations are classified
into external bodily hallucinations, tactile hallucinations, kinaesthetic hallucinations and internal,
visceral hallucinations (see Table 1). 1 The term
somaesthetic hallucination is used to refer to a hallucinatory experience in one or several of the sensory
modalities mentioned above.2
Hallucinations of bodily sensations are relatively
infrequent and sometimes pose phenomenological
challenges in clinical practice. In this article, we
review the phenomenology, diagnostic implications,
putative pathophysiology and treatment of visceral
hallucinations.
Phenomenology
Visceral sensations arise from internal organs, are
poorly localised and more likely to be unpleasant.3,4
They are represented in the secondary sensory cor-
medial nociceptive system
prefrontal cortex
cingulated cortex
lateral nociceptive system
somatosensory cortices
basal ganglia
amygdala
hippocampus
insula
brainstem
periaqueductal grey
matter
A-delta afferents
thalamus
contralateral
spinothalamic tract
spinal cord
C-fibre afferents
Figure 1. Anatomical components of the ‘pain matrix’: visceral pain is thought to elicit more response from within the medial nociceptive
system. Reproduced with permission from Jones AKP, Kulkarni B, Derbyshire SWG, et al. Pain mechanisms and their disorders: Imaging in clinical
neuroscience. Br Med Bull 2003;65:83-93
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Visceral hallucinations
tex and limbic regions.4 Visceral hallucinations may
present as pain, heaviness, stretching or distension,
palpitation, etc.5 Schizophrenic visceral sensations are
varied, but lack the superficial nature of external bodily (tactile) hallucinations, for instance:
‘There is a tearing feeling in his head and in his back,
a burning in his stomach, pain in his teeth, a rolling in his
brain, a tugging at his heart…’5
Although this article focuses primarily on visceral
hallucinations we will also briefly mention external
bodily hallucinations. External bodily sensations are
superficial sensations, such as touch, temperature and
proprioception. These sensations are well localised
and represented in the primary somatosensory cortex.3 External bodily hallucinations are usually varied, for instance:
‘The patient feels himself laid hold of, touched over his
whole body, he feels tickling in his thigh and right up to his
neck, pricking in his back and in his calves, a curious feeling in his neck, heat in face; hot sand is strewn over his face;
filth is put in his hair…’5
Formication is a type of tactile hallucination in
which the individual experiences the sensation of
insects crawling over or under the skin. In Ekbom’s
syndrome – delusions of infestation – the individual
may report a tactile hallucinatory experience.1
Differences in cortical localisation possibly reflect
the different pattern of tactile and visceral input to
the cerebral cortex. There are also differences in the
cortical processing of tactile and visceral sensations,
which account for the perceptual differences
observed between the two sensory modalities.3
The other phenomenological difference between
tactile and visceral hallucinations is that visceral hallucinations are not verifiable. When the patient
describes visceral hallucinations there is no external
referent, ie ‘there is nothing for the physician to see’.6
On the other hand, tactile hallucinatory modalities
may be verified or otherwise, ie one can see whether
there is a touch or not.7
Differential diagnosis
Visceral hallucinations occur in both psychiatric and
organic disorders, particularly neurological disorders.
Psychiatric disorders
Visceral hallucinations can occur in schizophrenia
although it is less common than other types of hallucinations in this condition. As mentioned earlier,
schizophrenic visceral sensations are limitless and are
usually described by the patient in a bizarre way.
Visceral sensations can also manifest as delusional
infestation. In this condition, the patient believes that
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Type
Description
Example
an abnormal perception
of heat and cold
‘my feet are on fire’
haptic
sensation of touch
‘a dead hand touched me’,
formication
hygric
a perception of fluid
‘I can feel water running on
my chest’
Kinaesthetic
hallucinations felt in
muscles and joints
subjects report that they
‘feel their muscles are
being squeezed’
Visceral
hallucinations of inner
organs
pain, stretching, heaviness,
etc
Superficial
thermic
Table 1. Types of hallucinations of bodily sensation
there is an animal inside their body; for example, a
wasp wandering around inside them.6
Transient epigastric hallucinations, which typically manifest as rising upper abdominal sensations,
can occur in bipolar disorder and unipolar major
depressive disorder.8
Neurological disorders
Visceral sensations, commonly epigastric sensations
known as ‘epigastric aura’, occur in the aura of temporal lobe epilepsy (complex partial seizures). These
are vague rising sensations from the epigastrium
towards the throat, and may be described as churning or pain in the stomach.9 Epigastric hallucinations
also occur during ictal and interictal periods although
they are much more common during a seizures
episode.8
Visceral sensor y hallucinations have been
described in limbic epilepsy involving insular lesions.
In one patient, the seizures started with a feeling of
‘butterflies in his throat’ followed by motor automatisms.10 Visceral sensations involving the throat, epigastrium and abdomen also occur in insular ictal
phenomena.10 Parkinson’s disease may present with
visceral hallucinations secondary to antiparkinsonian
medications. One patient developed cenesthetic hallucinations (that refer to somatic hallucinations of
visceral origin) during pergolide and levodopa treatment. She felt as if her bowels and bladder extruded
from the distal parts of her upper limbs. She
scratched her arms in order to avoid these extrusions.11
Visceral hallucinations may also occur in multiple
sclerosis and thalamic pain syndrome.12
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Pathophysiology
Functional neuroimaging techniques have been
employed to understand the pathophysiology of hallucinations. These techniques include positron emission tomography (PET), single photon emission
computed tomography (SPECT) and functional magnetic resonance imaging (fMRI). These techniques
are often used to detect changes in regional cerebral
blood flow (rCBF) in certain forms of PET and
SPECT, and changes in blood oxygen level-dependent (BOLD) response in fMRI. However, PET and
SPECT techniques may also be used to measure
regional brain metabolism and neurotransmitter
receptor binding.
Hallucinations are associated with sensory modality-specific activation in cerebral areas involved in
normal sensory processing.13 This finding has been
well studied in auditory and visual hallucinations.
During auditory and visual hallucinations, there is
increased brain activity in the regions specific to the
sensory modality of the hallucination as well as dysfunction in the connections between different brain
regions. 14 Also, functional neuroimaging studies
have revealed that in auditory and visual hallucinations primarily, there is hyperactivation in the secondar y sensor y cortex. Dysfunction in prefrontal
premotor, cingulate, subcortical and cerebellar
regions has also been observed in the hallucinatory
experiences.15
However, there are only limited studies investigating the neural correlates of visceral and tactile hallucinations. An fMRI study of a young man with
schizophrenia experiencing tactile hallucinations during which he was ‘touched by spirits’ showed an association with activation of corresponding primar y
somatosensor y and posterior parietal cortices. 16
Another study of a similar case using EEG, showed
findings consistent with the fMRI study.17 The activation of somatosensory cortices corresponded with
that of the patients’ phenomenological experience
of being touched by spirits.
An MRI scan of an elderly man with delusional
parasitosis, who felt worms moving around in his
mouth, revealed an old infarction of the right putamen and his symptoms responded to treatment with
pimozide. 18 A SPECT scan, before and after
responding to clomipramine, of an elderly woman
who believed ‘something was moving in her
abdomen’, revealed hypoperfusion of the left
temporoparietal cortices at the height of her
symptoms.19
It has been suggested that somatic and visceral
pain is distinct qualitatively and has different neural
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Visceral hallucinations
correlates in that somatic pain elicits more response
from within the lateral system of the pain matrix,
which incorporates lateral thalamic nuclei, insula and
secondary somatosensory cortices (concerned with
pain localisation), and visceral pain from the medial
system, which incorporates the midline and intralaminar thalamic nuclei (MITN), amygdala and anterior cingular cortex (more concerned with its
affective significance) (see Figure 1).20
In general, visceral pain evokes greater unpleasantness than somatic pain. Visceral pain elicits immobilisation, while somatic pain is more likely to
precipitate a ‘flight-flight’ response. Therefore, there
is a greater involvement of motor regions in its cerebral representation. Visceral pain is likely to be harder
to localise.20
The recent developments in the neurobiology of
pain – visceral and somatic – may help us to understand the underlying possible neurobiological mechanisms of visceral hallucinations.
Treatment
Treatment of visceral hallucinations would depend
on the underlying syndrome or disorder. Much of
what is thought to be functional in this regard may
well, given sophisticated neuroimaging investigations, prove actually to have organic correlates.
Thorough clinical evaluation of someone presenting with visceral hallucination is important to be able
to differentiate the likely aetiology and provide
appropriate treatment. For example, visceral hallucinations occurring in schizophrenia may respond
to antipsychotic drugs, but in epilepsy these hallucinations require, primarily, treatment with anti convulsants.
Conclusion
The phenomenology of visceral hallucinations does
not readily fit in with the conventional definition of
hallucinations, in that they are not verifiable, unlike
hallucinations of other sensory (auditory, visual and
tactile) modalities, whose reality can be refuted by an
observer.
Visceral hallucinations have a varied aetiology
encompassing both functional and organic disorders,
although specialist neuroimaging may demonstrate
associated anomalies in cerebral neurophysiology.
When assessing someone presenting with visceral hallucinations, the possibility of organic aetiology
should be borne in mind in order to inform effective treatment. Further neuroimaging studies are
required to understand the neural correlates of visceral hallucinations.
10
Declaration of interests
None declared.
Dr Kathirvel is a Consultant Psychiatrist in the
Department of General Psychiatry, Institute of Mental
Health/Woodbridge Hospital, Buangkok Green Medical
Park, Singapore and Professor Mortimer is Foundation
Chair at the University of Hull and Honorary
Consultant Psychiatrist at NAViGO Health and Social
Care CIC (North East Lincolnshire Mental Health
Services)
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