Somatoparaphrenia is a type of
monothematic delusion
A monothematic delusion is a delusional state that concerns only one particular topic. This is contrasted by what is sometimes called ''multi-thematic'' or ''polythematic'' delusions where the person has a range of delusions (typically the case of ...
where one denies ownership of a limb or an entire side of one's body. Even if provided with undeniable proof that the limb belongs to and is attached to their own body, the patient produces elaborate
confabulations
In psychology, confabulation is a memory error defined as the production of fabricated, distorted, or misinterpreted memories about oneself or the world. It is generally associated with certain types of brain damage (especially aneurysm in the a ...
about whose limb it really is or how the limb ended up on their body.
In some cases, delusions become so elaborate that a limb may be treated and cared for as if it were a separate being.
Somatoparaphrenia differs from a similar disorder,
asomatognosia Asomatognosia is a neurological disorder characterized as loss of recognition or awareness of part of the body.Vallar, G. & Ronchi, R. (2009). Somatoparaphrenia: a body delusion. A review of the neuropsychological literature. Experimental Brain Res ...
, which is characterized as loss of recognition of half of the body or a limb, possibly due to
paralysis
Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 ...
or
unilateral neglect
Hemispatial neglect is a neuropsychological condition in which, after damage to one hemisphere of the brain (e.g. after a stroke), a deficit in attention and awareness towards the side of space opposite brain damage (contralesional space) is obse ...
.
For example, asomatognosic patients may mistake their arm for the doctor's. However, they can be shown their limb and this error is temporarily corrected.
Somatoparaphrenia has been reported to occur predominantly in the left arm of one's body, and it is often accompanied by left-sided paralysis and
anosognosia
Anosognosia is a condition in which a person with a disability is cognitively unaware of having it due to an underlying physical or psychological (e.g., PTSD, Stockholm syndrome, schizophrenia, bipolar disorder, dementia) condition. Anosognosia c ...
(denial or lack of awareness) of the paralysis. The link between somatoparaphrenia and paralysis has been documented in many clinical cases, and while the question arises as to whether paralysis is necessary for somatoparaphrenia to occur, anosognosia is not, as documented by cases with somatoparaphrenia and paralysis with no anosognosia.
Causes
It has been suggested that damage to the posterior
cerebral regions (
temporoparietal junction
The temporoparietal junction (TPJ) is an area of the brain where the temporal and parietal lobes meet, at the posterior end of the lateral sulcus (Sylvian fissure). The TPJ incorporates information from the thalamus and the limbic system as well ...
) of the
cortex
Cortex or cortical may refer to:
Biology
* Cortex (anatomy), the outermost layer of an organ
** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain''
*** Motor cortex, the regions of the cerebral cortex i ...
may play a significant role in the development of somatoparaphrenia. However, more recent studies have shown that damage to deep cortical regions such as the posterior insula and subcortical structures such as the
basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an extern ...
, the thalamus and the white matter connecting the thalamus to the cortex may also play a significant role in the development of somatoparaphrenia.
It has also been suggested that involvement of deep cortical and subcortical grey structures of the temporal lobe may contribute to reduce the sense of familiarity experienced by somatoparaphrenic patients for their paralyzed limb.
Diagnosis
Treatment
One form of treatment that has produced a more integrated body awareness is
mirror therapy
Mirror therapy (MT) or mirror visual feedback (MVF) is a therapy for pain or disability that affects one side of the patient more than the other side. It was invented by Vilayanur S. Ramachandran to treat post-amputation patients who had phantom ...
, in which the individual who denies that the affected limb belongs to their body looks into a mirror at the limb. Patients looking into the mirror state that the limb does belong to them; however body ownership of the limb does not remain after the mirror is taken away.
See also
*
Allochiria
Allochiria is a neurological disorder in which the patient responds to stimuli presented to one side of their body as if the stimuli had been presented at the opposite side. It is associated with spatial transpositions, usually symmetrical, of s ...
*
Body integrity dysphoria
Body integrity dysphoria (BID, also referred to as body integrity identity disorder, amputee identity disorder and xenomelia, formerly called apotemnophilia) is a mental disorder characterized by a desire to have a sensory or physical disabili ...
*
Body schema
Body schema is a concept used in several disciplines, including psychology, neuroscience, philosophy, sports medicine, and robotics. The neurologist Sir Henry Head originally defined it as a postural model of the body that actively organizes and m ...
*
Cotard delusion
Cotard's syndrome, also known as Cotard's delusion or walking corpse syndrome, is a rare mental disorder in which the affected person holds the delusional belief that they are dead, do not exist, are putrefying, or have lost their blood or intern ...
*
Phantom limb
A phantom limb is the sensation that an amputated or missing limb is still attached. Approximately 80 to 100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience painf ...
References
{{Delusion
Delusional disorders
Psychosis
Delusions