WHAT IS ASOMATOGNOSIA?
Asomatognosia is generally known as a disorder of body awareness caused by neurological damage (Dieguez, Staub, and Bogousslavsky, 2007 & Pinel, 2006). The deficit in body awareness can take the form of forgetting, ignoring, denying, disowning, or misperceiving the body (entirely or partially) (Arzy, Overney, Landis, and Blanke, 2006 & Dieguez et al., 2007). The duration of symptoms for asomatognosia can vary in a span of minutes, hours, or months. There are two major ways of viewing asomatognosia – as one specific disorder, or as a general definition under which many different disorders can be categorized into. To add to the confusion, many of the disorders have multiple names that are used within the literature.
When asomatognosia is viewed generally, Dieguez et al. (2007) explains that it can further be categorized as being productive, where something appears (i.e. hand is seen as rotting) or defective, where something disappears or is missing (i.e. hand is no longer viewed as being attached to the body). Patients with asomatognosia can shift between having productive or defective symptoms very rapidly. From these two categories, the disorders falling under asomatognosia can be additionally specified according to the patient’s attitude towards their own body.
There are three different types of attitudes including indifferent, delusional, or critical (Dieguez et al., 2007). An indifferent attitude is defined as when the client seems to act as if nothing has changed or has gone wrong while a delusional attitude is when the client rationalizes in order to explain the change. Finally, a critical attitude is when the client has awareness of the change or has strange feelings concerning their body and tries to explain them, usually by making comparisons (i.e. it feels like my hand is just a dead weight). Dieguez et al. (2007) describe several disorders that they would categorize under asomatognosia (see Figure 1). This paper will only focus on a few of these in greater detail including hemiasomatognosia, somatophrenia, and misoplegia.
Hemiasomatognosia occurs when lesions are located in the right gyrus supramarginalis and in surrounding underlying structures (Dieguez et al., 2007). Patients with hemiasomatognosia act as if half of their body no longer exists. In some cases, patients will even deny that half of their body ever existed. If these patients are given proof of the existence of the other half of their body, they tend to have either of the following reactions: acceptance or delusional explanation. If they respond to evidence of their body with delusions, they are usually diagnosed with somatophrenia.
Somatophrenia is very similar to hemiasomatognosia in the fact that patients will deny that parts of their body belong to them. They tend to claim that the body part, generally the contralesional hand or arm, is missing or has been stolen (Dieguez et al., 2007). When asked whose arm is by them, they may respond that the arm belongs to someone else (i.e. a relative – alive or dead and/or medical staff), that it is an animal (i.e. snake), or its part of a rotting corpse. There have also been cases where patients describe that their arm is no longer theirs because it has been possessed by a relative, an unknown ghost, or even the devil. Generally, even after patients with somatophrenia are shown that their affected limbs are attached to the rest of their body they do not accept the evidence. If they do have a lucid moment, its temporary and they will go back to the delusions (Dieguez et al., 2007).
Misoplegia is more severe than somatophrenia (Pearce, J. 2007). It is defined as a hatred for the affected limb which is usually presented by the following behaviors: shouting, swearing, or hitting the arm and leg. It can develop from prior somatophrenia, denial, or personification of that particular limb. Pearce (2007) reports that it is very rare and only 6 cases of its occurrence have been published. Misoplegia has been found to occur when there has been damage to three areas of the brain: the right parietal lobe, right optic thalamus, and/or the right thalamoparietal radiation (Dieguez et al., 2007 and Pearce, 2007).
For all these cases, it is still unknown why some patients will show complete denial, will personify, or will show hatred for their affected limb(s). The mechanisms underlying these disorders need to be studied further before any conclusions are made.
Figure 2: Categorizing asomatognosia according to Dieguez et al (2007)’s model of Asomatognosia.
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