Somatoparaphrenia

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Somatoparaphrenia is a type of monothematic delusion 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 about whose limb it really is, or how the limb ended up on their body.[1][2] In some cases, delusions become so elaborate that a limb may be treated and cared for as if it were a separate being.[1]

Somatoparaphrenia differs from a similar disorder, asomatognosia, which is characterized as loss of recognition of half of the body or a limb, possibly due to paralysis or unilateral neglect.[3] 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.[1]

Somatoparaphrenia has been reported to occur predominately in the left arm of one's body,[4] and it is often accompanied by left-sided paralysis and anosognosia (denial or lack of awareness) of the paralysis. The link between somatoparaphrenia and paralysis has been documented in many clinical cases [5] 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.[6]

Causes[edit]

It has been suggested that damage to the posterior cerebral regions (temporoparietal junction) of the cortex may play a significant role in the development of somatoparaphrenia.[7][8] However, more recent studies have shown that damage to deep cortical regions such as the posterior insula[9] and subcortical structures such as the basal ganglia,[10] the thalamus and the white matter connecting the thalamus to the cortex may also play a significant role in the development of somatoparaphrenia.[11] 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.[11]

Treatment[edit]

One form of treatment that has produced a more integrated body awareness is mirror therapy, 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.[12]

See also[edit]

References[edit]

  1. ^ a b c Feinberg, T., Venneri, A., Simone, A.M., et al. (2010). The neuroanatomy of asomatognosia and somatoparaphrenia. Journal of Neurology, Neurosurgery & Psychiatry, 81, 276-281
  2. ^ Bottini, G., Bisiach, E., Sterzi, R., Vallar, G. (2002): "Feeling touches in someone else's hand." Neuroreport 13 (2), 249–252.
  3. ^ Vallar, G. & Ronchi, R. (2009). Somatoparaphrenia: a body delusion. A review of the neuropsychological literature. Experimental Brain Research, 192:3, 533-551
  4. ^ Coltheart, M. (2005). Delusional belief. Australian Journal of Psychology, 57, 72
  5. ^ Vallar, G., & Ronchi, R. (2009). Somatoparaphrenia: A body delusion. A review of the neuropsychological literature. Experimental Brain Research, 192, 533
  6. ^ Invernizzi P, Gandola M, Romano D, Zapparoli L, Bottini G, Paulesu E. What is mine? Behavioral and anatomical dissociations between somatoparaphrenia and anosognosia for hemiplegia. Behav Neurol. 2013;26(1-2):139-50.
  7. ^ Feinberg T. E.; Haber L. D.; Leeds N.E. (1990). "Verbal asomatognosia". Neurology. 40 (9): 1391–1394. PMID 2392224. 
  8. ^ Feinberg T. E.; Roane D. M.; Ali J. (2000). "Illusory limb movements in anosognosia for hemiplegia.". J Neurol Neurosurg Psychiatry. 68 (4): 511–513. PMC 1736869Freely accessible. PMID 10727491. 
  9. ^ Cereda C.; Ghika J.; Maeder P.; Bogousslavsky J. (2002). "Strokes restricted to the insular cortex.". Neurology. 59 (12): 1950–1955. PMID 12499489. 
  10. ^ Healton E. B.; Navarro C.; Bressman S.; Brust J. C. (1982). "Subcortical neglect.". Neurology. 32 (7): 776–778. PMID 7201116. 
  11. ^ a b Gandola M, Invernizzi P, Sedda A, Ferrè ER, Sterzi R, Sberna M, Paulesu E, Bottini G. An anatomical account of somatoparaphrenia. Cortex. 2012Oct;48(9):1165-78. doi:10.1016/j.cortex.2011.06.012. Epub 2011 Jun 22. PubMed PMID 21774922
  12. ^ Fotopoulou, A., Jenkinson, P.M., Tsakiris, M., Haggard, P., Rudd, A. & Kopelman, M.D. (2011). Mirror-view reverses somatopharaphrenia: Dissociation between first- and third-person perspectives on body ownership. Neuropsychologia, 49, 3946-3955