Asomatognosia

Contents

  1. Definition and Clinical Features
  2. Neuroanatomy and Pathophysiology
  3. Associated Syndromes and Differentials
  4. References

Definition and Clinical Features

Asomatognosia is a severe neurological disorder of body schema characterized by a loss of recognition or awareness of a part of one's own body. Most typically, this manifests as a profound failure to acknowledge the existence of a hemiplegic left arm or leg following a stroke. The condition can be broadly divided into two clinical presentations:

  • Verbal Asomatognosia: The patient explicitly denies ownership of the affected limb, often stating that the arm or leg does not belong to them.
  • Nonverbal Asomatognosia: The patient fails to use, care for, or protect the affected limb. This includes failing to dress it, wash it, or safely position it to prevent injury, even if they do not explicitly deny ownership verbally.
Patient demonstrating asomatognosia of the left arm

In asomatognosia, a patient may completely ignore their paralyzed limb, failing to dress or groom it, or explicitly deny that the limb belongs to them.

Neuroanatomy and Pathophysiology

The anatomical correlate of asomatognosia is typically damage to the non-dominant (usually right) cerebral hemisphere. Specific localizations frequently include lesions in the right supramarginal gyrus (part of the parietal lobe) and the underlying posterior corona radiata. These lesions are most commonly due to a cerebrovascular event, such as an ischemic stroke. Cases associated with right thalamic lesions have also been reported.

There is a strong clinical predilection for asomatognosia to affect the left side of the body (following right hemisphere lesions). However, it is theorized that this apparent asymmetry may simply be a reflection of the profound aphasic problems associated with left-sided lesions, which might mask the clinical expression or limit the assessment of asomatognosia for the right side of the body.

Associated Syndromes and Differentials

Asomatognosia is closely related to several other neurobehavioral syndromes affecting body schema and spatial awareness:

  • Hemispatial Neglect: Virtually all patients with asomatognosia exhibit concurrent hemispatial neglect (usually on the left). This profound inattention to one side of space seems to be a precondition for the development of asomatognosia. Indeed, some authorities use the term asomatognosia synonymously with "personal neglect."
  • Somatoparaphrenia: A specific, often bizarre delusion where the patient not only denies ownership of the neglected limb (asomatognosia) but actively attributes it to another person, such as the examiner or a relative sitting nearby in the room.
  • Anosognosia: While anosognosia is the unawareness or denial of the illness or deficit itself (e.g., denying that one is paralyzed), asomatognosia is the denial of the body part. The two are closely related and often co-occur, but they are dissociable on clinical and experimental grounds.
  • Confabulation: When patients provide elaborate, false explanations for why a limb is in their bed or why it does not belong to them, some authorities consider this verbal manifestation of asomatognosia to be a form of confabulation.

 

References

Feinberg TE, Haber LD, Leeds NE. Verbal asomatognosia. Neurology 1990; 40: 1391-1394

 

Cross References

Anosognosia; Confabulation; Neglect; Somatoparaphrenia