This is Not my Body: the Disrupted Bodily Self of Neurological Patients

In normal conditions, humans build the feeling that the "real me" or the "I" is the subject of perception, action and thought and, therefore, that conscious experiences are linked to a unitary entity, the "self". This is what is called self-consciousness. It is also known that the self "resides" in the body: the link between the self and the body (i.e., bodily self-consciousness, BSC) is guaranteed by the integration of multiple signals coming from outside (e.g., visual, tactile information) and inside (i.e., interoceptive signals such as the heartbeat) the body.

Neurological damage and/or dysfunctions can affect our self-consciousness at different levels, implying bodily features or not.

Somatoparaphrenia (SP) is a neuropsychological condition in which patients usually experience the feeling that one or more body parts do not belong to them anymore (i.e., disownership), with the frequent delusional attribution to another person. This term originates from the Greek: παρα + φρεν, φρενos means "against the mind", and σωμα, σωματos refers to the "body". SP patients have been described starting with the end of the 19th century, but only in 1942 Gerstmann introduced the term "somatoparaphrenic symptoms", which are defined as: "illusions or distortions concerning the perception of, and confabulations or delusions referring to the affected limbs or side" (p. 895), and "specific psychic elaboration with respect to the affected members or side of the body, believed or experienced as absent" (p. 912).

Very often, these bodily delusion affects the left hemi-body, after a right-brain lesion, even if cases of "crossed somatoparaphrenia" (i.e., left-brain lesion and SP affecting the right hemi-body) are on record. A distal-to-proximal gradient in the disownership manifestations has been detected, with the hand being more often affected, followed by the limbs (arm/leg) and only rarely the whole hemi-body. Specific reports about SP affecting the face are not on record.

While SP has sometimes a delusional component, disownership is the most frequent manifestation of patients: when pure disownership is detected in patients, the disorder has been also called asomatognosia. Different symptoms can include the feeling of estrangement for the affected body part, or more complex delusional misidentifications of the impaired hemi-body, but more rarely.