Source : FISH ’S Clinical psychopathology

Body image distortions

Hyperschemazia, or the perceived magnification of body parts, can occur with a variety of organic and psychiatric conditions. When part of the body is painful it may feel larger than normal. When there is partial paralysis of a limb, the affected segment feels heavy and large, as in Brown–Sequard paralysis when the side with the extrapyramidal signs is hyperschematic, in peripheral vascular disease, in multiple sclerosis and following thrombosis of the posterior inferior cerebellar artery. In the latter two the hyperschemazia is unilateral. It may also occur in non-organic conditions such as hypochondriasis, depersonalisation and conversions disorder, and the distortion of image that is associated with feelings of fatness in anorexia nervosa is probably the best known.

The perception of body parts as absent or diminished is known as aschemazia or hyposchemazia respectively and is most likely to occur in parietal lobe lesions such as in thrombosis of the right middle cerebral artery, following transaction of the spinal cord or in health volunteers when

underwater. Hyposchemazia must be distinguished from nihilistic delusions.

Sims’ (2003) comprehensive description of body image distortions cites Critchley (1950) as describing a patient with a parietal lobe infarct who had complex hyper- and hyposchemazia, ‘It felt as if I was missing one side of my body (the left), but it also felt as if the dummy side was lined with a piece of iron so heavy that I could not move it … I even fancied my head to be narrow, but the left side from the centre felt heavy, as if filled with bricks’.

Koro or the belief that the penis is shrinking and will retract into the abdomen and cause death is found in South-East Asia and is thought to be due to a faulty understanding of anatomy. The diagnostic equivalent is probably anxiety disorder. Paraschemazia or distortion of body image is described as a feeling that parts of the body are distorted or twisted or separated from the rest of the body and can occur in association with hallucinogenic use, with an epileptic aura and with migraine on rare occasions.

Hemisomatognosia is a unilateral lack of body image in which the person behaves as if one side of the body is missing and it occurs in migraine or during an epileptic aura. Anosognosia is ‘denial of illness’ and one study (Cutting, 1978) found that 58% of those with right hemisphere strokes

denied their hemiplegia early after stroke and refused to admit to any weakness in their left arm. This belief typically remains despite manifest demonstration that it is paralysed. Some patients show bizarre attitudes to their paralysed limb, known as somatoparaphrenia (delusional beliefs about

the body). They may have too many, they may be distorted, inanimate, severed or in other ways abnormal (Halligan et al, 1995). They may claim the limb belongs to a specified other person (Bisiach et al, 1991). Hemispatial neglect is the neglect of the hemispace on the contralateral side to the lesion when performing tasks, and a specific example, Gerstmann syndrome (lesion of dominant parietal lobe) consists of agraphia, acalculia, finger agnosia and right/left disorientation.