Perception › Body Image Disturbance

Gerstmann Syndrome

Named after the neurologist who first described the combination of the four features together as a recognisable cluster arising from a common site of brain injury.

Gerstmann syndrome is a cluster of four features occurring together: difficulty naming or identifying individual fingers (finger agnosia), difficulty telling left from right, difficulty writing (agraphia), and difficulty with simple calculation (acalculia). It is included in this family because finger agnosia and left-right disorientation are, at heart, disturbances of body awareness, even though the full cluster extends beyond body image alone.

The four features have traditionally been grouped together because they are classically described as arising from a single, localised area of injury, though how tightly the four genuinely travel together in practice has long been debated.

Recognition features

• Difficulty naming, identifying, or distinguishing individual fingers on request, including one's own (finger agnosia)
• Difficulty correctly identifying left and right, on the person's own body or when directed toward another person
• Difficulty writing, out of proportion to any other language difficulty (agraphia)
• Difficulty with simple calculation, such as basic subtraction (acalculia)

Eliciting it at interview

• Test each of the four components individually with simple bedside tasks: naming touched fingers with eyes closed, following left/right commands, writing a short sentence to dictation, and performing simple mental subtraction
• Record which of the four features are present, since not every case shows the complete cluster
• Consider a wider cognitive and neurological assessment given the range of functions affected, and involve neuropsychology where available

Distinguishing features

• Differs from a general language disorder in that the writing difficulty is classically described as disproportionate to any accompanying difficulty with spoken language
• Differs from other body-image disturbances in this family by involving a specific tetrad of features rather than a single distorted sensation
• Finger agnosia and left-right disorientation link the syndrome to the body-image family, while agraphia and acalculia extend beyond it into broader cognitive function

Common misconceptions

• That all four features must be present to consider the diagnosis clinically relevant; partial presentations are recognised and still worth documenting carefully
• That finger agnosia means the person cannot feel their fingers; the difficulty is in naming and identifying them, not in basic sensation

Related phenomena

Body Image Disturbance · Visual Asymbolia

Illustration

During a bedside assessment, a 58-year-old man cannot reliably say which finger has been touched when his eyes are closed, confuses left and right when asked to raise his right hand, produces only a scrawled, illegible line when asked to write his address, and struggles to subtract seven from a given number, despite otherwise conversing fluently and appropriately throughout the interview.

References

• Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 3, 'Disorders of Perception'.