Definition

Noun: A neurological condition characterized by the inability to identify an object by touch alone, despite intact sensation in the hands and fingers. It is a disorder of tactile recognition.

Usage

The term is used in medical and neurological contexts to describe a specific sensory deficit. It is typically used as a singular, uncountable noun.

Examples

• The patient's astereognosis was confirmed when he could not distinguish a key from a coin while his eyes were closed.
• A common test for astereognosis involves asking the individual to identify common objects placed in their hand without visual cues.
• The lesion in the parietal lobe caused astereognosis, impairing her ability to recognize objects by feel.

Advanced Usage

• Clinical Assessment: The term is central to neurological examinations. A finding of asterognosis can help localize a brain lesion, often to the contralateral parietal lobe.
• Differentiation: It is important to distinguish asterognosis from mere numbness or loss of sensation (anesthesia). In asterognosis, the basic senses of touch, pressure, and vibration are intact, but the brain cannot synthesize this information into a recognizable percept.

Variants and Related Words

• Tactile Agnosia: This is a more general term under which astereognosis is often categorized. Agnosia refers to a failure of recognition, and "tactile agnosia" can sometimes be used synonymously with astereognosis.
• Stereognosis: The normal, intact ability to recognize objects by touch, which is lost in astereognosis.

Synonyms

• Tactile agnosia (in specific usage)
• Somatosensory agnosia

Antonyms

• Stereognosis

Noun

1. a loss of the ability to recognize objects by handling them