Graphesthesia
Encyclopedia
Graphesthesia is the ability to recognize writing on the skin purely by the sensation of touch. Its name derives from Greek
graphē ("writing") and aisthēsis ("perception"). Graphesthesia tests combined cortical sensation; therefore, it is necessary that primary sensation be intact bilaterally.
During medical or neurological examination
graphesthesia is tested in order to test for certain neurological conditions such as; lesions in nerve roots, peripheral nerves, brainstem, spinal cord
, sensory cortex
or thalamus
. An examiner writes single numbers or simple letters on the skin (usually the palm) with something dull like the back of pen, pen light, tongue depressor, etc. Prior to the start of testing, an agreement must be reached between the examiner and the patient as to the orientation of the letters. During testing, the examiner should gently wipe the palm between each drawing to clearly indicate to the patient that a new letter or symbol is being drawn.
The patient provides a verbal response identifying the figure which was drawn. If the patient has a speech or language impairment which prevents him from verbalizing an answer, the answer can be selected from a series of images which are shown to him. Most people are able to determine the letters which are being written on the skin. In cases where the patient is unable to correctly identify the letters (agraphesthesia), he/she would be referred to a specialist for further evaluation.
Loss of graphesthesia indicates either parietal lobe damage on the side opposite the hand tested or damage to the dorsal columns pathway at any point between the tested point and the contralateral parietal lobe.
Testing graphesthesia can be substituted for stereognosis
if a patient is unable to grasp an object.
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
graphē ("writing") and aisthēsis ("perception"). Graphesthesia tests combined cortical sensation; therefore, it is necessary that primary sensation be intact bilaterally.
During medical or neurological examination
Neurological examination
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired...
graphesthesia is tested in order to test for certain neurological conditions such as; lesions in nerve roots, peripheral nerves, brainstem, spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, sensory cortex
Sensory cortex
The sensory cortex can refer informally to the primary somatosensory cortex, or it can be used as an umbrella term for the primary and secondary cortices of the different senses : the visual cortex on the occipital lobes, the auditory cortex on the temporal lobes, the primary olfactory cortex on...
or thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
. An examiner writes single numbers or simple letters on the skin (usually the palm) with something dull like the back of pen, pen light, tongue depressor, etc. Prior to the start of testing, an agreement must be reached between the examiner and the patient as to the orientation of the letters. During testing, the examiner should gently wipe the palm between each drawing to clearly indicate to the patient that a new letter or symbol is being drawn.
The patient provides a verbal response identifying the figure which was drawn. If the patient has a speech or language impairment which prevents him from verbalizing an answer, the answer can be selected from a series of images which are shown to him. Most people are able to determine the letters which are being written on the skin. In cases where the patient is unable to correctly identify the letters (agraphesthesia), he/she would be referred to a specialist for further evaluation.
Loss of graphesthesia indicates either parietal lobe damage on the side opposite the hand tested or damage to the dorsal columns pathway at any point between the tested point and the contralateral parietal lobe.
Testing graphesthesia can be substituted for stereognosis
Stereognosis
Stereognosis is the ability to perceive and recognize the form of an object using cues from texture, size, spatial properties, and temperature...
if a patient is unable to grasp an object.