Graphesthesia
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. During medical or neurological examination graphesthesia is tested in order to test for certain neurological conditions such as; lesions in brainstem, spinal cord, sensory cortex or thalamus. An examiner writes single numbers or simple letters on the skin (usually the palm) with something that will provide a clear stimulus, such as a broken tongue depressor, pen cap etc. Prior to the start of testing, an agreement may be reached between the examiner and the patient as to the orientation of the letters, although this is often unnecessary, since orientation and size of the figures are rarely an issue. The crucial aspect of testing graphesthesia, as with any sensory testing, is to establish that the patient understands the test, hence the test is commenced, in the hemiplegic patient, on the normal, intact hand. This also allows the examiner to establish the patient's numeracy, since semi-numerate patients may have difficulties performing the task. The patient provides a verbal response identifying the figure