Two point discrimination is the ability to distinguish that two objects touching the skin are two distinct points and not one. Two point discrimination is often tested with two sharp points during a neurological examination and is used to identify how finely innervated an area of skin is. In clinical settings, two point discrimination is a widely used technique for determining tactile agnosia. It should be completed with the patient’s eyes closed and it relies on the ability and/or willingness of the patient to subjectively report what she/he is feeling . The physician may use a simply a reshaped paperclip to do this test. The physician may alternate randomly between touching the patient with one point or with two points on the area being tested (e.g. finger, arm, leg, toe). The patient is then asked to report whether one or two points was felt. The smallest distance between two points that still results in the perception of two distinct stimuli is recorded as the patient’s two-point threshold. Performance on the two extremities can be compared for inconsistencies.
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