Impaired Touch Discrimination After Stroke: A Quantiative Test

Abstract

The ability to discriminate differences in tactile stimuli, such as textures, is commonly and characteristically impaired after stroke. Assessment of tactile discrimination is cur rently compromised by measures that are not quantitative and standardized, do not as sess active touch sensibility, or are not suitable for use in clinical settings with stroke patients. Therefore, a test that addressed these limitations was developed. The Tac tile Discrimination Test required subjects to discriminate differences in finely graded plastic ridged surfaces using a three-alternative forced choice design. Test-retest reli ability, based on a sample of 35 stroke patients, was high (r = 0.92), and changes of the magnitude of 27 percent spatial increase (PSI) can be detected with 95 percent confidence, which is sufficiently accurate for clinical monitoring. A matched pairs study of 50 stroke and 50 unimpaired subjects found that normal performance scores were contained within the 3-46 PSI range. The conservative criterion of abnormal ity was defined as 46 PSI, with a zone of uncertainty from 31 to 61 PSI. The test dif ferentiated well impaired performance relative to normal standards. These results sup port the application of the Tactile Discrimination Test as a quantitative, standardized measure appropriate for testing stroke patients in clinical settings. Key Words: Cere brovascular disorders—Standardized assessment—Somsatosensory—Tactile—Hand.