Testing sensibility, including touch-pressure, two-point discrimination, point localization, and vibration

Sensibility is much more than protective sensation, and the examiner needs to consider the various degrees of residual sensibility that influence both diagnosis and prognosis. Towards that end, objective tests of the extent and nature of peripheral nerve involvement should be employed. Objective tests reflect the current condition of sensibility and are not affected by cognitive influences, such as re-education. Most current clinical instruments used for measurement of sensibility fail to meet the criteria of an objective test because they: (1) can be shown to lack necessary sensitivity, and (2) are too variable. As a consequence, regardless of whether these instruments have been used in controlled clinical studies or are in common use, their results will not replicate with repeated testing. Unfortunately, therefore, sensibility changes will potentially go unrecognized in a large number of patients and many will be detected only in the later stages of peripheral nerve abnormality, when possibilities of treatment are less effective. This article discusses sensibility testing from the standpoint of what is known regarding strengths and weaknesses of various tests and sensory modalities, and makes an appeal for clinicians to review the instruments they use critically for sensibility measurement with regard to stimulus control. Clinicians must insist on validity and reliability in their instruments before they have confidence in the data obtained.