Evaluating sustained touch-pressure in severe sensory deficits: meeting an unanswered need.
Sensation is critical to the functional abilities of the hand. Although evaluation techniques are available to measure a patient's ability to appreciate moving touch (MT), no test is available to assess appreciation of sustained touch-pressure (STP). A new device, designed to apply constant stimuli of known intensity, was developed and used to evaluate STP appreciation in an experimental and a control group. The experimental group consisted of six patients with severe sensory deficits due to cortical dysfunction. Each subject was evaluated for STP appreciation on the tip of the index finger of the affected side of the body. The results showed that five of the patients had some STP appreciation; the sixth had none. Furthermore, in the patient group, STP appreciation faded with time; appreciation was much greater four and six seconds after the stimulus onset than it was after 18 to 20 seconds. In the control group the sensation did not fade away. The lowest weight tested (23 g) was seldom detected by three of the five patients although it was readily sensed by all healthy individuals. An unexpected finding was that the 350-g weight was more difficult to appreciate for three of the five subjects than were the 150-g and 250-g weights. This experiment demonstrated that STP, an important component of sensation, can be evaluated quickly and accurately in the clinical environment and that the magnitude of the deficit in STP is correlated with the severity of the disability in the patient seeking physiotherapy.