Evaluation of Psychophysical Responses After Mechanical Stimulation.

This study evaluates the test-retest reliability of psychophysical responses to non-injurious sharp stimuli applied via a robotic system. The accurate assessment of acute mechanical pain, such as the pain associated with surgical incisions or non-suicidal self-injury, is challenging due to the subjectivity of pain and the risk of tissue damage with traditional mechanical stimulation methods. To overcome this barrier, researchers have developed a non-injurious sharp blade model that mimics the sensory characteristics of incisional pain without causing tissue damage. However, manual application of this blade introduces operator-dependent variability in force, speed, and duration. This study utilizes a novel robotic stimulator equipped with a non-injurious blade to deliver controlled stimuli. The experimental design involves healthy adult volunteers with two identical testing sessions separated by a minimum interval of 48 hours. During these sessions, participants undergo quantitative sensory testing (QST), including the evaluation of pain and tolerance thresholds using the robotic system on the ventral forearm. Additional measurements include pain threshold to pinprick stimulation, muscle stiffness, pain catastrophizing (Sullivan et al., 1995), and conditioned pain modulation. These results will establish the precision and reliability of this robotic system that are required for further clinical and experimental pain research.

Inclusion Criteria: * Age between 18 and 60 years. * No history of chronic pain, neuromuscular disorders, or any disease that affects the nociceptive system and prevents its evaluation under normal conditions. * Willingness and ability to fully understand the content and scope of the experiment and to comply with its instructions. * Having signed the informed consent. Exclusion Criteria: * Pregnancy. * History of chronic pain, neuromuscular disorders, or any disease that affects the nociceptive system and prevents its evaluation under normal conditions. * History of addictive behavior, defined as abuse of alcohol, cannabis, opioids, or other drugs. * History of mental illnesses. * Presence of fever, tuberculosis, malignant tumors, infectious processes, or acute inflammatory processes. * Use of analgesics within 24 hours prior to participation in the experiment. * Skin lesions, scars, or dermatological conditions in the area of stimulus application. * Lack of cooperation.