Vibrotactile sense in patients with different upper limb disorders compared with a control group.

Background: Upper limb disorders (ULDs) are common, and so are the difficulties with regard to their specific diagnoses. According to diagnostic consensus criteria, specific diagnoses include neuropathy and muscular- and connective-tissue disorders (MCDs). There is a need for valid objective diagnostic tools to reveal underlying mechanisms for specific diagnoses.
Objective: To investigate the possible differences in vibration perception threshold (VPT) and tolerance to suprathreshold stimulation (STS) between controls and specific diagnostic ULD patient groups with uni- and bilateral neuropathy and/or MCD.
Methods: In 161 ULD patients and 40 controls, the VPT of the median, ulnar, and radial nerves innervating the hand was examined by vibrometry using the "method of limits". The tolerance to STS of the anterior forearm was tested in 128 of the patients and all controls.
Results: The ULD patients in all diagnostic groups had significantly higher VPT (P<0.05) in all the nerves in limbs, with and without diagnoses compared with controls. Only patient groups defined with neuropathy demonstrated significantly higher VPT in the limb with diagnoses compared with the contralateral limb without diagnoses. The highest VPTs were found in the patient group with unilateral neuropathy and MCD, and for the radial nerve, VPT was significantly higher than that for patients with unilateral MCD alone. These findings were confirmed by almost similar findings in STS responses.
Conclusions: The ULD patients generally demonstrated increased VPT compared with controls, indicating a neurogenous component independent of specific ULD diagnosis. Contralateral significant findings in limbs without diagnoses compared with controls indicate central neurogenous affection and/or the possibility of certain exposures elevating VPT before a positive status of a limb diagnosis is attained. Significantly higher VPT values in limbs with neuropathy diagnoses compared with limbs without and not in MCD alone, may indicate peripheral sensibilization or nerve affection only in the group with a specific diagnosis of neuropathy. These findings underline the importance of specific diagnoses among ULD patients.