Figure 4.

Oscillatory response to digit stimulation in healthy control and carpal tunnel syndrome. (A) In both subject groups, digit stimulation evoked alpha (7–14 Hz) and beta (15–28 Hz) event-related desynchronization from ∼100–500 ms and ∼100–350 ms, respectively (blue areas). This was followed by beta event-related synchronization (red areas) at ∼400–750 ms. (B) On average, subjects with carpal tunnel syndrome demonstrated less alpha and beta event-related desynchronization than healthy controls. However, differences between groups were only significant in the beta band for median nerve-innervated digits between groups at ∼200–350 ms (asterisk, grey rectangle). (C) Comparison of median and ulnar digits within each group showed that within carpal tunnel syndrome, greater event-related desynchronization was present for ulnar versus median nerve-innervated digits. This was not the case for healthy controls, suggesting that the extent of event-related desynchronization may be indicative of altered endogenous cortical processing in carpal tunnel syndrome.