engleski

Activation patterns in response to opposite sequences of radial neurodynamic test performed to maximum tolerable pain

Aim: To investigate non-invasively the pattern of muscular activation in response to elongation stress of the radial nerve. Methods: Electromyographic signals and joint angles were recorded continuously from 10 asymptomatic volunteers, bilaterally. The test movements were those of the radial neurodynamic test (RNT) performed until the onset of subjectively maximal tolerable painful symptoms in two reverse sequences. Onsets of muscle activation were visually detected from the measured EMG signals and placed into the EMG activation maps. Volunteers were instructed to signalize verbally (i) the first onset of painful symptoms and (ii) the onset of subjectively maximal tolerable pain during the execution of the RNT manoeuvres. Results: Activation mapping showed that the upper trapezius was consistently the first muscle to be activated in the proximal (shoulder first) RNT sequence, while brachioradialis and extensor carpi radialis were consistently activated before others in a distal (wrist first) RNT sequence. The onset of muscle activation always appeared near the first onset of pain, with muscle activation starting before the first onset of painful symptoms in the great majority of cases (89%). Conclusion: The muscle activation patterns differed significantly between the test manoeuvres, leading to the conclusion that muscles near the joint first moved tend to become active before others probably following peripheral neural convergence. The onset of muscle activation was reported to commonly appear shortly before the onset of pain, which questions the notion of an NFR-based mechanism.

muscle, nerve, neurodynamics, nociceptive flexor reflex, tonus

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