Pain and muscular responses to a neural tissue provocation test in the upper limb.

Pain and muscular responses to a Neural Tissue Provocation Test with bias to median nerve were examined in 20 asymptomatic subjects. The test was performed on both arms with the cervical spine in a neutral position and in contralateral sideflexion as a sensitizing manoeuvre. The angle of elbow extension at the time of onset of pain and muscle activity in trapezius, biceps and triceps muscles was measured using an electrogoniometer. Muscle activity was recorded by surface electromyography. Results indicate that pain responses and muscle activity of trapezius are present in the majority of normal subjects. The onset of pain was highly reliable and compared favourably with detection of muscle activity onset. There was no significant difference of the angle of the elbow with the onset of pain between arms. Hence in patients with unilateral neck or upper limb pain a difference between sides might be indicative of a possible neural tissue involvement. Pain and muscular responses were influenced by the position of the cervical spine. This finding suggests that cervical contralateral sideflexion has a sensitizing effect on neural tissues. There was an association between the onset of pain and onset of trapezius muscle activity in all painful trials. However, muscle activity was also present in subjects with no pain.