Upper limb tension tests as tools in the diagnosis of nerve and plexus lesions: Anatomical and biomechanical aspects

Objective. To analyse the validity of nerve tension tests used in the diagnosis of nerve (root) and plexus lesions of the upper extremity. Design. In six arms of embalmed human bodies, in situ measurements were performed to assess the effect of nerve tension tests on the median, ulnar and radial nerves and the cords of the brachial plexus. Background. In clinical practice it is useful to have fast, easy and cheap tests for the diagnosis of nerve (root) lesions of the upper extremity, analogous to Lasègue’s Straight Leg Raising test. Methods. The Upper Limb Tension Tests for the median, ulnar and radial nerves, as well as the Upper Limb Tension Tests combined with contralateral rotation and lateral bend of the cervical spine (Upper Limb Tension Test+) were used to generate tension to these nerves. Buckle force transducers were used to assess tensile forces in the nerves and in the medial, lateral and posterior cords of the brachial plexus. Results. Nerve tension introduced in the distal part of the median, ulnar and radial nerves was transmitted upward to the cords of the brachial plexus. Exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ turned out to be sensitive and specific tension tests. Mechanical tension caused by the Upper Limb Tension Test+ was not significantly higher than that caused by the Upper Limb Tension Tests. The Upper Limb Tension Tests cannot be used to selectively stress cervical nerve roots. The findings justify investigation of exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ on their clinical validity. Relevance Before nerve tension tests for the median, ulnar and radial nerves can be introduced to clinical practice it is necessary to assess their validity quantitatively.