Quantitative in vivo longitudinal nerve excursion and strain in response to joint movement: a systematic literature review

Abstract

Background: Neural system mobilization is widely used in the treatment of several painful conditions. Data on nerve biomechanics is crucial to inform the design of mobilization exercises. Therefore, the aim of this review is to characterize normal nervous system biomechanics in terms of excursion and strain. Methods: Studies were sought from Pubmed, Physiotherapy Evidence Database, Cochrane Library, Web of Science and Scielo. Two reviewers' screened titles and abstracts, assessed full reports for potentially eligible studies, extracted information on studies' characteristics and assessed its methodological quality. Findings: Twelve studies were included in this review that assessed the median nerve (n = 8), the ulnar nerve (n = 1), the tibial nerve (n = 1), the sciatic nerve (n = 1) and both the tibial and the sciatic nerves (n = 1). All included studies assessed longitudinal nerve excursion and one assessed nerve strain. Absolute values varied between 0.1 mm and 12.5 mm for median nerve excursion, between 0.1 mm and 4.0 mm for ulnar nerve excursion, between 0.7 mm and 5.2 mm for tibial nerve excursion and between 0.1 mm and 3.5 mm for sciatic nerve excursion. Maximum reported median nerve strain was 2.0%. Interpretation: Range of motion for the moving joint, distance from the moving joint to the site of the lesion, position of adjacent joints, number of moving joints and whether joint movement stretches or shortens the nerve bed need to be considered when designing neural mobilization exercises as all of these factors seem to have an impact on nerve excursion.