Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis.

Abstract

Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA). Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group). Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n=2916 nerves) was reported most commonly, followed by the common fibular nerve (n=2580 nerves) and the radial nerve (n=2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n=1810; mean,5.14 mm2 ; 95% CI,4.33 to 5.96); common fibular nerve assessed at the fibular head (n=1460; mean,10.18 mm2 ; 95% CI,8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n=1120; mean,12.90 mm2 ; 95% CI,9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal. Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.