Sonographic reference values of cranial nerve size: A systematic review and meta‐analysis

Abstract

Introduction/Aims Ultrasonography of the cranial nerves has recently gained attention for assessment of inflammatory, compressive, or degenerative neuropathies. However, sonographic reference values of cranial nerves have received less attention than those of peripheral nerves. In this systematic review and meta‐analysis we aimed to provide current evidence of sonographic reference values for cranial nerve size. Methods By searching Medline (via PubMed), Scopus, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, we conducted a systematic review and meta‐analysis of studies that reported ultrasound measurements of the facial, spinal accessory, and hypoglossal nerves in healthy adults. We included studies that reported either the sonographic cross‐sectional area (CSA) or the nerve diameter; the included nerves were subgrouped according to the site of nerve measurement. Results Fourteen studies with a total of 661 participants and 1437 ultrasound nerve measurements met the inclusion criteria. The anatomical sites for each nerve were combined to provide single‐nerve mean measurements. We found an overall mean nerve diameter of 0.80 mm for the facial nerve, 0.63 mm for the spinal accessory nerve, and 1.82 mm2 for hypoglossal nerve CSA. Discussion This meta‐analysis provides reference values for the diameter and cross‐sectional area of the facial, spinal accessory, and hypoglossal nerves at different sites, which can be used as guidance in clinical practice to detect pathological changes in cranial nerve size in cranial neuropathies. We recommend further validation in large‐scale studies as well as standardization of the scanning protocols.

Sonographic reference values of nerve size in children: A systematic review and meta‐analysis

“…Random‐effects meta‐analysis models were used to estimate the pooled nerve CSA and diameter. Heterogeneity was evaluated using the I 2 statistic and chi‐square test. An I 2 statistic of over 50% indicated substantial heterogeneity and P < .05 was consistent significant heterogeneity.…”

“…Five published meta-analyses provide sonographic nerve crosssectional area (CSA) reference values in adults, [2][3][4][5][6] whereas fewer studies have focused on the pediatric population. 7,8 The first sonographic measurements in children were reported in 2008.…”