Abstract
Clinically significant evaluation of the diameters of nerve roots by ultrasonography requires the establishment of a normal reference range. Although there are multiple reports of nerve root diameters in normal subjects, none of them describe how to normalize and compare data derived from different facilities that may differ in their methodology, equipment, techniques, and recording sites during data acquisition. The aim of the present investigation was to establish a dataset of normal values using 100 healthy subjects, and to identify the factors that affect the normal ranges of cervical nerve root diameters with regard to age, sex, laterality, and root segments. Compared to previous reports, smaller standard deviations (0.07-0.21) were obtained, and the coefficient of variation ranged from 0.02 to 0.08, which facilitated the precise evaluation of cervical nerve roots. Age had a significant effect on the sixth cervical nerve root (C6) in male participants, and sex had a significant effect at C6 in participants in their 60s. To establish the normal values suitable for use across different facilities, acquired using different equipment, further development of various aspects, including the sophisticated recording techniques and data-sharing capabilities, is essential.