Reporting terminology for lumbar disk herniations: axial segmentation of the preneural foraminal portion of the lumbar nerve roots.

Through the past decades, many attempts have been made to standardize lumbar disk herniation–related terminology (1, 2). Two different, and not necessarily parallel, sets of characteristics of a herniated disk (HD) are taken into account in the reporting of cross-sectional images of the lumbar spine. First, is the absolute attributes of the HD (ie, morphology, location, volume, etc), and second is the relationship of the HD to its neighboring neural structures. The absolute attributes of a HD are only one set of factors that determine the pattern and degree of compromise of the neighboring neural structures. The morphology and cross-sectional areas of the involved lumbar vertebral and neural foraminae, along with the degree of the epidural fat, are the other determining factors. Although standardized nomenclature has been proposed for the absolute attributes of a HD, descriptive terminology is used for the elaboration of the relationship of a HD to its neighboring neural structures. Terms such as “abuts,” “impinges,” “flattens,” “indents,” “compresses,” “displaces,” and “distorts” are useful in the description of the effects of a HD on the adjacent thecal sac (TS) and intracanalicular dural nerve root sleeves (DNRSs). The effects of a HD on specific intracanalicular nerve roots may at times also be ascertained by using highresolution axial T2-weighted sequences of the lumbar spine. In particular, compromise (or maximal degree of compromise) of a lumbar nerve root (LNR) at a level just proximal to its respective neural foraminal exit could be pinpointed to a specific segment of the nerve. In this context, a 3-tiered descriptive division of the preneural foraminal portion of a LNR, into the lateral thecal sac, junctional, and dural root sleeve segments (Figs 1 and 2) may be of value. This partitioning is particularly suitable at