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Nomenclature and Classification of Lumbar Disc Pathology
Reporting
When interpretations are made utilizing clinical data, the nature of the clinical data and degree of confidence in them may be appropriate parts of the report. The report should distinguish interpretations that are made on purely morphologic grounds from those using clinical data. The sources of the morphologic data should be described.
Reports should classify each disc examined into broad diagnostic categories. Further specificity may be appropriate depending upon the data and the purpose of the examination.
The ability to distinguish between various forms of herniation and between broad-based protrusion and bulging depends upon the adequacy of available imaging data and the judgment of the interpreter. Likewise, knowing whether or not there is a thin thread of continuity between displaced disc material and disc of origin, or whether there is a small lapse in the integrity of the outer fibers of anulus, may not be possible, except by surgical observation.
Interpretations are made with various degrees of confidence. Statement of the degree of confidence is an important component of communication. The reporter should characterize the interpretation as "Definite" if there is no doubt, "Probable" if there is some doubt but the likelihood is greater than 50%, and "Possible" if there is reason to consider but the likelihood is less than 50%. The source and quality of the data are important qualifiers of the degree of confidence. It may be appropriate to characterize the interpretation with one degree of confidence based upon morphologic criteria and another if clinical data are considered. If the interpreter has information enough to do so, he may further suggest that the imaging findings are, or are not, related to the patient's symptoms, but the descriptive terms and diagnostic categories proposed in this model are not meant to infer any relationship to symptoms or need for treatment. Suggestions for additional studies to improve the level of confidence are often appropriate.
Coding
The International Classification of Diseases (ICD) has been published under various names since 1900. Beginning in 1948, the World Health Organization (WHO) revised ICD approximately every ten years. The Ninth Revision (ICD-9)45 was due for revision in 1987, but the first volume, the Tabular List, of the revision (ICD-10) was not prepared until 1992 and, as of 2000, has not been implemented in the United States. In practice, most coding in the United States follows a modification, the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM),42 which is officially updated in October of each year. Attempts to provide more specific coding for spinal disorders, such as that of the North American Spine Society, 13 have not been widely utilized because medical care providers and hospitals must use ICD-9-CM for reimbursement from government and private insurers.
A modification of WHO's Fascicle V, Surgical Procedures, called the ICD-9-CM Procedure Classification, published as Volume 3 to ICD-9-CM,42 is used in the United States primarily by hospitals for coding procedures and complications that occur during hospitalization. Its validity has been studied with regard to spine procedures.10,11 In the United States, for coding of examination, management, and procedures to care for spinal disorders, most physicians use the Current Procedural Terminology (CPT),1 updated yearly by the American Medical Association.
In ICD-9-CM, the three digit diagnosis code 722. is termed "Intervertebral disc disorders." A fourth digit, following the decimal is used variously to specify site or type of pathology.
The first four sub-categorizations (722.0, 722.10, 722.11, and 722.2) are for cervical, thoracic, lumbar, or site-unspecified "Displacement of intervertebral disc without myelopathy." Listed as "Instructional Notations," by way of examples of what may be included, are "Discogenic Syndrome, Herniation of Nucleus Pulposus, Intervertebral disc extrusion, prolapse, protrusion, rupture, and Neuritis or Radiculitis due to displacement or rupture of intervertebral disc." The fourth subcategorization, 722.3, is designated "Schmorl's nodes."
Sub-categorizations 722.4, 722.5, and 722.6 are for "Degeneration of intervertebral disc" in the cervical, thoracic or lumbar, and unspecified regions, respectively. Instructional Notations specify inclusion of "degenerative disc disease" and "narrowing of intervertebral disc or space."
Sub-categorization 722.7 is labeled "Intervertebral disc disorder with myelopathy." It does not specify displacement of the disc. Fifth digits are added for regional location. Sub-categorization 722.8 is labeled "Postlaminectomy syndrome."
"Other and unspecified disc disorder" is the diagnostic label of 722.9, with Instructional Notations to include "calcification of intervertebral cartilage or disc" and "Discitis." Observations of imaging variations of unknown significance can be coded 793.7, which ICD-9-CM describes as "Nonspecific abnormal findings on radiological and other examination of body structure, Musculoskeletal."
ICD-10 lists intervertebral disc disorders under the "Other Dorsopathies" Section. Digits after the decimal for codes "M50." and "M51." provide separate codes for cervical or lumbar/thoracic "disc disorder with myelopathy," "disc disorder with radiculopathy," "other disc displacement," "other disc degeneration," "other disc disorders," and "Schmorl's nodes."
Translation of the disc nomenclature recommended here into ICD-9-CM codes presents relatively little difficulty. Discs characterized herein as "herniated" should be coded under 722.0, 722.10, 722.11, or 722.2. A disc described as "bulging" without further specification as to the cause of the bulging should not be coded as a displacement, but, like other observations of uncertain significance as 722.9 "other and unspecified disc disorder" or as 793.7, "nonspecific abnormal findings on radiographic examination" (musculoskeletal). Intravertebral herniation (Schmorl's node) should be coded 722.3. Though ICD-9-CM language characterizing "intervertebral disc disorder with myelopathy" does not specify that the disc is displaced, that is the logical implication, so it is better to code a displaced disc causing myelopathy as 722.7, rather than choose 722.0/1/2 which would introduce the contradictory language of "without myelopathy." Various permutations of disc degeneration should be coded 722.4/5/6 and can be added, where appropriate to codes that describe displacement. Nonspecific discitis and other not-elsewhere-classified disc disorders should be coded 722.9; except, of course, when specific pathogens, neoplastic disorders, or non-degenerative arthridites are known, in which case the specific diagnosis should be used, instead of, or in addition to, 722.9.
Translation of recommended terminology into ICD-10 is also fairly straight-forward and follows the same principles. ICD-10 takes the demands on clinical knowledge a step further by providing separate codes for "disc disorder with radiculopathy" (M50.1, M51.1), "disc disorder with myelopathy" (M50.0, M51.0), and "other disc displacement" (M50.2, M51.2). The emphasis is on the clinical neurologic status with "disorder" and "displacement" being used almost synonymously, which contrasts with the aim of nomenclature to provide specificity to disc pathology and morphology. The differing axes of coding and terminology requirements are best bridged by assuming that disc herniations are coded as "other disc displacement" unless known to accompany radiculopathy or myelopathy, in which case they are best coded as "disc disorder with radiculopathy" or "disc disorder with myelopathy." Like ICD-9-CM, ICD-10 provides specific codes for Schmorl's nodes (M51.4) and for disc degeneration (M50.3, M51.3). ICD-10 provides separate codes for "other specified intervertebral disc disorders" (M50.8, M51.8) and for "Intervertebral disc disorder, unspecified" (M50.9, M51.9).
Sciatic pain, lumbago, regional spinal pain syndromes, and radiculopathies and myelopathies not known to be caused by disc herniation are provided unique codes in both ICD-9-CM and ICD-10. Codes for disc disorders or displacements should only be used when a diagnosis of abnormal disc morphology is intended.
Procedural coding systems present little challenge to diagnostic nomenclature, since diagnoses are inferred but not defined by procedural codes. CPT provides codes for examination, management, and procedural services, including, in some instances the naming of diagnoses to help define the procedure; for example, operations to remove displaced disc material are characterized as "excision of herniated intervertebral disk" or as "diskectomy," as descriptors of certain procedures done through a laminotomy or laminectomy approach (63001-63048). Procedure 62287 is characterized as "shtmliration procedure, percutaneous, of nucleus pulposus of intervertebral disk."
| Preface | Introduction | Recommendations | Discussion (part 1) |
| Discussion (part 2) | Glossary | References | Appendix |