A variety of traditional outcome measures have been reported in studies pertaining to the cervical spine. For example, several grading or classification schemes have been used to report the outcomes of cervical spine surgery in patients with cervical myelopathy secondary to
conditions including rheumatoid arthritis, cervical spondylosis, and ossification of the posterior longitudinal ligament. Although a number of classification systems for myelopathy have been reported, perhaps the most commonly used are the (a) Ranawat classification (5), (b) Nurick classification system (6), (c) Japanese Orthopaedic Association (JOA) score (7), and, more recently, the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) (8). Other myelopathy classifications include the Cooper myelopathy scale (9) and European myelopathy score (10). The Myelopathy Disability Index (MDI) is a patient-based outcome questionnaire that will be discussed in the next section (11).

The Ranawat classification scale was originally devised to evaluate the neurologic function of patients undergoing cervical spine fusion for rheumatoid involvement of the cervical spine (12). Class I is normal or intact. Patients with subjective weakness with hyperreflexia and paresthesias are class II. When patients develop objective weakness with long tract signs, they are categorized as class III. Class III is further subdivided into IIIA, which is composed of patients who are ambulatory, and IIIB, which is composed of patients who are nonambulatory (Table 21.1A).

In addition to the Ranawat scale, the American Rheumatism Association (ARA) functional grading system developed by Steinbrocker has been used to evaluate the overall functional status of patients with rheumatoid arthritis (Table 21.1B) (13). The ARA functional grading system is not a spine specific instrument but rather used to assess the physical function of patients with rheumatoid arthritis taking into account their overall disease burden from rheumatoid arthritis. Although this scale has been used to report postoperative improvement (14,15), the ARA classification system is so crude that it has largely been dismissed by present-day rheumatologists (11). The problem with the ARA functional grading system and, to a lesser degree, the Ranawat neurologic classification system is that they both lack sensitivity to change—they fail to differentiate quite significant clinical changes between classes II and III, and they are also subject to great interobserver error.

Nurick originally proposed a grading scheme to measure the degree of walking difficulty in patients with myelopathy secondary to cervical spondylosis (6). The Nurick grading scheme expands the grades from four on the Ranawat classification scheme to six (Table 21.2). It adds two additional grades (grades 3 and 4) to better differentiate the degree of walking dysfunction. These two additional grades create further distinction between grades IIIA and IIIB in the Ranawat scheme. Grade 3 in the Nurick scale describes the individual who cannot work inside or outside the home because of walking difficulty and grade 4 describes a patient requiring some form of assistance to ambulate. This expansion in the Nurick scheme increases its sensitivity while maintaining simplicity and ease of use. This has resulted in the widespread use of this outcome measure by many investigators. Several other classification systems, based on variations of the Nurick grading system, have also been used to measure the degree of walking disability (16, 17 and 18).

The JOA score is probably the most comprehensive of the traditional measures quantifying the degree of impairment secondary to myelopathy. It is objective in nature and measures both upper and lower extremity motor and sensory dysfunction as well as bladder function. A total of 17 points can be scored (Table 21.3) (7,19). Lower scores indicate worse function and higher scores better function. While the JOA score is the most comprehensive, it has several limitations. When comparing its grading of lower extremity function with the Nurick grade, it is less sensitive and less descriptive. The JOA uses five scores instead of six in the Nurick scheme and the three intermediate scores all assume the need for an assist device (Nurick grade 4). One might also argue that the score is perhaps too heavily weighted with respect to sensory dysfunction with 6 out of 17 total points used to measure it. Finally, measurement of upper extremity function, while an excellent principle to include, would require some translation or cross-cultural adaptation for more widespread use across other populations because in the JOA score grading is based on the ability or inability to use chop sticks. The JOA has recently been revised to make it more patient oriented and to make it more scientific from the standpoint of medical statistics (20). The product of this revision is the JOACMEQ, which is currently being validated in a surgical setting (8). In this questionnaire, factor analysis was used to divide the
24 questions into different factorial domains, and the domains were categorized by interpreting the context of the questions that were divided into each domain. The five domains into which the 24 questions were divided were designated as (a) lower extremity function, (b) quality of life, (c) cervical spine function, (d) bladder function, and (e) upper extremity function. Then the equations to calculate the score for each domain were assembled in order to intuitively indicate the status of patients in the five different functional domains. The numbers prefixed to the answers chosen by the patients were multiplied by the coefficients so that the difference between the minimum score representing the worst condition and the maximum score representing the best condition would become 100. The equations were further manipulated by other supplemental coefficients so that the minimum score became 0 and the maximum score became 100 to make recognition of the status of the patient as intuitive as possible. The authors are currently investigating if the changes in the patient’s functional status after surgical treatment would be accurately reflected by the changes in the scores in the different domains.