1 Introduction to deformity severity measures for ankylosing spondylitis

Arthritis is a relatively loosely defined disorder affecting joints characterized by pain and swelling, progressive loss of function through destruction of the cartilage surfaces with resultant stiffness, loss of motion and eventual deformity. It is commonly identified as the leading cause of disability in the developed world. The human spinal column, with its average of 23 discs and 53 joints, is a prime target for manifestations of arthritic disorders. In general, arthritic disorders are differentiated into inflammatory “arthritic” diseases and degenerative “wear-and-tear” disorders, the latter generally being referred to as “arthrosis” outside of the English-speaking world. Despite its predilection towards arthritic diseases, the classification of its disease patterns has been almost entirely left to subspecialized Internal Medicine physicians with emphasis on inflammatory disorders. Within the field of “Rheumatology”, the main emphasis of providing structural analysis has mainly revolved around ankylosing spondylitis (AS), which had posed challenges in providing timely diagnosis due to lack of clear serologic or histologic diagnostic criteria. As any review of the literature will readily identify rheumatoid arthritis (RA) or juvenile rheumatoid arthritis (JRA) with their relatively clearly defined presentation and diagnostic pathways, have surprisingly not received well—publicized classification attempts in terms of disease severity or manifestation patterns. One notable exception of severity scores within Rheumatology is the Ranawat score, which was initially presented with the functional status of rheumatoid arthritis patients in mind. Even in the presence of atlanto-axial instability, which is a rather typical spinal affliction of Rheumatoid Arthritis, the prevailing scientific literature has used direct measurements of the atlas-dens interval (ADI), or has provided measurements for the space available for the cord (SAC), again as a continuum expressed in direct measurements of millimeters, rather than in a graded form [1]. There are also many well-delineated sub-entities within the inflammatory disorders, which have again not received further refinement in the form of severity scales or disease-specific classifications. From a surgeons’ perspective the absence of disease rating-systems for most inflammatory diseases is somewhat surprising, since increasingly complex and perhaps effective medical therapies have become available and results of treatment in terms of measurable joint disease regression would seem to benefit from an outcomes analysis based on severity scales.

2 Current classification systems for ankylosing spondylitis

In contrast to these sero-positive disorders, ankylosing spondylitis (AS) has been extensively covered with disease severity descriptors and classification systems, of which this chapter reviews a few pertinent examples. Many of these systems appeared to have arisen out of diagnostic uncertainty which historically had affected this particular disorder. In the process of developing diagnostic criteria, which were excluded for purposes of this book, the further evolution of assessment categories resulted in actual disease severity description concepts, which qualified as severity scales applicable to the spine, and are therefore listed in this chapter.

Diagnostic criteria for ankylosing spondylitis (AS) were first specified at a conference in Rome in 1963 [2] which focused on the anatomical and clinical components of the disease to include radiographic measures of the sacroiliac joints and pain, stiffness, and spinal motion. These criteria were later modified, resulting in the New York criteria formulated in 1966 which added grades of severity [3].

In 1984, van Der Linden et al proposed a modification of substituting the Rome pain criterion for the New York criterion [4]. In 1988, Mander et al created the Enthesis index (also known as the Newcastle Enthesis Index) which emphasized the clinical component of pressure applied to 66 different anatomical sites [5]. A 0 to 3 point pain scale was created and the total score was the sum of all sites. This measure was modified in 2003 and called the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) [6]. The 66 palpable enthesis were reduced to 13 and pain intensity was omitted. The total score was based on the sum of the individual enthesis.

In 1988, the Dougados Articular Index was published and is similar in nature to the Enthesis Index but focused on 10 joint sites using the same 0 to 3 point pain scale [7]. In 1991, Dougados et al as part of the European Spondylarthropathy Study Group (ESSG) developed criteria that included family history and other related comorbid conditions [8]. In the same year, the Stoke Ankylosing Spondylitis Spine Score (SASSS) was developed with a focus on grading the severity of lateral lumbar and pelvic x-rays [9]. This was modified in 2005 by adding a score for the cervical spine [10].

Beginning in 1994, a series of measures known as the Bath Ankylosing Spondylitis indices were developed including a radiology index (BASRI-s) and a metrology index (BASMI) which have also experienced modifications [11–13].

In 2002 and 2003, the Ankylosing Spondylitis spine Magnetic Resonance Imaging (ASspiMRI) system and the Berlin MRI Spine Score were developed, respectively [14–16]. Both systems use MRI to evaluate spinal lesions. The ASspiMRI has an activity score and a chronicity score covering the entire spine. The Berlin score modified the ASspiMRI by excluding the evaluating and scoring of erosions.

In 2005, the Spondyloarthritis Research Consortium of Canada (SPARCC) Magnetic Resonance Imaging (MRI) Spinal Inflammation Index was developed in a similar fashion to the other two MRI systems [17, 18]. This system also evaluates the entire spine, but only the 6 most severe vertebral units are scored.

In 2006, Maksymowych et al developed the Edmonton Ankylosing Spondylitis Metrology Index [19]. This index focused on cervical, chest, lumbar and hip mobility and severity is assigned based on the percentile rank of each.

3 Summary

Our ability to predict which patients will do best and respond to specific treatments is undoubtedly tied to the patients’ overall disease severity when they seek treatment. While clinical presentation is important in assessing severity measures that include additional factors such as functional capacity nutritional status, bone density or composite structural balance assessment may be more useful in predicting outcomes for spinal disorders in patients with ankylosing diseases than the present day systems allow for. For spine providers, review of the currently available systems will hopefully spur on the evolution of a new generation of more comprehensive systems of severity scales for the fascinating and perplexing field of spinal arthritis disorders.

4 References

1 Bennet New York Criteria*

Bennet PH, Wood PHN, (1968) Population studies of rheumatic diseases. Amsterdam: Exerpta Medica Foundation, 456–457

CONTENT

RATING

2 Braun Ankylosing Spondylitis spine Magnetic Resonance Imaging (ASspiMRI)

Braun J, van der Heijde D (2002) Imaging and scoring in ankylosing spondylitis. Best Pract Res Clin Rheumatol; 16:573–604.

Braun J, Baraliakos X, Golder W, et al (2003) Magnetic resonance imaging examinations of the spine in patients with ankylosing spondylitis, before and after successful therapy with infl iximab: evaluation of a new scoring system. Arthritis Rheum; 48:1126–1136.

SCALE ILLUSTRATION

CONTENT

RATING

3 Creemers Modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS)

Creemers MC, Franssen MJ, van’t Hof MA, et al (2005) Assessment of outcome in ankylosing spondylitis: an extended radiographic scoring system. Ann Rheum Dis; 64:127–129.

Related posts:

5.1 Spine Classifications and Severity Measures 5.3 Deformity severity measures: 5.3.2 Spine Classifications and Severity Measures 5.3 Deformity severity measures: 5.3.4 Deformity severity measures: spondylolisthesis 5.5 Osteoporosis severity measures 5.4 Degenerative measures: 5.4.1 Degenerative measures: cervical myelopathy 5.3 Deformity severity measures: 5.3.1 Spine Classifications and Severity Measures

Stay updated, free articles. Join our Telegram channel

Join