Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 105. Spinal disorders are among the most common medical conditions with significant impact on health related quality of life, use of health care resources and socio-economic costs. Spinal surgery is still one of the fastest growing areas in clinical medicine. | 1044 Section Tumors and Inflammation a b c Figure 1. Horizontal and Vertikal Instability d a c Normal anatomy of the occipitocervical junction. b Advanced stage of instability and resorption of the lateral masses of the atlas. The dens axis moves upward into the foramen magnum. d Horizontal instability in the atlantoaxial segment with decreased posterior atlantodental interval and increasing anterior atlantodental interval. Vertical instability with upward migration of the dens into the foramen magnum. Classification The commonly used classification is the Ranawat classification 20 which differentiates between the different stages of the rheumatoid influence on the patient s mobility Table 1 . This relatively crude differentiation is hardly able to assess the situation of these patients satisfactorily. Important items such as hygienic independence eating capacities and general use of the hands are not included in the classification but are of the utmost importance to the patient. Therefore the classification is barely sufficient to serve as an outcome measurement of surgery. For the practical clinical user the recently published and validated Core Questions 17 have proven to be a useful basis for assessment. Table 1. Ranawat classification Class I Pain no neurological deficit Class II Subjective weakness hyperreflexia dysesthesias Class III Objective weakness long-tract signs Class IIIA Ambulatory Class IIIB Non-ambulatory Rheumatoid Arthritis Chapter 37 1045 Clinical Presentation As known from other conditions in the spine radiological changes are not always concordant with the clinical symptomatology. Therefore major instabilities may be without symptoms and minor alterations may be very painful. History The history of RA is generally evident when the spine becomes involved. Therefore diagnosis does not cause any clinical problems. The cardinal symptom of atlantoaxial instability is suboccipital pain pain exacerbation on head rotation or flexion Sometimes a .
