LETTERS
Diffuse idiopathic skeletal hyperostosis in a patient with situs inversus To The Editor: Diffuse idiopathic skeletal hyperostosis is a common clinical entity seen by rheumatologists and radiologists. Numerous articles have been written about the radiographic abnormalities seen in this condition (1-4). Typically, the thoracic spine is most involved, with calcifications along the anterolateral aspect of the vertebral bodies. continuing across the intervertebral disc space. These bony excrescences most commonly involve the fourth through the eleventh thoracic vertebrae. It has also been noted that these calcifications, while involving both the right and left anterolateral aspects of the vertebral column, more commonly occur on the right side. It bas been postulated that this relative sparing on the left is due to the “protective” effect of the pulsating descending thoracic aorta ( 5 ) . In one large anatomic study, it was found that osteophytes did not develop, or developed to a substantially lesser degree, in areas where the aorta was in close contact with the vertebral column. This area roughly corresponds to the fifth through the eleventh thoracic vertebrae. From the point where the aorta becomes a midline structure, the osteophytes take on a symmetric occurrence (6).
Figure 1. Chest radiograph, showing a right-sided cardiac silhouette and a right-sided gastric air bubble.
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Another factor believed to be a determinant in the position of vertebral osteophytes is the amount of soft tissue in close approximation to the vertebral column. Since new bone cannot form across normal connective tissue fibers (2), osteophytes can only proliferate in an area devoid of soft tissue. Here, in the so-called annular area (a potential empty space between the vertical vertebral surface, the inner layers of the longitudinal ligament, and the fibers which connect the latter with the disc), an osteophyte can proliferate until it meets one of the tissue boundaries. A lack of left-sided thoracic osteophytes could be due to the possible obliteration of this annular area by the pressure of the aorta (7). In patients with complete situs inversus, there is transposition of all internal organs to their mirror-image position. This condition places the descending thoracic aorta on the right side. If, indeed, the descending thoracic aorta plays a role in determining the position of vertebral calcification, a patient having diffuse idiopathic skeletal hyperostosis
Figure 2. Anteroposterior view of the thoracic spine, showing flowing bony excrescences on the left lateral aspect of the vertebral column.
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LETTERS
and complete situs inversus should have a predominance of calcification on the left lateral aspect of the vertebral bodies. We report such a case. A 55-year-old black man presented tb the emergency room of the Veterans Administration Medical Center, Washington, DC complaining of upper back discomfort. The patient noted stiffness of the upper back which was worse in the morning and after periods of inactivity. These symptoms had been present for several months, but had become worse in the preceding 2 weeks. He also reported the recent onset of pain in the right midfoot area. On physical examination, the heart sounds were most readily auscultated on the right and the liver palpated on the left, suggesting situs inversus. There was limitation of range of motion in the lumbar and thoracic spine, and chest expansion was 2.6 cm. A chest radiograph and an anteropostenor view of the thoracic spine were obtained. They demonstrated a right-sided cardiac silhouette, a right-sided gastric air bubble (Figure 1). and flowing bony excrescences occurring predominahtly on the left lateral aspect of the vertebral column (Figure 2). Radiographic examination of the right foot revealed exuberant bony proliferation of the midtarsal area, similar to the type described by Resnick (8). There was no evidence to suggest ankylosing spondylitis, and the sacroiliac joints were radiographically normal. We are aware of only one other case of complete situs inversus and left-sided vertebral bridging, reported in 1962 (9). Several cases of right-sided descending thoracic aortas and left-sided vertebral bridging have also been reported (9-11). All of these reported cases appear to support the observation that the position of the descending thoracic aorta plays a role in the location of vertebral calcification. Kenneth M. Bahrt, MD David J. Nashel, MD Glen Haber, DPM Veterans Administration Medical Center Washington, DC I . Resnick D, Niwayama G:Radiographic and pathologic features of spinal involvement in diffuse idiopathic skeletal hyperostosis (DISH).Radiology 11939-568, 1976 2. Oppenheimer A: Calcification and ossification of vertebral ligaments (spondylitis ossificans Iigamentatosa):roentgen study of pathogenesis and clinical significance. Radiology 38: 160-173, 1942
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Forestier J , Lagier R: Ankylosing hyperostosis of the spine. Clin Orthop 74:65-83, 1971 Smith CF, Pugh DG, Polky HF: Physiologic vertebral ligamentous calcification: an aging process. Am J Roentgenol 74: 10491058. 1955
Resnick D, Niwayama G: Diffuse idiopathic skeletal hyperostosis (DISH):ankylosing hyperostosis of Forestier ahd RotesQuerol, Diagnosis of Bone and Joint Disorders. Edited by D Resnick, G Niwayama. Philadelphia, WB Sanders, 1981, pp I 4 18-1452
Nathan H: Osteophytes of the vertebral column: an anatomical study of their development according to age, race, and sex with
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considerations as to their etiology and significance. J Bone Joint Surg 44-A:243-267, 1%2 Culver GJ, Pirson HS: Asymmetry of osteophytosis in the thoracic spine. Am J Roentgenol 76: 1157-1 160, 1956 Resnick D, Shaul SR. Robins JM: Diffuse idiopathic skeletal hyperostosis (DISH):Forestier’s disease with extraspinal manifestations. Radiology 115513-524, 1975 Nathan H. Schwartz A: Inverted pattern of development of thoracic vertebral osteophytes in situs inversus and in other instances of right descending aorta. Radio1 Clin (Basel) 3 I :150158, 1%2 Culver GJ, Pirson HS:Preventive effect of aortic pulsations on osteophyte formation in the thoracic spine. A m J Roentgenol
84:937-940. 1960 I I . Shapiro R, Batt HD: Unilateral thoracic spondylosis. Am J Roentgenol 83:66&662, 1960
Reply to Sharp’s letter To the Editor: We appreciate Dr. John Sharp’s thoughtful comments on the Preliminary Ctiteria for Clinical Remission in Rheumatoid A r t k t i s (Sharp JT: Preliminary criteria for remission in rheumatoid arthritis [letter]. Arthritis Rheum 25:1144, 1982). In the last paragraph of the paper we emphasized the point reiterated by Dr. Sharp, namely the need for validation of these preliminary criteria by prospective studies in various groups of patients. Dr. Sharp’s second point relates to the appropriateness of a “partial remission” category. In our study this term was used as a device to force participating rheumatologists into making a decision for or against inclusion of a particular patient in the “complete remission” category. The aim was to delineate the borderline between remission and active disease with greater precision, and not to derive criteria for a state of partial remission. In the discussion we stated that “the issue of staging and defining levels of disease activity is an important one, which has not been addressed in this study.” We concur completely with Dr.Sharp that the ultimate expression of a remission in the individbal patient may be a function of disease severity, duration, and other variables, e.g., joint damage or deformity. A comprehensive, prospective analysis of endpoints in a large rheumatoid arthritis population might well lead to a panel of complete remission criteria, which would take these variables into account. The committee considered these issues but believed they fell beyond its mandate and resources when the study was initiated in 1976. Robert S. Pinals, MD University of Tennessee Memphis, TN Alfonse T. Masi, MD, Dr PH University of Illinois College of Medicine at Peoria Peoria, IL
