Ossification of the posterior longitudinal ligament in ankylosing spondylitis

Abstract

Arthritis and Rheumatism, Yagan et a1 (1) reported a case of ossification of the posterior longitudinal ligament (PLL) in a patient with HLA-B27 positive ankylosing spondylitis (AS). We have recently seen a similar case, which we report here.The patient was a 39-year-old man with a 13-year history of inflammatory low back pain and stiffness, and decreasing range of motion of the lumbar spine. In the past few years, his symptoms had extended to the cervical spine. There was no history of urethritis, diarrhea, psoriasis, peripheral arthritis, uveitis, conjunctivitis, or cardiac symptoms.Physical examination disclosed dorsal kyphosis, forward craning of the cervical spine, and severe restriction of motion of both the cervical and the lumbar spine, in all directions. Chest expansion was reduced to 1.5 cm.Laboratory evaluation revealed an erythrocyte sedimentation rate (Westergren) of 39 m d h o u r , a C-reactive protein level of 3.2 mg/dl (normal <0.5), and a serum IgA level of 626 mg/dl (normal 50-350). HLA typing was positive for the B27 antigen.Radiographic examination of the pelvis showed ankylosis of both sacroiliac joints, erosions, and irregular periosteal new bone formation ("whiskering") at the ischial tuberosities, together with osteitis of the symphysis pubis. Radiographs of the lumbar and the dorsal spine showed squaring of the vertebral bodies and apophyseal joint sclerosis and ankylosis. Cervical spine radiographs (Figure 1) demonstrated squaring of the vertebral bodies, marginal syndesmophytes, apophyseal joint sclerosis and fusion, and ossification of the PLL extending from Cl to C6. A radiolucent line was visible between the posterior aspect of the vertebral bodies and the ossified PLL.PLL ossification is an uncommon condition with an unclear etiology. It is most frequently reported in Japanese people (2,3). In 1978, Resnick et a1 (4) reported finding PLL ossification in 50% of 74 North American patients who had diffuse idiopathic skeletal hyperostosis (DISH), and suggested that there was an association between the 2 conditions.The report by Yagan et al in 1983 (1) described the first case of PLL ossification in a patient with a clear diagnosis of B27 positive AS. That patient also had an ossification of the anterior longitudinal ligament of the cervical spine, similar to that seen in DISH. Although the patient showed no other signs of DISH in the thoracic or the lumbar spine, the authors wondered "whether the ossification of the anterior longitudinal ligament of cervical spine-similar to that seen in diffuse idiopathic skeletal hyperostosis-contributed to the development of PLL ossification in the patient's neck." Unlike their patient, ours showed no signs of DISH in the cervical, lumbar, or dorsal spine.This report confirms the hypothesis by Yagan et a1 that PLL ossification and AS may coexist in a patient.

Diffuse idiopathic skeletal hyperostosis: Differentiation from ankylosing spondylitis

“…Although ossifi cation of the posterior longitudinal ligament has been described in AS [24][25][26][27], it is much more frequent in DISH [23]. Apophyseal joint alteration-involving partial or complete ankylosis of the zygapophyseal, costovertebral, and costotransverse joints-is typically present in advanced AS, whereas only some narrowing with hypertrophic alterations and capsular ossifi cation can be observed in these joints in DISH.…”

“…DISH may also be associated with ossifi cation of the posterior longitudinal ligament, especially of the cervical spine, which can further aggravate the spinal canal stenosis [23]. Some degree of ossifi cation of the syndesmoses of the vertebral arches and of the posterior longitudinal ligament can occasionally also be observed in patients with AS without any signs of DISH [24][25][26][27].…”

Cervical myelopathy caused by ossification of the posterior longitudinal ligament in ankylosing spondylitis

“…In the previously reported cases of OPLL in AS, the ossification was mild or moderate and was diagnosed incidentally during radiologic evaluation for AS (7)(8)(9)(10). The present case is characterized by the involvement of the dorsal and lumbar spine and by a large and striking cervical OPLL, causing myelopathy.…”

“…This is a condition of unclear etiopathogenesis, which is more frequent in the Japanese population (3)(4)(5) and in patients with DISH (6). It has also been observed in patients with AS (7)(8)(9)(10)(11).…”

Ossification of the posterior longitudinal ligament in three geographically and genetically different populations of ankylosing spondylitis and other spondyloarthropathies

“…The presenting complaints of OPLL were tetraparesis after a mild hyperextension injury to the neck in one patient25 and spinal cord compression with gait problems in another24; in the remaining five the OPLL was an unexpected radiological finding in AS patients not having clinically evident neurological symptoms. There is a report of concordant twins, both with AS, but only one had OPLL 28. In all cases the diagnosis of OPLL was made on plain lateral radiographs and in all cases the OPLL was documented in the cervical spine.…”