Best Clue to Low Back Pain Case: Vision Problem

Fisher MC, Stone JH, and Palmer WE. Case Records of The Massachusetts General Hospital: A Man with Back Pain, Fatigue, Weight Loss, and Knee Swelling. N Engl J Med (2014) 371:1447-1455. October 9, 2014. doi: 10.1056/NEJMcpc1404517

A 50-year-old man presents with a 2-year history of progressive back pain, which diminishes with walking, in this case study in the New England Journal of Medicine.

The patient fell 11 months before admission, and reported increasing back spasms. He also reports a single episode of iritis of the left eye 15 years ago.

The case study authors note that the patient has a history of obesity, depression, gout, and nephrolithiasis, among other comorbidities.

A spinal MRI shows the disk space between the 10th and 11th thoracic vertebral body filled with fluid, and bone marrow edema in T10 and T11.

One possibility is diskitis-osteomyelitis; another is fracture with pseudoarthrosis.

These physicians posit that a systemic inflammatory process could explain this patient’s back pain and other features. Possible culprits include sarcoidosis, spondyloarthropathies, reactive arthritis, and inflammatory bowel disease (but the patient does not have the common markers for these diseases).

The history of iritis leads to a strong suspicion of ankylosing spondylitis (AS), which becomes the final diagnosis based on results from a CT scan. The HLA-B27 allele is absent, which is the case for 10% of AS patients. The authors caution that HLA-B27 status may not be useful for diagnosis, as many AS patients will be HLA-B27-negative while many HLA-B27-positive patients won't have AS.  

Fracture risk in AS follows two main paths, the authors explain. One causes bone resorption and erosion, while the other leads to formation of new bone at entheses and joint margins as well as syndesmophytes.
Treatment strategies should target whichever of these inflammatory pathways is mediating symptoms of joint stiffness and bone erosion, they say, and leading to mechanical weakness of existing bone.

TNF inhibitors achieve “profound symptomatic improvement” in about 70% of patients, the authors state, even for those with advanced joint fusion.