Back pain and oedematous Schmorl node: a diagnostic dilemma

Abstract

A 26-year-old female from India presented with progressive, unremitting low back pain for over 1 year. She had been treated unsuccessfully for left-sided sacroiliitis, pelvic floor dysfunction, ankylosing spondylitis and seronegative spondyloarthritis. MRI lumbar spine showed a Schmorl node with surrounding marrow oedema at L4, the relevance of which is not clear in literature. One year after initial presentation, a biopsy of this lesion revealed culture positive diagnosis of spinal tuberculosis. Despite advances in imaging, delayed diagnosis is not uncommon in spinal tuberculosis (TB). In our case, it was also attributed to an unknown early lesion: Schmorl node with surrounding oedema. Any association of this lesion with spinal TB has previously not been reported.

Keywords: Bone and joint infections; Infections; TB and other respiratory infections.

Figure 1

Initial presentation: sagittal CT (A), sagittal T1 (B) and short tau inversion recovery (C) MRIs showing a Schmorl node at L4 level with mild surrounding marrow oedema.

Figure 2

Contrast-enhanced T1-weighted sagittal MRIs showing progression of disease. (A) MRI obtained 4 weeks prior to biopsy. Enhancement of L4 vertebral body was seen but due to presence of Schmorl node which may present with enhancement, infection was thought to be less likely but follow-up recommended. (B) MRI obtained at the first episode of clinical worsening, 6 days after start of thrice-weekly antimycobacterial therapy. The image shows loss of vertebral body height and new epidural abscess formation. Daily antimycobacterial therapy was initiated after biopsy but the patient was switched to thrice-weekly therapy on day 16 after smear conversion. Clinical worsening occurred 6 days into thrice-weekly therapy (day 22 of first initiating antimycobacterial treatment) as shown here. The patient was switched back to daily therapy for a week, and subsequently again back to thrice-weekly therapy. (C) MRI obtained at the second episode of clinical worsening, 12 days into the second round of thrice-weekly therapy (day 41 of first initiating antimycobacterial treatment). Image shows increased loss of height of vertebral body and increased component of epidural abscess. Patient was switched back to and continued on daily therapy after this event.