A 76-year-old male patient with a history of chronic low back pain presented to the emergency room with four days of lower limb pain and difficulty walking.
Physical exam revealed lumbar pain and signs of neurogenic claudication (Panel A,B,C,D,E,F). Lateral plain radiographs of the lumbosacral spine were initially obtained (Panel A) and demonstrated a marked reduction of the interspinous space at level L4-L5, with close approximation and sclerosis of spinous processes. MR images showed signal abnormality of the spinous processes with edematous bone areas, depicted by low signal intensity on T1-weighted images (WI) (Panel B) and high signal intensity on T2/ short-tau inversion recovery (STIR) sequence (Panel D), in association with edema of the interspinous ligament. There was a posterior epidural cyst compressing the dural sac, better seen on sagittal (Panel C) and axial T2 WI (Panel F). Note the contrast-enhancement related to active inflammatory changes depicted on sagittal contrast-enhanced fat-saturated T1WI (Panel E).
Baastrup’s disease (also known as “kissing spine syndrome”) is a relatively common disorder of the vertebral column, characterized by low back pain arising from inflammatory changes of adjacent spinous processes and soft tissues between them, most commonly at the level L4–L5.
Clinically, this condition is often misdiagnosed as facet joint syndrome or intervertebral disc pathology, resulting in incorrect treatment and persistence of symptoms.
MR imaging is very useful in evaluating soft tissue abnormalities, such as interspinous ligament edema or fluid, representing bursitis. Rarely, intraspinal cysts can occur due to propagation of the bursa into the posterior epidural space and may cause symptomatic spinal stenosis and neurogenic claudication.
In the case mentioned above, the new onset of neurogenic claudication in a patient with known Baastrup’s disease raised the suspicion of central canal stenosis.
Treatment remains debatable. Proposed therapies include conservative treatment with percutaneous steroid injections and surgical therapies, such as excision of the bursa or osteotomy.
Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/amj-20-139). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Written informed consent was obtained from the patient. Due to COVID-19 restrictions this was made by telephone informed consent. Since the images are entirely anonymised, written consent was waived.
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Cite this article as: Brito C, Matias S. Baastrup’s disease: beyond kissing spine. AME Med J 2021;6:22.