Baastrup's Disease, Interspinal Bursitis, and Dorsal Epidural Cysts: Radiologic Evaluation and Impact on Treatment Options.

Baastrup's disease or "kissing spines syndrome" was first described as a cause of lumbar pain before computerized tomography (CT) and magnetic resonance imaging (MRI) scanning existed. The diagnosis was based on x-ray studies, which showed that the spinous processes, especially in the lower lumbar spine, became approximated to each other and this was a generator of positional back pain. Biomechanically, the interspinous and supraspinous ligaments that are degenerated in Baastrup's disease normally contribute significantly to sagittal alignment. Ligamentous stenosis and anterolisthesis would be the expected pathology with deterioration of these ligaments and were initially described on CT and MRI in patients with symptoms similar to Baastrup's disease as isolated individual case reports. This review will highlight the relationship between the various clinical presentations, biomechanics, and overlap of Baastrup's disease with interspinous bursitis, segmental stenosis, and instability, presenting them as a disease continuum rather than as separate disease processes.