Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in hypertrophy and sclerosis with focal midline pain and tenderness relieved by flexion and aggravated by extension.
It tends to be more common in the elderly 1.
Focal midline pain and tenderness relieved by flexion and aggravated by extension.
This process can result in a degenerative hypertrophy, inflammatory change (as seen in case 1) and even a pseudoarthrosis with bursa formation. This interspinous bursa may extend between the ligamentum flavae in the midline forming an epidural cyst and further contributing to the already existing canal stenosis 2.
This condition is usually seen in patients with excessive lordosis of the lumbar spine.
- older age
- central canal stenosis 7
Plain radiograph and CT
- often shows close approximation and contact of adjacent spinous processes (kissing spines)
- there is resultant enlargement, flattening and reactive sclerosis of apposing interspinous surfaces
May demonstrate interspinous bursal fluid and a posterocentral epidural cyst(s). MRI can be very helpful in determining whether there is resulting posterior compression of the thecal sac.
May demonstrate FDG-avidity when associated with an inflammatory response such as bursitis 5,6. Best diagnostic clue for avoiding misinterpretation may be scrutinising sagittal multiplanar reconstructions (MPR) and involvement being limited to spinous processes (see case 9), which is rare in malignancy 6.
Treatment and prognosis
Both conservative and surgical options are available for treatment. Local steroid injection into the interspinous processes will often ease the back pain. Surgical options include interspinous process decompression devices (e.g. Wallis system, X STOP), and steroid/local anaesthetic injection into the bursa.
History and etymology
It is named after Christian Ingerslev Baastrup, Danish radiologist (1855-1950) 3.
- 1. Kwong Y, Rao N, Latief K. MDCT findings in Baastrup disease: disease or normal feature of the aging spine?. AJR Am J Roentgenol. 2011;196 (5): 1156-9. doi:10.2214/AJR.10.5719 - Pubmed citation
- 2. Chen CK, Yeh L, Resnick D et-al. Intraspinal posterior epidural cysts associated with Baastrup's disease: report of 10 patients. AJR Am J Roentgenol. 2004;182 (1): 191-4. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Edling L. Christian Ingerslev Baastrup: in Memoriam. Acta Radiologica 1951;35:326-330. https://doi.org/10.3109/00016925109137579.
- 4. Rutherford EE, Tarplett LJ, Davies EM et-al. Lumbar spine fusion and stabilization: hardware, techniques, and imaging appearances. Radiographics. 27 (6): 1737-49. doi:10.1148/rg.276065205 - Pubmed citation
- 5. Lin E. Baastrup's disease (kissing spine) demonstrated by FDG PET/CT. Skeletal Radiol. 2008;37 (2): 173-5. doi:10.1007/s00256-007-0379-2 - Pubmed citation
- 6. Rosen RS, Fayad L, Wahl RL. Increased 18F-FDG uptake in degenerative disease of the spine: Characterization with 18F-FDG PET/CT. J. Nucl. Med. 2006;47 (8): 1274-80. Pubmed citation
- 7. Maes R, Morrison WB, Parker L et-al. Lumbar interspinous bursitis (Baastrup disease) in a symptomatic population: prevalence on magnetic resonance imaging. Spine. 2008;33 (7): E211-5. doi:10.1097/BRS.0b013e318169614a - Pubmed citation