Baastrup syndrome

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 degenerative hypertrophy, inflammatory change (as seen in case 1) and even a pseudoarthrosis with bursa formation. This interspinous bursa may extend between the ligamenta flava 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.

  • 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 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. The best diagnostic clue for avoiding misinterpretation may be scrutinising sagittal multiplanar reconstructions (MPR) and involvement being limited to spinous processes, which is rare in malignancy 6

Both conservative and surgical options are available for treatment. Local steroid injection into the interspinous processes / ligament region could often ease the back pain 8. Surgical options include interspinous process decompression devices (e.g. Wallis system, X STOP), and steroid/local anesthetic injection into the bursa.

It is named after Christian Ingerslev Baastrup, Danish radiologist (1855-1950) 3.

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Article information

rID: 960
Section: Signs
Synonyms or Alternate Spellings:
  • Kissing spines syndrome
  • Kissing spine
  • Baastrup's syndrome
  • Arthrosis interspinosa
  • Baastrup disease
  • Baastrup sign
  • Kissing spines
  • Diarthrosis interspinosa
  • Baastrup's disease

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Cases and figures

  • Case 1: T1 fat sat with gad
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  • Case 1: T2
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  • Case 2: STIR
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  • Case 2: T2
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  • Case 3: with X-Stop decompression
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  • Case 4
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  • Case 5: STIR sagittal
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  • Case 6
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  • Case 7: FDG PET/CT of kissing spines
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  • Case 8
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