Baastrup disease

Last revised by Joshua Yap on 13 Jan 2023

Baastrup disease/syndrome (also referred to as kissing spines) is a cause of low back pain characterized by interspinous bursitis and other degenerative changes of the bones and soft tissues where adjacent spinous processes in the lumbar spine rub against each other.

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) 

  • 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

Local steroid injection into the interspinous processes/ligament region may often ease the back pain 8. Surgical options include interspinous process decompression devices.

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

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Cases and figures

  • Case 1a: T1 fat sat with gad
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  • Case 1b: T2
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  • Case 2a: STIR
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  • Case 2b: T2
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  • Case 3: with X-STOP decompression
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  • Case 4
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  • Case 5: STIR
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  • Case 6
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  • Case 7: FDG PET/CT
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  • Case 8
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