Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in focal midline pain and tenderness relieved by flexion and aggravated by extension.
Epidemiology
It tends to be more common in the elderly.
Pathology
This process can result in a degenerative hypertrophy, inflammatory change and even a pseudarthrosis 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.
This condition is usually seen patients with excessive lordosis of the lumbar spine.
Radiographic features
Plain film 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.
FDG-PET/CT
may demonstrate FDG-avidity when associated with inflammatory response such as bursitis.
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