Baastrup's disease as a cause of neurogenic claudication: a case report.

STUDY DESIGN: A rare case of Baastrup's disease as a cause of spinal canal stenosis in a patient with double-level spondylolisthesis is reported.

OBJECTIVES: To report an intraspinal synovial cyst as an extension of neoarthrosis of Baastrup's disease causing spinal canal stenosis, and to review the relevant literature.

SUMMARY OF BACKGROUND DATA: Baastrup's disease, more commonly known as kissing spines, has been implicated as a cause for low back pain. Neoarthrosis between the spinous processes has been described, but this is the first report in the literature of an extension of the synovial cavity to the intraspinal space resulting in extradural compression.

METHODS: A 50-year-old woman with double-level spondylolisthesis and symptoms of instability and neurogenic claudication was evaluated and treated using spinal decompression and fusion.

RESULTS: Radiographs showed a double-level spondylolisthesis at L3-L4 and L4-L5 levels, and magnetic resonance imaging showed the presence of a neocyst formation in the interspinous region and another cyst in the posterior epidural space at the same level causing dural compression. There was a suggestion of continuity between the two cysts that was confirmed at surgery. The neoarthrosis and the cyst were excised, and spinal decompression and fusion were performed. The patient had good relief of symptoms.

CONCLUSIONS: Baastrup's disease leading to neoarthrosis formation with synovial cavity and causing low back pain has been reported previously. The cyst can enter into the epidural space through the midline cleft of the ligamentum flavum to result in extradural compression.