Close, impinging and overriding spinous processes in the thoracolumbar spine: the relationship between radiological and scintigraphic findings and clinical signs.
Authors: Zimmerman M, Dyson S, Murray R
Journal: Equine veterinary journal
Summary
# Editorial Summary Zimmerman, Dyson and Murray's 2012 study of 582 horses presenting with suspected back pain and poor performance sought to establish whether radiological abnormalities of thoracolumbar spinous processes—including close, impinging and overriding configurations—correlated with clinical signs of back pain and scintigraphic evidence of increased radiopharmaceutical uptake. Using comprehensive diagnostic protocols including radiography, scintigraphy and selective diagnostic analgesia of the forelimbs, hindlimbs, back and sacroiliac joints, the researchers found significant associations between both the severity of spinous process radiological changes and the degree of scintigraphic uptake with the presence of thoracolumbar pain; combined radiological and scintigraphic abnormalities proved the most predictive. Notably, osteoarthritis of the synovial intervertebral articulations represented a stronger indicator of thoracolumbar pain than spinous process lesions alone, although concurrent pathology in both structures carried the highest risk. The findings underscore a critical clinical lesson: forelimb or hindlimb lameness and sacroiliac joint pathology frequently masquerade as primary thoracolumbar pain, making systematic diagnostic analgesia essential regardless of imaging findings, and emphasising that radiological and scintigraphic abnormalities alone cannot reliably diagnose back pain without compatible clinical signs and negative regional analgesic blocks.
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Practical Takeaways
- •Radiographs and scintigraphy together are more informative than either alone for thoracolumbar pain diagnosis, but diagnostic analgesia remains essential for accurate localization and ruling out referred pain from limbs or sacroiliac joints
- •Presence of spinous process lesions on imaging does not automatically mean they are the primary pain source—always perform systematic diagnostic analgesia of forelimbs, hindlimbs, and sacroiliac joints before attributing poor performance to back pain
- •Horses with multiple concurrent spinal lesions (spinous process abnormalities plus intervertebral joint osteoarthritis) are at highest risk for thoracolumbar pain; breed predisposition exists with Thoroughbreds more commonly affected
Key Findings
- •Significant association between radiological grades of spinous process abnormalities and thoracolumbar pain in 582 horses presented for back pain
- •Increased radiopharmaceutical uptake in spinous processes correlated with thoracolumbar pain, with combination of radiological and scintigraphic findings providing strongest prediction
- •Horses with concurrent osteoarthritis of synovial intervertebral articulations and spinous process lesions had highest likelihood of thoracolumbar pain compared to single pathology
- •Thoroughbreds were significantly over-represented with thoracolumbar pain compared to Warmbloods and TB crosses; forelimb/hindlimb lameness and sacroiliac joint pain can mimic primary thoracolumbar pain