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Contrast-enhanced computed tomography and myelography in six horses with cervical stenotic myelopathy
B R Moore1, T C Holbrook, J D Stefanacci
1North Carolina State University, Department of Food Animal and Equine Medicine, Raleigh 27606.
Insights
Contrast-enhanced computed tomography (CECT) and myelography accurately detect spinal cord compression in horses with cervical stenotic myelopathy (CSM). CECT provides superior qualitative data and validated measurements of vertebral canal stenosis.
Area of Science:
- Veterinary Neurology
- Diagnostic Imaging
- Equine Pathology
Background:
- Cervical stenotic myelopathy (CSM) is a neurological condition in horses.
- Accurate diagnosis of spinal cord compression is crucial for understanding CSM pathogenesis.
- Myelography and computed tomography (CT) are imaging modalities used to assess equine spinal cord lesions.
Purpose of the Study:
- To compare the diagnostic accuracy of myelography and contrast-enhanced computed tomography (CECT) in identifying spinal cord compressive lesions in horses with CSM.
- To evaluate the qualitative information provided by CECT regarding the nature and location of spinal cord compression.
- To validate CECT for measuring the minimum sagittal diameter (MSD) and assess its correlation with generalized vertebral canal stenosis in CSM.
Main Methods:
- Six horses with confirmed CSM and three unaffected control horses were examined.
- Myelography and CECT were performed on all horses.
- Histopathology of the spinal cord was used as the gold standard to identify compressive lesions.
- Minimum sagittal diameter (MSD) measurements from CECT were compared with necropsy measurements.
Main Results:
- Both myelography and CECT identified all 10 histopathologically confirmed compressive lesions.
- CECT had a lower rate of false positives (1 lesion) compared to myelography (2 lesions).
- CECT provided detailed qualitative information on lesion source, severity, and location, including vertebral canal stenosis and peripheral nerve root compression.
- CECT-derived MSD values strongly correlated with necropsy measurements.
- CSM-affected horses showed significantly narrowed MSD values (P < 0.05) from C3-C6 compared to controls.
Conclusions:
- CECT is a highly accurate and valuable tool for diagnosing spinal cord compression in horses with CSM, offering detailed qualitative insights.
- CECT effectively quantifies vertebral canal stenosis, a key feature in CSM pathogenesis.
- CECT-validated measurements confirm generalized vertebral canal stenosis as a significant factor in CSM development.
Abstract:
The cervical spines of 6 horses with cervical stenotic myelopathy (CSM) were examined using myelography and contrast-enhanced computed tomography (CECT). Histopathology of the spinal cord of these horses identified 10 neurologically significant compressive lesions. Myelography and CECT were both able to demonstrate all 10 spinal cord compressive lesions, but myelography falsely identified 2 sites and CECT falsely identified 1 site as compressive lesions of the spinal cord which were not supported by histopathology. Additional qualitative information was obtained by CECT regarding the source, severity and location of spinal cord compression. Computed tomography identified stenosis of the vertebral canal with circumferential loss of contrast agent and documented lateral compressive lesions of the spinal cord due to malformed articular facets. Compression of the peripheral nerve roots by malformed articular facets encroaching on the intervertebral foramen was easily identified by CECT in the axial plane. No compressive lesions were identified in 3 unaffected horses by either method. Minimum sagittal diameter (MSD) values obtained from CECT images were strongly correlated with necropsy measurements, validating CECT as an accurate method of obtaining MSD values. The MSD values in the CSM-affected horses were significantly narrowed (P less than 0.05) from C3C6 regardless of the site of spinal cord compression, when compared with the unaffected controls. This finding supports previous reports suggesting that generalised stenosis of the vertebral canal is an important feature in the pathogenesis of cervical stenotic myelopathy.