Long‐term clinical and magnetic resonance imaging follow‐up of dogs with osseous‐associated cervical spondylomyelopathy

Abstract

Background: Osseous-associated cervical spondylomyelopathy (OA-CSM) is a complex disorder with limited long-term survival. The longitudinal progression is currently unknown. Objective: To describe changes on magnetic resonance imaging (MRI) over a 2-year minimum period. We hypothesized that spinal lesions would progress in the majority of dogs. Animals: Eleven dogs previously diagnosed with OA-CSM were prospectively studied. Nine dogs were treated medically, whereas 2 were treated surgically. Methods: Clinical and MRI follow-up were performed with a median time between MRI studies of 30 months (range, 24-54). Morphologic assessment evaluated vertebral canal stenosis, spinal cord compression, foraminal stenosis, and articular processes, among other variables. Morphometric assessment included vertebral canal area, spinal cord area, area of the articular processes, and foraminal height. Results: On follow-up MRI, the most affected site at the initial examination in medically treated dogs had progressed in 4 of 9 dogs, improved in 4, and was unchanged in 3. Clinically, all dogs except 2 medically treated dogs were unchanged to improve at follow-up. Initially, 50 of 60 (83.3%) intervertebral spaces had vertebral canal stenosis, whereas in the follow-up MRI 82.3% did. Of the sites with stenosis, 45.7% were unchanged, 18.6% improved, and 38.9% worsened. Morphometry identified significant decreases in vertebral canal and spinal cord areas at C4-C5 through C6-C7, and significant progression of articular process irregularities at C3-C4 and C6-C7. Conclusions and Clinical Importance: This long-term follow-up study of dogs with OA-CSM did not identify clinical or MRI progression of lesions in the majority of dogs.

Association of neurologic signs with high‐field MRI findings in 100 dogs with osseous‐associated cervical spondylomyelopathy

“…However, a long-term MRI study of dogs with OA-CSM did not observe intervertebral disc protrusions in dogs with intervertebral disc degeneration and articular process degenerative changes after a median period of 30 months. 22 The percentage of dogs with extradural intraspinal cysts (25%) was similar to previous reports in OA-CSM. 1,4 In the present study, most of these dogs had cysts that were partially responsible for spinal cord and/or nerve root compression, although their long-term relevance is unknown.…”

“…Interestingly, two longterm follow-up studies of OA-CSM dogs using CT (median follow-up time 28 months) or MRI (median follow-up time 30 months) found that while imaging changes and clinical signs were likely to continue progressing slowly after diagnosis, a worsening of morphologic changes did not necessarily equate to a worsening of neurologic grade. 21,22 It is possible that OA-CSM is a genetically complex disease and that these younger dogs with more severe changes are a reflection of more severe, yet undetermined genetic factors.…”

“…1,4 In the present study, most of these dogs had cysts that were partially responsible for spinal cord and/or nerve root compression, although their long-term relevance is unknown. Canine extradural spinal cysts have been documented to develop over time, 22 as well as to reduce or resolve spontaneously without specific treatment. 22,27 A study limitation was that only the most severe site of compression was used in dogs with multiple sites of spinal cord compression, thus there may have been an underestimation of the importance of secondary compressive sites.…”

“…Canine extradural spinal cysts have been documented to develop over time, 22 as well as to reduce or resolve spontaneously without specific treatment. 22,27 A study limitation was that only the most severe site of compression was used in dogs with multiple sites of spinal cord compression, thus there may have been an underestimation of the importance of secondary compressive sites. Also, 92% of sites between C2 and T1…”

Comparing the clinical presentation and outcomes of dogs receiving medical or surgical treatment for osseous‐associated cervical spondylomyelopathy

“…One study found that although surgical management frequently resulted in neurologic improvement and offered a better long‐term prognosis, some medically managed dogs still had a good quality of life for several years 3 . Similarly, recent studies have demonstrated slow or no notable progression of clinical signs and imaging findings in dogs with OA‐CSM that were available for a follow‐up period of at least 18 months 11,12 …”