Resumen de Osseous-associated cervical spondylomyelopathy in dogs: 27 cases (2000–2012)
Objective—To evaluate the signalment, neurologic examination and imaging findings, and outcome in dogs treated medically or surgically for osseous-associated cervical spondylomyelopathy (OACSM).
Design—Retrospective case series.
Animals—27 client-owned dogs.
Procedures—Medical records for dogs with OACSM (diagnosis made in 2000 through 2012) were reviewed. Collected data included signalment, neurologic examination findings (graded from 0 [normal] to 5 [tetraplegia]), imaging findings, treatment, and outcome. From MRI and CT images, measurements were obtained for subjective grading of spinal cord compression.
Results—Among the 27 dogs, the median age was 2 years; there were 15 Great Danes, 3 Mastiffs, 3 Newfoundlands, and 6 other large-breed dogs. For medically treated dogs (n = 7), the median initial neurologic grade was 2; for surgically treated dogs (20), the median initial neurologic grade was 3. Magnetic resonance imaging revealed dorsolateral spinal cord compression in 22 dogs and lateral spinal cord compression in 5 dogs. Dogs with more severe compressions were slightly more likely to undergo surgical than medical treatment. Median survival time of medically treated dogs was 43 months, and that of surgically treated dogs was 60 months. Fifteen of 19 dogs treated surgically had improved neurologic grades at 4 to 8 weeks after surgery and had a good to excellent long-term outcome.
Conclusions and Clinical Relevance—Surgical treatment of dogs with OACSM resulted in neurologic improvement and was associated with a good long-term outcome. For dogs that received medical treatment, neurologic deterioration continued but some patients did well for several years. (J Am Vet Med Assoc 2014;244:1309–1318) Cervical spondylomyelopathy is a neurologic syndrome that affects large- and giant-breed dogs. The syndrome encompasses lesions involving osseous and soft tissue structures of the cervical portion of the vertebral column that result in vertebral canal stenosis.1,2 Dogs with CSM can be classified into 2 groups: those with OACSM and those with DACSM.3,4 Dogs with OACSM are usually young (1- to 3-year-old) large- and giant-breed dogs; vertebral malformation or degenerative changes of the vertebral arches, including the lamina and articular facet joints with degenerative changes of the joints including synovial cysts5 and joint capsule proliferation, result in dorsal or dorsolateral spinal cord compression. These dogs may also have malformation of the pedicles resulting in lateral spinal cord compression.1,2 Dogs with DACSM are usually middle-aged large-breed dogs (primarily Doberman Pinschers) that have a Hansen type II disk protrusion with or without vertebral malformation and ligament flavum hypertrophy, which typically results in ventral spinal cord compression.3,6 Magnetic resonance imaging has become the diagnostic imaging tool of choice for detection of CSM in dogs.7,8 The etiopathogenesis of CSM is thought be multifactorial with genetic, congenital, conformational, and nutritional components.2,3,9–13 One study14 in Borzoi revealed a recessive mode of inheritance of CSM.
Many of the veterinary medical articles published in the last decade regarding CSM in dogs have focused on DACSM.6,8,9,15–19 Reports17,20–26 of dogs with OACSM are fewer, and the information regarding cases of OACSM was often combined with information regarding cases of DACSM. In a recent MRI study27 of 13 Great Danes with CSM, osteoarthritic changes of the articular facet joints were found to be common; 81 of 94 (86%) evaluated joints in the cervical portion of the vertebral column were affected.
In studies of dogs28,a and horses29 with cervical spinal cord compression, various measurements of the vertebrae and vertebral canal have been obtained to assess spinal cord compression. Cervical vertebral ratios30 and intervertebral and intravertebral ratios28 were not found to be clinically useful. In studies31,32 in which Doberman Pinschers with DACSM were compared with unaffected dogs, thresholds to differentiate between the 2 groups on the basis of radiographic or MRI findings could not be established. In horses, there was no significant difference in spinal cord height, width, or area between those with and those without cervical spinal cord compression.29 Another studya evaluated Great Danes with OACSM with regard to loss of epidural fat and presence of dorsal and lateral spinal cord compressions but did not measure the spinal cord in affected versus unaffected areas.
Surgical decompression by dorsal cervical laminectomy is the treatment of choice for spinal cord compressions caused by the articular facet joints, laminae, ligamentum flavum, or multiple ventral disk protrusions.3,20 The surgical technique has been described previously.2,10,33,34 In a review of 20 dogs treated with dorsal cervical laminectomy for CSM caused by either dorsal or ventral spinal cord compression, 14 (70%) of the dogs were neurologically worse 2 days after surgery.20 The aim of the study reported here was to retrospectively determine the signalment, neurologic examination findings, CSF analysis findings if available, and advanced imaging findings of dogs with OACSM and to assess the outcome for patients that underwent surgical treatment (dorsal cervical laminectomy) or medical treatment. Secondary goals were to develop more objective criteria for grading the severity of compression on MRI and to determine whether there was a correlation between degree of spinal cord compression and the severity of neurologic signs. Our hypothesis was that in dogs with OACSM, the compression from the articular facet joints may cause diagonal compression of the spinal cord without affecting the height or width of the spinal cord.
