Cervical Spondylomyelopathy - Disc Associated (Wobbler’s Syndrome)
Cervical spondylomyelopathies encompasses a number of cervical vertebral abnormalities. These include vertebral malarticulation/malformation, intervertebral disk extrusion and protrusion, articular facet disease, and spinal ligamentous disease. These abnormalities often result in ataxia or a “wobbly” gait, hence the clinically descriptive term used. The constellation of these pathologic alterations contribute to the diverse clinical and pathologic conditions grouped together under the heading “wobbler syndrome”. Hence, wobbler syndrome does not describe a single specific disease entity.
While the pathophysiologic processes associated with these clinical abnormalities are complex, two general clinical manifestations predominate: an osseous-associated form in younger large to giant breed dogs and a disc-associated form in older large breed dogs.
The form of wobbler syndrome as epitomized in the middle-aged to older Doberman is characterized by ventral compressive spinal cord lesions primarily in the caudal cervical area. These lesions result primarily from ligamentous hypertrophy and intervertebral disk (usually annulus fibrosis) protrusion. While the pathophysiology of this disease is not entirely understood, some degree of caudal cervical instability possibly coupled with increased flexion force (due to the pull of gravity in a comparatively large head size) predisposes to damage to the intervertebral disk elements and the associated vertebral articulations. The associated vertebral abnormalities are more often a secondary change associated with the consequences of IVDD and the subsequent pathological forces placed upon the vertebral elements. It is also possible that an inherent degeneration occurs in the intervertebral disk as an initiating factor as the disk itself provides significant stability to the spinal column. It is also possible that some degree of vertebral malformation predisposes to the IVDD. Hypertrophy of the associated ligamentous supporting structures (dorsal longitudinal ligament, dorsal intervertebral ligament, ligamentum flavum) is most likely a secondary reaction of the body in an attempt to decrease this instability and “strengthen” or to naturally “fuse” these vertebral segments. Bony malformation alone rarely results in spinal cord compression in this clinical condition. Hypertrophied “soft” tissue, however, often encroaches into the vertebral canal, eventually leading to spinal cord compression. In addition to compression damage to axons and neurons, impingement of spinal cord vessels results in ischemic damage to the spinal cord. This ischemic spinal cord injury often contributes significantly to the clinical signs. In some instances, actual extrusion of nuclear material from the intervertebral disk may also occur.
While the pathophysiologic processes associated with these clinical abnormalities are complex, two general clinical manifestations predominate: an osseous-associated form in younger large to giant breed dogs and a disc-associated form in older large breed dogs.
The form of wobbler syndrome as epitomized in the middle-aged to older Doberman is characterized by ventral compressive spinal cord lesions primarily in the caudal cervical area. These lesions result primarily from ligamentous hypertrophy and intervertebral disk (usually annulus fibrosis) protrusion. While the pathophysiology of this disease is not entirely understood, some degree of caudal cervical instability possibly coupled with increased flexion force (due to the pull of gravity in a comparatively large head size) predisposes to damage to the intervertebral disk elements and the associated vertebral articulations. The associated vertebral abnormalities are more often a secondary change associated with the consequences of IVDD and the subsequent pathological forces placed upon the vertebral elements. It is also possible that an inherent degeneration occurs in the intervertebral disk as an initiating factor as the disk itself provides significant stability to the spinal column. It is also possible that some degree of vertebral malformation predisposes to the IVDD. Hypertrophy of the associated ligamentous supporting structures (dorsal longitudinal ligament, dorsal intervertebral ligament, ligamentum flavum) is most likely a secondary reaction of the body in an attempt to decrease this instability and “strengthen” or to naturally “fuse” these vertebral segments. Bony malformation alone rarely results in spinal cord compression in this clinical condition. Hypertrophied “soft” tissue, however, often encroaches into the vertebral canal, eventually leading to spinal cord compression. In addition to compression damage to axons and neurons, impingement of spinal cord vessels results in ischemic damage to the spinal cord. This ischemic spinal cord injury often contributes significantly to the clinical signs. In some instances, actual extrusion of nuclear material from the intervertebral disk may also occur.
Age of Onset: Greater than 5 years of age
Sex Predisposition: Any sex of animal can be affected
Clinical Course:
Signs usually progress relatively slowly over weeks to months. Occasionally, acute exacerbation of clinical signs may occur
Signs usually progress relatively slowly over weeks to months. Occasionally, acute exacerbation of clinical signs may occur
Clinical Signs:
Posture and Appearance
Scuffing of nails on weight-bearing digits of the pelvic limbs
Head may be held in a flexed position
Movement
Ambulatory tetraparesis (pelvic limbs are typically worse than the thoracic limbs)
Truncal ataxia
Proprioception
General proprioceptive deficits to the pelvic limbs
Muscle Atrophy
Atrophy of the supraspinatus and infraspinatus muscles
Posture and Appearance
Scuffing of nails on weight-bearing digits of the pelvic limbs
Head may be held in a flexed position
Movement
Ambulatory tetraparesis (pelvic limbs are typically worse than the thoracic limbs)
Truncal ataxia
Proprioception
General proprioceptive deficits to the pelvic limbs
Muscle Atrophy
Atrophy of the supraspinatus and infraspinatus muscles
Spinal - Cervical spinal cord
Disc-Associated: C5-C7
Disc-Associated: C5-C7
Unknown
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