Experimental chronic compressive cervical myelopathy

Abstract

v, A canine model simulating both cervical spondylosis and its results in delayed progressive myelopathy is presented. This model allowed control of compression, an ongoing assessment of neurological deficits, and evaluation using diagnostic images, frequent electrophysiological tests, local blood flow measurements, and postmortem histological examinations. Subclinical cervical cord compression was achieved in 14 dogs by placing a Teflon washer posteriorly and a Teflon screw anteriorly, producing an average of 29% stenosis of the spinal canal. Four dogs undergoing sham operations were designated as controls. Twelve of the animals undergoing compression developed delayed and progressive clinical signs of myelopathy, with a mean latent period to onset of myelopathy of 7 months.Spinal cord blood flow studies using the hydrogen clearance method showed a significant transient increase in blood flow immediately after compression and a decrease before sacrifice. Somatosensory evoked potential studies indicated progressive deterioration during the period of compression. Magnetic resonance images revealed intramedullary changes. Histological studies showed abnormalities overwhelmingly within the gray matter, including changes in vascular morphology, loss of large motor neurons, necrosis, and cavitation. Axonal degeneration and obvious demyelination were rarely seen. The most profound morphological changes occurred at the site of greatest compression. It is proposed that a momentary arrest of microcirculation occurs during extension of the neck because of loss of the reserve space in the compromised spinal canal. This microcirculatory disturbance is predominant in the watershed area of the cord and mainly affects the highly vulnerable anterior horn cells, leading to neuronal death, necrosis, and eventual cavitation at the junction of the dorsal and anterior horns. Additional supportive evidence of this hypothesis was derived from the literature. KEY WORDS 9 cervical spondylosis 9 cervical myelopathy 9 spinal cord compression 9 magnetic resonance imaging 9 somatosensory evoked potentials 9 dog

Degenerative spondylolisthesis does not influence surgical results of laminoplasty in elderly cervical spondylotic myelopathy patients

“…In elderly Japanese CSM patients, the rate of occurrence of dynamic factors, such as instability of the vertebral column [1,[6][7][8]29], was shown to be higher than for static factors, such as developmental canal stenosis [24], by radiological analysis [26]. Furthermore, CSM patients 65 years and older with spondylolisthesis had a high incidence of degenerative spondylolisthesis (DS) at C3-C4 or C4-C5 [14].…”

Pathobiology of cervical spondylotic myelopathy

“…Using a series of arguments, different groups have expressed their uncertainty as to whether ischemia is a crucial physiological event in CSM. Specifically, a number of clinical and experimental protocols demonstrate that patients or laboratory animals with moderate CSM have no [21] or only mild signs of ischemia [22,23] while pathologic evidence of ischemia is found only when severe canal stenosis is coexisting [24,25]. Moreover, some experimental studies found only minor changes in blood flow during compression and decompression [26].…”

Risk of spinal cord injury in patients with cervical spondylotic myelopathy and ossification of posterior longitudinal ligament: a national cohort study

“…Although the supporters of conservative treatment may assert the fact that the failure rate for surgical treatment may account for 15%-30% of the cases, 26 surgical decompression and stabilization of the spine is nonetheless advocated for patients with progressive or severe symptoms of CSM. 1,7,8,26 In a previous large data study conducted by Wu et al, cervical SCI was found to be more likely to happen in patients with OPLL, with an estimated 32.16-fold higher risk than in the age-and sex-matched group. 31 That being said, conservative treatment for patients with established OPLL should be conducted with great caution.…”