Compressive Cervical Myelopathy in Young Texel and Beltex Sheep

Cervical Vertebral Stenotic Myelopathy in a Nelore Calf

This paper aims to report clinical, laboratory, radiographic, and pathological features in a case of cervical vertebral stenotic myelopathy (CVSM) affecting a 4-month-old Nelore calf for the first time. During physical examination, the calf could stand if assisted when lifting by the tail but fallen to the ground when trying to walk. Attempts to flex and extend the neck to the right side failed. Radiographs findings consisted of reduced intervertebral spaces, and misalignments between the endplates, more evident between the C3 and C4 vertebrae, resulting in narrowing of the spinal canal and compression of the spinal cord. Grossly, C4 showed cranial articular surface malformation, abnormal metaphyseal growth plate development, reduced vertebral body size and deformity. Histologically, C4 showed an abnormal vertebral bone development characterized by moderate replacement of trabecular bone by fibrous tissues, multifocal areas of dystrophic hyaline cartilage development, and cartilaginous growth failure along the metaphyseal growth plate. Cervical spinal cord within the stenotic vertebral canal showed swollen neurons with central chromatolysis, areas of Wallerian degeneration, and necrotic debris. In contrast with the well-known Wobbler syndrome in horses, the etiology of CVSM in cattle remains undetermined, and further genetic and pathological studies must be conducted to elucidate it.

Extent of cord pathology in the lumbosacral enlargement in non-traumatic versus traumatic spinal cord injury

This study compares remote neurodegenerative changes caudal to a cervical injury in degenerative cervical myelopathy (DCM) (i.e., non-traumatic) and incomplete traumatic spinal cord injury (tSCI) patients, using MRI-based tissue area measurements and diffusion tensor imaging (DTI). Eighteen mild to moderate DCM patients with sensory impairments (mJOA score: 16.2±1.9), 14 incomplete tetraplegic tSCI patients (AIS C&D), and 20 healthy controls were recruited. All participants received DTI and T2*-weighted scans in the lumbosacral enlargement (caudal to injury) and at C2/C3 (rostral to injury). MRI readouts included DTI metrics in the white matter (WM) columns and cross-sectional WM and gray matter area. One-way ANOVA with Tukey's post-hoc comparison (p<0.05) was used to assess group differences. In the lumbosacral enlargement, compared to DCM, tSCI patients exhibited decreased fractional anisotropy in the lateral (tSCI vs. DCM, -11.9%, p=0.007) and ventral WM column (-8.0%, p=0.021), and showed trend toward lower values in the dorsal column (-8.9%, p=0.068). At C2/C3, compared to controls, fractional anisotropy was lower in both groups in the dorsal (DCM vs. controls, -7.9%, p=0.024; tSCI vs. controls, -10.0%, p=0.007) and in the lateral column (DCM: -6.2%, p=0.039; tSCI: -13.3%, p<0.001), while tSCI patients had lower fractional anisotropy than DCM patients in the lateral column (-7.6%, p=0.029). WM areas were not different between patient groups but were lower compared to controls in the lumbosacral enlargement (DCM: -16.9%, p<0.001; tSCI, -10.5%, p=0.043) and at C2/C3 (DCM: -16.0%, p<0.001; tSCI: -18.1%, p<0.001). In conclusion, mild to moderate DCM and incomplete tSCI lead to similar degree of degeneration of the dorsal and lateral columns at C2/C3, but tSCI results in more widespread white matter damage in the lumbosacral enlargement. These remote changes are likely to contribute to the patients' impairment and recovery. DTI is a sensitive tool to assess remote pathological changes in DCM and tSCI patients.

The Pathophysiology of Degenerative Cervical Myelopathy and the Physiology of Recovery Following Decompression

Background: Degenerative cervical myelopathy (DCM), also known as cervical spondylotic myelopathy is the leading cause of spinal cord compression in adults. The mainstay of treatment is surgical decompression, which leads to partial recovery of symptoms, however, long term prognosis of the condition remains poor. Despite advances in treatment methods, the underlying pathobiology is not well-known. A better understanding of the disease is therefore required for the development of treatments to improve outcomes following surgery. Objective: To systematically evaluate the pathophysiology of DCM and the mechanism underlying recovery following decompression. Methods: A total of 13,808 published articles were identified in our systematic search of electronic databases (PUBMED, WEB OF SCIENCE). A total of 51 studies investigating the secondary injury mechanisms of DCM or physiology of recovery in animal models of disease underwent comprehensive review. Results: Forty-seven studies addressed the pathophysiology of DCM. Majority of the studies demonstrated evidence of neuronal loss following spinal cord compression. A number of studies provided further details of structural changes in neurons such as myelin damage and axon degeneration. The mechanisms of injury to cells included direct apoptosis and increased inflammation. Only four papers investigated the pathobiological changes that occur in spinal cords following decompression. One study demonstrated evidence of axonal plasticity following decompressive surgery. Another study demonstrated ischaemic-reperfusion injury following decompression, however this phenomenon was worse when decompression was delayed. Conclusions: In preclinical studies, the pathophysiology of DCM has been poorly studied and a number of questions remain unanswered. The physiological changes seen in the decompressed spinal cord has not been widely investigated and it is paramount that researchers investigate the decompressed spinal cord further to enable the development of therapeutic tools, to enhance recovery following surgery.

Inadvertent intrathecal injection of Gudair vaccine leading to recumbency and ataxia in replacement gimmers: a case of ‘OJD staggers’ in North East England

Five of 730 replacement gimmers in a 5000-ewe crossbred flock presented with progressive ataxia and recumbency over a two-week period. On gross postmortem examination, there was spinal cord compression and large fibrogranulomatous masses in the spinal canal of two lambs. Histological examination of one mass and the adjacent tissues revealed chronic active necrotising and granulomatous inflammation with acid-fast bacilli and severe granulomatous osteomyelitis, respectively. PCR of the mass was positive for Mycobacterium aviumsubspecies paratuberculosis (MAP). Lambs had been injected six weeks previously with a Johne’s disease vaccine (Gudair, Merial Animal Health). Gross and histological findings unequivocally suggest an intrathecal injection; the acid-fast bacilli and PCR-positive result for MAP confirm that the maladministration of vaccine was the cause of the pathology. Great care must be taken when injecting sheep in the neck region to avoid iatrogenic damage. Clinical signs may manifest some weeks or months after injection.

Pathobiology of Degenerative Cervical Myelopathy

Degenerative cervical myelopathy (DCM) is a common spinal cord disease caused by chronic mechanical compression of the spinal cord. The mechanism by which mechanical stress results in spinal cord injury is poorly understood. The most common mechanisms involved in the pathobiology of DCM include apoptosis, inflammation, and vascular changes leading to loss of neurons, axonal degeneration, and myelin changes. However, the exact pathophysiologic mechanisms of DCM are unclear. A better understanding of the pathogenesis of DCM is required for the development of treatments to improve outcomes. This review highlights the mechanisms of injury and pathology in DCM.