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- Title
Spinale Ataxie aufgrund einer Halsmarkskompression verursacht durch ein Melanom im extraduralen atlantookzipitalen Halsbereich bei einem ataktischen Pony.
- Authors
Brunner, Selina; Fürst, Anton E.; Sánchez-Andrade, José Suárez; Rasper-Hössinger, Melina; Jackson, Michelle A.
- Abstract
This case report describes the case of a 16-year-old minishetlandpony gelding with acute and progressive ataxia. The horse was presented to the Equine Department of the Vetsuisse-Faculty of Zurich with a staggering gait, an ataxia grade 3/5 (according to Mayhew’s Ataxia Scale), as well as hindlimbs weakness to the point of falling over. In the neurological examination, the consciousness and behavior and the cranial nerves were normal, but the proprioception was decreased in all four limbs, especially in the hindlimbs. The symptoms could then be localized to a spinal cord problem in the cervical region. X-ray images of the cervical spine were taken; however, these showed only mild osteoarthritis of the synovial joints C5-C6 and C6-C7, probably an incidental finding, and could not explain the neurological symptoms. The pony was then discharged and a treatment with NSAID’s (Flunixin meglumin;1mg/kg BID, p.o.) started. At home, the symptoms deteriorated rapidly to the point of recumbency. The pony was readmitted few days later. The gait analysis showed stiff hindquarters and ataxia of 4/5. After 20 minutes the gelding was again recumbent and not able to get up alone. The next diagnostical step was a myelography followed by computed tomography with contrast medium. For this the horse was placed in general anesthesia. A cerebrospinal fluid puncture was performed in the median at the level of the cranial end of both atlas-wings. Cerebrospinal fluid was taken and sent for cytological examination. Next the contrast medium Omnipaque (Omnipaque® 350; 10–15ml/100kg, in total 20ml) was injected over the duration of 5 minutes. First, laterolateral images of the cervical spine were obtained in normal position, as well as in hyperextension and hyperflexion. Immediately after the radiological examination, a computed tomographic examination of the entire spine was performed using a 40-slice helical CT scanner (Somatom Sensation Open, Siemens AG, Switzerland). In the CT images a well-limited, large mass dorsal and to the right of the spinal cord and medulla oblongata could be clearly identified. The mass showed to be soft tissue dense and resulted in a high-grade extradural compression of the spinal cord at C1-C2. Thus, the diagnosis after CT myelography was a soft tissue dense mass at C1-C2, in the epidural space, leading to extradural compression of the spinal cord. Due to the advanced symptoms and the poor prognosis, the pony was euthanized and sent for a full post-mortem examination. Grossly, a 4cm round, dark gray to black mass was detected in the epidural space, in the area of the atlanto-occipital junction. The adjacent muscles around C1-C2, where the mass was located, showed a focal black discoloration. The spinal cord itself showed no macroscopic changes. Histological examination revealed an infiltratively growing mass into muscles and dura mater, that consisted of spindle-shaped to round neoplastic cells with dark-brown, granular cytoplasm. The neoplasm exhibited signs of malignancy like invasion of surrounding tissue and vessels and cell pleomorphism. No infiltration of tumor cells was detected in the spinal cord itself. However, a high-grade focal degenerative myelopathy could be detected. Finally, the diagnosis after dissection was a malignant melanocytic tumor (melanoma) in the vertebral canal at the atlanto-occipital junction with a consecutive high-grade focal degenerative myelopathy, which most likely had caused the neurological symptoms. This case shows that, also when no external melanomas are visible in a horse, internal melanomas cannot be excluded and the primary tumor can also occur in an atypical location, such as the spinal canal.
- Subjects
ZURICH (Switzerland); SWITZERLAND; AUTOPSY; SPINAL cord compression; JOINTS (Anatomy); SPINAL canal; CERVICAL vertebrae; SIEMENS AG; DURA mater; EPIDURAL space
- Publication
Pferdeheilkunde, 2024, Vol 40, Issue 2, p108
- ISSN
0177-7726
- Publication type
Article
- DOI
10.21836/PEM20240202