• Multifocal soft tissue attenuating nodular-like foci are distributed throughout the arachnoid space from C2 to T4
• Areas where these coalesce cause varying degrees of spinal cord compression, which is severe at mid C2, mild to moderate at C3 and mildly at C6; range HU = 65-80
• Circumferential thinning of the arachnoid contrast, indicative of an intramedullary lesion, is seen at the caudal aspect of C5 with central HU = 65-75
• Possible bilateral increased size of the dorsal and ventral nerve roots of C7 & C8
• No extradural abnormalities in the cervical or cranial thoracic spine
• Caudal neurocranium is normal, aside from large accumulations of contrast in the arachnoid space and ventricles.
• No paraspinal abnormalities.

1) Multinodular cervical & cranial thoracic intradural-extramedullary foci.

2) Secondary multifocal spinal cord compression – most severe at midbody of C2

3) Intramedullary lesion at caudal C5

4) Possible bilateral C7 & C8 dorsal and ventral nerve root enlargement.

There were two lesions that could explain the acute paraplegia, either a transverse myelitis at caudal C5 or the cord compression at C2. With the elevated Houndsfield units, there was concern for a hemorrhagic component for all of the lesions. In a middle age Doberman, a coagulopathy was considered. This dog was a vonWillibrand heterogeneous carrier. It was unknown to the owner if there had been any prior issues with bleeding since she had only adopted dog 3 months prior. However, the CSF acquired was subjectively more hemorrhagic than the neurologist expected for the smoothness of the procedure. There are minimal reports in dogs of multiple intradural-extramedullary spinal lesions, including multifocal nephroblastoma in a 1-year-old Pitbull and presumed steroid responsive meningoarteritis (SRMA) in a 9-month-old Weimaraner. In people, tumors predominate the diagnoses, but multiple cysts are also reported. Therefore, neoplasia was also considered for this dog.

Following the CT procedures, surgical decompression for the C2 lesions was discussed with the owner, recognizing this would be more a diagnostic procedure that therapeutic because of the C5 lesion. The owner did not want to pursue surgery because of concern there would not be therapeutic value. Thoracic and abdominal radiographs were performed to screen for neoplasia; no abnormalities were identified.

In the interim, the CSF analysis revealed a severe inflammation. The CSF results more specifically were: colorless, hazy, WBC = 2360 normal (0-5), RBC = 50 (normal = 0), protein = 342 and glucose = 75. The nucleated cell count was 81-82% lymphocytes, 12-13% nondegenerate neutrophils and 5-7% large mononuclear cells. The lymphoid population is predominated by small lymphocytes. No evidence of an infectious agent or neoplasia. CSF were assessed further with culture and sensitivity, titres and PARR to exclude lymphoma. All were negative The owner had elected for empirical medical management based on the CT exam and initial CSF results.

Steroid therapy and antibiotics were initiated. Within the week following the exam, the dog could stand and would take a few steps with support. There was continued improvement at the 2 week recheck. Antibiotic therapy was discontinued based on the results additional CSF testing. The dogs was walking with some support due to residual ataxia at 6 months. It was lost to follow-up at this point.

In conclusion, the most appropriate presumptive diagnosis in this cases is an sterile inflammatory myelopathy. Based on response to medical management, it could be considered a steroid-responsive myelitis and arachnoiditis (true SRMA is typically predominated by neutrophils). Bleeding events remain possible as well and may have contributed to the episodic signs that rapidly progressed to plegia.

References

Kutara et al. ( 2019) Magnetic resonance imaging findings of an intradural extramedullary hemangiosarcoma in a dog. J Vet Med Sci. 2019 Oct 24;81(10):1527-1532. doi: 10.1292/jvms.19-0260. Epub 2019 Sep 4.

Henker et al. (2018) Multifocal Spinal Cord Nephroblastoma in a Dog. J Comp Pathol. 2018 Jan;158:12-16. doi: 10.1016/j.jcpa.2017.10.176. Epub 2017 Dec 1.