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5.5-year-old FS Borzoi Painful episodes. Painful when touched on nose or head. Hx of mass-like lesion in nasopharynx. Previous cervical MRIs elsewhere: 10/17/15 – No macroscopic clinically significant lesions 10/25/15 – Contrast enhancing small lesion at left-sided C2, Surgically excised following MRI, Histopathologic Dx – fibroblastic meningioma 12/03/15 – No macroscopic clinically significant lesions

DICOM download available here; videos below

T2-sagittal and transverse images of the cranial cervical vertebral column

T2-sagittal and transverse images of the caudal cervical vertebral column

Dorsal STIR images of the cranial cervical vertebral column

Dorsal STIR images of the caudal cervical vertebral column

T1-weighted images, transverse, cranial cervical vertebral column

T1-weighted images, transverse, caudal cervical vertebral column

T2* imaging of the caudal cervical vertebral column

What's Your Diagnosis? Answers revealed after the Imaging Interpretation Session

– no abnormal contrast enhancing tissue at cranial C2 where prior mass was excised

– spinal cord parenchyma and spinal nerves are normal signal intensity and do not abnormally contrast enhance at the prior surgery site.

– surgery site is unremarkable for this postoperative period (>1.5 years)

– persistent small low signal focus in left venous sinus at caudal C6 in all imaging series and no flow artifact is identified this area of the venous sinus in any imaging series – left venous sinus is mildly enlarged

– in the T2* images, there is a tubular low signal or signal void structure within the left venous sinus from midbody of C6 to caudal endplate (1.5 cm).

1) No evidence of meningioma regrowth at cranial C2 nor secondary myelopathy

2) Left venous sinus thrombosis at caudal C6 (left-sided).

A hemilaminectomy was performed at C6-7 and a thrombus was removed from the left venous sinus. PT/PTT were run prior to surgery because of suspicion for a coagnulopathy; both were within normal limits. Dog recovered from surgery and treated with warfarin therapy. An underlying etiology for the cervical thrombosis was not identified. The meningioma diagnosis from Oct 25 was also questioned and re-review by pathologist speculated that the tissue has some features of non-neoplastic tissue that could have been associated with thrombosis and scar tissue. The dog represented in Jan 2018 with recurrent painful episodes. A new venous thrombus was identified. With this event, warfarin therapy and pain management was instituted, and thrombosis and pain resolved. Vertebral venous anomalies have been reported in sighthound and an association with these and clinical signs have been hypothesized. In this case, the thrombosis was confirmed, as well as subsequent cervical venous sinus thrombosis. There is a suspicion that the tissue removed at C2 could have been an initial thrombosis event as well.

1) Vernon et. al. (2017). Vertebral venous system abnormalities identified with magnetic resonance imaging in sighthounds. Vet Radiol Ultrasound. (2017). Jul;58(4):399-410. doi: 10.1111/vru.12492. Epub 2017 Mar 23.

2) Rhue et al. (2017) Bilateral Vertebral Venous Sinus Thrombosis Causing Cervical Spinal Cord Compression in a Dog. Front. Vet. Sci., 08 February 2017 |

3) Bozynski et al. (2012). Compressive Myelopathy Associated With Ectasia of the Vertebral and Spinal Arteries in a Dog. Veterinary Pathology, 49(5), 779–783.