Bilateral Vertebral Venous Sinus Thrombosis Causing Cervical Spinal Cord Compression in a Dog

Abstract

A 10-year-old male neutered mixed breed dog was evaluated for cervical hyperesthesia and tetraparesis. Magnetic resonance imaging of the brain and cervical spinal cord identified an extradural compressive lesion over the body of C2 caused by marked dilation of the vertebral venous sinuses. Following intravenous contrast administration both vertebral sinuses had heterogeneous contrast enhancement consistent with incomplete thrombi formation. An abdominal ultrasound also showed a distal aortic thrombus. A definitive cause for the thrombi formation was not identified, but the patient had several predisposing factors which may have contributed. The patient was treated with a combination of warfarin, clopidogrel, and enoxaparin as well as analgesics. Within 48 h of initiation of warfarin therapy, the tetraparesis and hyperesthesia were markedly improved. Repeat abdominal ultrasound 3 weeks after discharge showed reduction in size of aortic thrombus. Neurologic function remained normal for 6 weeks following initiation of treatment. Seventy-four days following initial diagnosis the patient rapidly declined and passed away at home. Necropsy was declined. This is the first report of vertebral venous sinus enlargement leading to spinal cord compression and tetraparesis in a dog. Additionally, warfarin in combination with clopidogrel and enoxaparin appeared to be a safe and effective treatment for the suspected thrombi reported in this case. Vertebral sinus enlargement secondary to thrombi should be considered as a differential diagnosis in patients presenting with tetraparesis and cervical hyperesthesia.

Keywords: MRI; coagulation; tetraparesis; thrombus; warfarin.

Figure 1

Left parasagittal images in (A) T2, (B) T1, and (C) T1 + C weighting. These depict the enlargement of the vertebral venous plexus/sinus resulting in the compression and dorsal elevation of the spinal cord. Enlargement of this plexus is present from the cranial aspect of C2 to the caudal aspect of C6.

Figure 2

Transverse images at the level of the mid body of C2, in (A) T2, (B) T2*, (C) T1, and (D) T1 + C weighting. The arrow indicates the signal void on the T2* image.

Figure 3

Reconstruction of the vertebral venous plexus (asterisks), vertebral veins (arrowheads), and internal carotid arteries (arrows). The intensity of the red signal indicates contrast enhancement, while the blue signal is less contrast enhanced. The heterogeneity of the blue signal in the plexus indicates heterogenous material in the sinus or turbulent flow.