Morphometrical Study of the Lumbar Segment of the Internal Vertebral Venous Plexus in Dogs: A Contrast CT-Based Study

Abstract

The internal vertebral venous plexus (IVVP) is a thin-walled, valveless venous network that is located inside the vertebral canal, communicating with the cerebral venous sinuses. The objective of this study was to perform a morphometric analysis of the IVVP, dural sac, epidural space and vertebral canal between the L1 and L7 vertebrae with contrast-enhanced computed tomography (CT). Six clinically healthy adult dogs weighing between 12 kg to 28 kg were used in the study. The CT venographic protocol consisted of a manual injection of 880 mgI/kg of contrast agent (587 mgI/kg in a bolus and 293 mgI/mL by continuous infusion). In all CT images, the dimensions of the IVVP, dural sac, and vertebral canal were collected. Dorsal reconstruction CT images showed a continuous rhomboidal morphological pattern for the IVVP. The dural sac was observed as a rounded isodense structure throughout the vertebral canal. The average area of the IVVP ranged from 0.61 to 0.74 mm2 between L1 and L7 vertebrae (6.3–8.9% of the vertebral canal), and the area of the dural sac was between 1.22 and 7.42 mm2 (13.8–72.2% of the vertebral canal). The area of the epidural space between L1 and L7 ranged from 2.85 to 7.78 mm2 (27.8–86.2% of the vertebral canal). This CT venography protocol is a safe method that allows adequate visualization and morphometric evaluation of the IVVP and adjacent structures.

Prevalence and clinical features of thoracolumbar intervertebral disc‐associated epidural hemorrhage in dogs

“…In humans, the epidural venous plexus is most prominent in the thoracic spine, and spontaneous spinal epidural hematomas most often occur in the thoracic and cervicothoracic region, followed by the thoracolumbar area 5,6,14,15 . In dogs, the venous plexus has been evaluated morphometrically in the cervical and lumbar spine 16‐18 . In a study evaluating the lumbar intervertebral venous plexus, the venous plexus was found to occupy the highest percentage of area relative to the vertebral canal most cranially at L1 18 .…”

“… 5 , 6 , 14 , 15 In dogs, the venous plexus has been evaluated morphometrically in the cervical and lumbar spine. 16 , 17 , 18 In a study evaluating the lumbar intervertebral venous plexus, the venous plexus was found to occupy the highest percentage of area relative to the vertebral canal most cranially at L1. 18 Given these findings, the potential for EH should be considered more highly in French Bulldogs with neurologic exam abnormalities localizing more cranially.…”

Vertebral vascular canal dysplasia in French and English Bulldogs: Clinical, CT, and MRI characteristics and prevalence

“…Yet, until recently, studies on the CT anatomy of venous drainage of the vertebral column and associated structures in dogs did not specifically visualize the basivertebral veins 30,31 . A recent publication did just so, although this study did not specifically report on the osseous canal or foramina in the vertebral body that allow passage of this often paired vein 32 . What characterizes a vascular canal of the vertebral body as “normal” (i.e., what dimensions or shapes are deemed “normal”) is not reported in veterinary literature.…”

“…30,31 A recent publication did just so, although this study did not specifically report on the osseous canal or foramina in the vertebral body that allow passage of this often paired vein. 32 What characterizes a vascular canal of the vertebral body as "normal" (i.e., what dimensions or shapes are deemed "normal") is not reported in veterinary literature. In human literature, several characteristics of basivertebral foramina and the basivertebral canal are published.…”

Advances in Animal Anatomy

“…The other species of domestic mammals studied in three of the articles were the dog and the cat. The research article by Ariete et al [ 5 ], which referred to the canine internal vertebral venous plexus (IVVP) of the lumbar segment, used contrast-enhanced computed-tomography (CT) to conduct a morphometrical study of the aforementioned vessels, the dural sac, and the vertebral canal. As part of the vertebral venous plexus, this IVVP is made of a paired thin-walled and valveless venous vessels with a rhomboidal pattern, placed on the floor of the vertebral canal, and included in the lumbar epidural space.…”