Spinal Epidural Venous Plexus Enlargement as a Cause of Neurologic Symptoms: Vascular Anatomy and MRI Findings
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.294546
Source of Support: None, Conflict of Interest: None
Keywords: Disc herniation, epidural plexus, inferior vena cava agenesis, intracranial hypotension, magnetic resonance imaging
In the differential diagnosis of radiculopathy and/or back pain, the most frequent etiologies include intervertebral disc herniation, followed by hematoma, tumor, and abscess., Epidural venous plexus dilation is an uncommon cause of these symptoms, and it is rarely reported in the literature., As pathological imaging features of the spinal venous system—unlike those of the spinal arterial system—are not well-known, vascular lesions within the epidural space are often overlooked or misdiagnosed. Here, we present imaging findings from three patients with neurologic symptoms caused by epidural venous engorgement of different etiologies.
A 45-year-old woman was admitted to the neurosurgery department with radiculopathy and severe lumbar pain. Lumbosacral magnetic resonance imaging (MRI) revealed a small, right-sided epidural lesion of mixed-signal intensity on T1-weighted images (T1WIs) and T2WIs, with heterogeneous contrast enhancement, located at the L2–L3 level [Figure 1]. The lesion was diagnosed by neurosurgeons as a disc herniation with slight disc fragment migration, although a radiologist suggested the presence of a coexisting epidural varix. During surgery, a congested and dilated epidural vein compressing the right L2 nerve roots was discovered, which caused massive and persistent bleeding. Slight disc protrusion was also observed. Hemostasis was successfully achieved with thermocoagulation, resulting in the reduction of vein volume and decompression of the dural sac and nerve roots.
A 43-year-old woman presented with a prolonged history of lumbar pain and radiculopathy, which were aggravated by activity and alleviated by rest. Lower limb varices were also observed. Lumbosacral MRI revealed numerous serpentine T1- and T2-hypointense lesions located epidurally within the spinal canal and around the vertebral column [Figure 2]. The lesions were diagnosed as dilated spinal venous plexuses. As the cause of the dilation was unclear, a computed tomography (CT) angiography of the abdominal vessels was performed, revealing inferior vena cava agenesis and extensive collateral circulation through the paravertebral veins and spinal venous plexuses [Figure 3]. Further follow-up was recommended.
A 43-year-old woman was admitted with suspected multiple sclerosis (MS). The diagnosis was confirmed by a lumbar puncture and brain MRI. On the second day after the procedure, the patient developed a postural headache and thoracic back pain. Thoracic spinal MRI revealed longitudinal T1- and T2-hypointense lesions located extradurally within the spinal canal [Figure 4] a and [Figure 4]b. The primary diagnosis was postpuncture hematoma; however, there had been no complications during lumbar puncture and the cerebrospinal fluid (CSF) was clear. In addition, the brain MRI revealed subtle thickening and enhancement of the pachymeninges and a slight downward shift of the cerebellar tonsils [Figure 5]. Ultimately, a diagnosis of postpuncture intracranial hypotension syndrome with engorged epidural veins was established. After 7 days of conservative treatment, the symptoms subsided and the epidural lesions were absent on follow-up spinal MRI [Figure 4] c and [Figure 4]d.
The venous drainage of the spine and spinal cord is complicated and extremely variable in its anatomy. It can be divided into intradural (intrinsic and extrinsic) and extradural components.
The intrinsic venous system is radially arranged within the spinal cord and drains into the sulcal veins (dorsal and ventral). The extrinsic system located at the level of the spinal pia includes the pial venous plexus, longitudinally oriented venous system, and radiculomedullary (radicular) veins. The pial collectors receive the sulcal veins and drain into the posterior and anterior median veins. The extrinsic system communicates with the epidural system via radicomedullary veins, which receive blood from anterior and posterior median veins and drain into external venous plexus. A unique zigzag course of those veins prevents reflux from the epidural veins into intradural veins.
The extradural system called the vertebral venous plexus (Batson plexus) is an extensive network of valveless veins running throughout the spine. It is divided into the following three sections:
The internal and external vertebral venous plexuses connect at the level of the intervertebral foramen. Finally, this system drains into the inferior vena cava, azygos vein, and pelvic veins. The vertebral venous plexuses also connect via anastomoses with the intracranial venous system and the veins of the scalp, skull, and face, as well as the sacral, pelvic, and prostatic venous plexuses. Spinal venous drainage depends on gravity, body position, and intrathoracic and intraabdominal pressure during phases of the respiratory cycle. The venous outflow from the epidural to extraspinal venous compartment is strictly unidirectional. This is maintained by the functional venous valves, although no such valves exist morphologicaly either in the epidural venous plexus/radicular veins. The epidural plexuses also participate in CSF reabsorption through arachnoid granulations within the spinal nerve roots.
First reported in the 1940s, the lumbar epidural varices occur with an estimated current incidence of 1.2%. The mechanism of their formation has not yet been established. The diagnosis of enlarged venous plexuses may be hindered by the subsidence of symptoms and normalization of the vein diameter in the supine position in patients with normal intracavitary pressure.
Disc herniation is a local factor that may contribute to venous varix formation by causing compression and endothelial injury, leading to thrombotic venous occlusion, as shown in our first case. Hanley et al. divided epidural varices into the following three types based on the MRI findings:
As the T1- and T2-signal intensity in thrombotic lesions is affected by the age of the thrombus, whereas the signal in disc herniation is affected by hydration, lumbar epidural varices can mimic lumbar disc herniation on MRI.
Venous varices in epidural space are occasioned also by varied vascular anomalies, malformations, and vascular tumors. In such circumstances, not only is there single varix visible on imaging but most likely there are also extensive arterialized venous lakes, such as in epidural arteriovenous fistulas (AVFs).
Increased intrathoracic or intra-abdominal pressure caused by large masses (e.g., tumors, lymphadenopathy, etc.) or pregnancy can obstruct the inferior vena cava. Other causes of varices include systemic factors, such as vascular anomalies; thrombosis of the iliac, superior, or inferior vena cava; Budd–Chiari syndrome; intracranial hypotension; and portal hypertension. In our second case, numerous multilevel serpentine varices within and around the spinal canal were considered highly likely to be a part of a more extensive vascular pathology. CT angiography revealed inferior vena cava agenesis with the formation of collateral pathways and dilation of epidural plexuses, resulting in intermittent compression of the spinal nerves.
Our third case illustrates a spinal manifestation of postlumbar puncture intracranial hypotension syndrome, which typically presents with postural headaches, but can also cause back pain. The MRI revealed dilated epidural plexuses and dural thickening and enhancement. According to the Monro–Kellie doctrine, epidural venous plexus engorgement in such cases results from decreased CSF volume.
In patients with back pain or radiculopathy of unclear etiology, venous plexus engorgement should be considered as a potential cause of neurologic symptoms. A spinal MRI is crucial for correct diagnosis. If necessary, detailed diagnostic imaging with systemic vein assessment and brain visualization should be performed. In many cases, a tailored spinal angiography allows to fully understand the vascular abnormality. Accurate diagnosis prevents unnecessary treatment and surgical complications.,
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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]