The Long and Winding Road: Thoracic Myelopathy Associated With Occipitocervical Dural Arteriovenous Fistula

Craniocervivcal Spinal Dural Arteriovenous Fistula Ligation via a Modified Suboccipital Craniectomy and C1 Laminectomy: Operative Video

Dural arteriovenous fistulas (dAVFs) are vascular malformations of the central nervous system that feature an arteriovenous shunt fed by dural arteries and can be intracranial or spinal.1-3 Spinal dAVFs are classically found at the nerve root sleeve.3 The arterial supply can often be predicted by the fistula location, whereas the symptomatology and risk of hemorrhage is determined by the venous drainage pattern.1-3 Craniocervical fistulas, a subset of dAVFs, may arise in association with the anterior condylar venous confluence or more dorsally in association with the transdural segment of the vertebral artery.1-3 This latter type of fistula typically has spinal venous drainage and may present with myelopathy from spinal cord venous congestion. We present a 61-year-old man who presented with a 2-week history of neck pain and paraparesis. Magnetic resonance imaging of the cervical spine revealed diffuse T2 hyperintensity of the cord from the pons to the level of the T1 vertebra. A computed tomography angiogram showed a possible dAVF at the craniocervical junction on the left. Because of the unclear nature of the patient's spinal cord lesion, a cerebral angiogram was performed. It confirmed a dAVF associated with the transdural segment of the left vertebral artery, with small dural feeders from the left vertebral artery and venous drainage into the anterior spinal vein. The patient underwent a modified suboccipital craniectomy and C1 laminectomy for dAVF ligation (Video 1). He was extubated postoperatively and discharged to a rehabilitation unit with improvement in lower extremity strength.

Spinal Dorsal Intradural Arteriovenous Fistulas: Natural History, Imaging, and Management

In this review, we describe the pathophysiology, diagnosis, and treatment of spinal dorsal intradural arteriovenous fistulas (DI-AVFs), focusing on novel research areas. DI-AVFs compose the most common subgroup of spinal arteriovenous lesions and most commonly involve the thoracic spine, followed by lumbar and sacral segments. The pathogenesis underlying DI-AVFs is an area of emerging understanding, thought to be attributable to venous congestion and hypertension that precipitate ascending myelopathy. Patients with DI-AVFs typically present with motor, sensory, or urinary dysfunction, although a wide swath of other less common symptoms has been reported. DI-AVFs can be subdivided by spinal region, which in turn is associated with 4 distinct clinical phenotypes: craniocervical junction (CCJ), subaxial cervical, thoracic, and lumbosacral. Patients with CCJ and lumbosacral DI-AVFs have particularly interesting presentations and treatment considerations. High-value diagnostic findings on MRI include flow voids, missing-piece sign, and T2-weighted intramedullary hyperintensity. However, digital subtraction angiography is the gold standard for diagnosis and localization of DI-AVFs and for definitive treatment planning. Surgical disconnection of DI-AVFs is almost universally curative and frontline treatment, especially for CCJ and lumbosacral DI-AVFs. Endovascular techniques evolve in promising ways, such as improved visualization, distal access, and liquid embolic techniques. The pathophysiology of DI-AVFs is better understood using newly identified radiologic diagnostic markers. Despite new techniques and devices introduced in the endovascular field, surgery remains the gold-standard treatment for DI-AVFs.

Treatment of high cervical arteriovenous fistulas in the craniocervical junction region

The craniocervical junction (CCJ) is a complex region. Rarely, arteriovenous fistulas (AVFs) can occur in the CCJ region. Currently, it is accepted that CCJ AVFs should only refer to AVFs at the C1-C2 levels. It is reasonable to assume that high cervical CCJ AVFs are being referred to when discussing CCJ AVFs. High cervical CCJ AVFs can be divided into the following four types: dural AVF, radicular AVF, epidural AVF and perimedullary AVF. Until now, it was difficult to understand high cervical CCJ AVFs and provide a proper treatment for them. Therefore, an updated review of high cervical CCJ AVFs is necessary. In this review, the following issues are discussed: the definition of high cervical CCJ AVFs, vessel anatomy of the CCJ region, angioarchitecture of high cervical CCJ AVFs, treatment options, prognoses and complications. Based on the review and our experience, we found that the four types of high cervical CCJ AVFs share similar clinical and imaging characteristics. Patients may present with intracranial hemorrhage or congestive myelopathy. Treatment, including open surgery and endovascular treatment (EVT), can be used for symptomatic AVFs. Most high cervical CCJ AVFs can be effectively treated with open surgery. EVT remains challenging due to a high rate of incomplete obliteration and complications, and it can only be performed in superselective AVFs with simple angioarchitecture. Appropriate treatment can lead to a good prognosis.

The role of venous anatomy in guiding treatment approach for dural arteriovenous fistulas of the craniocervical junction; case series & systematic review

BACKGROUND

Dural arteriovenous fistulas (DAVF) of the craniocervical junction (CCF) are an uncommon entity with the following venous drainage pattern: inferior, superior and mixed. Patients may present with subarachnoid hemorrhage, myelopathy or brainstem dysfunction. CCJ DAVF can be treated with microsurgery or with transarterial and transvenous embolization, depending on the venous drainage pattern. We present our institutional experience of treating CCJ DAVFs along with a systematic review of the literature.

METHODS

Six patients with CCJ DAVF were treated at our institution over five years. Data was collected using electronic medical record review. Systematic review was performed on CCJ DAVF using the PubMed database from 1990 to 2021. We characterized venous drainage patterns, treatment choices, and outcomes to create a classification system.

RESULTS

50 case reports, consisting of 115 patients, were included in our review. 61 (53.0 %) patients had inferior drainage while 32 (27.8 %) patients had superior drainage and 22 (19.2 %) patients had mixed venous drainage. Patients with inferior drainage had the fistulous connection at the foramen magnum while patients with superior drainage had a fistulous connection at C1-C2 (p value = 0.026). Patients with inferior drainage were more likely to present with myelopathy while patients with superior drainage presented with hemorrhage (p value = 0.000).

CONCLUSIONS

Classifying the venous drainage pattern is essential in making treatment decision. Transvenous embolization works best with large superior venous drainage. If endovascular treatment is not an option, then surgical clipping can achieve successful cure. Transarterial embolization is a reasonable option in cases with a large arterial feeder.

Clinical features, angio-architectural phenotypes, and treatment strategy of foramen magnum dural arteriovenous fistulas: a retrospective case series study

Background

The rarity and complex angioarchitecture of foramen magnum dural arteriovenous fistulas (DAVFs) make its treatment difficult and controversial. We aimed to describe their clinical features, angio-architectural phenotypes, and treatments, through a case series study.

Methods

We first retrospectively studied cases of foramen magnum DAVFs treated in our Cerebrovascular Center, and then reviewed the published cases on Pubmed. The clinical characteristics, angioarchitecture, and treatments were analyzed.

Results

A total of 55 patients were confirmed with foramen magnum DAVFs, which included 50 men and 5 women, with a mean age of 52.8 years. Most patients presented with subarachnoid hemorrhage (SAH) (21/55) or myelopathy (30/55), depending on the venous drainage pattern. In this group, 21 DAVFs were supplied by only the vertebral artery (VA), three by only the occipital artery (OA), three by only the ascending pharyngeal artery (APA), and the remaining 28 DAVFs were supplied by two or three of these feeding arteries. Most cases (30/55) were treated with only endovascular embolization, 18 cases (18/55) with only surgical disconnection, five cases (5/55) with combined therapy, and two cases rejected treatment. The angiographic outcome of complete obliteration was achieved in most patients (50/55). In addition, two cases of foramen magnum DAVFs were treated by us in a Hybrid Angio-Surgical Suite (HASS) with good outcomes.

Conclusions

Foramen magnum DAVFs are rare and their angio-architectural features are complicated. The treatment option (microsurgical disconnection or endovascular embolization) should be weighed carefully, and combined therapy in HASS could be a more feasible and less invasive treatment option.

Venous congestion as a central mechanism of radiculopathies

Compression of roots/nerves can disrupt some of their functions, but does not necessarily cause pain. This is illustrated by the frequency of nearly asymptomatic spinal stenosis or disc herniations. In fact, pain of radiculopathies (and nerve entrapments) may mostly be the consequence of intraneural oedema induced by microscopical venous stasis around roots/spinal ganglia (or nerves) not or poorly shown by imaging. This narrative review first lists arguments for a role of congestion of vasa-nervorum in the pathophysiology of radiculopathies, including those induced by disc herniation and spinal stenosis, but also other sources of overpressures in spinal venous plexuses (pregnancy, vena cava atresia and thrombosis, portal hypertension, epidural varices, arterio-venous fistula, vertebral hemangioma or hemangioblastoma). It also details sources of venous congestion around nerves outside the spine, from pelvis (May-Thurner syndrome, Nut-cracker syndrome) to buttocks (superior and inferior gluteal veins), and even thighs and legs. A better recognition of a preeminent role of venous congestion in radiculopathies, plexopathies, and nerve entrapments, should have major consequences: (i) discard the dogma that compression is mandatory to induce root/nerve suffering, since root/nerve adherences in two locations can impair blood flow in vasa-nervorum through root/nerve stretching; (ii) implementation of sensitive techniques to visualise impingement of blood flow around or within roots and nerves; (iii) better prevention of roots/nerves adherence, or arachnoiditis induced by extravascular fibrin deposition secondary to venous stasis.; (iv) optimizing treatments dampening clot formation and/or extravascular fibrin leakage in the intradural/peridural spaces, or around roots/nerves, like guided injection of tissue plasminogen activator.

Foramen Magnum Dural Arteriovenous Fistula Presenting With Thoracic Myelopathy: Technical Case Report With 2-Dimensional Operative Video

BACKGROUND AND IMPORTANCE

Dural arteriovenous fistulas (dAVFs) are vascular abnormalities of the central nervous system that can cause a wide array of neurological dysfunction depending on their location, flow, and propensity to rupture. Symptomatic dAVFs at the cranio-cervical junction usually result in hemorrhage or cervical myelopathy. Distantly located dAVFs of the foramen magnum are a rare cause of thoracic intrinsic myelopathy.

CLINICAL PRESENTATION

An 83-yr-old man presented with progressive lower extremity weakness, numbness, and difficulty walking along with episodes of bowel incontinence. Magnetic resonance imaging of the cervical spine demonstrated multilevel cervical disc disease with stenosis and longitudinal cervical cord signal change extending into the upper thoracic spinal cord. Cerebral and spinal angiography revealed a dAVF in the lateral foramen magnum region. Given the location, feeding vasculature, and morphology of the fistula, endovascular embolization was not attempted. Microsurgical resection with confirmative indocyanine green fluorescent imaging was performed with adequate obliteration of the fistula. The patient's neurological baseline was preserved postoperatively with improvement of lower extremity numbness.

CONCLUSION

We present a brief overview of this neuropathologic entity and demonstrate microsurgical resection of a foramen magnum dAVF through operative video. Craniocervical dAVFs should remain on the differential diagnosis of patients presenting with progressive thoracolumbar myelopathy.

Asymptomatic spinal dural arteriovenous fistula: case series and systematic review

OBJECTIVE

Spinal dural arteriovenous fistulas (SDAVFs) commonly present with symptoms of myelopathy due to venous congestion in the spinal cord; asymptomatic SDAVFs are rarely encountered. To elucidate the clinical characteristics of asymptomatic SDAVFs, the authors present 5 new cases of asymptomatic SDAVF and report the results of their systematical review of the associated literature.

METHODS

Five databases were systematically searched for all relevant English-language articles on SDAVFs published from 1990 to 2018. The clinical features and imaging findings of asymptomatic SDAVFs were collected and compared with those of symptomatic SDAVFs.

RESULTS

Twenty cases, including the 5 cases from the authors' experience, were found. Asymptomatic SDAVFs were more prevalent in the cervical region (35.0%); cervical lesions account for only 2% of all symptomatic SDAVFs. The affected perimedullary veins tended to drain more cranially (50.0%) than caudally (10.0%). Four cases of asymptomatic SDAVF became symptomatic, 1 case spontaneously disappeared, and the remaining 15 cases were unchanged or surgically treated.

CONCLUSIONS

The higher prevalence of asymptomatic SDAVFs in the cervical spine might be a distinct feature of asymptomatic SDAVFs. Given that venous congestion is the pathophysiology of a symptomatic SDAVF, abundant collateral venous pathways and unique flow dynamics of the CSF in the cervical spine might prevent asymptomatic cervical SDAVFs from becoming symptomatic. In cases in which venous congestion is avoidable, not all asymptomatic SDAVFs will become symptomatic.