The Occipital Emissary Vein: A Possible Marker for Pseudotumor Cerebri.

BACKGROUND AND PURPOSE: Transverse sinus stenosis can lead to pseudotumor cerebri syndrome by elevating the cerebral venous pressure. The occipital emissary vein is an inconstant emissary vein that connects the torcular herophili with the suboccipital veins of the external vertebral plexus. This retrospective study compares the prevalence and size of the occipital emissary vein in patients with pseudotumor cerebri syndrome with those in healthy control subjects to determine whether the occipital emissary vein could represent a marker of pseudotumor cerebri syndrome. MATERIALS AND METHODS: The cranial venous system of 46 adult patients with pseudotumor cerebri syndrome (group 1) was studied on CT venography images and compared with a group of 92 consecutive adult patients without pseudotumor cerebri syndrome who underwent venous assessment with gadolinium-enhanced 3D-T1 MPRAGE sequences (group 2). The presence of an occipital emissary vein was assessed, and its proximal (intraosseous) and distal (extracranial) maximum diameters were measured and compared between the 2 groups. Seventeen patients who underwent transverse sinus stent placement had their occipital emissary vein diameters measured before and after stent placement. RESULTS: Thirty of 46 (65%) patients in group 1 versus 29/92 (31.5%) patients in group 2 had an occipital emissary vein (P < .001). The average proximal and distal occipital emissary vein maximum diameters were significantly larger in group 1 (2.3 versus 1.6 mm, P <.005 and 3.3 versus 2.3 mm, P < .001). The average maximum diameters of the occipital emissary vein for patients who underwent transverse sinus stent placement were larger before stent placement than after stent placement: 2.6 versus 1.8 mm proximally (P < .06) and 3.7 versus 2.6 mm distally (P < .005). CONCLUSIONS: Occipital emissary veins are more frequent and larger in patients with pseudotumor cerebri syndrome than in healthy subjects, a finding consistent with their role as collateral venous pathway in transverse sinus stenosis. A prominent occipital emissary vein is an imaging sign that should raise the suspicion of pseudotumor cerebri syndrome.

Analysis of 30 Spinal Angiograms Falsely Reported as Normal in 18 Patients with Subsequently Documented Spinal Vascular Malformations.

BACKGROUND AND PURPOSE: The early diagnosis of spinal vascular malformations suffers from the nonspecificity of their clinical and radiologic presentations. Spinal angiography requires a methodical approach to offer a high diagnostic yield. The prospect of false-negative studies is particularly distressing when addressing conditions with a narrow therapeutic window. The purpose of this study was to identify factors leading to missed findings or inadequate studies in patients with spinal vascular malformations. MATERIALS AND METHODS: The clinical records, laboratory findings, and imaging features of 18 patients with spinal arteriovenous fistulas and at least 1 prior angiogram read as normal were reviewed. The clinical status was evaluated before and after treatment by using the Aminoff-Logue Disability Scale. RESULTS: Eighteen patients with 19 lesions underwent a total of 30 negative spinal angiograms. The lesions included 9 epidural arteriovenous fistulas, 8 dural arteriovenous fistulas, and 2 perimedullary arteriovenous fistulas. Seventeen patients underwent endovascular (11) or surgical (6) treatment, with a delay ranging between 1 week and 32 months; the Aminoff-Logue score improved in 13 (76.5%). The following factors were identified as the causes of the inadequate results: 1) lesion angiographically documented but not identified (55.6%); 2) region of interest not documented (29.6%); or 3) level investigated but injection technically inadequate (14.8%). CONCLUSIONS: All the angiograms falsely reported as normal were caused by correctible, operator-dependent factors. The nonrecognition of documented lesions was the most common cause of error. The potential for false-negative studies should be reduced by the adoption of rigorous technical and training standards and by second opinion reviews.

Intraforaminal Location of Thoracolumbar Radicular Arteries Providing an Anterior Radiculomedullary Artery Using Flat Panel Catheter Angiotomography.

BACKGROUND AND PURPOSE: Flat panel catheter angiotomography performed during the selective injection of intersegmental arteries offers a multiplanar assessment of the intraforaminal course of the radicular arteries providing an anterior radiculomedullary artery. Injury of anterior radiculomedullary arteries during transforaminal epidural steroid injections can result in spinal cord damage. Evaluations of the intraforaminal location of these arteries have so far been limited to anteroposterior views or the examination of cadaveric material. This study documents the in vivo intraforaminal location of thoracolumbar arteries providing an anterior radiculomedullary artery with flat panel catheter angiotomography. MATERIALS AND METHODS: Ninety-four flat panel catheter angiotomography acquisitions obtained during the selective injection of intersegmental arteries providing an anterior radiculomedullary artery were reviewed. Measurements obtained from sagittal reconstructions were converted into a scatterplot visualization. Patients' age, sex, and side and level of the injection were recorded. RESULTS: The location of radicular arteries could be ascertained in 78 of 94 flat panel catheter angiotomography acquisitions (33 women and 45 men, 22-82 years of age). Fifty-three acquisitions (67.9%) were on the left side, and 25 (32.1%), on the right, between T2 and L3. The arteries were found in the anterosuperior quadrant of the neural foramen in 75 cases (96.2%), in the posterosuperior quadrant in 2 cases (2.6%), and in the anteroinferior quadrant in 1 case (1.3%). None were located in the posteroinferior quadrant. No differences in location were observed with age, sex, side of injection, or vertebral level. CONCLUSIONS: Avoiding needle placement in the superior half of the neural foramen, specifically the anterosuperior quadrant, can reduce the risk of spinal cord injury during transforaminal epidural steroid injection.

Ascending and Descending Thoracic Vertebral Arteries.

Thoracic vertebral arteries are anastomotic chains similar to cervical vertebral arteries but found at the thoracic level. Descending thoracic vertebral arteries originate from the pretransverse segment of the cervical vertebral artery and curve caudally to pass into the last transverse foramen or the first costotransverse space. Ascending thoracic vertebral arteries originate from the aorta, pass through at least 1 costotransverse space, and continue cranially as the cervical vertebral artery. This report describes the angiographic anatomy and clinical significance of 9 cases of descending and 2 cases of ascending thoracic vertebral arteries. Being located within the upper costotransverse spaces, ascending and descending thoracic vertebral arteries can have important implications during spine interventional or surgical procedures. Because they frequently provide radiculomedullary or bronchial branches, they can also be involved in spinal cord ischemia, supply vascular malformations, or be an elusive source of hemoptysis.

Normal Venous Phase Documented during Angiography in Patients with Spinal Vascular Malformations: Incidence and Clinical Implications.

BACKGROUND AND PURPOSE: A key angiographic sign observed in patients with spinal vascular malformations is the absence of a normal venous phase. While this finding alone is often believed to rule out a lesion impacting the perimedullary venous drainage, the observation of a venous phase in several patients with vascular malformations led us to reconsider the validity of that sign. MATERIALS AND METHODS: Eighty-one patients with 6 spinal arteriovenous malformations, 16 perimedullary arteriovenous fistulas, 61 spinal epidural or dural AVFs, and 1 paravertebral AVF (2 patients had multiple lesions) were reviewed. The venous phase was defined as normal, absent, or indeterminate. The venous phase timing was analyzed in patients with spinal dural or epidural AVFs. RESULTS: The existence of a venous phase could not be determined for technical reasons in 23 patients. A venous phase was documented in 25 of 58 patients (43%), including 16 of 49 vascular malformations (40.0%) with perimedullary venous drainage. Twelve of the 30 patients (40.0%) with dural or epidural AVFs had a normal venous phase, appearing, on average, 10.1 seconds and best visualized 15.0 seconds after opacification of the artery of Adamkiewicz. CONCLUSIONS: A normal venous phase was observed in 43% of patients with spinal vascular malformations, and within an acceptable delay (<18 seconds) in 40% of slow-flow AVFs. While it remains an important angiographic sign, the observation of a normal venous phase cannot be used to exclude the presence of a vascular malformation or justify interrupting a diagnostic spinal angiogram.

Transmedullary Venous Anastomoses: Anatomy and Angiographic Visualization Using Flat Panel Catheter Angiotomography.

Flat panel catheter angiotomography, a recently developed angiographic technique, offers a spinal equivalent to the venous phase obtained during cerebral angiography. This report of 8 clinical cases discusses the flat panel catheter angiotomography appearance of a type of spinal venous structure until now principally known through the analysis of postmortem material, transmedullary venous anastomosis. The illustrated configurations include centrodorsolateral, median anteroposterior, median anteroposterior with duplicated origin, and combined centrodorsolateral/median anteroposterior transmedullary venous anastomoses, while a pathologic example documents the potential role of transmedullary venous anastomoses as collateral venous pathways. Two of the reported configurations have not been previously documented. Transmedullary venous anastomoses are normal venous structures that need to be differentiated from spinal cord anomalies, such as intramedullary vascular malformations.

Focal compression of the upper left thoracic intersegmental arteries as a potential cause of spinal cord ischemia.

BACKGROUND AND PURPOSE: This study was prompted by recurrent angiographic observations of focal stenoses involving the proximal segment of the left upper thoracic intersegmental arteries, a few centimeters distal to their origin. The purpose was to investigate the nature and prevalence of this anomaly. MATERIALS AND METHODS: The existence of non-ostial thoracic intersegmental artery stenoses was evaluated in 50 angiograms; the contribution of stenosed branches to the anterior spinal artery was recorded. Angiograms performed in 3 patients with right-sided aortas were also reviewed. The topographic relationships of the upper thoracic intersegmental artery with surrounding structures were investigated in 3 cadavers. RESULTS: Thirty-seven non-ostial stenoses were found in 26 patients (52%), predominantly on the left side (92%), between T3 and T8, most frequently at T4 and T5 (54%). Severe lesions were observed in 10% of cases. Patients with stenoses had fewer detectable anterior radiculomedullary arteries between T3 and T5 (35% versus 54%). Upper intersegmental artery stenoses, documented on the left side of all 3 specimens, appeared to be caused by the recurrent path of these intersegmental arteries related to the leftward position of the thoracic aorta, and by their course around reinforced paramedian longitudinal strands of the endothoracic fascia. CONCLUSIONS: Upper thoracic intersegmental artery stenoses are frequent. They result from the leftward deviation of the descending aorta and the existence of a fixed point along the course of the intersegmental arteries related to the endothoracic fascia. Because contributors to the spinal vascularization often originate at similar levels, these stenoses may play a role in the susceptibility of the upper and midthoracic spinal cord to ischemia.

A critical inventory of preoperative skull replicas.

INTRODUCTION: Physical replicas of organs are used increasingly for preoperative planning. The quality of these models is generally accepted by surgeons. In view of the strong trend towards minimally invasive and personalised surgery, however, the aim of this investigation was to assess qualitatively the accuracy of such replicas, using skull models as an example. METHODS: Skull imaging was acquired for three cadavers by computed tomography using clinical routine parameters. After digital three-dimensional (3D) reconstruction, physical replicas were produced by 3D printing. The facsimilia were analysed systematically and compared with the best gold standard possible: the macerated skull itself. RESULTS: The skull models were far from anatomically accurate. Non-conforming rendering was observed in particular for foramina, sutures, notches, fissures, grooves, channels, tuberosities, thin-walled structures, sharp peaks and crests, and teeth. CONCLUSIONS: Surgeons should be aware that preoperative models may not yet render the exact anatomy of the patient under consideration and are advised to continue relying, in specific conditions, on their own analysis of the native computed tomography or magnetic resonance imaging.

Flat panel catheter angiotomography of the spinal venous system: an enhanced venous phase for spinal digital subtraction angiography.

BACKGROUND AND PURPOSE: While spinal DSA remains the reference standard technique for spinovascular imaging, visualizing spinal veins remains challenging due to their small size and motion artifacts. This study evaluates the ability of FPCA to overcome these obstacles. MATERIALS AND METHODS: Sixty-three FPCAs, performed by intersegmental artery injections in 57 patients, were prospectively evaluated. Entrance skin doses were compared with standard spinal DSA runs, including a venous phase and cerebral FPCAs. FPCA contributions were stratified as 1) provided no added information, 2) complemented spinal DSA findings, 3) assisted therapy planning, and 4) contributed principal diagnostic findings. RESULTS: No complications were observed. Diagnoses included vascular malformations (44%), stroke (9%), venous anomalies (10%), other (9%), and unremarkable (28%). Mean entrance skin doses were of 419 mGy for FPCA, 161 mGy for spinal DSA with venous phase, and 309 mGy for cerebral FPCAs. FPCA contributed the principal diagnostic finding in 16 cases (25.4%), assisted therapy planning in 13 cases (20.6%), complemented spinal DSA findings in 12 cases (19.1%), and provided no additional information in 20 cases (31.7%). In 8 of these 20 cases, FPCA documented a spinal venous anatomy that was poorly visualized or not visualized on spinal DSA. CONCLUSIONS: Spinal FPCA is safe, with a moderate increase in radiation dose, compared with spinal DSA with venous phase or cerebral FPCA. It proved particularly valuable for therapy planning and the diagnosis of venous abnormalities. This study suggests that FPCA has an important role to play in the evaluation of the spinal venous system.

Unilateral hypoplasia of the rostral end of the superior sagittal sinus.

BACKGROUND AND PURPOSE: Hypoplasia of the rostral third of the SSS is a well-known variant and constitutes the most frequent variation of the SSS after preferential drainage to one of the transverse sinuses. Our aim was to describe unilateral hypoplasia of the rostral end of the SSS. MATERIALS AND METHODS: CTA performed in 100 consecutive patients studied for conditions other than dural sinus thrombosis was reviewed for the presence of a unilateral or bilateral hypoplastic rostral SSS. Associated dural venous sinus anomalies were recorded as well. The angiographic anatomy of unilateral hypoplastic rostral SSS was illustrated by 2 cases further imaged with DSA. RESULTS: Unilateral hypoplastic rostral SSS was found in 7 patients (7%). In all cases, compensatory drainage occurred through a large superior frontal vein that joined the SSS in the region of the coronal suture. Three of the 7 patients with a unilateral hypoplastic rostral SSS had at least another dural venous sinus anomaly. Complete or bilateral hypoplastic rostral SSS was noted in 3 patients (3%). CONCLUSIONS: Unilateral hypoplastic rostral SSS is more than twice as frequent as bilateral hypoplastic rostral SSS. It is the most frequently encountered variation of the SSS. Knowledge of this anatomic variation is important to avoid diagnostic pitfalls and to avoid erroneously mistaking it for a thrombosis. Four types of variations of the rostral SSS may be identified: 1) classic anatomy with a fully developed rostral SSS; 2) duplication of the rostral SSS; 3) complete or bilateral hypoplastic rostral SSS; 4) unilateral hypoplastic rostral SSS. The 4 types of rostral SSS variations can be explained by studying the embryologic development of the SSS.

Arteria lusoria: developmental anatomy, clinical, radiological and surgical aspects.

The left aortic arch with an aberrant right subclavian artery, or arteria lusoria, is the most common aortic arch anomaly, occuring in 0.5-2.5% of individuals. Four vessels arise sequentially from the aortic arch: the right common carotid artery, the left common carotid artery, the left subclavian artery and the aberrant right subclavian artery, which crosses upwards and to the right in the posterior mediastinum. It results from a disruption in the complex remodelling of the paired branchial arches, typically of the right dorsal aorta distal to the sixth cervical intersegmental artery. The diagnosis and differentiation of arch anomalies is based on findings at chest radiography in association with those at esophagography. It is usually asymptomatic. When symptomatic, it produces dysphagia lusoria or dyspnea and chronic coughing. Treatment is indicated for symptomatic relief of dysphagia lusoria and for prevention of complications due to aneurysmal dilatation.

Sturge-Weber syndrome with cerebellar involvement.

Sturge-Weber syndrome is a rare neurocutaneous disorder that typically presents with angiomas involving the face, ocular choroid and ipsilateral supratentorial leptomeninges. Posterior fossa involvement is extremely rare. We present two patients with simultaneous supra- and infratentorial involvement. Magnetic resonance imaging (MRI) and digital subtracted angiography (DSA) findings are discussed.

Bilateral segmental agenesis of the vertebrobasilar junction: developmental and angiographic anatomy.

BACKGROUND AND PURPOSE: Bilateral vertebrobasilar junction agenesis is an exceptional anatomic variation. This article explores the angiographic characteristics of this variant and its embryologic mechanisms. MATERIALS AND METHODS: Two observations of bilateral agenesis of the vertebrobasilar junction are reported. A case of atheromatous disease of the vertebrobasilar junction is shown to highlight characteristics distinguishing such a lesion from the reported variant. RESULTS: In the 2 reported cases, the distal segment of both vertebral arteries (VAs) and the proximal portion of the basilar artery (BA) were absent. In addition, distal connections of the BA with the posterior cerebral arteries (PCA) were also lacking. As a consequence, the remaining portion of the BA was isolated from its usual sources of blood supply, which was provided by a persistent carotid-basilar anastomosis. CONCLUSION: The developmental mechanism underlying bilateral agenesis of the vertebrobasilar junction likely involves the anterior radicular artery of C1. This branch of the proatlantal artery normally becomes the adult distal VA and the proximal BA. The lack of cranial connection of the BA with the PCA may be secondary to the proximal vertebrobasilar agenesis and the resulting paucity of antegrade flow within the BA. Alternatively, the absence of both the proximal and distal connections of the BA could be the result of a similar, yet unknown, developmental mechanism. From a clinical standpoint, this vascular anomaly was discovered incidentally in our 2 patients, a finding consistent with the assumed congenital nature of the variant.

Wyburn-Mason syndrome associated with thyroid arteriovenous malformation: a first case report.

A 31-year-old woman with a prior history of Wyburn-Mason syndrome, complicated previously by a left thalamic intracerebral hemorrhage at age 21, complained of sudden left vision loss due to a central retinal vein occlusion. Angiography revealed a left thyroid arterio-venous malformation (AVM) in addition to ones found intracerebrally. The pathogenesis and embryogenesis of this finding including the management of AVMs in Wyburn-Mason syndrome are discussed.

Developmental anatomy of the distal vertebral artery in relationship to variants of the posterior and lateral spinal arterial systems.

BACKGROUND AND PURPOSE: A certain number of anatomic variants involving the distal vertebral artery (VA) are explained by variations in size and connection of the lateral spinal artery (LSA). This study examined the possible role of another branch of the VA, the posterior spinal artery (PSA), in the development of similar vascular variations. MATERIALS AND METHODS: Four types of variations in the distal VA, including the C1 and C2 origins of the posterior inferior cerebellar artery (PICA), the duplication of the distal VA, and the aberrant course of the distal VA, are illustrated by 9 angiographic observations. RESULTS: For each type of VA variant listed above, examples resulting from variations in size and connection of the LSA and PSA could be matched. CONCLUSION: Variation in size and connection of the PSA is at the origin of a set of anatomic variations of the distal VA similar, but not identical, to the vascular variants linked to the LSA.

Isolated posterior cerebral artery dissection: report of three cases.

Isolated dissection of the posterior cerebral artery (PCA) is a rare but important cause of stroke in younger patients, particularly women. We present 3 cases of dissection of the P2 segment of the PCA. In 2 patients, an association with minor axial head trauma was documented, suggesting shearing injury of the PCA as it crosses over the free edge of the tentorium. The clinical and imaging findings are discussed, and the therapeutic management is reviewed.

Oromaxillofacial osseous abnormality in Sturge-Weber syndrome: case report and review of the literature.

We report a case of a 17-month-old child affected by Sturge-Weber syndrome who had unusually rapid overgrowth of the left frontal, temporal, orbital, and maxillary regions. CT angiography illustrated osteohypertrophy with periostitis and associated soft tissue hypertrophy directly corresponding to the distribution of the cutaneous port-wine stain. Extended maxillectomy was performed because of rapid growth and clinical debilitation, with surgical pathology revealing juvenile ossifying fibroma.