Cranial dural arteriovenous shunts: selection of the ideal lesion for surgical occlusion according to the classification system.

BACKGROUND: The types of cranial dural arteriovenous fistulae (cDAVFs) that constitute good surgical candidates are unclear despite the use of classifications. We aimed to compare the DES classification with other classification schemes in identifying "ideal lesions for surgery." The DES scheme is based on two features: the level of the shunt (BVS, bridging vein shunt; DSS, dural sinus shunt; ISS, isolated sinus shunt; EVS, emissary vein shunt) and the type of leptomeningeal venous reflux (LVR) (direct, exclusive, strained). METHODS: In this observational cohort study, the angiographies of 20 consecutive patients treated over 1 year were analyzed retrospectively. We defined cDAVFs as ideal for surgery, if cure may be achieved by disconnecting the arterialized draining vein through a single craniotomy. To evaluate the performance of each classification scheme in identifying the "ideal lesion for surgery," we carried out a sensitivity analysis of the Borden, Cognard, and DES schemes. RESULTS: Eight lesions were Borden type 3 and 1 type 2, and 11 type 1. According to Cognard, 2 lesions were type IV, 2 type III, 1 type IIa+b, 11 type I, and 4 lesions could not be clearly classified. According to the DES scheme, 8 lesions were DSS, 4 BVS, 3 ISS, and 5 EVS. All 4 lesions classified as BVS in the DES were ideal lesions for surgery (sensitivity, specificity, PPV, NPV 100%). Not all high-grade lesions according to Borden were good surgical candidates. CONCLUSION: The DES scheme, as opposed to other classifications, facilitates the therapeutic decision-making especially for selecting candidates for surgery.

Falcotentorial Location of Dural Arteriovenous Fistulas Derived from the Neural Crest as a Risk Factor for Aggressive Clinical Course.

The topographical distribution of dural arteriovenous fistulas (DAVFs) was analyzed based on the embryological anatomy of the dural membrane. Sixty-six consecutive cases of intracranial and spinal DAVFs were analyzed based on the angiography, and each shunt point was identified according to the embryological bony structures. The area of dural membranes was categorized into three different groups: a ventral group located on the endochondral bone (VE group), a dorsal group on the membranous bone (DM group), and a falcotentorial group (FT group) in the falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae. The FT group was derived from the neural crest and designated when the dural membrane was formed only with the dura propria (meningeal layer of the dura mater) and not from the endosteal dura. Olfactory groove, falx, tent of the cerebellum, and nerve sleeve of spinal cord were categorized in the FT group, which presented later in life and which had a male predominance, more aggressive clinical presentations, and significant cortical and spinal venous reflux. The FT group was formed only with the dura propria that was considered as an independent risk factor for aggressive clinical course and hemorrhage of DAVFs.

Proposal of a Classification System of Cavernous Sinus Dural Arteriovenous Fistulas and Treatment Strategies Based on Angioarchitecture: A Cohort Study of 116 Patients.

BACKGROUND: Cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) are commonly treated by transvenous embolization, but the details of treatment need to be more clearly defined. We propose a classification of CS-DAVF that can contribute to formulating endovascular treatment process. METHODS: CS-DAVF was classified into seven categories based on the cumulative CS range and drainage patterns. CS-DAVF angioarchitecture, clinical characteristics, treatment strategies, and outcomes of CS-DAVF patients treated in our hospital from 2012 to 2021 were summarized and analyzed. RESULTS: Among the 116 patients with CS-DAVF: Type 1, 71 (61.2%); Type 2, 9 (7.8%); Type 3, 18 (15.5%); Type 4, 2 (1.7%); Type 5, 8 (6.9%); Type 6, 3 (2.6%); and Type 7, 5 (4.3%). Inter-CS or inferior petrosal sinus drainage was relatively rare in Types 1 and 6 (P < 0.001 and P < 0.001); basilar venous plexus drainage was more prevalent in Types 2, 5, and 7(P = 0.019). Inferior petrosal sinus occlusion was more commonly seen in Types 2, 3, and 5 (P = 0.005). The most frequent first symptoms and symptoms at admission in patients with CS-DAVF is ocular/orbital symptoms, occurring in 64 cases (55.2%) and 104 cases (89.7%), respectively. In this study, 108 patients (93.1%) underwent endovascular embolization. Among those who received endovascular embolization, 96 (88.9%) CS-DAVFs were treated via transvenous embolization. In long-term follow-up, 98 cases (84.5%) achieved cure, and 17 cases (14.7%) showed symptomatic improvement. CONCLUSION: Our proposed classification system based on cumulative CS range and drainage patterns can assist in formulating treatment strategies for transvenous embolization.

[Intracranial dural arteriovenous fistulae. Experience after 81 cases and literature review]. / Fístulas durales arteriovenosas intracraneales. Experiencia con 81 casos y revisión de la literatura.

OBJECTIVES: To analyse the clinical, radiological and therapeutic variables of intracranial dural arteriovenous fistulae (DAVF) treated at our institution, and to assess the validity of the Borden and Cognard classifications and their correlation with the presenting symptoms. MATERIAL AND METHODS: The DAVF identified were retrospectively analysed. They were classified according to their location, drainage pattern and the Borden and Cognard classifications. We recorded the different treatments, their complications and efficacy. RESULTS: There were 81DAVF identified between 1975 and 2012. The cavernous sinus (CS) location was the most frequent one. The Borden and Cognard classifications showed an interobserver Kappa index of 0.72 and 0.76 respectively. The odds ratio of aggressive presentation in the presence of cortical venous drainage (CVD) was 19.3 (2.8-132.4). No location, once adjusted by venous drainage pattern, showed significant association with an aggressive presentation. Endovascular transarterial treatment of cavernous sinus DAVF achieved symptomatic improvement of 78%, with a complication rate of 5%. The DAVF of non-CS locations, with CVD, treated surgically were angiographically shown cured in 100% of the cases, with no treatment-related complications. CONCLUSIONS: The presence of CVD was significantly associated with aggressive presentations. The Borden and Cognard classifications showed little interobserver variability. Endovascular treatment for CS DAVF is safe and relatively effective. Surgical treatment of non-CS DAVF with CVD is safe, effective and the first choice treatment in our environment.

Evaluating performance of the spetzler-martin supplemented model in selecting patients with brain arteriovenous malformation for surgery.

BACKGROUND AND PURPOSE: Our recently proposed point scoring model includes the widely-used Spetzler-Martin (SM)-5 variables, along with age, unruptured presentation, and diffuse border (SM-Supp). Here we evaluate the SM-Supp model performance compared with SM-5, SM-3, and Toronto prediction models using net reclassification index, which quantifies the correct movement in risk reclassification, and validate the model in an independent data set. METHODS: Bad outcome was defined as worsening between preoperative and final postoperative modified Rankin Scale score. Point scores for each model were used as predictors in logistic regression and predictions evaluated using net reclassification index at varying thresholds (10%-30%) and any threshold (continuous net reclassification index >0). Performance was validated in an independent data set (n=117). RESULTS: Net gain in risk reclassification was better using the SM-Supp model over a range of threshold values (net reclassification index=9%-25%) and significantly improved overall predictions for outcomes in the development data set, yielding a continuous net reclassification index of 64% versus SM-5, 67% versus SM-3, and 61% versus Toronto (all P<0.001). In the validation data set, the SM-Supp model again correctly reclassified a greater proportion of patients versus SM-5 (82%), SM-3 (85%), and Toronto models (69%). CONCLUSIONS: The SM-Supp model demonstrated better discrimination and risk reclassification than several existing models and should be considered for clinical practice to estimate surgical risk in patients with brain arteriovenous malformation.

Neurosurgical vascular malformations in children under 1 year of age.

PURPOSE: This study aims to analyze the clinical and radiological findings, timing and type of treatment, and outcome in children under 1 year of age that presented with neurosurgical vascular malformations. METHODS: A retrospective review of 23 children under 1 year of age with neurosurgical vascular malformations was performed at a single institution between 1999 and 2009. RESULTS: The lesions found in this age group were: 10 vein of Galen aneurysmal malformations (VGAMs), 5 arteriovenous malformations (AVM), 2 pial arteriovenous fistulas (AVF; 1 in the brain and 1 in the spinal cord), 2 cavernous malformations, 2 dural sinus malformations (DSMs) in the posterior fossa with negative angiography which after surgery turned out to be embryonal malformations of dural sinuses, 1 sacular aneurysm, and 1 dural arteriovenous fistula (DAVF) that drained toward the vein of Galen. Of the 10 patients with VGAM, 8 presented choroidal type and 2 mural type. Two patients with choroidal VGAM were born in dramatically severe clinical condition; therefore, we decided to withhold aggressive treatment, and they died within 48 h after birth. The other eight patients with choroidal VGAM received endovascular treatment between 1 and 3 staged embolizations. In four of them, total occlusion was achieved and subtotal and partial in the others. One patient had complications and evolved with severe developmental delay. Another patient with partial occlusion died, and another patient with previous developmental delay stopped treatment because of parental decision making. Five patients evolved with normal development and one with mild delay. Only one patient required shunt. Hydrocephalus was solved after endovascular treatment in the rest of the patients. Regarding the five AVMs, four were treated with microsurgical approach achieving total resection of the lesion and normal developmental milestones except for one patient with brainstem AVM that was admitted with quadriparesis and coma. In the patient with basal ganglia AVM, the lesion spontaneously disappeared. From the two pial AVFs, the frontal one was microsurgically treated and the spinal one received endovascular session achieving 50% of lesion occlusion for which further treatment is needed. The two cavernous malformations were operated achieving total resection with normal development. The two children with DSM received surgical resection without complications and normal development. The rare case of sacular aneurysm at this age was occluded at the time of diagnostic procedure due to the bad clinical condition of the patient and the hematoma was removed immediately in the operating room. The only case of DAVF died of respiratory intercurrence after three sessions of endovascular treatment. CONCLUSIONS: In this neonatal age group (first year of life), we can find the whole range of neurosurgical vascular pathology: VGAM, AVM, cavernous malformation, DSM, pial AVF, DAVF, and sacular aneurysm. VGAM is the most frequent vascular malformation during the first year of age. The early treatment of vascular malformations prevents its adverse effects on a developing brain. A multidisciplinary team composed by endovascular and surgical specialists is necessary to discuss and treat each case.

Endovascular management of spinal vascular malformations.

Spinal vascular malformations are rare diseases with a wide variety of neurological presentations. In this article, arteriovenous malformations (both from the fistulous and glomerular type) and spinal dural arteriovenous fistulae are described and an overview about their imaging features on magnetic resonance imaging (MRI) and digital subtraction angiography is given. Clinical differential diagnoses, the neurological symptomatology and the potential therapeutic approaches of these diseases which vary depending on the underlying pathology are given. Although MRI constitutes the diagnostic modality of first choice in suspected spinal vascular malformation, a definite diagnosis of the disease and therefore the choice of suited therapeutic approach rests on selective spinal angiography. Treatment in symptomatic patients offers an improvement in the prognosis. In most spinal vascular malformations, the endovascular approach is the method of first choice; in selected cases, a combined or surgical therapy may be considered.

Cranial dural arteriovenous fistulas: modification of angiographic classification scales based on new natural history data.

This article presents a modification to the existing classification scales of intracranial dural arteriovenous fistulas based on newly published research regarding the relationship of clinical symptoms and outcome. The 2 commonly used scales, the Borden-Shucart and Cognard scales, rely entirely on angiographic features for categorization. The most critical anatomical feature is the identification of cortical venous drainage (CVD; Borden-Shucart Types II and III and Cognard Types IIb, IIa + b, III, IV, and V), as this feature identifies lesions at high risk for future hemorrhage or ischemic neurological injury. Yet recent data has emerged indicating that within these high-risk groups, most of the risk for future injury is in the subgroup presenting with intracerebral hemorrhage or nonhemorrhagic neurological deficits. The authors have defined this subgroup as symptomatic CVD. Patients who present incidentally or with symptoms of pulsatile tinnitus or ophthalmological phenomena have a less aggressive clinical course. The authors have defined this subgroup as asymptomatic CVD. Based on recent data the annual rate of intracerebral hemorrhage is 7.4-7.6% for patients with symptomatic CVD compared with 1.4-1.5% for those with asymptomatic CVD. The addition of asymptomatic CVD or symptomatic CVD as modifiers to the Borden-Shucart and Cognard systems improves their accuracy for risk stratification of patients with high-grade dural arteriovenous fistulas.

The variant with the absence of the superior petrosal venous and sinus: A potential pitfall of transvenous balloon-assisted embolisation of Borden type II transverse-sigmoid dural arteriovenous fistula.

We describe a patient with Borden type II transverse-sigmoid dural arteriovenous fistula. On the venous phase of the left vertebral artery injection, there was no superior petrosal veins and sinus on the side of lesion. After transvenous balloon-assisted Onyx embolisation, the patient developed extensive venous infarction from venous occlusion. This report calls attention to a highly unusual variant in which the superior petrosal veins and sinus are absent, and the cerebellar veins will be drained by tributaries of the bridging veins in this circumstance. In such circumstances, occlusion of the bridging vein on the tentorial cerebellar surface may lead to complications during transverse-sigmoid dural arteriovenous fistula embolisation.

Carotid Cavernous Fistulas and Dural Arteriovenous Fistulas of the Cavernous Sinus: Validation of a New Classification According to Venous Drainage.

BACKGROUND: Multiple carotid cavernous fistula (CCF) classifications have been proposed. However, they lacked predictive factors for the clinical presentation, natural history, and hemorrhagic risk. Our aim was to externally validate a new classification according to venous drainage (i.e., the Thomas classification [TC]) to assess its relationship with symptoms, endovascular treatment, and outcomes. METHODS: We performed a multicenter retrospective review of CCFs at 2 major academic institutions. The CCFs were classified using the Barrow classification (BC) and TC systems. RESULTS: The data from 94 patients with a diagnosis of CCF were collected during a study period 23 years, 4 months. Of these 94 patients, 89 had undergone CCF treatment and 5 had experienced spontaneous occlusion. Complete occlusion was achieved in 89.9% of the treated patients. Complications occurred in 5.3% of the patients, including permanent deficits in 2.1%. TC type 4 was associated with cortical symptoms compared with type 2 (P = 0.003) and type 3 (P < 0.001). The BC was not able to detect significant differences among the symptom types. Significant differences were found using the TC for the transarterial-only, transvenous anterior-only, and transvenous posterior-only approaches (P < 0.001, P = 0.03, and P = 0.001, respectively). The transvenous posterior and transvenous anterior approach were significantly associated with type 2 and 3 TC, respectively. Excluding direct CCFs, the BC was not related to the treatment approach. No significant differences in the outcomes were found. However, a trend toward a lower occlusion rate for TC type 4 compared with type 3 was observed. CONCLUSION: The TC provided useful information regarding the fistula anatomy and venous hemodynamics, which correlated with the clinical symptoms and treatment strategy.

[Subcortical calcification on CT in Borden type III intracranial dural arteriovenous fistula].

We herein report a 67-year-old female who presented with progressive dementia and disturbance of consciousness. Brain CT showed multiple subcortical calcifications with edema. Enhanced CT showed multiple abnormal vessels in the left hemisphere. Electroencephalography indicated diffuse spike and slow wave complex, so non-convulsive status epilepticus was diagnosed. Cerebral angiography revealed several feeder arteries with retrograde leptomeningeal venous drainage. We diagnosed her with Borden type III cerebral dural arteriovenous fistulas. Trans-arterial embolization with n-butyl-2-cyanoacrylate was performed, and she has experienced no epileptic attacks for at least ten months. Calcification changes are sometimes seen in Borden type II dural arteriovenous fistulas but not in aggressive types, such as Borden type III. It is important to suspect dural arteriovenous fistulas when we encounter patients with progressive dementia or/and epilepsy with cerebral calcification lesions, as this may be a treatable disease condition.

Electrophysiological Assessment and Classification of Motor Pathway Function in Patients With Spinal Dural Arteriovenous Fistula.

PURPOSE: The diagnosis of spinal dural arteriovenous fistula (SDAVF) is difficult and often delayed because clinical features are often nonspecific. We assessed the motor function electrophysiologically in patients with SDAVF. METHODS: Motor-evoked potentials after transcranial magnetic stimulation and compound muscle action potentials and F-waves after electrical stimulation in the ulnar and tibial nerves were measured from the abductor hallucis (AH) muscles in 14 patients with SDAVF (SDAVF group), 12 patients with compressive thoracic myelopathy (CTM group), and 16 normal subjects (control group). The peripheral conduction time determined from abductor hallucis muscles (PCT-AH) and the central motor conduction time determined from abductor hallucis muscles (CMCT-AH) were calculated. According to the neurological findings, patients in the SDAVF group were classified to upper motor neuron (UMN) sign and lower motor neuron (LMN) sign categories. RESULTS: CMCT-AH in the SDAVF and CMT groups were significantly longer than those in the control group. PCT-AH in the SDAVF group was significantly longer than that in the control and CMT groups. Twelve patients in the SDAVF group showed abnormal CMCT-AH and/or PCT-AH. Abnormal CMCT-AH and PCT-AH were detected in five cases that exhibited UMN sign and/or LMN sign. Three cases with abnormal CMCT-AH and normal PCT-AH exhibited UMN sign. LMN sign without UMN sign was observed in four cases with abnormal PCT-AH and normal CMCT-AH. CONCLUSIONS: Our study revealed abnormalities in the corticospinal tract and/or lower motor neurons, and classified the patients with SDAVF into three types: the UMN type, LMN type, and mixed type.

Three-Dimensional Evaluation and Classification of the Anatomy Variations of Vertebral Artery at the Craniovertebral Junction in 120 Patients of Basilar Invagination and Atlas Occipitalization.

BACKGROUND: Patients with basilar invagination and atlas occipitalization usually present abnormal anatomy of the vertebral arteries (VAs) at the craniovertebral junction (CVJ). OBJECTIVE: To describe and further classify different types of VA variations at the CVJ with 3D visualization technology. METHODS: One hundred twenty patients with basilar invagination and atlas occipitalization who had undergone 3-dimensional computed tomographic angiography (3D-CTA) were retrospectively studied. Imaging data were processed via the separating, fusing, opacifying, and false-coloring-volume rendering technique. Abnormal anatomy of the VA at the CVJ was categorized and related anatomic parameters were measured. RESULTS: Seven different types were classified. Type I, VAs enter the cranium after leaving VA groove on the posterior arch of atlas (26.7% of 240 sides); Type II, VAs enter an extraosseous canal created in the assimilated atlas lateral mass-occipital condyle complex before reaching the cranium (53.3%); Type III, VA courses above the axis facet or curves below the atlas lateral mass then enter the cranium (11.7%); Type IV, VAs enter the spinal canal under the axis lamina (1.3%); Type V, high-riding VA (31.3%); Type VI, fenestrated VA (2.9%); Type VII, absent VA (4.2%). Distance from the canal of Type II VA to the posterior facet surface of atlas lateral mass (5.51 ± 2.17 mm) means a 3.5-mm screw can be safely inserted usually. Shorter distance from the midline (13.50 ± 4.35) illustrates potential Type III VA injury during exposure. Decreased height and width of axis isthmus in Type V indicate increased VA injury risks. CONCLUSION: Seven types of VA variations were described, together with valuable information helpful to minimize VA injury risk intraoperatively.

Dural arteriovenous shunts: a new classification of craniospinal epidural venous anatomical bases and clinical correlations.

BACKGROUND AND PURPOSE: The craniospinal epidural spaces can be categorized into 3 different compartments related to their specific drainage role of the bone and central nervous system, the ventral epidural, dorsal epidural, and lateral epidural groups. We propose this new classification system for dural arteriovenous shunts and compare demographic, angiographic, and clinical characteristics of dural arteriovenous shunts that develop in these 3 different locations. METHODS: Three hundred consecutive cases (159 females, 141 males; mean age: 47 years; range, 0 to 87 years) were reviewed for patient demographics, clinical presentation, multiplicity, presence of cortical and spinal venous reflux, and outflow restrictions and classified into the 3 mentioned groups. RESULTS: The ventral epidural group (n=150) showed a female predominance, more benign clinical presentations, lower rate of cortical and spinal venous reflux, and no cortical and spinal venous reflux without restriction of the venous outflow. The dorsal epidural group (n=67) had a lower mean age and a higher rate of multiplicity. The lateral epidural group (n=63) presented later in life with a male predominance, more aggressive clinical presentations, and cortical and spinal venous reflux without evidence of venous outflow restriction. All differences were statistically significant (P<0.001). CONCLUSIONS: Dural arteriovenous shunts predictably drain either in pial veins or craniofugally depending on the compartment involved by the dural arteriovenous shunt. Associated conditions (outflow restrictions, high-flow shunts) may change that draining pattern. The significant differences between the groups of the new classification support the hypothesis of biological and/or developmental differences in each epidural region and suggest that dural arteriovenous shunts are a heterogeneous group of diseases.

Preoperative evaluation of spinal vascular malformation by MR angiography: how reliable is the technique: case report and review of literature.

Contrast-enhanced MR angiography (MRA) has been increasingly used in the evaluation of spinal vascular malformations. Even though MR spinal angiography has several advantages over catheter spinal angiography (DSA), however, spinal DSA must never be omitted before operation, even if the vascular malformation is nicely demonstrated by MR angiography. We report a case of spinal vascular malformation in which MR angiography provided great images which almost convinced everyone about the type and site of malformation/fistula. The images were so convincing that it was almost decided to skip catheter based angiography, citing reason of disadvantages of catheter based angiography over MR angiography. However, spinal DSA was luckily done which completely changed the type and site of malformation and helped in avoiding failed surgery. We conclude that even though catheter based spinal angiography has disadvantages over MRA, it should never be omitted from the diagnostic protocol.

Dural arteriovenous fistula of the lateral foramen magnum region: A review.

The lateral foramen magnum region is defined as the bilateral occipital area that runs laterally up to the jugular foramen. The critical vasculatures of this region are not completely understood. Dural arteriovenous fistulas that occur in this region are rare and difficult to treat. Therefore, we searched PubMed to identify all relevant previously published English language articles about lateral foramen magnum dural arteriovenous fistulas, and we performed a review of this literature to increase understanding about these fistulas. Four types of dural arteriovenous fistulas occur in the lateral foramen magnum region. These include anterior condylar confluence and anterior condylar vein dural arteriovenous fistulas, posterior condylar canal dural arteriovenous fistulas, marginal sinus dural arteriovenous fistulas, and jugular foramen dural arteriovenous fistulas. These dural arteriovenous fistulas share similar angioarchitectures and clinical characteristics. The clinical presentations of lateral foramen magnum dural arteriovenous fistulas include pulsatile tinnitus, intracranial hemorrhage, myelopathy, orbital symptoms, and cranial nerve palsy. Currently, head computed tomography, computed tomography angiography, magnetic resonance imaging, magnetic resonance angiography and digital subtraction angiography (DSA) are useful for diagnosing dural arteriovenous fistulas, and of these, DSA remains the "gold standard." Most lateral foramen magnum dural arteriovenous fistulas need to be treated due to their aggressive symptoms, and transvenous embolization presents the best options. During treatment, it is critical to accurately place the microcatheter into the fistula point, and intraoperative integrated computed tomography and DSA data are very helpful. Other treatments, such as transarterial embolization, microsurgery or conservative treatment, can also be chosen. After appropriate treatment, most patients with lateral foramen magnum dural arteriovenous fistulas achieve satisfactory outcomes.

[The spinal dural arteriovenous fistula is an underdiagnosed vascular malformation].

The spinal dural arteriovenous fistula is the most common spinal vascular malformation, and it is severely underdiagnosed. The symptoms can mimic those of spinal stenosis. Today, the diagnosis is made by an advantageous combination of MR time-resolved imaging of contrast kinetics and digital subtraction angiography posing low risk to the patient. Treatment is primarily direct microsurgical obliteration. Early treatment is essential, since outcome is dependent on preoperative clinical status.

Spinal dural arteriovenous fistulas: a congestive myelopathy that initially mimics a peripheral nerve disorder.

Spinal dural arteriovenous fistula (SDAVF) is a rare and enigmatic disease entity. The clinical features and structural changes have been recognized since 1926, and the pathophysiology and the essentials of treatment since 1974, but up to the present day it is unknown why these fistulas develop. The fistula between a radicular artery and the corresponding radicular vein within the dural root sleeve leads to congestion of the venous outflow of the spinal cord and eventually ischaemia. Patients, who are mostly middle-aged men, develop a progressive myelopathy, which at the early stages of the disease often mimics a polyradiculopathy or anterior horn cell disorder. By the time involvement of upper motoneurons or sacral segments makes the diagnosis of SDAVF inescapable, patients suffer from considerable neurological deficits. The diagnosis relies on MRI, which shows swelling of the spinal cord, with a centrally located hyperintense signal on T2-weighted images, and with hypointense 'flow void' phenomena dorsal to the cord, representing enlarged and tortuous veins. Catheter angiography is required to determine the exact location of the fistula as well as the angio-architecture, on which the mode of treatment depends. If the arterial feeder of the fistula is a tributary of the anterior spinal artery, embolization is not possible. After embolization recanalization may occur, but this is rarely seen after filling of the draining vein with glue. Alternatively, operation is a safe and permanent mode of treatment. No prognostic factors have been reliably established. Muscle strength and gait disturbances respond better to treatment than pain and symptoms related to damage of sacral segments. In any middle aged male patient with ascending motor or sensory deficits in the legs, SDAVF should be considered in order to prevent irreversible handicap.

A novel formula for the classification of blood vessels according to symmetry, asymmetry and hypoplasia.

A new mathematical formula for calculating the symmetry, asymmetry and hypoplasia of blood vessel segments is presented for discussion. The study was conducted using the computed tomography (CT) files from 80 patients (34 men and 46 women) from the Silesian University Hospital, Silesia, Poland, who were between the ages of 12 to 76 and had undergone CT angiography of the circle of Willis. With the use of Gradual Angiographic Image Data Analyser software and double shuttled glasses, CT files were reconstructed. In addition, 80 renal arteries (RAs) from spontaneously aborted foetuses ranging in age from 14 to 30 weeks (24 male and 16 female) were injected with latex and also included in the study. Digital images of the RAs were taken using a Camedia 4040 camera and analysed using original analysis software. A novel formula entitled the Vascular Asymmetry Coefficient (VAC) was derived for this purpose and displays the differences between the mean diameters of blood vessel segments expressed as a percentage of the wider vessel with respect to the major diameter. The asymmetrical classification for a vascular segment of a vessel is given when the difference between the mean diameters of the vascular segment, as represented by the wider vessel, is greater than VAC > 10%. The hypoplastic classification is reserved for blood vessels where the difference between the diameter of the two segments is expressed as a percentage of the wider vessels and is greater than VAC > 40%. While there have been inconsistent and arbitrary classifications for the qualitative criteria of blood vessels, this newly presented algorithm can be used as a standardised tool and has a considerable range of uses, particularly when comparing blood vessel symmetry, asymmetry and hypoplasia prior to bifurcation, and unification.

Spinal Arteriovenous Shunts: Angioarchitecture and Historical Changes in Classification.

The purposes of this study were to review historical changes in the classification of spinal arteriovenous (AV) shunts and to propose a practical classification system. The associated literature regarding the classification of spinal AV shunts was reviewed in the angiography era between 1967 and 2015. The classification systems of spinal AV shunts and a proposed classification system were presented with neuroradiological imaging and medical illustrations. There have been seven major classification systems based on the evolution of diagnostic methods as well as treatments for spinal AV shunts: the first description of spinal AV shunts diagnosed and classified using spinal angiography in 1971; the second classification based on a case report of intradural direct perimedullary arteriovenous fistulas (AVFs) treated by microsurgery in 1987; the third classification based on a case series of intradural perimedullary AVFs treated by endovascular interventions in 1993; the fourth and fifth classification systems based on a case series of spinal AVFs and arteriovenous malformations (AVMs) treated by microsurgery or endovascular interventions in 2002; the sixth classification based on a case series of cranio-spinal dural AV shunts in 2009; and the seventh classification based on a case series of extradural AVFs treated by microsurgery and endovascular interventions in 2011. Based on historical reports, the author proposed a classification system according to the sites (dural, intradural, and extradural) and types (AVF and AVM) of AV shunts. By learning the historical background, we may obtain a clearer understanding of the complex and confusing classification system of spinal AV shunts.