Comparison of efficacy between clazosentan and fasudil hydrochloride-based management of vasospasm after subarachnoid hemorrhage focusing on older and WFNS grade V patients: a single-center experience in Japan.

Subarachnoid hemorrhage often leads to poor outcomes owing to vasospasm, even after successful aneurysm treatment. Clazosentan, an endothelin receptor inhibitor, has been proven to be an effective treatment for vasospasms in a Japanese randomized controlled trial. However, its efficacy in older patients (≥ 75 years old) and those with World Federation of Neurosurgical Societies (WFNS) grade V has not been demonstrated. We retrospectively evaluated the efficacy of clazosentan in older patients and those with WFNS grade V, using real-world data. Patients with subarachnoid hemorrhage treated before and after the introduction of clazosentan were retrospectively evaluated. The patients were categorized into two groups (clazosentan era versus pre-clazosentan era), in which vasospasm management and outcomes were compared. Vasospasms were managed with fasudil hydrochloride-based (pre-clazosentan era) or clazosentan-based treatment (clazosentan era). Seventy-eight patients were included in this study: the clazosentan era (n = 32) and pre-clazosentan era (n = 46). Overall, clazosentan significantly reduced clinical vasospasms (clazosentan era: 31.3% versus pre-clazosentan era: 60.9%, p = 0.01), delayed cerebral ischemia (DCI) (9.4% versus 39.1%, p = 0.004), and vasospasm-related morbidity and mortality (M/M) (3.1% versus 19.6%, p = 0.03). In subgroup analysis of older patients or those with WFNS grade V, no significant difference was observed in clinical outcomes, although both DCI and vasospasm-related M/M were lower in the clazosentan era. Clazosentan was more effective than fasudil-based management in preventing DCI and reducing vasospasm-related M/M. Clazosentan could be used safely in older patients and those with WFNS grade V, although clinical outcomes in these patients were comparable to those of conventional treatment.

Postsurgical dural supply to the spinal cord arteriovenous malformation in spinal arteriovenous metameric syndrome.

Dural supply from the external carotid system in cerebral arteriovenous malformations (AVMs) is well known, but actual angiographic evidence of dural supply to spinal cord AVMs (SCAVMs) has not been reported. Here, we report a case of dural supply to the conus SCAVM in the spinal arteriovenous metameric syndrome segment 25-30. Thirteen years after spinal surgery (T12-L2 laminoplasty), spinal angiography showed multiple dural supplies from the dorsal somatic branches, prelaminar arteries, and radiculomeningeal arteries to the SCAVM at the level of the previous spinal surgery. To the best of our knowledge, this is the first reported case with dural supply to the spinal cord. This case demonstrates that the extradural and extraspinal branches can supply the spinal cord in rare instances of spinal dural adhesions following repeated hemorrhages and surgical intervention under a metameric link background.

FLOW-diverted Glue Embolization to Target lesions (FLOW-GET) technique for spinal vascular diseases: A technical note.

We present and exemplify the flow-diverted glue embolization to target lesions (FLOW-GET) technique for spinal vascular diseases. In this technique, the occlusion of the posterior intercostal artery or dorsal muscular branch by coils diverts the injected glue from the segmental artery to the target lesions. This technique was applied to a ruptured retrocorporeal artery aneurysm and spinal dural arteriovenous fistulas. The FLOW-GET accomplished the complete obliteration of all lesions. This simple and useful technique can be applied to spinal vascular lesions even if a microcatheter is not placed in proper feeders or advanced close to the shunt points or aneurysms.

A novel omnidirectional tin-alloyed ring retractor for craniotomy in neurosurgery: technical note.

In neurosurgical operations, proper craniotomy using retractors is necessary. Various surgical instruments are used for this purpose, including standard retractors and multipurpose head frame retractor systems. However, the conventional multipurpose head frame system is often not optimal for use in some craniotomies and postures because of its size and complexity of setting. We have invented a new omnidirectional tin-alloyed (ODT) ring retractor for craniotomy with malleability and shape memory characteristics to resolve these issues. It is principally elliptical in shape, approximately 30 × 20 cm in diameter, and sufficiently firm. Accordingly, this ODT ring can retract the surgical field in all directions. Here, we report our experiences of 281 neurosurgical craniotomies using this ODT ring retractor system in various craniotomy sites and postures. Our novel ODT ring retractor is useful because of its low profile, multidirectional retractability, and less obstructiveness with its malleability. It could be used with pediatric patients where strong traction is not desirable.

Maximum Nidus Depth as a Risk Factor of Surgical Morbidity in Eloquent Brain Arteriovenous Malformations.

BACKGROUND: Eloquent location of a brain arteriovenous malformation (BAVM) is known to increase the surgical risk. Surgical removal of such BAVMs is challenging. Useful indicators for the safe removal of eloquent BAVMs are needed. The aim of this study was to determine the surgical risk factors for these challenging entities. METHODS: The authors retrospectively reviewed 29 motor and/or sensory BAVM patients who underwent surgeries. The risk factors for surgical morbidity were analyzed. As a new risk factor, maximum nidus depth, was evaluated. RESULTS: Complete obliteration was achieved in 28 patients (96.6%). Postoperative transient and permanent neurological deteriorations were seen in nine patients (31.0%) and five patients (17.2%), respectively. In univariate analysis, maximum nidus depth (p = 0.0204) and asymptomatic onset (p = 0.0229) were significantly correlated with the total morbidity. In multivariate analysis, only maximum nidus depth was significantly correlated with total morbidity (p = 0.0357; odds ratio, 2.78598; 95% confidence interval, 0.8866-8.7535). The cut-off value for the maximum nidus depth was 36 mm for total morbidity (area under the curve [AUC], 0.7428) and 41 mm for permanent morbidity (AUC, 0.8833). The cutoff value of the maximum nidus size was 30 mm for total morbidity (AUC, 0.5785) and 30 mm for permanent morbidity (AUC, 0.7625). AUC was higher for the maximum nidus depth than it was for the maximum nidus size. CONCLUSIONS: Maximum nidus depth was significantly associated with surgical morbidity of eloquent BAVMs. The maximum nidus depth is a novel and a simpler indicator of the risk of surgical morbidity.

Simmons Angled microguidewire INsertion to the Target (SAINT) technique in neuroendovascular therapy.

Advancing appropriate microcatheters is essential for treatment. However, we still encounter inaccessible arterial branches because of the anatomical arrangement. While many successful techniques regarding microcatheters have been reported, there have been very few reports of microguidewire-shaping techniques. We developed the Simmons-Angled microguidewire INsertion to the Target (SAINT) technique for insertion of the microguidewire into inaccessible arterial branches. The SAINT technique is feasible for selection and insertion into arteries that are inaccessible with conventional methods.

[A Case of Bilateral Carotid Injury Caused by Vinyl Umbrella Penetration Successfully Treated with Endovascular Therapy].

Here, we have reported a case pertaining to a 59-year-old man with bilateral traumatic carotid artery injury caused by vinyl umbrella penetration who was successfully treated. The patient fell from the stairs while holding an umbrella, which penetrated his neck. On admission, the patient was in a comatose state and the umbrella had been removed. Active bleeding was observed on the left side of the neck. Hence, tracheal intubation was performed to support respiration. Neck and head contrast-enhanced CT revealed bilateral extravasations from the carotid arteries and right middle cerebral artery(MCA)occlusion. Left carotid angiography showed extravasation from the external carotid artery(ECA), which was treated with coil embolization. Right carotid angiography revealed bleeding from the ECA and internal carotid artery(ICA)and occlusion of the MCA. The ECA and ICA were occluded by coil and n-butyl-2-cyanoacrylate embolization. After the procedures, the patient developed a large right cerebral infarction with massive brain swelling; therefore, external decompression was performed. Subsequently, the patient became alert and was able to walk with support within a month. Bilateral carotid injury is severe and difficult to treat. Endovascular therapy may be effective for the management of bilateral carotid injuries.

Long-term outcomes following thrombectomy for acute ischemic stroke in patients with a left ventricular assist device: a case series and literature review.

BACKGROUND: Left ventricular assist devices (LVADs) were developed for the treatment of patients with severe heart failure (HF) as a bridge to heart transplantation (HT). Although long-term LVAD support results in substantial improvements, their long-term use often leads to severe acute ischemic stroke (AIS). Serious neurological events make it difficult to continue LVAD support, and these patients are excluded as candidates for HT. AIS remains a challenging problem in patients receiving LVAD support. Recently, although thrombectomy has been established in selected patients who are independent, it has not been established in patients who are not completely independent, such as those with LVAD support. METHODS: We describe four AIS patients with severe HF who were implanted with an LVAD as a bridge to HT. Five mechanical thrombectomies were performed for AIS associated with an LVAD in four patients. A literature review is presented and compared to the present results. RESULTS: Good recanalization was achieved in all patients. In three cases, marked neurological improvement was observed, and modified Rankin Scale (mRS) scores were maintained without deterioration. The median total follow-up period was 592 days. In one patient, HT was successfully performed after thrombectomy. Currently, two of the patients without neurological deficits are awaiting HT. CONCLUSIONS: Embolism is a major problem encountered by patients under LVAD support while waiting for an HT. Thrombectomy for AIS associated with LVAD support is a useful and safe treatment modality. It is possible to maintain a reasonable mRS score in patients who are not completely independent.

Extremely rare persistent primitive artery passing through the jugular foramen with symptomatic ipsilateral carotid artery stenosis.

Primitive arteries are persistent fetal anastomoses between the carotid and vertebral-basilar circulation. Although rare, persistent primitive arteries can remain at birth. A 73-year-old woman presented with cerebral infarction to the posterior circulation caused by symptomatic common carotid artery stenosis with an unnamed and extremely rare persistent primitive artery. This anomalous vessel branched from the extracranial internal carotid artery and passed through the ipsilateral jugular foramen into the posterior cranial fossa and merged into the basilar artery. To our knowledge, this is the first case of a persistent primitive artery passing through the jugular foramen with symptomatic common carotid artery stenosis.

Moyamoya disease concurrent with Graves' disease treated by direct bypass: clinical features and treatment strategies.

BACKGROUND: Moyamoya disease (MMD) concurrent with Graves' disease (GD) is rare. There is no guideline about optimizing thyroid hormones and the appropriate timing of surgical treatment for MMD with GD. METHODS: We encountered eight patients with MMD and GD presenting with cerebral ischemia who were treated by direct bypass. Thyroid hormones [free thyroxin (fT4) and free triiodothyronine (fT3)], thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb) were measured sequentially. After thyrotoxic conditions were medically optimized, revascularization surgery was performed by superficial temporal artery-middle cerebral artery (STA-MCA) double bypass in all cases. Clinical outcomes were estimated by modified Rankin scale (mRS) at discharge and 3 months after surgery. RESULTS: In six patients with thyrotoxicosis, the fT4, fT3, and TRAb (range) at the onset of cerebral ischemia were 4.81-10.30 pg/ml, 13.08-31.90 pg/ml, and 3.5-83.8 IU/l, respectively. At surgery, mean (range) fT3 and fT4 were optimized to 3.02 (1.01-4.87) pg/ml and 1.09 (0.41-1.68) ng/dl, respectively. In the thyrotoxic cases, it took 70-310 days (mean, 142 days) to optimize thyroid hormones before surgery. There was no neurological aggravation after surgery, and outcome was excellent at 3 months with mRS scores ≤2 in all cases. CONCLUSIONS: For MMD concurrent with GD, optimizing thyroid hormones followed by STA-MCA double bypass was successful to prevent cerebral ischemic events.

Perioperative Management of Spinal Arteriovenous Malformation Embolization: Delayed Venous Thrombosis and Implications for Severe Back Pain.

BACKGROUND AND PURPOSE: The prognosis of untreated spinal arteriovenous malformations (SAVMs) is poor. Embolization plays an important role in the management of intramedullary SAVMs. Delayed aggravation due to spinal venous thrombosis following successful embolization has been reported; however, perioperative management strategies to prevent thrombosis have not been explored. We present our single-center experience of SAVM embolization and perioperative management, including anticoagulation. MATERIAL AND METHODS: We retrospectively evaluated 18 patients with SAVMs who underwent transarterial embolization. Perioperative anticoagulation therapy was administered to selected patients. We compared the characteristics of the patients, including perioperative management procedures, between those with and without postoperative worsening following embolization. RESULTS: Acute postoperative worsening within 1 week occurred in 4 (22.2%) patients. Of these, immediate worsening was observed in one patient as a procedure-related complication. Delayed worsening after 24 h was observed in 3 patients, caused by delayed venous thrombosis with severe back pain. Rescue anticoagulation for delayed worsening improved symptoms in two patients. A comparison between patients with and without acute postoperative worsening revealed significant differences in age (median 46.5 vs. 26.5 years, p = 0.009) and the presence of postoperative back pain (75.0% vs. 0%, p = 0.005); however, there was no significant difference in use of selective anticoagulation (p = 0.274). CONCLUSION: The results of this study suggest that SAVM embolization can cause acute worsening due to postoperative venous thrombosis with severe back pain, which may be reversed by anticoagulation therapy. Back pain is an important finding that suggests venous thrombosis, and anticoagulation should be urgently administered.

[Azygos anterior cerebral artery aneurysm in a patient with Noonan syndrome].

Noonan syndrome(NS)is a common, clinically and genetically heterogeneous condition characterized by distinctive facial features, short stature, congenital heart disease, and other comorbidities. However, there have been only a few case reports of cerebrovascular abnormalities in patients with NS. Especially, the cases of intracranial aneurysms with NS are very rare. In addition, comorbidities of azygos anterior cerebral artery(ACA)and NS have not been reported before now. We encountered such a rare case of azygos ACA unruptured aneurysm in patient with NS. The case was 64-year-old woman with NS complaining of gait disturbance. The three-dimensional CT angiography(3D-CTA)showed azygos ACA and an unruptured saccular aneurysm at the distal end of the A2 segment. An operation for this aneurysm was performed. We reviewed clinical features of NS with cerebrovascular disease such as aneurysm.

Successful embolization of ventricular arteriovenous malformation supplied by the choroidal artery: A case report and literature review.

Background: Ventricular arteriovenous malformations (AVMs) are localized in the ventricles and are mainly fed by the anterior choroidal artery (AChoA) and posterior choroidal artery (PChoA). Surgical resection of ventricular AVMs is difficult as the lesions are localized deep in the brain. Therefore, endovascular treatment is expected to treat ventricular AVMs. However, embolization from the AChoA and PChoA carries the risk of ischemic complications. Even though there are some major reports on embolization strategies from the choroidal arteries, embolization of these arteries remains technically challenging. In this article, we report two successful cases of ventricular AVM embolization using AChoA and PChoA. Case Description: Case 1: A 34-year-old male presented with intraventricular hemorrhage (IVH). Subsequently, ventricular AVM embolization in the anterior horn was performed using n-butyl-2-cyanoacrylate (NBCA) through the AChoA and medial PChoA, and complete obliteration was observed without neurological deterioration. Case 2: A 71-year-old female presented with IVH. Subsequently, ventricular AVM embolization in the lateral ventricle was performed through the AChoA and lateral PChoA with Onyx and NBCA, and partial obliteration was observed without complications. Furthermore, Gamma Knife surgery for residual lesions resulted in complete obliteration. Conclusion: Embolization through the choroidal arteries for ventricular AVMs is an effective curative or adjunctive treatment.

De Novo Radicular Arteriovenous Fistula After Treatment of Spinal Arteriovenous Fistula: A Case Report and Literature Review.

De novo spinal dural arteriovenous fistulas (AVFs) have been reported as metachronous AVFs However, metachronous spinal AVFs are extremely rare, and their pathogenesis remains uncertain. We report a case of de novo radicular AVF (RAVF) following treatment for spinal AVF at the craniocervical junction (CCJ). We also reviewed the literature and discussed the pathogenesis of metachronous spinal AVF. A 64-year-old male patient diagnosed with spinal AVF at the CCJ supplied from the right C1 segmental artery was treated with Onyx-18 (eV3 Inc, CA, USA) trans-arterial embolization, resulting in partial occlusion. Angiography showed a slight residual shunt two weeks after the embolization without another shunt lesion. A five-year follow-up spinal angiography showed de novo RAVF at the C4 level and complete occlusion of the first AVF. The second AVF was not treated because it was asymptomatic, and the patient remained asymptomatic. De novo RAVF was found to develop five years after the embolization of a CCJ-spinal AVF in a patient. This is the first case of de novo RAVF post-treatment of a spinal AVF. This case demonstrated that RAVF could develop as an acquired disease.

Cerebral venous thrombosis associated with hyperhomocysteinemia and iron-deficiency anemia induced by autoimmune gastritis: A case report and literature review.

Cerebral venous thrombosis (CVT) is a rare disease, occurring in 0.5%-1% of all patients with strokes. Systemic and hereditary diseases and traumas are potential causes of CVT. We report a case of CVT and systemic thromboembolism complicated with hyperhomocysteinemia and iron-deficiency anemia caused by autoimmune gastritis. A 47-year-old female patient was admitted to the emergency department due to difficulty in movement, impaired consciousness, and urinary incontinence. Brain computed tomography (CT) and magnetic resonance imaging (MRI) showed bilateral thalamic edema associated with venous sinus thrombosis and embolic cerebral infarction in the deep white matter of the bilateral cerebral hemispheres. In addition, contrast enhanced whole-trunk CT scan showed deep femoral thrombosis and pulmonary artery embolism. She had no medical history of diseases or drug use that may cause thrombosis. Blood test results revealed iron-deficiency anemia and hyperhomocysteinemia, which were determined to be the cause of systemic thromboembolism. The patient tested positive for intrinsic factor antibodies. Moreover, the patient was diagnosed with autoimmune gastritis by gastrointestinal endoscopy. Therapies including anticoagulant and replacement with iron and vitamin B12 were administered. The patient was discharged from the hospital without neurological deficits. A favorable clinical course was achieved with anticoagulant administration and replacement therapy with iron and vitamin B12 for cerebral arteriovenous embolism that developed due to autoimmune gastritis.

Pure spinal intraosseous arteriovenous fistula: A case report.

Spinal osseous arteriovenous fistula (AVF) is a rare disease with a characteristic angioarchitecture involving an intraosseous venous pouch (VP) of the vertebral body where the feeders are converging. Using spinal angiography alone, it is difficult to distinguish spinal osseous AVF from classical spinal epidural AVF (EDAVF) with fistulas in the epidural VP and bone erosion because both subtypes have an angiographically similar dilated VP appearance. Thus, spinal osseous AVF may be often misdiagnosed as spinal EDAVF. With advancing imaging techniques, it would be possible to determine the exact location of the fistula. Here, we present the case of a 37-year-old woman with a pure spinal thoracic osseous AVF and radiculopathy. She was diagnosed with spinal intraosseous AVF using high-resolution three-dimensional rotational angiography (3D-RA). The fistula was located in the Th1 lateral mass with a VP where multiple osseous feeders were converging. There was paravertebral venous drainage without intradural venous drainage. Transvenous embolization with Onyx and coils was performed through the azygos vein to the lateral epidural venous plexus, resulting in complete obliteration. This case suggests that 3D-RA reconstructed images are essential for accurate diagnosis and successful treatment of this condition. It is important to occlude only intraosseous VPs by accurate subtype diagnosis. Transvenous embolization is a treatment option for spinal intraosseous AVF with paravertebral epidural venous drainage.

Angiographic Index for the Treatment Efficacy and Functional Outcomes of Spinal Cord Arteriovenous Shunts: the Vertebral Blush Sign.

BACKGROUND: The functional outcomes in spinal cord arteriovenous shunts (SCAVSs) are usually unpredictable from current assessments of treatment results. We aimed to investigate and propose a new index marker, the vertebral blush (VB) sign, for assessing the treatment efficacy of SCAVSs. METHODS: This retrospective cohort study enrolled patients diagnosed with SCAVSs between June 2012 and May 2021. The VB sign was defined as the angiographic finding of reappearance or enhanced contrast staining of the vertebral bodies fed by shunt-related arteries observed after shunt occlusion. The primary outcome was the improvement in motor/sensory disturbances or sphincter impairments within 1 year after treatment. The secondary outcome was shunt recanalization. VB sign characteristics and associations with outcomes were analyzed. RESULTS: Of 65 patients with SCAVSs, 57 were eligible for VB sign assessment; among these, there were 26 with the VB sign and 31 without the VB sign. Among vascular shunts perimedullary arteriovenous fistula showed the greatest difference in prevalence rate between those with and without the VB sign (33.3%, n = 9/27 versus 10.0%, n = 3/30; P = 0.031). On multivariable logistic regression analysis, SCAVSs with the VB sign had significantly more favorable outcomes than those without the VB sign (adjusted odds ratio, 5.61; 95% confidence interval, 1.48-21.23; P = 0.01). There was no relationship between the VB sign and secondary outcomes (P = 0.35). CONCLUSION: The VB sign is independently associated with functional recovery after shunt occlusion and could be an assessment tool for the treatment efficacy of SCAVSs.

Optimal guiding catheter position during advancement of the guiding catheter into the carotid artery from the aortic arch via transfemoral approach.

BACKGROUND: Guiding catheter (GC) advancement into the target carotid artery is a crucial step in neuroendovascular therapy. In difficult anatomies, alternative methods have been reported to overcome difficult carotid access for swift GC advancement. However, studies focusing on the positional relationship between the GC and inner catheter (IC) at the aortic arch are lacking. METHODS: We evaluated the impact of the positional relationship between the GC and IC on whether the GC position affects catheter support or system straightening. We retrospectively reviewed 89 patients who underwent neuroendovascular therapy. We assessed the time to carotid access across difficult arch anatomies. The GC position was divided into Position 1, descending aorta level; Position 2, aortic arch level; and Position 3, origin of the left common carotid artery or innominate artery. We also evaluated the GC support and straightening effects in an in vitro vascular model study. RESULTS: The coaxial catheter flexion angle at the aortic arch was significantly larger when the GC was set to Position 3 (p < 0.0001). A significantly shorter time to carotid access was observed with Positions 2 and 3 than with Position 1 in the difficult arch anatomy group. In the in vitro vascular model evaluation, the catheter support effect significantly increased as the GC position became closer to the IC tip (p < 0.0001) and straightening effect significantly increased as the GC moved to Position 2 from Position 1 (p < 0.0001). CONCLUSION: During GC advancement, the GC positional relationship changed the support of the coaxial system with system straightening. The optimal GC position, Position 3, facilitated swift GC advancement.

A Novel Magnetic Resonance Imaging-Compatible Titanium Alloy Wire-Reinforced Endotracheal Tube.

Reinforced endotracheal tubes (ET) are advantageous in preventing tube obstruction and kinking by procedural compression during neurosurgeries. However, the standard reinforced ET contains an embedded stainless steel (SS) helical wire, which produces artifacts and heat during magnetic resonance imaging (MRI). Therefore, MRI is not indicated in the presence of a reinforced ET containing SS. To overcome this challenge, we developed an MRI-compatible titanium (Ti) reinforced ET. A newly developed Ti alloy helical wire was inserted in a reinforced ET. Here, we report our first clinical experience with six patients who underwent neurosurgery intubated with this Ti-alloy-reinforced ET. The Ti-alloy-reinforced ET was used in six patients requiring reinforced ET intubation. It was clearly delineated on radiography, and metal artifacts were small on computed tomography. Patients intubated with the Ti-alloy-reinforced ET could safely undergo MRI under sedation. MR images without remarkable susceptibility artifacts were obtained without noted adverse effects. We invented a novel Ti-alloy-reinforced ET. This device allows clinical use during MRI because it is less susceptible to artifacts in high magnetic fields.

Angiographic classification of the inferior sagittal sinus based on the venous drainage patterns.

PURPOSE: The inferior sagittal sinus (ISS) and its tributaries have received little attention because of its inconspicuous appearance, and its anatomical variations are also unknown. This study aimed to evaluate the morphological variations of the ISS. MATERIALS AND METHODS: We retrospectively reviewed 518 patients in whom cerebral angiography was clinically indicated. The detailed angioarchitecture of the cerebral venous system, including the ISS and their tributaries, and the morphological variations of the ISS were evaluated. Abnormalities of the rostral third superior sagittal sinus (SSS) were also evaluated. RESULTS: The ISS was visualized in 270 (52.1%) patients. We proposed an angiographic ISS classification according to the venous drainage patterns: Type 0, not visualized; Type 1, small ISS with faint tributaries; Type 2, moderate ISS with developed tributaries; and Type 3: large ISS with well-developed tributaries, which are responsible for the venous drainage of the anterior frontal lobe. The frequency of each ISS type was as follows: Type 0, 248 (47.9%); Type 1, 211 (40.7%); Type 2, 44 (8.5%); and Type 3, 15 (2.9%). The mean ISS size was significantly larger with an increase in the type of ISS (p < 0.0001). The rostral third SSS hypoplasia was observed in all cases of Type 3. The hypoplasia of the rostral third SSS and development of the ISS were strongly correlated and complementary to each other. CONCLUSION: This study provided the angiographic ISS classification, and our proposed angiographic ISS classification could be helpful in better understanding of the ISS anatomy and its venous drainage pattern.