Yasunari Niimi

Background and Purpose: There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography. Methods: We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV. Results: Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0–5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm. Conclusion: Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.

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.

Background: A spinal epidural arteriovenous fistula (SEAVF) is a rare type of arteriovenous shunt that occurs mainly in the thoracic or lumbar spine. Patients with SEAVF develop motor/sensory disturbances of the lower extremities and sphincter dysfunction. Among these symptoms, sphincter impairments show less improvement than others, and its relevance to neurophysiological monitoring has not been documented. Case Description: A 77-year-old woman presented with progressive motor weakness and numbness in the lower extremities and urinary and fecal incontinence. Spinal magnetic resonance imaging showed spinal cord edema in Th5-Th11 and enlarged perimedullary veins. We performed spinal angiography and endovascular treatment under intraoperative neurophysiological monitoring (IOM), including sensory evoked potential (SEP), motor evoked potential (MEP), and bulbocavernosus reflex (BCR) monitoring. Diagnostic angiography revealed a SEAVF with perimedullary venous drainage fed by the left L2 segmental artery. The shunt was completely embolized using N-butyl-2-cyanoacrylate. Although SEP and MEP of the lower legs were recordable during treatment, anal MEP and BCR were not observed. The sphincter symptoms improved 1.5 years after the treatment. Follow-up angiography revealed no shunt recurrence and improved venous congestion. Anal MEP and BCR were detected during angiography, indicating neurophysiological improvement in sphincter function. The prolonged latency of the monitoring suggested a pudendal nerve injury. Conclusion: This case report first described improvement of the IOM correlated with the functional recovery of sphincters after embolization of a SEAVF. Follow-up neurophysiological monitoring is important to assess the functional recovery of the sphincter.

Background: We aimed to quantify the tortuosity of the middle cerebral artery (MCA) and assess its effects on radiological and clinical outcomes in patients with acute MCA occlusions who received mechanical thrombectomy (MT). Methods: This retrospective study enrolled 53 patients with acute ischemic stroke due to MCA M1 or M2 segment occlusion who underwent MT using stent retrievers (SRs). Tortuosity index (TI) was defined to quantify the tortuosity of the MCA M1 segment using the following formula: (actual distance / straight distance) × 100. For each patient, four TIs were measured in the anteroposterior and caudal views for both ipsilateral and contralateral sides to the occluded site (TI-APi, TI-APc, TI-CAUi, and TI-CAUc, respectively) using magnetic resonance angiography (MRA) or computed tomography angiography (CTA). We defined the first-pass effect (FPE) as first-pass mTICI classification ≥2b reperfusion. Results: Patients who did not achieve FPE had significantly higher TI-APi (112 vs. 106; P = 0.004), TI-APc (111 vs. 105; P = 0.005), TI-CAUi (110 vs. 105; P = 0.002), and TI-CAUc (110 vs. 105; P = 0.001) than those who achieved FPE. In multivariable analysis, higher TI-APi, TI-CAUi, and TI-APc were independently associated with an increased rate of unsuccessful FPE (odds ratio (OR) [95% confidence interval (CI)]: 1.25 [1.02–1.61], 1.21 [1.01–1.45], and 1.27 [1.03–1.73], respectively). TI-CAUi, TI-APc, and TI-CAUc were also independent predictors of the occurrence of intracranial hemorrhage after MT (OR [95% CI]: 1.15 [1.01–1.38], 1.14 [1.01–1.38], 1.25 [1.02–1.52], respectively). Conclusions: The TIs of the MCA M1 segment on both ipsilateral and contralateral sides were associated with unfavourable outcomes after MT.

A high flow arteriovenous shunts in newborns may require urgent endovascular treatment right immediately after delivery if high output cardiac failure is resistant to medical treatment. The umbilical approach is often the first choice of the access route for endovascular treatment in the newborn. It is, however, not infrequent that the patient has an extensive lesion, which necessitates a second session of treatment because of the limitation of the usable amount of the contrast material in one session. In such a case, re-puncturing the femoral artery is difficult and carries the risk of leg ischemia. On the other hand, leaving the umbilical sheath for the second procedure carries risks of infection, thrombosis, and vessel injury. Herein we introduce our umbilical vessel catheter (UVC) retro-exchange technique (U-RET) in which we replace the umbilical sheath to a 3.5Fr UVC at the end of the first endovascular procedure to preserve the umbilical artery access and prepare for the repeated use. We believe that this method minimizes the risks of infection and vessel injury.

Background: Spontaneous spinal epidural hematoma (SSEH) is rare in children. Vascular malformation including arteriovenous fistulas and venous malformation is a rare cause of SSEH. Case description: A 5-year-old girl presented with 2 episodes of SSEH at the upper thoracic spine and non-hemorrhagic episodes with spontaneous neurological recovery. Diagnostic study with MRI and spinal angiography demonstrated an unusual epidural arteriovenous fistula (AVF) with venous ectasia similar to venous malformation. She underwent embolization of the AVF with NBCA with mild transient neurological deterioration. Follow up angiography showed persistent occlusion of the embolized fistula and inconsistent visualization of another AVF to the patent venous ectasia. Conclusions: This type of epidural AVF seems to be more common in children and tends to cause multiple neurologic episodes due to SSEH, venous expansion or thrombosis. Endovascular embolization with NBCA should be the first choice of treatment for this disease, unless emergent hematoma evacuation is necessary. Embolization should target at only the fistula site without significant penetration into the venous ectasia. Follow up is necessary for potential reappearance of AVF, even if AVF is occluded at the time of treatment. Time resolved MRI is useful to detect AVFs, thus for diagnosis and follow up of this disease.

SUMMARY: Intradural AVF below the conus medullaris may develop either on the filum terminale or the cauda equina (lumbosacral and coccygeal radicular nerves). Although not a few filum terminale AVFs are found in the literature, only 3 detailed cauda equina AVFs have been reported. Here, we analyze the angiographic and MR imaging findings of our cauda equina and filum terminale AVF cases, supplemented with literature research to characterize the radiologic features of the 2 entities. On angiography, filum terminale AVFs were invariably supplied by the extension of the anterior spinal artery accompanied by a closely paralleling filum terminale vein. Cauda equina AVFs were fed by either a radicular or a spinal artery or both arteries, often with a characteristic wavy radicular-perimedullary draining vein. On thin-section axial MR imaging, the filum terminale AVF draining vein joined the spinal cord at the conus medullaris apex, but that of the cauda equina AVF joined above the conus medullaris apex.