Two Cases of Mechanical Thrombectomy in Patients with Fenestration of the M1 Segment of the Middle Cerebral Artery.

M1 fenestration of the middle cerebral artery is rare. We present two patterns of acute thromboembolic conditions in M1 fenestrations treated with mechanical thrombectomy. Case 1 was a male in his 60s presenting with right hemiparesis and aphasia. Angiography showed acute left M1 proximal occlusion; the first direct aspiration revealed two parallel routes, and the second aspiration achieved complete recanalization of the left M1 fenestration. Case 2 was a male in his 70s presenting right hemiparesis and aphasia. Angiography revealed a sudden stair-like narrowing of the left M1 in the intermediate part, and a retrograde blood flow cavity was observed on the upper side of the distal part. Mechanical thrombectomy was performed to diagnose the upper limb occlusion of the left M1 fenestration, and successful recanalization was achieved through direct aspiration. Anatomical variations, such as fenestration, should be considered to reduce complication risks.

Wallerian degeneration of the ipsilateral middle cerebellar peduncle after lower pontine paramedian infarct diagnosed by magnetic resonance imaging.

We reported a case of Wallerian degeneration of the unilateral middle cerebellar peduncle (MCP) that developed after ipsilateral paramedian lower pontine infarction. The patient was a 70-year-old woman with right hemiparesis and dysarthria. Using a 3-Tesla scanner, cranial magnetic resonance imaging was performed, and an infarct was found at the left paramedian lower pons. Seven months later, an abnormal signal was found at the central portion of the left MCP, indicative of Wallerian degeneration of the pontocerebellar tract (PCT). There was no abnormality at the contralateral MCP. Usually, Wallerian degeneration of the bilateral MCPs may develop after unilateral paramedian pontine infarction, because bilateral PCTs cross each other at the midline of the basis pontis. In the present case, however, Wallerian degeneration was found at only the ipsilateral MCP. The contralateral PCT was not affected because the PCT runs in the craniocaudal direction, and our patient had a lower pontine infarct. The location of the pontine infarct (affected PCT) and the Wallerian degeneration of the side of the MCP were well correlated.

Endovascular Treatment for Acute Ischaemic Stroke Caused by Vertebral Artery Dissection: A Report of Three Cases and Literature Review.

Vertebrobasilar artery dissection is an uncommon cause of acute ischaemic stroke (AIS). Optimal endovascular management has not been established. This study aimed to share our experience with endovascular reperfusion therapy for vertebrobasilar artery occlusion due to vertebral artery dissection (VAD). We retrospectively reviewed 134 consecutive patients with AIS who received urgent endovascular reperfusion therapy between November 2017 and November 2019. Three patients diagnosed with VAD were investigated. The evaluation included mechanisms of vertebrobasilar artery occlusion due to VAD, variations in endovascular procedures, and functional outcomes. Dissections at the V3, V4 and extension of V3 to V4 segments were seen in one patient each. The mechanism of AIS was different in each patient: occlusion of the distal non-dissected artery due to an embolus from the dissection site (distal occlusion), haemodynamic collapse of the entire vertebrobasilar artery system due to the arterial dissection itself (local occlusion), or coexistence of distal occlusion and local occlusion (tandem occlusion). The endovascular reperfusion therapy was performed corresponding to the abovementioned mechanisms: mechanical thrombectomy for distal occlusion, stenting for local occlusion, and a combination of thrombectomy and stenting for tandem occlusion. In all three patients, effective recanalization and functional independence (modified Rankin Scale scores of 0-2 at 90 days after the onset) were achieved. Endovascular treatment corresponding to the individual mechanism of AIS may improve patient outcomes.

[Usefulness of Bilateral rSO2 Monitoring for Predicting Cerebral Hyperperfusion Syndrome after Carotid Artery Stenting].

OBJECTIVE: Cerebral hyperperfusion syndrome(CHS)and cerebral hyperperfusion phenomenon(CHP)induce intracranial hemorrhage and can become critical complications after carotid artery stenting(CAS). The purpose of the present study was to predict and avoid CHS after CAS using bilateral rSO2 intraoperative monitoring. METHODS: We retrospectively analyzed 100 consecutive patients who underwent CAS between January 2012 and May 2014 in our institution. We performed continuous bilateral rSO2 monitoring from anesthetic induction to the day following CAS. CHS was defined as the deterioration of neurological conditions post-CAS, no ischemic changes on post-CAS head CT or brain MRI, an increase in cerebral blood flow(CBF)and cerebral blood volume(CBV), and shortening of the mean transit time(MTT)or time to peak(TTP)on CT perfusion. To compare the CHS/CHP group and non-CHS/CHP group, we defined four parameters:rSO2 difference(rSO2 at the endpoint of the procedure-baseline rSO2), ΔrSO2 difference(affected side rSO2 difference-unaffected side rSO2 difference), rSO2 ratio(rSO2 at the endpoint of the procedure/baseline rSO2), and ΔrSO2 ratio(affected side rSO2 ratio/unaffected side rSO2 ratio). RESULTS: There were 2 CHS cases(2.2%)and 3 CHP cases(3.3%). In the CHS/CHP group, the ΔrSO2 difference and ΔrSO2 ratio were significantly higher than those in the non-CHS/CHP group(p value<0.05);however, no significant differences were found in the affected side rSO2 difference(p value=0.063)and affected side rSO2 ratio(p value=0.054)between the groups. CONCLUSION: We could promptly detect CHS and CHP in all cases by using continuous bilateral rSO2 monitoring and analysis of the ΔrSO2 difference and ΔrSO2 ratio.

Diagnosis of a C3 segmental type of vertebral artery by magnetic resonance angiography: report of two cases.

We report two cases in which the vertebral artery (VA) entered the spinal canal via the intervertebral foramen at the C2-C3 disc level, an extremely rare variation regarded as a C3 segmental type of VA, that we diagnosed by magnetic resonance angiography. The C2 segmental type of VA, in which the VA enters the spinal canal via the C1-C2 intervertebral space, is relatively common. It is important to identify these variations before surgery of the craniovertebral junction or interventional procedures to prevent complications.

The safety and efficacy of preoperative embolization of meningioma with N-butyl cyanoacrylate.

OBJECTIVE: Preoperative embolization of meningioma is commonly performed; however, there is no consensus on the best embolic material to reduce intraoperative blood loss and surgery time. METHOD: We retrospectively assessed the safety and efficacy of 56 cases of preoperative embolization of the middle meningeal artery with N-butyl cyanoacrylate (NBCA) in 105 cases of surgery for meningioma. We also defined a blood loss to tumor volume ratio to compensate for bias caused by tumor volume, and analyzed limited cases (the embolized group n = 52, the non-embolized group n = 21) of the convexity, the parasagittal region, the falx, and the sphenoidal ridge. RESULT: The blood loss to tumor volume ratio was significantly less in the embolized group (p < 0.007). Preoperative embolization could be useful for cases with the external carotid artery as the dominant feeder vessel (p < 0.02); however, the efficacy decreased for cases with an internal carotid artery feeder. Transient complications occurred in four cases (hemiparesis secondary to edema: two cases; intratumoral bleeding: one case; trigeminal nerve disorder: one case). The cases that showed a postoperative increase in edema or intratumoral bleeding were large tumors with the early filling of veins. For such cases, surgeons should pay close attention to slow injection speed and higher NBCA viscosity, not to cause the occlusion of draining vessels. CONCLUSION: Tumor embolization with NBCA can be safely performed, and the procedure significantly reduces intraoperative blood loss.

Risk factors for coil protrusion into the parent artery and associated thrombo-embolic events following unruptured cerebral aneurysm embolization.

OBJECTIVE: Advances in vascular reconstruction devices and coil technologies have made coil embolization a popular and effective strategy for treatment of relatively wide-neck cerebral aneurysms. However, coil protrusion occurs occasionally, and little is known about the frequency, the risk factors and the risk of thrombo-embolic complications. METHOD: We assessed the frequency and the risk factors for coil protrusion in 330 unruptured aneurysm embolization cases, and examined the occurrence of cerebral infarction by diffusion-weighted magnetic resonance imaging (DW-MRI). RESULT: Forty-four instances of coil protrusion were encountered during coil embolization (13.3% of cases), but incidence was reduced to 33 (10% of cases) by balloon press or insertion of the next coil. Coil protrusion occurred more frequently during the last phase of the procedure, and both a wide neck (large fundus to neck ratio) (OR = 1.84, P = 0.03) and an inadequately stable neck frame (OR = 5.49, P = 0.0007) increased protrusion risk. Coil protrusions did not increase the incidence of high-intensity lesions (infarcts) on DW-MRI (33.3% vs 29% of cases with no coil protrusion). However, longer operation time did increase infarct risk (P = 0.0003). Thus, tail or loop type coil protrusion did not increase the risk of thrombo-embolic complications, if adequate blood flow was maintained. CONCLUSION: Coil protrusion tended to occur more frequently in cases of wide-neck aneurysms with loose neck framing. Moderate and less coil protrusion carries no additional thrombo-embolic risk, if blood flow is maintained, which can be aided by additional post-operative antiplatelet therapy.

Rupture of an aneurysm of the superior cerebellar artery feeding a dural arteriovenous fistula.

We experienced a very rare case of bleeding from an aneurysm of a branch of the superior cerebellar artery, which feeds a dural arteriovenous fistula (DAVF) of the posterior fossa. The aneurysm was not detected on initial angiography and 2 episodes of rebleeding resulted in deterioration of the patient's condition. Although rare, aneurysms of the pial feeding arteries should be considered as a cause of bleeding in cases of DAVF.

Risk factors and prevention of guiding catheter-induced vasospasm in neuroendovascular treatment.

Mechanically-induced vasospasm often occurs during guiding catheter insertion, occasionally preventing catheter advancement to the desired location. Delicate manipulation would be impossible without the proper positioning of guiding catheters, and vasospasm-induced cerebral hypoperfusion may cause thrombotic complications. From June 2012 to December 2013, we prospectively analyzed 150 endovascular treatment cases, excluding acute cases, for the frequency of vasospasm, risk factors, and countermeasures. The associated risk factors such as the Japanese-style State-Trait Anxiety Inventory (STAI) score; anatomy and devices; and the efficacies of warm compresses, intra-arterial lidocaine/nicardipine, and tranquilizers were analyzed. Groups 1, 2, and 3 comprised 50 patients each with controls, tranquilizer administration, and prophylactic warm compresses/intra-arterial drug injection, respectively. Moderate or severe vasospasm was seen in approximately 40% patients in each group; however, severe vasospasm was absent in Group 3. Mild vasospasm-induced cerebral infarction occurred in one patient each in Groups 1 and 2. Vasospasm during diagnostic angiography [odds ratio (OR) = 10.63; P = 0.01], many ≥ 30° vessel curves [OR = 4.21; P = 0.01], and the high STAI score [OR = 1.84; P = 0.01] were risk factors for severe vasospasm. Although the relationship between anxiety and sympathetic tone remained unclear, tranquilizer administration relieved vasospasm. Warm compresses and the intra-arterial drug infusion were also useful for relieving vasospasm. Prophylactic measures such as a tranquilizer and warm compresses are expected to alleviate vasospasm; in addition, countermeasures such as the intra-arterial injection of lidocaine/nicardipine are effective.

A case of curable dementia treated by effective endovascular embolization for dural arteriovenous fistula.

BACKGROUND: We report a case in which an effective endovascular treatment cured the worsening of dementia due to a dural arteriovenous fistula (dAVF). CASE REPORT: A 73-year-old woman suffered for 1.5 years from gait disturbance and disorientation that were suspicious of dementia. A brain MRI revealed that her symptoms were likely due to dAVF. An angiography provided a definitive diagnosis of dural transverse-sigmoid sinus fistula. Transvenous embolization completely occluded the fistula and led to a significant improvement of her cognitive function in tandem with a restoration of the cerebral blood flow. CONCLUSION: Endovascular treatment for dAVF is sometimes effective in treating worsening dementia, which might be due to the drastic change in cerebral blood flow in the area relevant to the cognitive function.

Memory impairment caused by cerebral hematoma in the left medial temporal lobe due to ruptured posterior cerebral artery aneurysm.

BACKGROUND: Cognitive disorders, such as memory disturbances, are often observed following a subarachnoid hemorrhage. We present a very rare case where rupture of a posterior cerebral artery aneurysm caused restricted damage to the hippocampus unilaterally, and caused memory disturbances. CASE PRESENTATION: A 56-year-old, right-handed man, with a formal education history of 16 years and company employees was admitted to our hospital because of a consciousness disturbance. He was diagnosed as having a subarachnoid hemorrhage due to a left posterior cerebral artery dissecting aneurysm, and coil embolization was performed. Subsequently, he had neither motor paresis nor sensory disturbances, but he showed disorientation, and both retrograde and anterograde amnesia. Although immediate recall and remote memory were almost intact, his recent memory was moderately impaired. Both verbal and non-verbal memories were impaired. Brain computed tomography (CT) and magnetic resonance imaging (MRI) revealed a cerebral hematoma in the left temporal lobe involving the hippocampus and parahippocampal gyrus, and single-photon emission computed tomography (SPECT) demonstrated low perfusion areas in the left medial temporal lobe. CONCLUSIONS: We suggest that the memory impairment was caused by local tissue destruction of Papez's circuit in the dominant hemisphere due to the cerebral hematoma.

Secondary histomorphological changes in cerebral arteries of normotensive and hypertensive rats following a carotid-jugular fistula induction.

Haemodynamic changes in cerebral circulation are associated with the natural ageing process and associated pathology, leading to the development of incapacitating neurological and neurovascular diseases. Due to inherent biological limitations, current literatures mostly aimed at studying the correlation descriptively or quantifying the relationship in vitro or using computational models. In this paper, a model of a carotid-jugular fistula in the rat was used to create a haemodynamic insult to the intracranial arterial circulation and subsequent venous drainage. An arterial-venous (AV) fistula was created in 12 rats, 6 of which are normotensive Wistar-Kyoto strain (WKY) and the rest spontaneously hypertensive strain (SHR) with an additional 6 in each strains designed as controls without previous surgery. After 4 weeks of convalescence, all 24 rats were euthanised and their cerebral circulation was examined histomorphologically. We confirmed an intrinsic morphological difference between normotensive WKY and hypertensive SHR and found a modest but significant arterial shrinkage in both strains induced with AV fistula. We also reported that alterations in blood flow are also associated with marked extracellular matrix changes. We concluded that the model was suitable for studying the relative contributions of altering haemodynamic patterns and venous drainage on cerebrovascular changes. We also found that hypertension modulated cerebral vascular changes in addition to disrupted blood flow.

Analysis of restenosis after carotid artery stenting: preliminary results using computational fluid dynamics based on three-dimensional angiography.

Currently carotid artery stenting (CAS) is a widely used technique for the treatment of carotid artery stenosis. However, some patients with restenosis following CAS have been reported, resulting in potential clinical problems. The purpose of this study was to investigate the hemodynamic changes before and after CAS to find the factors that may influence restenosis. Five patients (two with restenosis, three without restenosis) were included in this study. The geometry and rheological conditions of the carotid arteries were obtained from three-dimensional digital subtraction angiography and ultrasound measurements. Computational fluid dynamics (CFD) modelling was performed to calculate wall shear stress (WSS), wall shear stress gradient (WSSG) and internal carotid artery (ICA) flow ratio. In addition, morphologic analysis was carried out. CFD results indicated that the WSSG of the restenosis group was significantly larger than that of the no-restenosis group. In the restenosis group, the WSS distribution after CAS showed a significant variation at the ICA. The average ICA flow ratio of the restenosis group was 43.5%, while in the no-restenosis group it was 68.6%. Furthermore, there were similar significant differences between the two groups during morphology analysis. CFD technology is useful for physicians in estimating haemodynamic changes during ICA stenosis treatment. These parameters, including ICA flow ratio and WSS distribution, may help to predict carotid restenosis. In future, CFD combined with other medical techniques such as digital subtraction angiography, MRI and pathology technologies will be available for the clinical estimation of ICA restenosis.

A comparison of estimation methods for computational fluid dynamics outflow boundary conditions using patient-specific carotid artery.

Computational fluid dynamics simulations can provide important hemodynamic insights for investigating the effectiveness of carotid artery stenting, but its accuracy is dependent on the boundary conditions such as the outflow pressure, which is difficult to obtain by measurements. Many computational fluid dynamics simulations assume that the outflow pressure is constant (P = 0), but this method is likely to produce different results compared to clinical measurements. We have developed an alternative estimation method called the minimum energy loss method based on the concept of energy loss minimization at flow bifurcation. This new method has been tested on computational fluid dynamics simulation of two patients treated with carotid artery stenting, and its flow ratio at internal carotid artery and wall shear stress distribution was compared with the constant zero outlet pressure method. Three different procedure stages (prestent, poststent, and follow-up) were analyzed. The internal carotid artery flow ratio using the minimum energy loss method generally matched well with ultrasound measurements, but the internal carotid artery flow ratio based on zero outlet pressure method showed a large difference. Wall shear stress distributions varied between methods in response to the change in internal carotid artery flow rate. This study demonstrates the importance of accurate outlet boundary condition for assessing the long-term efficacy of carotid artery stenting and the risk of restenosis in treated patients.

Agraphia caused by left thalamic hemorrhage.

A 71-year-old right-handed man was admitted to our hospital with right hemiparesis and sensory impairment associated with mild aphasia. Although aphasia gradually resolved within 2 weeks after stroke onset, his writing ability remained disturbed. A computed tomography (CT) scan at stroke onset revealed a hematoma in the left thalamus, but no cortical lesions were observed. Further, a single-photon emission CT (SPECT) scan showed decreased blood flow in the left thalamus, in the cortical region extending from the left superior temporal gyrus to the parietal lobe, and in the frontal lobe. It is possible that agraphia may have directly resulted from the thalamic lesion, but SPECT findings strongly suggested that a general decrease in left cortical function concomitant with a disruption of the thalamocortical and cortico-thalamocortical projection fibers produced these cognitive deficits.