Kazushi Maeda

Mechanical Thrombectomy for Acute Basilar Artery Occlusion in Early Therapeutic Time Window

Background: The natural history of basilar artery occlusion (BAO) is devastating, with morbidity rates increasing up to 80%. However, the efficacy of recanalization therapy for BAO has not been established as yet. Objective: We analyzed consecutive cases of BAO treated with mechanical thrombectomy (MT) to evaluate its safety and efficacy and to determine factors associated with the prognosis. Methods: Between October 2011 and September 2016, MT was performed in 34 patients with BAO. MT was performed using the Penumbra system and stent retriever. CT perfusion was used for evaluating patients. Cerebral blood flow (CBF) maps and cerebral blood volume (CBV) maps were evaluated. CBF/CBV mismatch was defined as ≥50% penumbra. Clinical outcomes were correlated with demographic, clinical, and radiographic findings. Results: The median baseline National Institutes of Health Stroke Scale score was 29 (14-33). The recanalization rate (≥thrombolysis in cerebral infarction grades 2b) was 100%. The median onset to recanalization time (OTR) was 197 (160-256) min. Favorable outcomes (modified Rankin Scale ≤2) at 90 days occurred in 56% (n = 19 of 34). The mortality rate at 90 days was 12% (n = 4 of 34). In univariate analysis, intravenous (IV) recombinant tissue-type plasminogen activator (rt-PA) use, and OTR were significantly associated with favorable outcomes. In a multivariate logistic regression model, IV rt-PA use and lower National Institute of Health Stroke Scale score were significantly related to favorable outcomes. Conclusion and Relevance: Multimodal endovascular therapy using the Penumbra system and stent retriever demonstrated a high recanalization rate and favorable outcomes for BAO. Both devices were feasible and effective in the treatment of BAO. An approach combining MT with IV thrombolysis provided a better recanalization rate and more favorable clinical outcomes.

A Rare Case of Chiari Type-1 Malformation Accompanied by Symptomatic Cerebrospinal Fluid Hypovolemia: Comparison of Congenital Chiari Type-1 Malformation and Acquired Chiari Malformation Secondary to Cerebrospinal Fluid Hypovolemia: Case Report

A 23-year-old woman was injured in a rear-end collision. She had general malaise and posterior neck pain, which were more severe when she was in an upright position. Magnetic resonance imaging (MRI) revealed the presence of cerebellar tonsil descensus and syringomyelia in the spinal cord. Radioisotope (RI) cisternography showed signs of an early accumulation of RI in the bladder, and a delayed accumulation of RI in the cerebral fornix. We considered the possibilities of cerebrospinal fluid (CSF) hypovolemia and congenital Chiari type-1 malformation as being responsible for her headache. To obtain a definitive diagnosis, we performed gadolinium (Gd)-enhanced MR cisternography and found evidence of CSF leakage. We performed an epidural blood patch (EBP), and her symptoms resolved. In 2 years since the episode, her symptoms have not recurred, and additional treatment has not been required. In addition, MRI performed 2 years after the EBP did not reveal any changes. There seems no previous report which described successful differentiation of pre-existing congenital Chiari type-1 malformation from the acquired one caused by symptomatic CSF hypovolemia. Because treatment protocols differ between these two conditions, the establishment of a correct diagnosis is important.

Abstract WP12: Mechanical Thrombectomy for Basilar Artery Occlusion

Background and Purpose: Basilar artery occlusion (BAO) is an infrequent cause of stroke, accounting for 1.1% of acute ischemic stroke cases. The natural history of patients with BAO is devastating, with morbidity rates of up to 80%. No previous randomized controlled studies on the efficacy of recanalization therapy have been reported. Methods: In the present single-center study, consecutive BAO patients were treated with mechanical thrombectomy (MT) using the stent retriever and the Penumbra system. Computed tomography perfusion was used for patient evaluation. Clinical outcomes were correlated with demographic, clinical, and radiographic findings. Results: Between October 2011 and March 2017, MT was performed in 37 patients with BAO (mean age 70.1±10.9). Mean baseline National Institutes of Health Stroke Scale was 23±11. Recanalization rate (≧thrombolysis in cerebral infarction 2b) was 100%. Mean onset to recanalization time (OTR) was 226.3±117.8minutes. Favorable outcome at 90 days (modified Rankin scale≦2) was 60.6%. Mortality rate at 90 days was 10.8%. In an univariate analysis, IV rt-PA use, and OTR were significantly associated with favorable outcomes. In a multivariate logistic regression model, IV rt-PA use and lower NIHSS score were significantly related to favorable outcomes. Conclusions: Multimodal endovascular therapy using the Penumbra system and/or stent retriever demonstrated high recanalization rates and improved outcomes in BAO. Both devices were feasible and effective in the treatment of BAO. An approach combining MT with IV thrombolysis provided better recanalization rates and improved clinical outcomes.

A case of delayed distal coil migration after coil embolization of an unruptured distal azygos anterior cerebral artery aneurysm: A case report and literature review

Intraprocedural coil migration during endovascular treatment for an aneurysm that might carry serious ischemic complications is well known. On the other hand, delayed coil migration after endovascular treatment for an aneurysm is very rare. A 77-year-old woman was incidentally diagnosed with unruptured aneurysm associated with distal azygos anterior cerebral artery (ACA). The aneurysm was located at the distal bifurcation of the azygos ACA and was wide necked (approximately 7 mm in diameter). Endovascular coil embolization was selected and the aneurysm was occluded successfully, but 29 days after endovascular therapy, follow-up computed tomography (CT) and magnetic resonance (MR) angiography revealed distal coil migration in the peripheral portion of the ACA. In addition, CT on day 57 after therapy revealed the migrated coil had moved more distally. Fortunately, in the course of these events, the patient remained asymptomatic. To the best of our knowledge, this represents the first case of delayed distal coil migration associated with relatively rare azygos ACA aneurysm, and also the first report confirming more distal coil movement over time. In the future, a large number of patients could develop this complication as more aneurysms are aggressively treated with endovascular treatment. Knowledge regarding the possibility of delayed coil migration is thus important.

Novel microguidewire-assist (MGA) manoeuver for coil embolisation of an unruptured middle cerebral artery aneurysm

We describe here a novel yet very simple technique, called microguidewire-assist (MGA) manoeuvre, for coil embolisation of unruptured intracranial aneurysms. A 79-year-old woman with a small, broad-necked middle cerebral artery (MCA) bifurcation aneurysm that incorporated the orifice of the acute-angled M2 superior trunk underwent coil embolisation. Since the balloon assist technique was not feasible, we inserted and retained only the microguidewire through M1 to the M2 superior trunk; subsequently, with appropriate use of the microguidewire, coil embolisation was completed. The MGA manoeuvre resulted in slight vessel straightening and subsequent changes in the angulation of the aneurysmal neck, with which stable placement of the platinum coil was successfully accomplished. For coil embolisation of small, broad-necked MCA aneurysms that partially straddle the M2 trunk, this manoeuvre might provide an effective therapeutic alternative if other techniques are not feasible.

Optimal thresholds for ischemic penumbra predicted by computed tomography perfusion in patients with acute ischemic stroke treated with mechanical thrombectomy

Background and purpose Optimal thresholds for ischemic penumbra detected by CT perfusion (CTP) in patients with acute ischemic stroke (AIS) have not been elucidated. In this study we investigated optimal thresholds for salvageable ischemic penumbra and the risk of hemorrhagic transformation (HT). Methods A total of 156 consecutive patients with AIS treated with mechanical thrombectomy (MT) at our hospital were enrolled. Absolute (a) and relative (r) CTP parameters including cerebral blood flow (aCBF and rCBF), cerebral blood volume (aCBV and rCBV), and mean transit time (aMTT and rMTT) were evaluated for their value in detecting ischemic penumbra in each of seven arbitrary regions of interest defined by the major supplying blood vessel. Optimal thresholds were calculated by performing receiver operating characteristic curve analysis in 47 patients who achieved Thrombolysis In Cerebral Infarction (TICI) grade 3 recanalization. The risk of HT after MT was evaluated in 101 patients who achieved TICI grade 2b–3 recanalization. Results Absolute CTP parameters for distinguishing ischemic penumbra from ischemic core were as follows: aCBF, 27.8 mL/100 g/min (area under the curve 0.82); aCBV, 2.1 mL/100 g (0.75); and aMTT, 7.30 s (0.70). Relative CTP parameters were as follows: rCBF, 0.62 (0.81); rCBV, 0.83 (0.87); and rMTT, 1.61 (0.73). CBF was significantly lower in areas of HT than in areas of infarction (aCBF, p<0.01; rCBF, p<0.001). Conclusions CTP may be able to predict treatable ischemic penumbra and the risk of HT after MT in patients with AIS.

A case with coil embolization for ruptured aneurysm associated with fenestration of the posterior inferior cerebellar artery

An 87-year-old man hospitalized for subarachnoid hemorrhage showed a ruptured aneurysm arising from fenestration of the posterior inferior cerebellar artery. Endovascular treatment was selected and the aneurysm and superior limb were embolized completely using three coils. Fenestration of the posterior cerebellar artery is exceedingly rare. In addition, we present a first case of aneurysm as fenestration of the posterior inferior cerebellar artery that was definitively identified as a cause of bleeding.