Impact of subcallosal artery origin and A1 asymmetry on surgical outcomes of anterior communicating artery aneurysms.

BACKGROUND: Surgical clipping of anterior communicating artery (ACoA) aneurysms remains challenging due to their complex anatomy. Anatomical risk factors for ACoA aneurysm surgery require further elucidation. The aim of this study is to investigate whether proximity of the midline perforating artery, subcallosal artery (SubCA), and associated anomaly of the ACoA complex affect functional outcomes of ACoA aneurysm surgery. METHODS: A total of 92 patients with both unruptured and ruptured ACoA aneurysms, who underwent surgical clipping, were retrospectively analyzed from a multicenter, observational cohort database. Association of ACoA anatomy with SubCA origin at the aneurysmal neck under microsurgical observation was analyzed in the interhemispheric approach subgroup (n = 56). Then, we evaluated whether anatomical factors associated with SubCA neck origin affected surgical outcomes in the entire cohort (both interhemispheric and pterional approaches, n = 92). RESULTS: In the interhemispheric approach cohort, combination of A1 asymmetry and aneurysmal size ≥ 5.0 mm was stratified to have the highest probability of the SubCA neck origin by a decision tree analysis. Then, among the entire cohort using either interhemispheric or pterional approach, combination of A1 asymmetry and aneurysmal size ≥ 5.0 mm was significantly associated with poor functional outcomes by multivariable logistic regression analysis (OR 6.76; 95% CI 1.19-38.5; p = 0.03) as compared with A1 symmetry group in the acute subarachnoid hemorrhage settings. CONCLUSION: Combination of A1 asymmetry and larger aneurysmal size was significantly associated with SubCA aneurysmal neck origin and poor functional outcomes in ACoA aneurysm surgery. Interhemispheric approach may be proposed to provide a wider and unobstructed view of SubCA for ACoA aneurysms with this high-risk anatomical variant.

Endovascular treatment of sphenoid wing dural arteriovenous fistula with pure cortical venous drainage.

Curative endovascular treatment of sphenoid wing dural arteriovenous fistula (dAVF) with pure cortical venous drainage is challenging because of its rarity, lack of accessible dural sinus for transvenous embolization (TVE), and proximity of skull base vital regions. Direct surgery to disconnect venous reflux has been favored. We report the curative endovascular treatment of two sphenoid wing dAVFs with pure cortical venous drainage. One patient revealed complete obliteration of dAVF by a single session of transarterial embolization (TAE). As part of strategic TAE for this complex dAVF, we used a novel approach to create a complete flow-arrest condition in which coils and an occlusion balloon were combined. A liquid agent was then injected across the pathological fistula and into the parent venous apparatus, thereby occluding the lesion. The other patient was treated with percutaneous TVE after TAE was unsuccessful. With a specific strategy and appropriate devices, the microcatheter was successfully introduced through sigmoid sinus, transverse sinus, superior sagittal sinus, and refluxing cortical vein by puncture of the jugular vein. Coils were deployed at the venous side of the fistula, resulting in successful obliteration of the dAVF. Sphenoid wing dAVF with pure cortical venous drainage could be curable by endovascular treatment with proper strategy and instruments when anatomical condition permits.

Efficacy of cilostazol in prevention of bradycardia during carotid artery stenting.

BACKGROUND: Hypotension and bradycardia are known to occur frequently in carotid artery stenting (CAS), which may lead to postprocedural complications. The purpose of this retrospective study was to assess the efficacy of cilostazol, a phosphodiesterase 3 inhibitor, for preventing bradycardia and hypotension in the periprocedural period. METHODS: The study population comprised 53 patients (54 lesions) with carotid artery stenosis who underwent CAS at our institution between 2004 and 2008. The patients were categorized by the use (group C, n = 26) or nonuse of cilostazol (group N, n = 28). The incidences of intraprocedural and postprocedural hypotension and bradycardia in each group were statistically assessed. RESULTS: Intraprocedural hypotension and bradycardia occurred in 9 cases (34.6%) and 4 cases (15.3%) in group C and in 5 cases (17.9%) and 15 cases (53.6%) in group N, respectively. Postprocedural hypotension and bradycardia occurred in 4 cases (15.4%) and 0 cases in group C and in 1 case (3.6%) and 3 cases (10.7%) in group N, respectively. The incidence of intraprocedural bradycardia (IBc) was significantly lower in group C (P = .0035). Logistic regression analysis revealed that the use of cilostazol decreased the risk of IBc 99.5% (odds ratio [OR] = .01, 95% confidence interval [CI]: 5.46 × 10(-6) to .04, P = .001) and distance from carotid bifurcation to maximum stenotic lesion was independently associated with IBc (OR = .46, 95% CI: .29-.74, P = .001). CONCLUSION: Use of cilostazol was associated with a lower incidence of IBc. Cilostazol may be a useful drug for the prevention of this complication.

Melatonin receptor agonists for treating delirium in elderly patients with acute stroke.

BACKGROUND: Delirium is considered to worsen life prognosis in elderly patients with stroke. We examined the effects of the melatonin receptor agonist ramelteon for treating delirium in elderly stroke patients with insomnia in comparison to the other drugs. METHODS: Elderly patients with delirium and insomnia after acute stroke who were treated with ramelteon (7 patients; mean age 76 years) and the other drugs (21 patients; mean age 77.3 years) between July 2011 and March 2012 at our hospital were retrospectively examined. RESULTS: All patients treated with ramelteon had a significant improvement within a week and were started on early and aggressive rehabilitation. No patient experienced oversedation, neurologic deterioration, or any other worsening effect associated with ramelteon treatment. CONCLUSIONS: Melatonin receptor agonists may be effective for the treatment of delirium in elderly patients with acute stroke.

Efficacy and safety of single versus dual antiplatelet therapy for coiling of unruptured aneurysms.

BACKGROUND: Although the efficacy of antiplatelet therapy for coiling of unruptured cerebral aneurysms has been reported, regimens for this therapy are not yet well established. The aim of this retrospective study was to analyze correlations among the modes of antiplatelet use, aneurysmal configuration, coiling methods, and complications to elucidate the optimal antiplatelet therapy for coiling. METHODS: The study population comprised 154 patients with unruptured aneurysms who underwent coiling with antiplatelet therapy at our institution between 2001 and 2009. The patients were categorized by mode of antiplatelet therapy (single [n = 64] or dual [n = 90]), neck size (wide [n = 80] or narrow [n = 74]), and technique used (simple [n = 42] or adjunctive [n = 112]). The incidences of hemorrhagic/ischemic complications and abnormalities on postprocedural diffusion-weighted magnetic resonance imaging (DWI) in each group were statistically assessed. RESULTS: Hemorrhagic complications occurred in 1 case (1.5%) with single antiplatelet therapy and in 2 cases (2.2%) with dual antiplatelet therapy. Symptomatic ischemic complications occurred in 5 cases (7.8%) with single therapy and in 4 cases (4.4%) with dual therapy. Abnormalities were detected by DWI in 27 cases (42%) with single therapy and in 31 cases (34%) with dual therapy. No significant difference was found between modes of antiplatelet therapy even when the technique used was taken into account. In cases of wide neck, however, there were significant differences in the rate of symptomatic ischemic complications (single, 21.7%; dual, 3.5%; P = .014) and DWI abnormalities (single, 37.8%; dual, 20.9%; P = .048). CONCLUSION: Our data suggest that dual antiplatelet therapy may better prevent ischemic complications from coiling for wide-necked aneurysms compared with single antiplatelet therapy.

[Research of postoperative complications after coil protrusions in embolization of unruptured cerebral aneurysms].

OBJECTIVES: Postoperative courses in "coil-protruded" cases in embolization of unruptured cerebral aneurysms remain unknown. The purpose of this study is to investigate postoperative complications after coil protrusions. METHODS: From May 2003 to December 2007, 90 consecutive cases with unruptured cerebral aneurysm treated by coil embolization were examined at National Cerebral and Cardiovascular Center. All patients received antiplatelet therapy prior to the procedure. The patterns of protrusions were classified into three; tail (T), loop (L), unraveled (U). RESULTS: Coil protrusions were observed in 17 cases (18.9%). Symptomatic ischemic complications occurred in 7 cases (7.8%). One case occurred in coil protrusions (group P) and 6 cases occurred in no coil protrusions (group N). Infarctions on MR diffusion-weighted image within 7 days after embolization were found in 10 cases (58.8%) in group P and in 28 cases (38.4%) in group N. Infarction on MR fluid attenuated inversion recovery 7 days or later were found in 0 in group P, and in 4 (5.5%) in group N. There were no significant differences. The number of each protrusion pattern was as follows: T was 12 cases, L was 3 cases and U was 2 cases. Symptomatic ischemia was observed in one case (8.3%) in T. Infarctions on MR diffusion-weighted image within 7 days after embolization were found in 7 (58.3%), 1 (33.3%) and 2 (100%), respectively. There were no significant differences between the three morphological patterns. CONCLUSION: In this retrospective study, coil protrusion after embolization of unruptured cerebral aneurysms on antiplatelet therapy, did not increase the incidence of ischemic complications.

[Carotid artery stenting for radiation-induced carotid stenosis].

PURPOSE AND METHODS: To evaluate the outcome and lesion characteristics in patients with radiation induced carotid stenoses (RI-CS) treated by carotid artery stenting (CAS), a total of five patients with RI-CS (six lesions) were retrospectively analyzed. RESULTS: Four lesions had their most stenotic site at the common carotid artery (CCA). All cases had contralateral carotid or vertebral artery stenosis (>50%). All patients had risk factors of atherosclerosis and all lesions contained unstable plaques at the stenotic site. A total of seven procedures were carried out and procedural success was obtained in all cases. Asymptomatic embolic infarctions associated with procedure were observed in four cases by diffusion-weighted MR imaging. In-stent thrombi were observed in two cases, one of which developed a neurological symptom three days after the procedure. CONCLUSION: CAS is a technically successful intervention for RI-CS. Care should be taken according to the characteristics of the plaque, which usually is vulnerable and long. Appropriate choice of a protection method could help in the reduction of unfavorable embolic complications and close postoperative follow up is mandatory.

Successful "blind-alley" formation with bypass surgery for a partially thrombosed giant basilar artery tip aneurysm refractory to upper basilar artery obliteration. Case report.

Partially thrombosed giant aneurysms that are located at the basilar artery (BA) bifurcation and are not amenable to clip application are among the most challenging lesions for neurosurgeons. They compress vital structures such as the brainstem and the thalamus, and the prognosis is extremely poor when they are left untreated. Although obliteration of the upper BA is a promising approach for these aneurysms, some lesions are refractory to this treatment, and effective additional strategies have not been clearly established. The authors report a case treated by placement of clips in the unilateral posterior cerebral artery (PCA) and posterior communicating artery as well as by superficial temporal artery-PCA bypass after unsuccessful upper BA obliteration. Complete thrombosis and dramatic shrinkage of the aneurysm were obtained.

Use of Simple Neck Extension to Improve Guiding Catheter Accessibility in Tortuous Cervical Internal Carotid Artery for Endovascular Embolization of Intracranial Aneurysm: A Technical Note.

BACKGROUND: In endovascular embolization of intracranial aneurysms, a tortuous cervical internal carotid artery can limit guiding catheter access to a sufficiently high position. Although intermediate distal access catheters can go beyond the tortuous segment of internal carotid arteries, they may increase the risk of procedure-related complications, require significantly complex technical procedures, and limit the use of adjunctive techniques. Using simple neck extension alone, we successfully improved guiding catheter access in 2 patients. METHODS: Through a provocative test, we confirmed suitability of manual neck extension in 2 patients with severe posterior curvature of a tortuous internal carotid artery. Intraoperatively, we manually extended the neck and stretched the curvatures. We guided a 6F guiding catheter superiorly and performed coil embolization with an occlusion balloon catheter in 1 case and with the balloon-assisted neck remodeling technique in 1 case. RESULTS: Coil embolization was completed without any adverse events in both cases. CONCLUSIONS: The simple neck extension technique successfully improved accessibility of the guiding catheter. As the need for safe and highly skilled intervention increases, our technique may be useful because it can reduce procedure-related complications and allow balloon-assisted techniques.

Infiltrated Embolization of Meningioma with Dilute Cyanoacrylate Glue.

We describe the efficacy and technical aspects of infiltrated preoperative embolization of meningioma by penetration of very dilute glue. In this method, a 13% n-butyl-cyanoacrylate (NBCA)-lipiodol mixture is injected extremely slowly from the middle meningeal artery (MMA) in a similar manner to plug and push injection of ethylene vinyl alcohol copolymer mixed with tantalum and dimethyl sulfoxide (Onyx®) after the tortuous side feeders are proximally embolized. The glue is infiltrated into small tumor arteries and extends to inaccessible feeders from deep meningeal arteries. Since 2011, we have used this technique in the embolization of 32 cases preoperatively diagnosed with meningioma. Intratumoral embolization was possible in 30 cases (94%), and a greater than 50% reduction in contrast area of contrast-enhanced T1-weighted MR imaging (T1-WI) was achieved in 18 cases (56%). Two cases achieved complete devascularization, showing a remarkable shrinkage in tumor size after embolization. If excessive reflux of embolization and the resulting migration of glue into normal arteries is achieved, this method provides extremely effective devascularization on surgical extirpation. It might also be applicable to surgically untreatable meningiomas as a semi-radical treatment option.

Long-Term Volume Reduction Effects of Endovascular Embolization for Intracranial Meningioma: Preliminary Experience of 5 Cases.

BACKGROUND: Preoperative endovascular embolization of intracranial meningiomas denatures the tumor tissue, reduces intraoperative blood loss, and facilitates surgical removal. However, as most meningiomas are surgically removed within a few days after embolization, the effect of long-term volume reduction of the tumor due to the endovascular embolization remains unknown. METHODS: Five patients with intracranial meningioma underwent endovascular embolization between January 2006 and December 2014 and were followed without surgical resection for >14 days. The reduction in tumor and peritumoral edema volumes on sequential head magnetic resonance imaging, along with the clinical symptoms, were retrospectively reviewed. RESULTS: All the tumors indicated a 10%-30% volume reduction 30 days after embolization, which continued thereafter; no meningioma regrowth was observed for >90 days in 2 of 5 cases. Moreover, the peritumoral edema volume was reduced by 30%-70% at 30 days after embolization, and no subsequent increase was observed for >60 days in 4 of 5 cases. The neurologic symptoms related to the tumor mass effect improved after embolization. CONCLUSIONS: Endovascular embolization of intracranial meningiomas with n-butyl cyanoacrylate reduced the tumor and peritumoral edema volumes by 10%-30% and 30%-70%, respectively, within 30 days. Volume and edema reduction effect of embolization may last longer than expected, beyond the timing when most meningiomas are resected after embolization. In this study, we described our preliminary results of the volume reduction of intracranial meningiomas that were embolized using n-butyl cyanoacrylate and monitored without any surgical resection for >14 days. We believe that our study makes a significant contribution to the literature because we showed that volume and edema reduction effect of embolization may last longer than expected, beyond the timing when most meningiomas are resected after embolization.

The role of alternative anastomosis sites in occipital artery-posterior inferior cerebellar artery bypass in the absence of the caudal loop using the far-lateral approach.

OBJECTIVE Occipital artery-posterior inferior cerebellar artery (OA-PICA) bypass is a technically challenging procedure for posterior fossa revascularization. The caudal loop of the PICA is considered the optimal site for OA-PICA anastomosis, however its absence can increase the technical difficulty associated with this procedure. The use of the far-lateral approach for accessing alternative anastomosis sites in OA-PICA bypass in patients with absent or unavailable caudal loops of PICA is evaluated. METHODS A morphometric analysis of OA-PICA bypass with anastomosis on each segment of the PICA was performed on 5 cadaveric specimens through the conventional midline foramen magnum and far-lateral approaches. The difficulty level associated with anastomoses at each segment was qualitatively assessed in each approach for exposure and maneuverability by multiple surgeons. A series of 8 patients who underwent OA-PICA bypass for hemodynamic ischemia or ruptured dissecting posterior fossa aneurysms are additionally reviewed and described, and the clinical significance of the caudal loop of PICA is discussed. RESULTS Anastomosis on the caudal loop could be performed more superficially than on any other segment (p < 0.001). A far-lateral approach up to the medial border of the posterior condylar canal provided a 13.5 ± 2.2-mm wider corridor than the conventional midline foramen magnum approach, facilitating access to alternative anastomosis sites. The far-lateral approach was successfully used for OA-PICA bypass in 3 clinical cases whose caudal loops were absent, whereas the midline foramen magnum approach provided sufficient exposure for caudal loop bypass in the remaining 5 cases. CONCLUSIONS The absence of the caudal loop of the PICA is a major contributing factor to the technical difficulty of OA-PICA bypass. The far-lateral approach is a useful surgical option for OA-PICA bypass when the caudal loop of the PICA is unavailable.

Outcome of carotid endarterectomy and stent insertion based on grading of carotid endarterectomy risk: a 7-year prospective study.

OBJECT: The authors of this study prospectively compared periprocedural neurological morbidity and the appearance of lesions on diffusion-weighted (DW) magnetic resonance (MR) imaging in patients who had undergone carotid endarterectomy (CEA) or carotid artery stent placement (CASP) with distal balloon protection, based on a CEA risk grading scale. METHODS: Patients undergoing CEA (139 patients) and CASP (92 patients) were classified into Grades I to IV, based on the presence of angiographic (Grade II), medical (Grade III), and neurological (Grade IV) risks. Although not randomized, the CEA and CASP groups were well matched in terms of the graded risk factors except for a greater proportion of neurologically unstable patients in the CEA group (11 compared with 3%, p = 0.037). There were greater proportions of asymptomatic (64 compared with 34%, p = 0.006) and North American Symptomatic Carotid Endarterectomy Trial-ineligible patients (29 compared with 14%, p < 0.0001) in the CASP group. The overall rates of neurological morbidity with ischemic origin and the appearance of lesions on DW MR imaging after CEA were 2.2 and 9.3%, and those after CASP were 7.6 and 35.9% (nondisabling stroke only), respectively. The only disabling stroke was caused by an intracerebral hemorrhage attributable to hyperperfusion in one case (0.7%) of CEA. There were no deaths. There was no significant association between neurological morbidity and the risk grade in patients who had undergone CEA, although the incidence of lesions on DW imaging was significantly greater in the Grade IV risk group compared with that in the other risk groups combined (42.1 compared with 4.2%, p < 0.0001). After CASP, a higher incidence of neurological morbidity and lesions on DW imaging was noted for the Grade II and III risk groups combined as compared with that in the Grade I risk group, regardless of a symptomatic or an asymptomatic presentation (neurological morbidity: 10.5 compared with 3.1%, respectively, p = 0.41; and DW imaging lesions: 47.4 compared with 19.4%, p = 0.01). The incidence of lesions on DW imaging after CEA was significantly lower than that after CASP except for the Grade IV risk groups. CONCLUSIONS: Despite a higher incidence of DW imaging-demonstrated lesions in the Grade IV risk group, there was no significant association between the risk group and neurological morbidity rates after CEA. The presence of vascular and medical risk profiles conferred higher rates of neurological morbidity and an increased incidence of lesions on DW imaging after CASP. Considering that no serious nonneurological complications were noted, CEA and CASP appear to be complementary methods of revascularization for carotid artery stenosis with various risk profiles.

[Therapeutic strategy for isolated dissecting aneurysms of the posterior inferior cerebellar artery: report of three cases and review of literature].

Dissecting aneurysm of the posterior inferior cerebellar artery (PICA) is a relatively rare disease and its treatment has not been well established. The authors analyzed the clinical and anatomical features of 38 reported lesions and three of our cases to clarify the "best therapeutic modality". The average age was 45.0 years old and 27 patients were male. Left-sided predominance (26 cases) was noted. As to the mode of onset, 23 cases were subarachnoid hemorrhage, 16 were ischemia, and 6 were Wallenberg's syndrome. Anatomically, the sites of dissection were located in the proximal segment of PICA in 31 lesions (75.6%). Review of the cases show that 30 (75%) patients underwent surgical therapy, and 7 (17.5%) patients underwent endovascular treatment. Twenty six patients who took surgical therapy and 5 patients who took endovascular treatment had excellent or good outcome. The critical point in therapeutic procedure is the preservation of perforating branches arising from PICA, therefore surgical trapping with the revascularization of PICA (usually extracranial-PICA anastomosis), in which these tiny branches are secured under microscopic manipulation, has the advantage in principle.

Reappearance of Cranial Nerve Dysfunction Symptoms Caused by New Artery Compression More than 20 Years after Initially Successful Microvascular Decompression: Report of Two Cases.

Reappearance of symptoms of cranial nerve dysfunction is not uncommon after successful microvascular decompression (MVD). The purpose of this study was to report two quite unusual cases of recurrent and newly developed hemifacial spasm (HFS) caused by a new conflicting artery more than 20 years after the first successful surgery. In Case 1, the first MVD was performed for HFS caused by the posterior inferior cerebellar artery (PICA) when the patient was 38 years old. After 26 symptom-free years, HFS recurred on the same side of the face due to compression by the newly developed offending AICA. In Case 2, the patient was first operated on for trigeminal neuralgia by transposition of the AICA at 49 years old, but 20 symptom-free years after the first MVD, a new offending PICA compressed the facial nerve on the same side, causing HFS. These two patients underwent reoperation and gained satisfactory results postoperatively. Reappearance of symptoms related to compression of the root exit zone (REZ) by a new offending artery after such a long symptom-free interval since the first effective MVD is rare. Here, we describe two such unusual cases and discuss how to manage and prevent such reappearance of symptoms after a long time interval.

Significance of Anomalous Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Common Trunk Compression in Microvascular Decompression for Hemifacial Spasm.

BACKGROUND: The anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) common trunk anomaly is reportedly one of the most common vessel variants in the posterior circulation, but reports of hemifacial spasm (HFS) associated with AICA-PICA common trunk are very rare. In the present study, we describe methods of microvascular decompression (MVD) for HFS caused by AICA-PICA common trunk compression. METHODS: Among 159 patients who underwent MVD for HFS, 16 patients had compression of the root exit zone by the AICA-PICA common trunk anomaly. The types of compression were classified into 2 groups: common trunk artery compression group and branching vessel compression group. RESULTS: The common trunk artery compression group consisted of 11 patients (69%), and the branching vessel compression group consisted of 5 patients (31%). The rostral branch (feeding the original AICA territory) coursed between the seventh and eighth cranial nerves in 5 patients, and in 13 patients (81%), the offending vessel harbored perforators around the root exit zone. Among 16 patients, 14 (87.5%) required interposition of the common trunk or the branching vessel, and in 2 patients, decompression was completed by the transposition method. Fifteen patients experienced sufficient results, and 1 had severe residual spasm. Transient facial palsy developed in 2 patients. No patients encountered recurrence. CONCLUSIONS: Reports concerning decompression methods of AICA-PICA common trunk anomaly are very rare. The tortuosity of the common trunk and perforators from the offending vessel make the usual repositioning of the offending artery much more difficult, and adequate decompression techniques are required for successful MVD.

Microvascular Decompression for Hemifacial Spasm Associated with Bilateral Vertebral Artery Compression.

BACKGROUND: Microvascular decompression (MVD) has been established as an effective treatment for hemifacial spasm (HFS). However, replacement of bilateral vertebral arteries (VAs) from the root exit zone (REZ) is difficult and requires special techniques. Reports of HFS cases associated with bilateral VA compression are quite rare. This study investigated the characteristics of these arteries and methods for safe and definite decompression. METHODS: Among 131 patients who underwent MVD for HFS, 33 patients (25.2%) had associated VA compression; 4 patients (3.1%) had bilateral VA compression. Sufficient dissection of the arachnoid membrane allowed good visualization around the REZ, and the dolichoectatic VAs were successfully transposed and fixed to the nearby dura mater in 3 cases. RESULTS: The offending arteries were bilateral VAs plus the posterior inferior cerebellar artery in 2 cases, bilateral VAs plus the anterior inferior cerebellar artery-posterior inferior cerebellar artery in 1 case, and bilateral VAs in 1 case. The contralateral VA of the symptomatic side was more ectatic, dolichoectatic, and tougher than the ipsilateral VA in 3 patients and was difficult to remove. In 3 patients treated with the transposition method, complete resolution of spasm was experienced immediately after surgery. Minimal residual spasm occurred in 1 patient treated with the interposition method. Transient facial palsy developed in 1 case, and moderate hearing loss developed in another case. CONCLUSIONS: HFS caused by bilateral VA compression is rare; however, replacement of VAs from the REZ is not easy because such VAs are invariably dolichoectatic and tough. Treatment of such cases requires special techniques.

Spreading depression induces long-lasting brain protection against infarcted lesion development via BDNF gene-dependent mechanism.

Preconditioning the rat brain with spreading depression for 48 h induces potent ischemic tolerance (infarct tolerance) after an interval of 12-15 days, consequently reducing the infarcted lesion size in the acute phase following focal cerebral ischemia. However, persistence of the morphological and functional neuroprotection has not yet been proven. We tested whether tolerance-derived neuroprotection against focal cerebral ischemia persists or merely delays the progress of cerebral infarction. Prolonged spreading depression was induced in mice by placing a depolarized focus with intracerebral microinfusion of KCl for 24 h; after intervals of 3, 6, 9 or 12 days, temporary focal ischemia was imposed. In the analysis of the infarcted lesion volume 24 h after ischemia, groups with 6 or 9 day interval demonstrated significantly smaller lesion volume compared to time-matched vehicle control group (P=0.002). Significant reduction in cerebral infarction was also observed at the chronic phase, namely 14 days after ischemia (33% reduction) (P=0.021) accompanied with less severe neurological deficits (38% reduction) (P=0.020). Using this technique, we also investigated if the mice with targeted disruption of a single BDNF allele (heterozygous BDNF-deficient mice) can gain the same potency of tolerance as the wild mice. In the result on infarcted lesion volumes following temporary focal ischemia, potent tolerance developed in the wild type (35% reduction) (P=0.007) but not in the heterozygous BDNF-deficient mice (<19% reduction) (P=0.155), indicating that BDNF expression level following spreading depression is contributing to infarct tolerance development.

Time-of-flight MR angiography targeted to coiled intracranial aneurysms is more sensitive to residual flow than is digital subtraction angiography.

BACKGROUND AND PURPOSE: For intracranial aneurysms treated with Guglielmi detachable coils, long-term follow-up is mandatory because coil compaction may occur and aneurysms may recur. The purpose of this study was to establish a noninvasive technique to visualize residual flow in coiled aneurysms. METHODS: We designed a 3D time-of-flight (3D-TOF) MR angiography (MRA) technique targeted to depict coiled aneurysms that employed a very short TE (1.54-1.60 ms) and a high spatial resolution (0.3 x 0.3 x 0.3 mm3 with zero-filling) to diminish spin dephasing. To diminish spin saturation, image volume was carefully positioned so that the neck of the targeted aneurysm was within 2 cm of the inflow portion along the stream of blood. Fifty-one MRA images of 39 coiled aneurysms in 39 patients were compared with digital subtraction angiography (DSA) images. DSA and MRA findings were interpolated retrospectively for parent and branch arteries' patency, as well as residual flow in aneurysms. In the latest 11 MR studies, a dark-blood 3D turbo spin-echo sequence was added to MRA to negate the effect high-signal-intensity thrombus. RESULTS: MRA visualized all parent and branch arteries with DSA confirmation. MRA visualized residual flow more frequently (38 studies) than did DSA (25 studies). Residual flow space visualized with MRA was always similar to or larger than that with DSA. The dark-blood sequence completely suppressed intraluminal high signal intensity on MRA images and confirmed that the high signal intensity was not due to thrombus. CONCLUSION: TOF MRA targeted to depict coiled intracranial aneurysms is noninvasive and superior to DSA in visualization of residual flow and, hence, useful for follow-up of coiled aneurysms.

Thromboembolic events associated with Guglielmi detachable coil embolization with use of diffusion-weighted MR imaging. Part II. Detection of the microemboli proximal to cerebral aneurysm.

BACKGROUND AND PURPOSE: The purpose of this study was to document the incidence and radiologic appearance of thromboembolic events during Guglielmi detachable coil (GDC) embolization for asymptomatic basilar artery (BA) bifurcation and BA-superior cerebellar artery (SCA) aneurysms by using diffusion-weighted (DW) MR imaging, with special emphasis on the evidence of thromboembolic events in vascular territories proximal from the treated aneurysm, which cause cerebellar infarction, and to discuss which step of the procedure (aneurysm or catheter manipulation) may play a role for most thromboembolic events. METHODS: Since 1999, 38 asymptomatic BA bifurcation and BA-SCA aneurysms were treated with GDCs at the National Cardiovascular Center. DW studies were performed for 26 patients between 2 and 5 days after GDC embolizations. All DW images were reviewed by two radiologists for depiction of abnormalities. These findings were retrospectively evaluated with clinical and technical factors of thromboembolic events. RESULTS: DW images showed new hyperintense lesions in 18 patients (69%), with seven (27%) incurring neurologic deteriorations. All symptomatic patients fully recovered by discharge. Fourteen (78%) of 18 patients showed new lesions proximal to the treated aneurysm; that is, in the cerebellar hemispheres. In three cases treated with the balloon-assisted technique, new hyperintense lesions were seen. CONCLUSION: In our experience, most thromboembolic events related to the use of the GDC embolization may be caused by catheter manipulation, especially in the case of the balloon-assisted technique. Caution should be exercised in the handling of catheters. Furthermore, a softer and smaller caliber catheter and simple GDC technique should be considered.