Olfactory hallucinations caused by an unruptured posterior communicating artery aneurysm improved by clipping: A case report with literature review.

Background: Unruptured cerebral aneurysms that lead to epilepsy are rare and olfactory hallucinations caused by such an aneurysm are extremely rare. Various treatments have been proposed, including wrapping, clipping with or without cortical resection, and coil embolization, but there is no consensus on the best approach. Case Description: We present a case of a 69-year-old female who experienced olfactory hallucinations caused by a posterior communicating artery aneurysm and was treated with clipping without cortical resection, with a positive outcome. Conclusion: According to our knowledge, there has been only one report of a posterior communicating artery aneurysm presenting with olfactory hallucinations has been reported, where clipping and cortical resection were performed. This is the first report of a posterior communicating artery aneurysm with olfactory hallucinations that was effectively treated with clipping alone. There have been a few similar reports of large middle cerebral artery aneurysms, most of which are believed to be caused by entorhinal cortex compression. Although a definitive treatment protocol for this condition remains elusive, we suggest that elimination of the pulsatile compressive stress exerted on the cerebral cortex through surgical clipping or coil embolization is crucial for achieving efficacious seizure management.

Hypoperfusion intensity ratio and CBV index as predictive parameters to identify underlying intracranial atherosclerotic stenosis in endovascular thrombectomy.

BACKGROUND AND PURPOSE: Intracranial atherosclerotic stenosis (ICAS)-related large vessel occlusion (LVO) is difficult to diagnose before endovascular thrombectomy (EVT) in an emergency. We hypothesized that hypoperfusion intensity ratio (HIR) and cerebral blood volume (CBV) index reflect collateral flow and would be useful parameters to predict underlying ICAS. MATERIALS AND METHODS: Clinical and perfusion imaging parameters of patients receiving EVT for LVO were reviewed retrospectively. Patients were divided into ICAS and embolism groups with angiographical findings. The association between prespecified parameters and underlying ICAS were assessed using multivariable logistic regression analyses. Discriminative ability was assessed using receiver operating characteristic analysis. RESULTS: Among 238 consecutive patients, 47 satisfied the inclusion criteria, including 10 with ICAS-related LVO. In ROC analyses, HIR showed good discrimination with a cutoff value of 0.22 (area under the curve, 0.85; 95%CI, 0.75-0.96; sensitivity, 0.84; specificity, 0.80) for underlying ICAS. CBV index showed excellent discrimination with a cutoff value of 0.90 (area under the curve, 0.92; 95%CI, 0.81-0.98; sensitivity, 0.92; specificity, 0.79). Multivariable logistic regression analysis revealed that HIR ≤ 0.22 (OR, 22.5; 95%CI, 2.9-177.0; P = 0.003) and CBV index ≥ 0.9 (OR, 75.7; 95%CI, 5.8-994.0; P < 0.001) were significantly associated with underlying ICAS. CONCLUSION: HIR ≤ 0.22 and CBV index ≥ 0.9 were associated with underlying ICAS and may predict underlying ICAS before EVT.

Meningioma in Down Syndrome.

BACKGROUND: Down syndrome comprises multiple malformations and is due to trisomy of chromosome 21. There is epidemiologic evidence that individuals with Down syndrome are at decreased risk for solid tumors including brain tumors. It has been suggested that some genes expressed on the extra copy of chromosome 21 act as tumor suppressor genes and contribute to protection against tumorigenesis. CASE DESCRIPTION: We report the first case to our knowledge of a patient with Down syndrome, an 8-year-old boy, with an intracranial meningioma, in which the status of chromosome 21 was examined. The diagnosis was based on histologic examination of the surgically resected tumor. Postoperatively, the patient's neurologic status improved, and there was no tumor regrowth in the next 2 years. Fluorescence in situ hybridization for chromosome 22 confirmed high allele loss involving the neurofibromin 2 gene locus, a finding typical in meningiomas. Fluorescence in situ hybridization also revealed chromosome 21 heterogeneity in tumor cells; not only cells with trisomy 21 but also cells with disomy and monosomy 21 were present. All blood cells from the patient manifested trisomy 21. CONCLUSIONS: Deletion of the chromosome 21 allele may be associated with tumorigenesis of meningioma in Down syndrome. This supports the hypothesis that some genes whose expression is increased on the extra copy of chromosome 21 function as tumor suppressor genes and that they contribute to the reduced tumor incidence in individuals with Down syndrome.

Epstein-Barr virus-associated primary central nervous system lymphoma in a patient with adult T-cell leukemia / lymphoma.

We present a case of Epstein-Barr virus (EBV)-associated primary central nervous system lymphoma (PCNSL) arising from a patient with cutaneous-type adult T-cell leukemia/lymphoma (ATLL). Extranodal sites affected by ATLL include the skin, lung, liver, gastrointestinal tract and central nervous system (CNS). CNS involvement usually occurs as an acute and lymphoma-type ATLL. PCNSL is a rare type of tumor and the vast majority of PCNSL are of B-cell lineage. Individuals with acquired, iatrogenic or congenital immunodeficiency are at increased risk of PCNSL, which is commonly associated with EBV. In our patient, the expression of latent infection membrane protein 1 (LMP1), EBV nuclear antigen 2 (EBNA2), and EBV-encoded small RNA (EBER) in tumor cells confirmed a type III latency of EBV infection. Human T-cell lymphotropic virus type I (HTLV-I) can induce immunodeficiency before the overt development of ATLL. The HTLV-I infection led to suppression of the immune system and the development of EBV-associated PCNSL. This is the first reported case of the clinicopathological features of EBV-associated PCNSL arising from a patient with ATLL.

Treatment strategy for giant aneurysms in the cavernous portion of the internal carotid artery.

BACKGROUND: As direct surgery to treat giant aneurysms of the ICA is difficult, ICA occlusion is the conventional treatment in patients with BTO tolerance. To determine whether bypass surgery should be performed after carotid occlusion by trapping or proximal occlusion, we developed a treatment strategy that includes BTO and SPECT. METHODS: We report 19 patients with symptomatic giant aneurysms in the cavernous portion of ICA. The appropriate type of bypass surgery was determined by the results of BTO and SPECT. The type of ICA occlusion selected was based on the evaluation of retrograde filling of the aneurysm during BTO. RESULTS: In all 19 patients, the ICA was sacrificed; 10 patients also underwent bypass surgery (low-flow bypass with STA-MCA anastomosis, n = 7; medium-flow bypass with radial artery graft, n = 2; high-flow bypass with vein graft, n = 1). Coil trapping was performed in 11 patients; proximal occlusion in 8. In 18 patients, there were no ischemic complications after treatment; 1 patient who had been treated by proximal ICA occlusion developed transient ischemia due to an intra-aneurysmal thrombus. Cranial nerve palsies were improved in 16 patients. CONCLUSIONS: Based on our experience, we recommend that patients with giant aneurysms in the cavernous portion of the ICA be evaluated by BTO and SPECT. In conjunction with bypass surgery, ICA trapping or proximal occlusion constitutes an effective treatment strategy.

Clinical features of aneurysms of the posterior cerebral artery: a 15-year experience with 21 cases.

OBJECTIVE: To investigate the characteristic clinical behavior and develop guidelines for the clinical management of posterior cerebral artery aneurysms, we reviewed 21 cases treated during a 15-year period. METHODS: Between 1988 and 2002, we treated 21 patients (10 male, 11 female; mean age, 49.8 yr) with posterior cerebral artery aneurysms at Kumamoto University Hospital and its affiliated hospitals. Data relating to the clinical, radiological, and surgical approaches were analyzed. RESULTS: There were 20 saccular aneurysms, 6 of which were giant or large aneurysms, and 1 dissecting aneurysm. Of the 21 patients, 15 presented with subarachnoid hemorrhage; in 3 patients, an unruptured saccular aneurysm was found incidentally during an evaluation for other cerebral pathological conditions. Two patients presented with progressive homonymous hemianopsia because of the mass effect of the aneurysm, and 1 patient experienced the sudden onset of homonymous hemianopsia because of thrombosis of the aneurysm and afferent artery. Open or endovascular surgery was performed in 19 patients: 14 made a good recovery, 2 had a moderate disability because of angiospasm or infarction after aneurysm trapping, 1 had a severe disability because of angiospasm and cerebral contusion, and 2 died because of severe angiospasm. Of 2 conservatively treated patients, 1 made a good recovery but the other died as a result of rebleeding. CONCLUSION: Posterior cerebral artery aneurysms have specific clinical characteristics compared with aneurysms located elsewhere. The aneurysmal site and size and the surgical technique did not significantly influence treatment outcomes.

Contribution of angiotensin-converting enzyme and angiotensin II to ischemic stroke: their role in the formation of stable and unstable carotid atherosclerotic plaques.

BACKGROUND: The angiotensin-converting enzyme/angiotensin II (ACE/Ang II) system is a strong contributor to intimal hyperplasia in atherosclerotic lesions. To illuminate its role in ischemic stroke, we examined the expression of ACE/Ang II in stable and unstable carotid atherosclerotic plaques from symptomatic and asymptomatic patients. METHODS: Using immunohistochemical methods, we studied differences between carotid atherosclerotic lesions obtained at carotid endarterectomy (CEA) from symptomatic (n = 36) and asymptomatic (n = 28) patients. The specimens were classified as stable (n = 30) and unstable (n = 34) plaques, and their fibrous cap, lipid core, and shoulder lesion were examined. We used antibodies against smooth muscle cells (SMC), macrophages, endothelial cells (EC), ACE, and Ang II. RESULTS: Of 28 lesions from asymptomatic patients, 20 (71.4%) manifested features characteristic of stable plaques: the expression of ACE/Ang II co-localized with SMC, EC, and macrophages in the shoulder lesion. In contrast, 26 of 36 symptomatic lesions (72.2%) exhibited the typical features of unstable plaques: dense accumulations of macrophages near the luminal surface in the shoulder lesion and weak immunoreactivity for ACE/Ang II, EC, and SMC. Furthermore, most of the lesions were accompanied by early stage atherosclerotic lesions (satellite lesions) that were strongly immunoreactive with macrophages, EC, and ACE/Ang II. CONCLUSIONS: ACE/Ang II expression may induce the proliferation of SMC and EC and result in the formation of carotid atherosclerotic plaques with a thick fibrous cap. Notably, the shoulder lesion of unstable plaques exhibited a thin fibrous cap and faintly expressed ACE/Ang II. Lack of the ACE/Ang II system may contribute to the final step in plaque rupture.

Analysis of mean transit time of contrast medium in ruptured and unruptured arteriovenous malformations: a digital subtraction angiographic study.

BACKGROUND AND PURPOSE: To clarify hemodynamic risk factors for hemorrhage in arteriovenous malformations (AVMs), the mean transit time (MTT) of feeding arteries and draining veins in AVMs with and without hemorrhage was measured and analyzed. METHODS: Morphological features such as the number and diameter of draining and feeding vessels and the AVM nidus volume were evaluated in 30 patients with supratentorial AVMs. The MTT of feeding arteries and draining veins was measured with the use of time-density curves obtained by digital subtraction angiography. The correlation between hemorrhage and morphology and hemorrhage and MTT was analyzed statistically. RESULTS: The nidus volume was not significantly different between hemorrhagic and nonhemorrhagic AVMs. However, between ruptured and unruptured AVMs there was a significant difference in the mean number of draining veins (1.5+/-0.69 versus 2.3+/-0.50; P=0.006), the MTT of the feeding artery (1.10+/-0.24 versus 1.62+/-0.55; P=0.03), and the ratio of the MTT of the draining to the feeding vessels (1.71+/-0.43 versus 1.05+/-0.07; P<0.001). CONCLUSIONS: A high ratio of the MTT of draining veins to feeding arteries suggests disequilibrium between nidal inflow and outflow. The consequent increased pressure in the draining vein may contribute to the development of AVM hemorrhage.

Surgical indications to maintain quality of life in elderly patients with ruptured intracranial aneurysms.

OBJECTIVE: We performed a retrospective study to assess long-term outcomes in very old patients with ruptured intracranial aneurysms. The aim of the study was to develop guidelines for choosing surgical or conservative treatment with the goal of maintaining patients' quality of life. METHODS: Between 1996 and 1999, 76 consecutive patients, aged 80 to 89 years, with ruptured intracranial aneurysms were treated at 18 participating centers. They were divided retrospectively into operated and nonoperated groups, and their preoperative characteristics and treatment outcomes were analyzed. Their Glasgow Outcome Scale and Barthel Index scores at least 2 years after the insult were recorded and analyzed from the perspective of their admission Hunt and Hess grade. RESULTS: Our retrospective review encompassed 5.9 years. Of the original 76 patients, 54 (71.1%) died, 13 (17.1%) had a good outcome (Barthel Index >or=60), and 9 (11.8%) had a poor outcome (Barthel Index <60). All patients with Hunt and Hess grades of III or higher at admission had poor outcomes irrespective of treatment. Of 32 patients with an initial Hunt and Hess grade of I or II, 19 (59.4%) underwent surgery; 9 of these patients (47.4%) had good outcomes. Conversely, of 13 nonoperated patients (40.6%), only 2 (15.4%) experienced good outcomes. In seven of the nine operated patients with good outcomes, the aneurysm was small (<12 mm) and located at the internal carotid artery-posterior communicating artery junction. CONCLUSION: Our results suggest that patients in the 9th decade of life with ruptured intracranial aneurysms can be considered for surgical treatment if they have a Hunt and Hess grade of I or II. The highest rate of favorable results was achieved in patients with small internal carotid artery-posterior communicating artery aneurysms.

High-risk age for rebleeding in patients with hemorrhagic moyamoya disease: long-term follow-up study.

OBJECTIVE: The prevention of rebleeding is one of the most important issues in the successful treatment of moyamoya disease with hemorrhagic onset. However, the natural course of hemorrhagic moyamoya disease and the characteristics of rebleeding remain unclear. METHODS: To study the natural course of the disease in conservatively treated patients, we analyzed long-term follow-up reports on 36 patients (12 male and 24 female) treated without bypass surgery at our hospitals before 1994 (mean follow-up, 12.7 +/- 7.1 yr; range, 2.9-27.0 yr). RESULTS: Of our 36 patients, 22 (61.1%) experienced rebleeding; there were 29 rebleeding episodes. The outcomes in patients with rebleeding were worse than in patients who did not rebleed (P < 0.05); in most cases, unsatisfactory results were attributable to rebleeding. Kaplan-Meier and multivariate analysis of rebleeding-free survival showed that age at onset (>36 yr) was a statistically significant risk factor; sex, hypertension, type of intracranial bleeding, and outcome after the first bleeding episode were not. Although the intervals between the first and subsequent episodes varied, both the rebleeding rate and the number of rebleeding episodes were highest in patients 46 to 55 years old. CONCLUSION: Rebleeding is the most important factor in unsatisfactory outcomes of patients with hemorrhagic moyamoya disease. Rebleeding seems to be age-related; rebleeding occurs at an increased rate when patients reach the age range of 46 to 55 years. Patients with hemorrhagic moyamoya must be followed up throughout their lives, even if their neurological status is excellent.

Intrathecal urokinase infusion through a microcatheter into the cisterna magna to prevent cerebral vasospasm: experimental study in dogs.

BACKGROUND AND PURPOSE: Our preliminary report on intrathecal urokinase (UK) infusion into the cisterna magna (CM) with a microcatheter showed good results in terms of vasospasm prevention in humans. In this study, we evaluated the relationship between different urokinase (UK) infusion sites and their effect on vasospasm prevention by using our canine subarachnoid hemorrhage (SAH) model. METHODS: At 24 hours after SAH induction, we injected 1000 IU/kg UK into the cisterna magna (CM) or lumbar sac (LS) of dogs by using a microcatheter inserted at the lumbar region. We then obtained serial angiograms and chronologically examined the changes in the mean diameter of the basilar artery (BA) during a 14-day period to determine the effect of the different injection sites on vasospasm prevention. At 24 hours after UK injection, one dog from each group was killed for gross inspection of the subarachnoid clot. To measure its concentration in the CM and sylvian fissure, UK (1000 IU/kg) was injected into the CM or LS of dogs without SAH; measurements were taken at 15-minute intervals until 4 hours after injection. RESULTS: At 24 hours after UK injection, subarachnoid clot in front of the brain stem persisted strongly in the LS group; it had almost disappeared in the CM group. In the LS group, there was severe and persistent BA constriction during the 14-day observation period. In the CM group, the BA was constricted on day 3; however, gradual dilatation occurred over time. The mean diameter of the BA on days 7, 10, and 14 was 48.2%, 53.9%, and 58.9% in the LS group and 62.6%, 70.5%, and 82.3% in the CM group. The difference between the two groups was significant on days 7, 10, and 14 (P <.05). In dogs without SAH, the average maximum UK concentration in the CM and the sylvian fissure was 2.5 and 6.7 times higher, respectively, in the CM group than in the LS group. CONCLUSIONS: In our canine SAH model, the administration of UK into the CM was significantly more effective in preventing cerebral vasospasms than was administration into the LS.

Single blood injection into the ventral cisterna magna through a microcatheter for the production of delayed cerebral vasospasm: experimental study in dogs.

BACKGROUND AND PURPOSE: We developed an experimental canine subarachnoid hemorrhage (SAH) model in which one-time blood injection by means of a microcatheter into the ventral cisterna magna (CM) is performed without direct CM puncture. We assessed the severity and duration of the vasospasm produced in this model. METHODS: Fresh autologous blood (0.25 or 0.5 ml/kg) or saline (0.5 ml/kg) was injected into the ventral CM of dogs through a microcatheter inserted at the lumbar region. Serial angiograms were obtained on days 3, 7, 10, and 14, and chronologic changes in the mean diameter of the basilar artery (BA) were recorded. The BA was examined histologically on day 7 after injection. RESULTS: A remarkable amount of clot was present in front of the brain stem at 24 hours after SAH induction. The clot was smaller in the 0.25 ml/kg SAH than in the 0.5 ml/kg SAH group. On day 3, narrowing of the BA was apparent in both SAH groups compared with the control (P <.05). The BA gradually returned to nearly normal on day 14 in the 0.25 ml/kg SAH group. Arterial narrowing was more severe and persistent in the 0.5 ml/kg SAH than in the 0.25 ml/kg SAH group (P <.05). Histologic examination of the BA on the 7th postinjection day confirmed narrowing of the lumen, indicative of arterial spasm, in both SAH groups. CONCLUSION: Our method of SAH induction by means of a single injection of blood directly into the ventral CM through a microcatheter induced severe, prolonged spasms in the canine BA. Because our model facilitates the induction of different-sized clots, we could control of the severity and duration of the induced vasospasms.

Pre- and post-treatment MR imaging and single photon emission CT in patients with dural arteriovenous fistulas and retrograde leptomeningeal venous drainage.

BACKGROUND AND PURPOSE: Dural arteriovenous fistulas (DAVFs) with disturbed regional cerebral blood flow (rCBF) include retrograde leptomeningeal venous drainage (RLVD). We examined rCBF disturbances in patients with DAVFs by studying MR imaging and single photon emission CT (SPECT) changes before and after treatment. METHODS: In 22 patients with DAVFs and RLVD, we studied their symptoms, pre- and post-treatment MR imaging and SPECT findings, and treatment results. Patients were assigned to two groups: Type 1 included those with RLVD into more than one venous sinus, and type 2, those with RLVD into a single venous sinus. RESULTS: Eleven patients had type 1 RLVD. In these patients, preoperative T2-weighted MR images showed no hyperintense areas, and angiographic evidence showed flow into more than one venous sinus. The other 11 patients had type 2 RLVD. In these patients, preoperative SPECT demonstrated hypoperfused areas that coincided with hyperintense areas on T2-weighted MR images. After treatment, the hyperintense areas disappeared, and symptoms improved in seven of these patients (type 2a). Their preoperative SPECT studies demonstrated preservation of vasoreactivity after an acetazolamide challenge. In the other four patients (Type 2b), the hyperintense areas and symptoms persisted after treatment. Their preoperative SPECT studies revealed a marked disturbance of vasoreactivity. CONCLUSION: In patients with drainage into a single venous sinus, we consistently observed areas of hyperintensity on MR images. These results and findings of hypoperfusion on SPECT scans apparently reflect venous congestion, whereas unpreserved vasoreactivity after an acetazolamide challenge on SPECT scans reflects venous infarction. The preservation of vasoreactivity after the challenge appears to be a good prognostic indicator.

Angiographic dilatation and branch extension of the anterior choroidal and posterior communicating arteries are predictors of hemorrhage in adult moyamoya patients.

BACKGROUND AND PURPOSE: The cause of intracranial bleeding in moyamoya disease patients is still unknown. To identify factors that contribute to bleeding, we assessed the angiographic findings of moyamoya disease patients. METHODS: We examined angiograms obtained from 107 moyamoya patients; 70 manifested ischemic and 37 had hemorrhagic lesions. Patients with intracerebral aneurysms or both hemorrhagic and ischemic lesions in the same cerebral hemisphere were not included. Patients were divided into those <20 years of age (n=47) and those > or =20 years of age (n=60). The right and left hemispheres in each patient were individually classified as hemorrhagic, ischemic, or asymptomatic. Each hemisphere was assessed for dilatation and branch extension of the anterior choroidal artery (AChA) and posterior communicating artery (P-CoM) and for the degree of proliferation of basal moyamoya vessels. These data were then statistically analyzed for correlation with intracranial bleeding events. RESULTS: The degree of proliferation of basal moyamoya vessels was not statistically correlated with hemorrhagic events. On the other hand, there was a correlation between hemorrhage and dilatation and abnormal branching of the AChA. In 27 of 37 hemorrhagic hemispheres (73.0%), this artery was dilated, and its abnormal branches served as collateral supply vessels to other regions. This phenomenon was observed in 4 of 5 hemorrhagic hemispheres from young patients; it was noted in fewer than one third of ischemic and asymptomatic hemispheres from this age group. Similarly, 71.9% of hemorrhagic hemispheres from adult patients manifested AChA dilatation and branching, and the difference between hemorrhagic hemispheres and those that were ischemic or asymptomatic was statistically significant (P<0.01). Although the incidence of dilatation and abnormal branching of the P-CoM was relatively low in hemorrhagic hemispheres from adult patients (18.8%), it was significantly higher than in the ischemic and asymptomatic hemispheres from this age group. Using dilatation and abnormal branching of the AChA and/or P-CoM as assessment criteria, we obtained high specificity (86.4%) and sensitivity (84.4%) for hemorrhagic events in adult moyamoya patients. CONCLUSIONS: In adult moyamoya patients, dilatation and abnormal branching of the AChA and/or P-CoM are strong predictors of hemorrhagic events.

Multimodal treatment of ruptured dissecting aneurysms of the vertebral artery during the acute stage.

OBJECT: The goal of this study was to implement an algorithm for and assess the multimodal (endovascular and microsurgical) treatment of patients with ruptured dissecting aneurysms of the vertebral artery (VA) during the acute stage. METHODS: During a 4-year period, the authors treated 19 ruptured dissecting aneurysms of the VA during the acute stage, within 3 days after the hemorrhage. Factors guiding management decisions were tolerance of the test occlusion and the site of the dissection. The algorithm takes into account these factors to select among treatment options, that is, trapping of the VA with Guglielmi Detachable Coils (GDCs); trapping of the VA and revascularization of the posterior inferior cerebellar artery (PICA); trapping of the VA and VA-posterior cerebral artery (PCA) anastomosis; and trapping of the VA, VA-PCA anastomosis, and revascularization of the PICA. Of the 15 aneurysms without PICA involvement, 14 were treated by trapping of the VA with GDCs and one by trapping of the VA and a VA-PCA bypass. The other four aneurysms with PICA involvement were treated by VA trapping and PICA revascularization. There was no episode of recurrent hemorrhage or ischemia during the posttreatment follow-up period. Although lateral medullary syndrome developed as a permanent complication in one patient, a good recovery was made by the other 18 patients by 6 months after the ictus. CONCLUSIONS: The factors that determine the appropriate treatment for ruptured dissecting aneurysms of the VA are tolerance of a test occlusion and the site of dissection. Favorable patient outcomes can be achieved when this algorithm is used.

Successful clipping of a distal posterior inferior cerebellar artery aneurysm located on the anterior surface of the medulla oblongata--case report.

A 55-year-old male presented with a ruptured distal posterior inferior cerebellar artery (PICA) aneurysm manifesting as subarachnoid hemorrhage. Angiography demonstrated a saccular aneurysm arising from the lateral medullary segment of the left PICA and located on the medial side of the left vertebral artery (VA) and the anterior surface of the medulla oblongata. A transcondylar fossa approach was used to ensure a sufficient operating field and to obtain adequate visualization of the aneurysm, the parent artery, and the perforating arteries to the medulla oblongata. The aneurysm dome protruded medially at the hairpin curve, and was located on the medial side of the left VA and on the anterior surface of the medulla oblongata. There was no vessel branches in the vicinity of the aneurysm. The aneurysm was successfully clipped with minimum retraction of the cerebellar hemisphere and medulla oblongata. Distal PICA aneurysms can be located at various sites in the posterior fossa. The exact location of the aneurysm must be established to select the best surgical approach.

Vertebral artery-posterior inferior cerebellar artery bypass with a superficial temporal artery graft to treat aneurysms involving the posterior inferior cerebellar artery.

OBJECT: In patients with aneurysms that require occlusion of the posterior inferior cerebellar artery (PICA), revascularization of this artery should be performed. A novel surgical method for revascularization of the PICA is presented. METHODS: After a segment of the superficial temporal artery (STA) was harvested, the aneurysm was treated by trapping, followed by placement of a vertebral artery (VA)-PICA bypass in which the STA segment was used as a graft. When the length of the proximal PICA was inadequate, the distal end of the STA was anastomosed to the proximal PICA in an end-to-side fashion. When the length of the proximal PICA was adequate, the STA was anastomosed to the proximal PICA in an end-to-end fashion. In either case, the proximal end of the STA was anastomosed to the VA in an end-to-side fashion. This procedure was used in nine patients whose aneurysms involved the PICA. Although partial lateral medullary syndrome developed in one of them, follow-up evaluation revealed graft patency in all patients. There were no instances of recurrent hemorrhage or ischemia. CONCLUSIONS: Although this procedure requires harvesting of an STA graft and two anastomoses, it facilitates anterograde flow to the PICA territory. It also involves minimal mobilization of brainstem perforating vessels and the proximal PICA.

Appropriate interval between embolization and surgery in patients with meningioma.

BACKGROUND AND PURPOSE: The best time for surgery after embolization of meningiomas remains unclear. We used the tumor-softening effect of embolization to determine this time. METHODS: Forty-two patients with intracranial meningiomas that received more than 50% of their blood supply from the external carotid artery underwent embolization before surgery. The interval between embolization and surgery and the tumor consistency at the time of surgery were recorded. The interval between embolization and surgery was divided into 3-day segments, and an average tumor consistency score was obtained in segments. Patients were assigned to two groups: group 1 underwent surgery on a specified day after embolization; group 2 underwent surgery at a later date. We compared tumor consistency, blood loss, length of hospitalization, surgical resection time, Simpson grade at surgery, and complication rate in both groups. RESULTS: On the polynomial regression curve, greatest tumor softening occurred 7-9 days after embolization. When the postembolization interval exceeded 10 days, no further softening occurred. Compared with group 1 patients, group 2 patients did not have an increased blood loss, a longer hospitalization, or a higher complication rate. In group 2, the surgical procedure required less time, and the Simpson grades were lower. CONCLUSION: In meningiomas that receive more than 50% of their blood supply from the external carotid artery, the optimal interval between embolization and surgery is 7-9 days. This interval allows the greatest degree of tumor softening, which makes it possible to remove the tumor more safely and easily.