Blood flow changes caused by distal filter protection and catheter aspiration in the internal carotid artery during carotid stenting: evaluation using carotid Doppler sonography.

BACKGROUND AND PURPOSE: If blood flow in the ICA is reduced by the use of a distal filter during CAS, flow stagnation proximal to the filter occurs and this increases the probability of floating debris. The floating debris that remains after filter retrieval may cause cerebral embolism. However, if blood flow is increased by aspiration of blood from the ICA through an aspiration catheter, debris could be removed while the filter is still in place. The purpose of this study was to investigate blood flow changes in the ICA induced by filter use and aspiration. MATERIAL AND METHODS: A filter-protection device (AngioGuard XP) was used during CAS in 13 consecutive patients with carotid stenosis. Blood flow velocity in the ICA was measured by carotid Doppler sonography during filter deployment, filter retrieval, and catheter aspiration. RESULTS: Blood flow velocity significantly decreased with filter placement and significantly increased with filter retrieval in patients with normal angiographic flow (P < .05). Aspiration of a 20-mL blood sample from the proximal ICA column significantly increased the blood flow velocity (P < .05). CONCLUSIONS: The blood flow changes in the ICA induced by the use of a distal filter may cause cerebral embolism in filter-protected CAS. A routine aspiration method can potentially reduce the amount of migrating debris during CAS, even in cases with angiographic normal flow.

Prior antiplatelet therapy and outcome following intracerebral hemorrhage: a systematic review.

OBJECTIVES: Antiplatelet therapy (APT) promotes bleeding; therefore, APT might worsen outcome in patients with intracerebral hemorrhage (ICH). We performed a systematic review and meta-analysis to address the hypothesis that pre-ICH APT use is associated with mortality and poor functional outcome following ICH. METHODS: The Medline and Embase databases were searched in February 2008 using relevant key words, limited to human studies in the English language. Cohort studies of consecutive patients with ICH reporting mortality or functional outcome according to pre-ICH APT use were identified. Of 2,873 studies screened, 10 were judged to meet inclusion criteria by consensus of 2 authors. Additionally, we solicited unpublished data from all authors of cohort studies with >100 patients published within the last 10 years, and received data from 15 more studies. Univariate and multivariable-adjusted odds ratios (ORs) for mortality and poor functional outcome were abstracted as available and pooled using a random effects model. RESULTS: We obtained mortality data from 25 cohorts (15 unpublished) and functional outcome data from 21 cohorts (14 unpublished). Pre-ICH APT users had increased mortality in both univariate (OR 1.41, 95% confidence interval [CI] 1.21 to 1.64) and multivariable-adjusted (OR 1.27, 95% CI 1.10 to 1.47) pooled analyses. By contrast, the pooled OR for poor functional outcome was no longer significant when using multivariable-adjusted estimates (univariate OR 1.29, 95% CI 1.09 to 1.53; multivariable-adjusted OR 1.10, 95% CI 0.93 to 1.29). CONCLUSIONS: In cohort studies, APT use at the time of ICH compared to no APT use was independently associated with increased mortality but not with poor functional outcome.

Third-body abrasive wear challenge of 32 mm conventional and 44 mm highly crosslinked polyethylene liners in a hip simulator model.

Hip simulator studies have shown that wear in the polyethylene liners used for total hip replacements increased with the larger-diameter femoral balls and could also be exacerbated by third-body abrasion. However, they also indicated that the more highly cross-linked polyethylene (HXPE) bearings were more wear resistant than conventional polyethylene (CXPE) bearings. Unfortunately the HXPE bearings appeared to be particularly sensitive to adverse wear conditions. One simulator study in particular indicated that poly(methyl methacrylate) (PMMA) debris increased wear sixfold by means of two-body abrasive interactions rather than the supposed third-body abrasion or roughening effects of the Co-Cr surfaces. There has been no confirmation of such novel theories. Therefore the goal of this study was to investigate the sensitivity of large-diameter HXPE bearings to the third-body PMMA wear challenge in a hip simulator model. An orbital hip simulator was used in standard test mode with a physiological load profile. The 32 mm control liners were machined from moulded GUR1050 and gamma irradiated to 35 kGy under nitrogen (CXPE). The 44 mm liners were also from moulded blanks, gamma irradiated to 75 kGy, machined to shape, given a proprietary heat treatment, and sterilized by gas plasma (HXPE). As in the published simulator model, the study was conducted in three phases. In phase 1, all cups were run in standard ('clean') lubricant for 1.5 x 10(6) cycles duration. In phase 2, three CXPE cups and six HXPE cups were run for 2 x 10(6) cycles with a slurry of PMMA particles added to the lubricant. In phase 3, the implants were again run in 'clean' lubricant for 2 x 10(6) cycles duration. In addition, three HXPE cups were run as wear controls for 5.5 x 10(6) cycles duration in clean lubricant. In phase-1, the HXPE liners demonstrated twelvefold reduced wear compared with the CXPE controls. The 32 mm and 44 mm Co-Cr balls were judged of comparable roughnesses. However, the surface finish of HXPE liners was superior to that of CXPE liners. In phase-2 abrasion, wear rates increased sixfold and eighty-fold for CXPE and HXPE bearings respectively. These data confirmed that HXPE bearings were particularly sensitive to 'severe' test modes. The Co-Cr balls revealed numerous surface patches representing transferred PMMA with average transient roughness increased to 25 nm and 212 nm for the 32 mm and 44 mm balls respectively. These PMMA patches produced an aggressive two-body abrasion wear of the polyethylene. After cleaning, the ball roughness returned to near normal. Therefore the Co-Cr roughness was not an issue in this severe test mode. In phase 3, the wear decreased to near the index values of phase 1, while liner roughness dropped by more than 90 per cent. The control CXPE liners now demonstrated twice the wear of the HXPE, as would be predicted comparing the diameter and cross-linking algorithms. No previous study has correlated polyethylene roughness profiles to wear performance. In phase 2, PMMA abrasion created significant damage to the polyethylene surfaces. The average roughness Sa of CXPE liners increased to 3.6 microm, a twenty-four-fold increase with some scratches up to 40 microm deep. The HXPE roughness also increased but only to 1.5 microm, a ninefold increase. The scratch indices Sz and Sp for HXPE surfaces were also 50 per cent less severe than on CXPE surfaces. However, within 2 x 10(6) cycles duration of phase 3, all liners had recovered to virtually their original surface finish in phase 1. In all test phases, the surface finish of the HXPE liners remained superior to control liners. These experimental data confirmed many of the results from the previous simulator study with the PMMA abrasion models. Thus the 44 mm liners appeared an excellent clinical alternative to the smaller ball designs used in total hip replacements.

Microbleeds on gradient-echo T2(*)-weighted MR images from patients with multiple simultaneous intracerebral haemorrhages.

BACKGROUND: Multiple simultaneous intracerebral haemorrhages (ICH) occur rarely and the mechanism remains unknown. In this report, we compare several clinical factors of multiple haemorrhages, including microbleeds, with single intracerebral haemorrhages and discuss a potential explanation for their occurrence. METHODS: One hundred and ninety consecutive patients with intracerebral haemorrhage who were admitted within 24 hours after onset from January 2003 to November 2005 were included in the study. Several clinical factors, including the number of microbleeds on gradient-echo T2(*)-weighted magnetic resonance images, were compared between patients with single and multiple haemorrhages. FINDINGS: Computed tomography scans revealed that nine patients had multiple intracerebral haemorrhages. In all cases, five or more microbleeds were revealed on T2(*)-weighted magnetic resonance images. This was significantly higher than the number of microbleeds in patients with single intracerebral haemorrhage (p < 0.05). Systolic blood pressure on admission was > or =200 mmHg in seven of the nine patients and was higher than in patients with a single haemorrhage (p = 0.05). CONCLUSIONS: Elevated blood pressure induced by an initial haemorrhage was speculated to be the result of secondary haemorrhages in some patients with multiple microbleeds. Thus, strict blood pressure control may help to prevent the occurrence of multiple haemorrhages.

Simultaneous multi-section perfusion CT and CT angiography for the assessment of acute ischemic stroke.

BACKGROUND: Introduction of helical computed tomography (CT) scanning has enabled rapid imaging of the vascular status by means of CT angiography and perfusion CT. By virtue of recent multi-detector technology, helical CT has the ability to perform both CT angiography and multi-section perfusion CT simultaneously. This study investigated the clinical feasibility of simultaneous assessment of perfusion CT and CT angiography in patients with acute ischemic stroke. METHOD: Perfusion CT and CT angiography were performed simultaneously in a series of consecutive 31 acute ischemic stroke patients. The time required for the entire processing was about 15 minutes. Contrast agent was used in a total dose of 100 ml (35 ml for perfusion CT and 65 ml for CT angiography). FINDINGS: Simultaneous perfusion CT scans and CT angiographies were of diagnostic quality for 29 patients (94%). In large territorial infarct patients, perfusion CT could predict all perfusion deficits of the final lesions (10 out of 10 lesions) and CT angiography could detect 9 of 10 occlusions of major cerebral arteries (90%). In patients with small lacunar or subcortical infarcts, perfusion CT could predict 9 out of 19 lesions (47.4%), and false-negative were encountered in small lesions (three patients) or in inadequate coverage of data acquisition (seven patients). Acute stage thrombolytic intervention could be carried out based on the findings, and the success of thrombolytic therapy could be demonstrated by follow-up study. CONCLUSIONS: Simultaneous perfusion CT and CT angiography is the very useful tool for the rapid and adequate diagnosis of almost all of the large territorial infarcts and some of non-territorial lacunar infarcts. It is an easy-to-perform and safe imaging technique to assess acute ischemic stroke.

Basilar artery vasculitis secondary to sphenoid sinusitis--case report.

A 35-year-old male presented with basilar artery vasculitis secondary to sphenoid sinusitis manifesting as rapidly deteriorating symptoms including consciousness disturbance and right hemiparesis. Computed tomography (CT) on admission showed sphenoid sinusitis without intracranial lesion. Emergency angiography demonstrated basilar artery stenosis. The neurological deterioration was considered to be caused by ischemia of the perforating arteries branching from the stenotic portion of the basilar artery. The patient was treated with urokinase infusion through a microcatheter just proximal to the stenosis 3 hours after the onset of the symptoms. His consciousness level and right hemiparesis markedly improved immediately after the procedure. Magnetic resonance (MR) imaging on day 5 revealed that extension of the sphenoid sinusitis into the prepontine cistern had formed an abscess which was attached to the clivus. The basilar artery was embedded in the abscess at the angiographic stenosis. Cerebrospinal fluid (CSF) analysis showed white blood cell count of 601/mm3 with 82% neutrophils, 89.2 mg/dl protein, and 31 mg/dl glucose. No causative organism in the CSF could be identified by smear or culture. Early MR imaging and CSF examination are recommended when patients present with both ischemic symptoms involving the basilar artery and opacification of the sphenoid sinus on CT to identify basilar artery vasculitis secondary to sphenoid sinusitis.

Neuronal damage in gerbils caused by intermittent forebrain ischemia.

OBJECT: The purpose of this study was to investigate the possibility of preventing cumulative neuronal damage after repetitive severe ischemia. METHODS: The authors monitored ischemic depolarization in the gerbil hippocampus, which has recently been shown to be a good experimental model of the effects of brief ischemia on the brain, and evaluated neuronal damage in the CA1 subregion 7 days after the ischemic insult. In a single-ischemia paradigm, the results indicate that induction of ischemia-induced neuronal damage depended on the duration of ischemic depolarization. Neuronal damage can be detected in the CA1 subregion after a period of depolarization lasting 210 seconds. Using a double-ischemia paradigm in which the animals were subjected to two periods of ischemia, there was apparently no accumulation of neuronal damage from the first ischemic episode to the second, provided the duration of the first period of ischemic depolarization did not exceed 90 seconds. Neuronal damage accumulated when the duration of the first ischemia episode exceeded 90 seconds, regardless of the duration of the reperfusion interval between the two ischemic insults. Finally, when the ischemic insult was spread over four separate episodes, each lasting 90 seconds (with a reperfusion interval of 5 minutes), neuronal damage was not found when the total depolarization period was less than 420 seconds. CONCLUSIONS: The authors conclude that cumulative neuronal damage may be avoided by adopting an intermittent ischemia approach. The implications of these results for human surgery requiring temporary occlusion of the cerebral arteries are discussed.

Embolization of cerebral arteriovenous malformations achieved with polyvinyl alcohol particles: angiographic reappearance and complications.

BACKGROUND AND PURPOSE: The appropriate choice of embolic materials with respect to the permanency of obliterated nidi after embolization and complications related to the procedure is essential for safe and effective embolization of cerebral arteriovenous malformations (AVMs). Our purpose was to ascertain the recanalization and complication rates after AVM treatment with polyvinyl alcohol (PVA) particles. METHODS: Between 1988 and 1994, 36 AVMs were embolized with PVA particles at our institution. Follow-up angiographic findings and occurrence of complications during the embolization procedures were analyzed retrospectively. RESULTS: Complete obliteration of the nidus immediately after embolization was achieved in five patients, and 80% to 99% obliteration was attained in 12 patients. Fifty-one follow-up angiographic examinations were performed 1 week to 60 months (mean, 7 months) after embolization in 31 patients. An increase in nidal size was seen on 15 follow-up angiograms (29%) and a decrease was seen in seven (14%). In 28 of the 51 angiograms obtained more than 1 month after follow up (mean, 13 months), 12 (43%) showed AVM enlargement. In four (80%) of five cases of complete obliteration, nidi reappeared on follow-up angiograms. Hemorrhagic complications occurred in three cases and ischemic ones in seven. One patient (3%) died and five (14%) suffered persistent neurologic deficits. CONCLUSION: Embolization with PVA particles can produce significant volume reduction in AVM nidal size, but recanalization is a distinct possibility.

Intra-aneurysmal pressure changes during angiography in coil embolization.

BACKGROUND: Although elevation of blood pressure in aneurysms induced by injection of contrast medium has been postulated as a major cause of rerupture of ruptured cerebral aneurysms during angiography, no study has proved the elevation of intra-aneurysmal pressure because of difficulty in measuring the intra-aneurysmal pressure during angiography. The present study demonstrated intra-aneurysmal pressure to be raised by injection of contrast medium, using a microcatheter introduced into aneurysms. METHODS: To confirm the accuracy of pressure measurement through a microcatheter, we measured intra-aneurysmal pressure in a plastic model of an artery and an aneurysm during and after injection of contrast medium through a microcatheter and a needle inserted into the aneurysm. In a clinical study, intra-aneurysmal pressures were measured through the microcatheter in nine cerebral aneurysms of seven patients. RESULTS: In the model experiment, changes in the pressure measured through the microcatheter correlated well with those observed through the needle. In the clinical study, intra-aneurysmal systolic pressures increased by 5-23 mm Hg immediately after injection of contrast medium for 1-3 s in four basilar tip, three internal carotid-ophthalmic, and one middle cerebral artery aneurysm, whereas no pressure change was observed in a posterior cerebral artery aneurysm. Systemic blood pressure during angiography remained unchanged in all cases. CONCLUSIONS: This abruptly elevated intra-aneurysmal pressure by injection of contrast medium might cause rerupture of an aneurysm soon after rupture of the aneurysm, especially when the rupture site is fragile.

Effect of acquired tolerance to ischemia on focal infarction in gerbils.

The protective effect of prior ischemia on focal cerebral infarction produced by permanent middle cerebral artery (MCA) occlusion was studied in a gerbil model. Forebrain ischemia for 2 and 5 minutes at an interval of 48 hours was used as the prior ischemic insult. Forty-eight hours after the second forebrain ischemia, the MCA was occluded. Progression of ischemic change caused by the MCA occlusion was delayed in the early ischemic period in animals with prior ischemia, as compared to animals without prior ischemia. The mean infarct volume 24 hours after the MCA occlusion was the same in animals with and without prior ischemia. Ischemic tolerance was acquired in this model, but had no effect on the extent of infarction caused by permanent ischemia.

Blood pressure monitoring in feeding arteries of cerebral arteriovenous malformations during embolization: a preventive role in hemodynamic complications.

To study the hemodynamics of arteriovenous malformations and to avoid hemodynamic complications during and after artificial embolization, we measured arterial blood pressures in 21 feeders in 14 patients through a microcatheter system. Before embolization, the pressures were significantly low in feeders with branches terminating in the malformation (terminal divided branches) and comparatively low in arteriovenous malformations with rapid blood flow through the malformation. The pressures in feeders with brain-nutrifying branches distal to the nidus (transient branches) were significantly high. Therefore, transient branches might be distinguishable from terminal divided branches with the use of feeder pressure monitoring. A hemorrhagic complication occurred in one patient. The feeder pressure in this patient was low before embolization and showed the maximum change among the patients after embolization. It seems that the lower the feeder pressure, the more likely complications are to occur, owing to remarkable hemodynamic alterations. Feeder pressure monitoring may be useful for preventing hemodynamic complications, especially when angiographic findings show feeding arteries giving off terminal divided or transient branches or rapid blood flow through the malformation.

Frequent TIA in the territory fed by the anastomosed STA after combined therapeutic ICA occlusion and extracranial-intracranial bypass: case report.

Frequent transient ischaemic attacks (TIAs) in the territory fed by the anastomosed superficial temporal artery (STA) after combined therapeutic internal carotid artery (ICA) occlusion and extracranial-intracranial bypass is described in a 52-year-old woman with a giant aneurysm in the supraclinoid portion of the left ICA showing impairment of visual acuity in the left eye and right upper quadrantanopia. After the balloon test occlusion of the left ICA which was tolerated, the left STA-middle cerebral artery anastomosis was performed and occlusion of the left ICA using detachable balloons was carried out a day later. TIAs corresponding to the territory fed by the anastomosed STA occurred nine times two to four days and five times eight to nine days after the ICA occlusion without new infarction on computed tomography (CT) scan. Single-photon emission computed tomography showed no hypoperfusion immediately after the initial TIA. CT scan revealed thrombosis of half of the aneurysm a day after the ICA occlusion. The patient developed the same TIA as previously by compression of the left anastomosed STA at the time of follow-up angiography which was carried out eight days after the occlusion. Although heparin was continuously administered after the ICA occlusion for two days, the initial TIA occurred during heparinization. Anticoagulation seemed to be inadequate judging from activated coagulation time and incomplete thrombosis of the aneurysm occurred during heparinization. It is likely that the TIAs are caused by embolism via the STA, which is a rare ischaemic complication.

Primary angiitis of the central nervous system: report of two cases and review of the literature.

Two cases of primary angiitis of the central nervous system with subarachnoid hemorrhage are reported. One patient was admitted with very thin and localized sulcal subarachnoid hemorrhage, followed by the development of multiple parenchymal edema. Although the first angiography showed only a mild narrowing of an artery, the second angiography demonstrated multiple segmental narrowings of arteries. An open biopsy failed to show histological changes. The second patient suffered from sylvian subarachnoid hemorrhage along with multiple intracerebral hemorrhages, with angiography that was diagnostic for angiitis. In both cases, predonine was initiated and further angiography clearly demonstrated a resolution of the angiitis. The usefulness of serial angiography for diagnosis in comparison with surgical biopsy and for monitoring the treatment of this disease is discussed. The occurrence of subarachnoid hemorrhage in this disease is also reviewed.

Vertebral artery dissecting aneurysm rebleeding after proximal occlusion--case report.

A 38-year-old male presented with vertebral artery dissecting aneurysm manifesting as subarachnoid hemorrhage. An attempt at trapping the aneurysm failed, so the vertebral artery could only be clipped proximally. Rebleeding occurred, resulting in death, probably due to excessive length of the dissection requiring thrombosis and/or retrograde dissection due to back pressure from the contralateral vertebral artery.

Surgical intervention for angiographically unexplained subarachnoid hemorrhage--report of three cases.

We report three patients with subarachnoid hemorrhage in which no causative lesion was detected angiographically. Surgical intervention revealed a ruptured aneurysm in all three cases, which were clipped successfully. Although the prognosis for a patient with subarachnoid hemorrhage of unknown cause is good, there still remain long-lasting unpleasant complaints probably arising from psychogenic factors. We especially recommend exploratory craniotomy when subarachnoid hemorrhage is located anterior to the circle of Willis, accompanied by thick and obviously lateralizing subarachnoid clots on computed tomography and/or rebleeding in the same anatomical location, even if no causative lesions can be found angiographically.

Dissecting aneurysm of the posterior cerebral artery treated with proximal ligation.

A rare case of a dissecting aneurysm of the P3 segment of the right posterior cerebral artery is presented that seems to have occurred in association with mild head injury. The patient was treated surgically because of repeated intramural hemorrhage and enlargement of the aneurysm. Proximal ligation produced thrombosis of the aneurysm without resulting in infarction in the region of the posterior cerebral artery. The mechanisms of the dissection, diagnosis, and treatment are briefly discussed.