Laser-induced thrombus formation in mouse brain microvasculature: effect of clopidogrel

Antiplatelet drugs have been evaluated by measuring platelet aggregation ex vivo, but in vivo studies were scanty. The purpose of this study was to observe the effects of an antiplatelet agent (clopidogrel) on the process of laser-induced thrombus formation in mice using intravital fluorescence microscopy. C57 BL/6J mice (n = 19) were anesthetized using chloral hydrate. The head of each mouse was fixed with a head holder, and a cranial window was made in the parietal region. Platelets were labeled in vivo by intravenous administration of carboxyfluorescein diacetate succinimidyl ester. Clopidogrel (1 mg/kg, n = 6; 10 mg/kg, n = 6) was administered orally for 2 days before the experiment. Another seven mice were used as controls. Laser irradiation (1,000 mA, 9.8 mW, diode-pumped solid-state (DPSS) laser 532 nm) was directed for 4 s at pial arteries to induce thrombus formation. Labeled platelets and thrombus were observed continuously under fluorescence microscopy. We recorded the area of thrombus after 30 min and determined the complete occlusion rate. After laser irradiation to the pial artery, complete occlusion rate was significantly lower in the clopidogrel (10 mg/kg) group (16%, 4/25 vessels) than in the control group (60%, 12/20 vessels) or clopidogrel (1 mg/kg) group (55%, 11/20 vessels). Area of platelet thrombus at 30 min after laser irradiation was significantly smaller in the clopidogrel (10 mg/kg) group (209 ± 128 μm(2)) than in the control group (358 ± 256 μm(2)) or clopidogrel (1 mg/kg) group (355 ± 57 μm(2)). The apparatus which we developed is convenient for inducing thrombus formation by causing endothelial cell damage to the brain surface vasculature in small animals without damage of extravascular tissue. Clopidogrel significantly inhibited laser-induced thrombus formation in pial arteries of mice in a dose-dependent manner.

Clopidogrel two doses comparative 1-year assessment of safety and efficacy (COMPASS) study in Japanese patients with ischemic stroke

BACKGROUND

Clopidogrel 75 mg once daily is licensed in Japan for the prevention of recurrent ischemic cerebrovascular events in adults as the usual dosage. However, a lower dose (50 mg) is an option in patients at an increased risk of bleeding depending on age, body weight and symptoms. This study compared the safety of both 75- and 50-mg doses of clopidogrel in patients with noncardioembolic ischemic stroke.

METHODS

This was a double-blind, double-dummy postmarketing clinical trial carried out across 118 Japanese institutions. Patients with an episode of noncardioembolic ischemic stroke at least 8 days prior to randomization, who were aged <75 years or had a body weight >50 kg were randomized to 50 or 75 mg clopidogrel once daily for 52 weeks. The primary endpoint was the incidence of bleeding adverse events. The secondary safety endpoints included the incidence of serious adverse events, serious bleeding adverse events and other prespecified adverse events. The secondary efficacy endpoint was the incidence of vascular events, including ischemic stroke, myocardial infarction, and peripheral artery disease.

RESULTS

A total of 1,110 patients were randomized to clopidogrel 50 mg (n = 558) or 75 mg (n = 552). No significant difference between the groups was detected in the incidence of bleeding adverse events, which was 14.0 and 16.5% in the clopidogrel 50- and 75-mg groups, respectively (hazard ratio = 0.831, 95% CI = 0.615-1.124, p = 0.2274). Additionally, there was no statistical difference with respect to any of the secondary safety endpoints. No significant difference between the groups was detected in the incidence of serious adverse events, which was 8.6 and 9.5% in the clopidogrel 50- and 75-mg groups, respectively (hazard ratio = 0.877, 95% CI = 0.597-1.289, p = 0.5035), and there was no significant difference between the groups in the incidence of serious bleeding events, which was 1.7 and 1.5% in the clopidogrel 50- and 75-mg groups, respectively (hazard ratio = 1.240, 95% CI = 0.489-3.142, p = 0.6496). The percentages of intracranial hemorrhage in the 50- and 75-mg groups were 0.18% (1/558) and 0.18% (1/552), respectively. The cumulative incidence of vascular events was somewhat lower in the 75-mg group, but was not statistically different (2.6 vs. 3.8%; p = 0.4118).

CONCLUSIONS

Clopidogrel 75 mg provides a clinically acceptable safety profile and suggests better clinical benefit as compared to clopidogrel 50 mg for the secondary prevention of ischemic stroke in Japanese patients who are <75 years old with a body weight >50 kg, considering the balance of safety and efficacy on this trial.

[Effect of RAAS inhibition on stroke prevention]

Recently, molecular and experimental studies revealed that the brain possesses its own renin-angiotensin-aldosterone system(RAAS) and the brain angiotensin(Ang) II plays an important role on stroke protection, mediating its effects through stimulation of AT2 and possibly the AT4 receptors. Moreover, the novel ACE2/Ang-(1-7)/Mas receptor axis was found to counterbalance the vasoconstrictive actions of the ACE/Ang II/AT1 receptor. Recent clinical trials indicate that blockade of RAAS has a potential role in stroke prevention, but was not conclusive. More carefully designed large clinical trial are needed to verify blood pressure-independent stroke prevention effect by RAAS inhibition.

Rivaroxaban vs. warfarin in Japanese patients with atrial fibrillation – the J-ROCKET AF study –

BACKGROUND

The global ROCKET AF study evaluated once-daily rivaroxaban vs. warfarin for stroke and systemic embolism prevention in patients with atrial fibrillation (AF). A separate trial, J-ROCKET AF, compared the safety of a Japan-specific rivaroxaban dose with warfarin administered according to Japanese guidelines in Japanese patients with AF.

METHODS AND RESULTS

J-ROCKET AF was a prospective, randomized, double-blind, phase III trial. Patients (n=1,280) with non-valvular AF at increased risk for stroke were randomized to receive 15 mg once-daily rivaroxaban or warfarin dose-adjusted according to Japanese guidelines. The primary objective was to determine non-inferiority of rivaroxaban against warfarin for the principal safety outcome of major and non-major clinically relevant bleeding, in the on-treatment safety population. The primary efficacy endpoint was the composite of stroke and systemic embolism. Non-inferiority of rivaroxaban to warfarin was confirmed; the rate of the principal safety outcome was 18.04% per year in rivaroxaban-treated patients and 16.42% per year in warfarin-treated patients (hazard ratio [HR] 1.11; 95% confidence interval 0.87-1.42; P<0.001 [non-inferiority]). Intracranial hemorrhage rates were 0.8% with rivaroxaban and 1.6% with warfarin. There was a strong trend for a reduction in the rate of stroke/systemic embolism with rivaroxaban vs. warfarin (HR, 0.49; P=0.050).

CONCLUSIONS

J-ROCKET AF demonstrated the safety of a Japan-specific rivaroxaban dose and supports bridging the global ROCKET AF results into Japanese clinical practice.

Malignant hypertension with reversible brainstem hypertensive encephalopathy and thrombotic microangiopathy

A 42-year-old woman presented with headache and nausea. Severe hypertension, renal dysfunction, thrombocytopenia, and anemia were present. A magnetic resonance imaging (MRI) scan of her head revealed widespread hyperintense lesions located in the brainstem and cerebellum on T2-weighted and fluid-attenuated inversion recovery imaging. Hypertensive encephalopathy was suspected, and antihypertensive therapy was started. A second MRI of the patient's head on day 12 of hospitalization revealed that the hyperintensities in the brainstem and cerebellum had almost disappeared, and that thrombocytopenia, anemia, and renal dysfunction had also gradually improved. Test results led to a diagnosis of malignant hypertension. This patient was regarded as suffering from malignant hypertension with reversible brainstem hypertensive encephalopathy (RBHE) and thrombotic microangiopathy (TMA). RBHE and TMA are known to occur as complications of malignant hypertension, but there has been no previous report of them occurring simultaneously. RBHE and TMA related to malignant hypertension are both conditions that can be improved by the rapid institution of antihypertensive therapy, and as such, early diagnosis and treatment are important. When treating patients with malignant hypertension, the possibility that it may be complicated by both RBHE and TMA must be kept in mind.

Abstract 2867: Factors Relating To An Early Visit To A Stroke Center In Patients With Transient Ischemic Attack: Analyses Of Data From A Multicenter Retrospective Study

Purpose: As transient ischemic attack (TIA) is a medical emergency associated with a high risk of early recurrent stoke, an immediate seeking medical attention is essential to reduce a risk of stroke after TIA. The purpose of this study was to investigate factors relating to an early visit to a stroke center in patients with TIA, using data of a multicenter retrospective study.

Methods: The subjects of this study were TIA patients admitted to 13 stroke centers within 7 days after onset between 2008 and 2009. The diagnosis of TIA was made in this study if clinical symptoms lasted less than 24 hours, regardless of imaging findings. We compared baseline characteristics between patients visiting a stroke center within 3 hours of TIA onset (early visit, EV group) and those after the initial 3 hours (late visit, LV group), using Chi-square tests.

Results: Four hundred sixty-four patients (292 men, mean age of 69 years) were registered. Of them, 240 patients (52%) belonged to the EV group and 220 (47%) used an ambulance. One hundred twenty-seven patients (27.4%) were referred from some other medical facility and 23 patients (5.0%) were from another department within the hospital. As compared to patients in the LV group, those in the EV group more commonly had motor symptoms (p < 0.0001) and consciousness disturbance (p = 0.0027), and were less commonly referred from some other medical facility (p < 0.0001) or from another department (p = 0.0057). Patients were less likely to have a past history of TIA in the EV group than in the LV group, but not significantly (p = 0.065).

Conclusions: Almost half of TIA patients visited a stroke center within 3 hours after onset. Motor symptoms and consciousness disturbance were related to an early visit. Referrals from some other medical facility or department were associated with delay in a contact to stroke specialists.

Delayed recurrent ischemic stroke after initial good recovery from pneumococcal meningitis

We describe unusual delayed recurrent episodes of ischemic stroke in a patient with initial good recovery from pneumococcal meningitis due to progressive arterial stenosis for over 3 months. We postulate that any of the following may have been responsible for his condition: widespread cerebral vasculopathy due to the effects of purulent material bathing the base of the brain, an immune-mediated para-infectious condition, or a rebound effect of the primary inflammatory reaction that was initially suppressed by dexamethasone. This case demonstrates that progressive arterial stenosis can evolve months after bacterial meningitis and should be recognized as a potential vascular complication.

Fisher syndrome with taste impairment

A 60-year-old woman was admitted to our hospital with a two day history of truncal ataxia and diplopia. Three days after admission, complete paresis of eye movements, left ptosis, taste impairment and absence of deep tendon reflexes appeared. The patient displayed normal facial movements; however, she reported decreased sensations of sweet and salty tastes. Anti-GQ1b antibodies were detected in the serum, and Fisher syndrome was therefore diagnosed. Intravenous immunoglobulin was administered starting five days after admission, with limitations of eye movements, areflexia and taste impairment showing improvements by 12 days after onset. Taste disturbance is rare in patients with Fisher syndrome. In this case, we hypothesize that autoantibodies may have targeted antigens in the chorda tympani, glossopharyngeal nerve or taste buds.

An adult case of pneumocephalus and pneumococcal meningitis associated with the sphenoid sinusitis

A 60-year-old man was admitted to our hospital after being found at his home in a comatose state. Cerebrospinal fluid and blood cultures were positive for Streptococcus pneumoniae. Brain magnetic resonance imaging (MRI) revealed sinusitis in the sphenoid sinus. Computed tomography demonstrated the presence of multiple air pockets in the basilar cistern, and we diagnosed pneumococcal meningitis complicated with pneumocephalus. Multiple cerebral infarctions were found on brain MRI after admission. In this case, pneumocephalus was secondary to pneumococcal meningitis due to sinusitis on admission, and multiple cerebral infarctions after admission. We demonstrated that early diagnosis is required for the successful treatment of pneumococcal meningitis.

Recurring extracranial internal carotid artery vasospasm detected by intravascular ultrasound

A 24-year-old woman presented with headache and left-sided focal signs following multiple episodes of right monocular visual impairment. Magnetic resonance angiography revealed a decreased vascular image intensity due to a suspicious stenosis in the right internal carotid artery (ICA). The stenosis was not demonstrated on duplex sonography as it was beyond the field of view of the investigation. Intravascular ultrasound (IVUS) revealed that the outer vessel diameter was significantly reduced during stenosis, supporting the presence of vasospasm. Idiopathic recurrent extracranial ICA vasospasm was diagnosed. Recurrent vasospasms of extracranial ICA may be a distinct entity that can cause ischemic stroke.

Progressive multiple cranial nerve palsies as the presenting symptom of meningeal carcinomatosis from occult colon adenocarcinoma

We herein describe a rare case of meningeal carcinomatosis in a 77-year-old woman who had bilateral deafness as the initial symptom of a previously undetected colon cancer malignancy. Meningeal carcinomatosis should be considered in the differential diagnosis in cases of abrupt-onset sensorineural deafness. Both MRI scans and cerebrospinal fluid evaluation are necessary diagnostic tools, and should be used in conjunction as each of these procedures could have false-negative results. This should apply even when there is no known primary malignancy.

Patent foramen ovale as a risk factor for cryptogenic brain abscess: case report and review of the literature

We encountered a patient with brain abscess presumably caused by dental infection. The patient displayed patent foramen ovale (PFO) and a giant Eustachian valve, through which spontaneous right-to-left shunt was revealed by transesophageal echocardiography. Reviewing the literature, we find additional cases where brain abscess originated from an increased amount of flora commonly found in the oral cavity that bypassed the pulmonary vascular bed and the lymphatic system through PFO. Additionally, a Eustachian valve should be considered an adjunctive risk factor for initiating a spontaneous right-to-left shunt and predisposing cryptogenic brain abscess in patients with PFO.

Effects of edaravone on muscle atrophy and locomotor function in patients with ischemic stroke: a randomized controlled pilot study

BACKGROUND AND OBJECTIVE

Stroke patients with severe leg paralysis are often bedridden in the acute and subacute phase, which increases the risk of disuse muscle atrophy in the chronic phase. The evidence to date indicates that oxidative stress plays an important role in the mechanism of disuse muscle atrophy. Therefore, the aim of this study was to determine if long-term radical scavenger treatment with edaravone following an acute stroke prevents the progression of disuse muscle atrophy and improves leg locomotor function in the chronic phase.

METHODS

This randomized controlled pilot study was conducted at 19 acute stroke and rehabilitation centers across Japan. Forty-seven ischemic stroke patients with at least leg motor weakness admitted within 24 hours of onset were randomly assigned to receive continuous intravenous infusions of edaravone 30 mg twice daily for 3 days (short-term group) or 10-14 days (long-term group). The primary endpoints of the study included the degree of leg disuse muscle atrophy, as measured by the percentage change from baseline in femoral muscle circumference 15 cm above the knee, and the improvement in leg locomotor function, as assessed by the maximum walking speed over 10 m, 3 months after the onset of stroke.

RESULTS

Three-month follow-up was completed by a total of 41 patients (21 in the short-term group and 20 in the long-term group). On admission, there was no significant difference in the severity of stroke or the grade of leg paresis between the two treatment groups. The grade of disuse muscle atrophy and incidence of gait impairment 3 weeks after stroke onset were also similar between the short- and long-term groups. However, disuse muscle atrophy of the paretic and non-paretic legs was significantly less severe in the long-term versus the short-term treatment group (3.6 ± 5.9% and 1.5 ± 6.0% vs 8.3 ± 5.2% and 5.7 ± 6.4%; p < 0.01 and p < 0.05) 3 months after stroke onset. Additionally, the maximum walking speed over a distance of 10 m was significantly greater in the long-term group (98 ± 67 vs 54 ± 55 cm/sec; p < 0.05).

CONCLUSION

Edaravone treatment for up to 14 days suppresses the progression of disuse muscle atrophy and improves leg locomotor function to a greater extent than shorter-term treatment in acute stroke patients. This suggests that the management of stroke may be improved with long-term edaravone therapy by providing myoprotective effects that ameliorate functional outcome in the chronic phase.

[Hypertension associated with stroke]

Antihypertensive treatment for hypertensive patients with stroke differs according to clinical subtypes (hemorrhage or ischemia) and phases (acute phase or chronic phase). In cerebral infarction that is not an indication for thrombolytic therapy, antihypertensive therapy is indicated when systolic pressure is > 220 mmHg or diastolic pressure is > 120 mmHg. In cerebral hemorrhage, a systolic blood pressure > 180 mmHg or a mean blood pressure > 130 mmHg is an indication for antihypertensive therapy. In the chronic phase of stroke, the eventual target of blood pressure control should be < 140/90 mmHg. Antihypertensive drugs recommened in the chronic phase are Ca channel blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), diuretics, etc. In patients with diabetes mellitus or atrial fibrillation, ACE inhibitors and ARBs are recommended.

Clinical review of 28 patients with basilar artery occlusion

BACKGROUND

We retrospectively analyzed factors related to the outcomes of patients with basilar artery occlusion.

METHODS

Twenty-eight patients with basilar artery occlusion admitted to our hospital within 24 hours after onset between April 2007 and December 2010 were included. We investigated parameters related to outcome, such as coexisting disease, clinical type, clinical severity at admission, the site of occlusion and the infarction lesion, the collateral flow from posterior communicating artery, therapy, and time to therapy after onset.

RESULTS

Of 28 patients with basilar artery occlusion, good outcomes occurred in 6 patients (21%) and poor outcomes occurred in 22 patients (79%). Clinical severity on admission was significantly different between the 2 groups. Three of 5 patients with percutaneous transluminal angioplasty achieved recanalization. Two of 3 cases with recanalization resulted in poor outcomes.

CONCLUSIONS

Clinical severity on admission was the determinant factor of functional prognosis in patients with basilar artery occlusion.

Candesartan cilexetil in the management of blood pressure for acute and recurrent stroke in Japan: the Challenge-Stroke study

The Challenge-Stroke study was conducted in Japanese patients initiated on candesartan cilexetil therapy within 3 months of suffering a stroke to investigate the clinical use of candesartan and its efficacy/safety in this therapeutic setting. A total of 869 patients formed the safety analysis set. In total, 79.6% of patients with brain hemorrhage (BH) and 60.2% with brain infarction (BI) began candesartan before post-stroke day 3 and 7, respectively. Baseline average blood pressure (BP) was 152.0/83.2 mmHg in the BH group and 165.2/89.8 mmHg in the BI group; this was reduced to 125.8/75.4 mmHg and 136.3/78.1 mmHg, respectively, at 1 year. The incidence of adverse drug reactions was 6.7 and 8.0%, respectively. There were 12 recurrent strokes in the BH group and 11 in the BI group after 1 year. The risk of recurrent stroke was significantly higher for BH patients with a final systolic BP ≥150 mmHg than for those with a final systolic BP <130 mmHg (hazard ratio: 6.807; p = 0.004). Aggressive antihypertensive therapy is currently employed in Japanese patients with acute stroke. Candesartan was safe and effective for BP control in acute stroke patients. Strict BP management may be useful for secondary prevention of stroke after BH.

Magnetic resonance imaging investigation of secondary degeneration of the mesencephalic substantia nigra after cerebral infarction

Secondary degeneration of the mesencephalic substantia nigra after cerebral infarction is widely known to occur in animal experiments, but has yet to be sufficiently investigated in human cerebral infarction. This study investigated the background and features of patients exhibiting secondary degeneration of the mesencephalic substantia nigra. The subjects comprised 43 patients admitted to our hospital for cerebral infarction between April 2007 and October 2010 showing secondary degeneration of the mesencephalic substantia nigra on cranial magnetic resonance imaging (MRI). We investigated clinical disease type, location of vascular occlusion, lesion site, and time from onset of symptoms to lesion identification by MRI. The clinical disease type was cardiogenic embolism in 29 patients (67%), atheromatous embolism (artery to artery) in 8 patients (19%), embolism (origin unknown) in 2 patients (5%), infarction after coil embolization for internal carotid aneurysm in 1 patient (2%), arterial dissection in 2 patients (5%), and vasculitis due to Takayasu disease in 1 patient (2%). Magnetic resonance angiography (MRA) identified the occluded vessel as the internal carotid artery in 19 patients (44%), the middle cerebral artery (M1) in 20 patients (47%), and the middle cerebral artery (M2) in 3 patients (7%); MRA was not performed in 1 patient (2%). The cerebral infarctions were striatal in 7 patients (16%) and striatal and cortical in 36 patients (84%). Hyperintense regions in the mesencephalic substantia nigra were observed in all patients after 7-28 days (mean, 13.3 days) on diffusion-weighted imaging or fluid-attenuated inversion recovery and T2-weighted MRI. Most patients with secondary degeneration of the substantia nigra demonstrated clinical disease comprising vascular occlusion of the internal carotid artery or the neighborhood of the middle cerebral artery, which was envisaged to cause a sudden drop in brain circulation across a wide area. Striatal infarctions were observed in all patients. Secondary degeneration of the substantia nigra appeared at 1-4 weeks after onset and disappeared after several months.

Usefulness of MRA-DWI mismatch in neuroendovascular therapy for acute cerebral infarction

BACKGROUND

This study evaluated the usefulness of MR angiography (MRA)-diffusion-weighted imaging (DWI) mismatch in neuroendovascular therapy over 3 h after onset of acute cerebral infarction.

METHODS

The subjects were 14 cases (age, 73 ± 8.4 years) who had an anterior circulation deficit on DWI/MRA on arrival and underwent neuroendovascular therapy over 3 h after onset. MRA-DWI mismatch (MDM) (+) was defined as 'major artery lesion (+) and diffusion-weighted image-Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≥6'; MDM (-) was defined as 'major artery lesion (+) and DWI-ASPECTS <6'.

RESULTS

Reperfusion was achieved in nine of 14 patients (64%) undergoing neuroendovascular therapy. Within the reperfusion group, in the five MDM (+) patients and the four MDM (-) patients, the outcome was a favorable clinical response in the MDM (+) group. The modified Rankin Scale (mRS) scores after 90 days were 0-2 in 3 (60%) and 3-6 in 2 (40%) of the MDM (+) group patients and 0-2 in 0 (0%) and 3-6 in 4 (100%) of the MDM (-) group patients. In the MDM (+) group, a good outcome was achieved. However, the number of cases was small, so this was not a significant difference. Within the non-reperfusion group, in the three MDM (+) patients and the two MDM (-) patients, the mRS scores after 90 days were 0-2 in 1 (33%) and 3-6 in 2 (67%) of the MDM (+) group patients and 0-2 in 0 (0%) and 3-6 in 2 (100%) of the MDM (-) group patients. In both groups, the outcome was poor.

CONCLUSIONS

With neuroendovascular therapy, a good outcome with reperfusion was achieved in the MDM (+) group compared to the MDM (-) group. This suggests that the presence or absence of MDM may be useful in determining prognosis after reperfusion.

[Aquired stuttering in addition to a recurrence of developmental stuttering caused by brain tumor in the corpus callosum]

We reported a 66-year-old right-handed man, in whom developmental stuttering had almost been cured previously, who suffered a brain tumor. He developed not only left hemiparesis but also speech dysfluency such as acquired stuttering and aphasia. MRI showed a brain tumor in the body of the corpus callosum. The main feature of his stuttering was repetition of syllables. His stuttering was associated without secondary phenomena such as tongue clicking. His stuttering demonstrated no adaptation benefit and no consistency effect. These results suggest that the stuttering in this patient might have characteristics of both developmental and acquired stuttering, which in turn may suggest that after brain tumor, acquired stuttering occurs in addition to a recurrence of developmental stuttering.