Cilostazol decreases duration of spreading depolarization and spreading ischemia after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Traditionally, angiographic vasospasm (aVS) has been thought to cause delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). However, successful treatment of aVS alone does not result in improved neurological outcome. Therefore, there may be other potential causes of poor neurological outcome, including spreading depolarization (SD). A recent study showed beneficial effects of cilostazol on DCI and neurological outcome. The present prospective clinical trial and experimental study focused on effects of cilostazol on SDs. METHODS: Fifty aSAH patients were treated with clip ligation and randomly assigned to a cilostazol (n = 23) or control group (n = 27). Effects of cilostazol on DCI, aVS, and SDs, measured with subdural electrodes, were examined. The effect of cilostazol on SD-induced perfusion deficits (spreading ischemia) was assessed in an aSAH-mimicking model. RESULTS: There was a trend for less DCI in the cilostazol group, but it did not reach our threshold for statistical significance (13.0% vs 40.0%, odds ratio = 0.266, 95% confidence interval [CI] = 0.059-1.192, p = 0.084). However, the total SD-induced depression duration per recording day (22.2 vs 30.2 minutes, ß = -251.905, 95% CI = -488.458 to -15.356, p = 0.043) and the occurrence of isoelectric SDs (0 vs 4 patients, ß = -0.916, 95% CI = -1.746 to -0.085, p = 0.037) were significantly lower in the cilostazol group. In rats, cilostazol significantly shortened SD-induced spreading ischemia compared to vehicle (Student t test, difference = 30.2, 95% CI = 5.3-55.1, p = 0.020). INTERPRETATION: Repair of the neurovascular response to SDs by cilostazol, as demonstrated in the aSAH-mimicking model, may be a promising therapy to control DCI. Ann Neurol 2018;84:873-885.

Continuous Monitoring of Spreading Depolarization and Cerebrovascular Autoregulation after Aneurysmal Subarachnoid Hemorrhage.

Delayed cerebral ischemia (DCI) is a prominent complication after aneurysmal subarachnoid hemorrhage (aSAH). Although vasospasm of proximal cerebral arteries has been regarded as the main cause of DCI, vasospasm of distal arteries, microthrombosis, impaired autoregulation, cortical spreading depolarization (CSD), and spreading ischemia are thought to be involved in DCI after aSAH. Here, we describe a patient with aSAH in whom CSD and cerebrovascular autoregulation were evaluated using simultaneous electrocorticography and monitoring of the pressure reactivity index (PRx) after surgical clipping of a ruptured posterior communicating artery aneurysm. In this patient, a prolonged duration of CSD and elevation of PRx preceded delayed neurological deficit. Based on this observation, we propose a relationship between these factors and DCI. Assessment of cerebrovascular autoregulation may permit detection of the inverse hemodynamic response to cortical depolarization. Detection of DCI may be achieved through simultaneous monitoring of CSD and PRx in patients with aSAH.

Decreased Flow Velocity with Transcranial Color-Coded Duplex Sonography Correlates with Delayed Cerebral Ischemia due to Peripheral Vasospasm of the Middle Cerebral Artery.

BACKGROUND AND OBJECTIVE: Despite intensive therapy, vasospasm remains a major cause of delayed cerebral ischemia (DCI) in worsening patient outcome after aneurysmal subarachnoid hemorrhage (aSAH). Transcranial Doppler (TCD) and transcranial color-coded duplex sonography (TCCS) are noninvasive modalities that can be used to assess vasospasm. However, high flow velocity does not always reflect DCI. The purpose of this study was to investigate the utility of TCD/TCCS in decreasing permanent neurological deficits. METHODS: We retrospectively enrolled patients with aSAH who were treated within 72 hours after onset. TCCS was performed every day from days 4 to 14. Peak systolic velocity (PSV), mean velocity (MV), and pulsatility index were recorded and compared between DCI and non-DCI patients. In patients with DCI, endovascular therapy was administered to improve vasospasm, which led to a documented change in velocity. RESULTS: Of the 73 patients, 7 (9.6%) exhibited DCI. In 5 of the 7 patients, DCI was caused by vasospasm of M2 or the more peripheral middle cerebral artery (MCA), and the PSV and MV of the DCI group were lower than those of the non-DCI group after day 7. Intra-arterial vasodilator therapy (IAVT) was performed for all patients with DCI immediately to increase the flow volume by the next day. CONCLUSIONS: Increasing flow velocity cannot always reveal vasospasm excluding M1. In patients with vasospasm of M2 or more distal arteries, decreasing flow velocity might be suggestive of DCI. IAVT led to increases in the flow velocity through expansion of the peripheral MCA.

Importance of Early Postoperative Body Temperature Management for Treatment of Subarachnoid Hemorrhage.

BACKGROUND: The importance of acute-phase brain temperature management is widely accepted for prevention of exacerbation of brain damage by a high body temperature. METHODS: In this study, we investigated the influence of body temperature in the early postoperative period on the outcomes of 62 patients with subarachnoid hemorrhage who were admitted to our department. Body temperature was measured from day 4 to day 14 after onset. The patients were divided into those treated with surgical clipping (clip group) and coil embolization (coil group), those graded I-III (mild) and IV-V (severe) based on the Hunt & Hess classification on admission, those with and without development of delayed cerebral ischemia (DCI), and those with favorable and poor outcomes. Body temperatures throughout the hospital stay were compared in each group. RESULTS: There was no significant difference in body temperature between the clip and coil groups or between the mild and severe groups, but body temperature was significantly higher in patients with DCI compared to those without DCI, and in patients with a poor outcome compared to those with a favorable outcome. CONCLUSIONS: Fever in the early postoperative period of subarachnoid hemorrhage is associated with development of DCI and a poor outcome.

Strategies and Pitfalls of Motor-Evoked Potential Monitoring during Supratentorial Aneurysm Surgery.

BACKGROUND: The aims of this study were to reveal the strategies and pitfalls of motor-evoked potential (MEP) monitoring methods during supratentorial aneurysm surgery, and to discuss the drawbacks and advantages of each method by reviewing our experiences. METHODS: Intraoperative MEP monitoring was performed in 250 patients. Results from 4 monitoring techniques using combinations of 2 stimulation sites and 2 recording sites were analyzed retrospectively. RESULTS: MEP was recorded successfully in 243 patients (97.2%). Direct cortical stimulation (DCS)-spinal recorded MEP (sMEP) was used in 134 patients, DCS-muscle recorded MEP (mMEP) in 97, transcranial electrical stimulation (TES)-mMEP in 11 and TES-sMEP in 1. TES-mMEP during closure of the skull was used in 21 patients. DCS-mMEP was able to detect waveforms from upper and/or lower limb muscles. Alternatively, DCS-sMEP (direct [D]-wave) could accurately estimate amplitude changes. A novel "early warning sign" indicating ischemia was found in 21 patients, which started with a transiently increased amplitude of D-wave and then decreased after proximal interruption of major arteries. False-negative findings in MEP monitoring in 2 patients were caused by a blood insufficiency in the lenticulostriate artery and by a TES-sMEP recording, respectively. CONCLUSIONS: The results of this study suggest that to perform accurate MEP monitoring, DCS-mMEP or DCS-sMEP recording should be used as the situation demands, with combined use of TES-mMEP recording during closure of the skull. DCS-sMEP is recommended for accurate analysis of waveforms. We also propose a novel "early warning sign" of blood insufficiency in the D-wave.

Cranioplasty and Duraplasty with Transcranial Color-Coded Duplex Sonography after Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Transcranial color-coded duplex sonography (TCCS) is a noninvasive technique for monitoring of cerebral vasospasm after neurosurgery for aneurismal subarachnoid hemorrhage. In this surgery, surgical materials are used. The goal of the study was to identify materials that can be used with ultrasound and to propose methods for cranioplasty and duraplasty using materials that permit TCCS. METHODS: The chosen neurosurgical materials were titanium mesh plate (TMP), Gore-tex, SEAMDURA, gelatinous sponge, and oxidized cellulose. B-mode imaging was recorded with the materials placed between urethane resin 10 mm in diameter and the urethane phantom model. TCCS was performed to detect middle cerebral artery flow through TMP and Gore-tex. RESULTS: TMP and SEAMDURA permitted penetration of ultrasound in B-mode and Doppler imaging, but the other materials did not do so. CONCLUSIONS: A postcraniotomy window (PCW) on a line extending from the horizontal portion of M1 using only TMP permitted flow imaging with TCCS. In external decompression, TCCS was effective only without use of Gore-tex around the postcraniotomy window. This method allows the middle cerebral artery flow to be detected easily.

Relationship between Aging and Enlargement of Intracranial Aneurysms.

BACKGROUND: To predict possible enlargement of cerebral aneurysms with aging, we retrospectively analyzed aneurysm size in relation to patient age and aneurysm site. METHODS: We included 1332 unruptured and 2362 ruptured aneurysms detected in patients from the Yamaguchi Prefecture, Japan, from 1995 to 2005. RESULTS: Age-specific site distribution was not found in the unruptured aneurysms. In the ruptured aneurysms, the incidence of anterior communicating artery (AComA) aneurysms was higher than that of internal carotid posterior communicating (ICPC) artery aneurysms among the patients aged 40-49 years (32.6% versus 14.4%), whereas the difference was small among the elderly patients aged 70-79 years (25.8% versus 24.9%). In the AComA aneurysms, either in the unruptured or ruptured cases, no age-related change in size was found. In the ICPC aneurysms, either in the unruptured or in the ruptured cases, the size of the aneurysms 7 mm or larger increased with age. CONCLUSIONS: The sizes of AComA aneurysms may remain stable with aging. Therefore, the risk of rupture may be similar in young and elderly patients. Meanwhile, ICPC artery aneurysms may continue to grow throughout the patient's life, with an increasing risk of rupture.

Adverse events after unruptured cerebral aneurysm treatment: a single-center experience with clipping/coil embolization combined units.

BACKGROUND: Indications of clipping (Clip) or coil embolization (Coil) for unruptured cerebral aneurysms (uAN) was not elaborated because prediction of rupture and risk of treatment are difficult. This study aims to determine the risk-benefit analysis of treating uAN by a comprehensive and retrospective investigation of the adverse events and sequelae in patients treated by our Clip/Coil combined units. METHODS: Clip and Coil were performed in 141 and 80 patients, respectively; Clip for middle cerebral artery AN and Coil for paraclinoid or basilar apex AN. Worsening of modified Rankin scale or mini-mental state examination was defined as major morbidity. Minor morbidity or transient morbidity was defined as other neurologic deficits. Mortality and these morbidities were considered as serious adverse events. Convulsion or events outside the brain were defined as mild adverse events. RESULTS: Total mortality and major morbidity were low. Incidence of serious adverse events was not significantly different between the Clip and Coil (17 patients [12.1%] and 6 patients [7.5%]), but the number of total adverse events was significantly different (32 patients [22.7%] in Clip vs. 8 patients [10.0%] in Coil). Because mild morbidities were significantly more frequent in the Clip (20 patients [14.2%]) compared with the Coil (2 patients [2.5%]). Convulsion occurred in 11 (7.8%) patients in the Clip but none in the Coil. CONCLUSIONS: Our combined unit decreased the occurrence of mortality/major morbidity; however, minor adverse effects were common, especially in the Clip group because of many intrinsic problems of Clip itself. This result suggests further consideration for the treatment modality for uAN.

Postoperative dural arteriovenous fistula in a patient with Cowden disease: a case report.

We report the case of a 37-year-old male with Cowden disease that caused a gradual neurological deficit because of rupture of a brain stem cavernous hemangioma. Removal of the hemangioma and hematoma was performed with an infrafacial triangle approach. Nine months after the operation, magnetic resonance imaging showed abnormal vessels on the cerebellar surface. Digital subtraction angiography showed a dural arteriovenous fistula (dAVF) from part of the meningeal artery to the ectatic inferior vermian vein with cortical reflux. After embolization, surgical obliteration of the dAVF was performed. Surgical findings showed neovascularization in the thickened dura, in which dural vessels shunted to cerebellar vessels through adhesion between the dura mater and cerebellar surface. Therefore, the thickened dura was removed with the cerebellar surface. This case suggests that postoperative angiogenesis may cause arteriovenous fistula in patients with Cowden disease.

Fragmental or massive embolization in cardiogenic stroke caused by nonvalvular atrial fibrillation.

BACKGROUND: After cardioembolic stroke (CES), left atrial thrombus (LAT) is detected by transesophageal echocardiography (TEE) in some cases but not in others. We propose that there are 2 types of embolization in CES: fragmental and massive embolization. METHODS: Consecutive patients with nonvalvular atrial fibrillation (AF) of acute CES or transient ischemic attack (TIA) were prospectively enrolled in the study between May 2009 and July 2011. TEE was performed within 7 days of admission. The patients were classified into 2 groups: those with occlusion of the main trunk (internal carotid artery, M1, and basilar artery; group M) and those with occlusion of other distal arteries (group D). Clinical features were compared between patients who did and did not have a thrombus on TEE. RESULTS: Of the 41 patients in the study, 21 were in group M and 20 were in group D. Age, sex, and treatment with tissue plasminogen activator did not differ significantly between the 2 groups. The rate of detection of LAT was significantly higher in group D (14% v 65%; P < .001). CONCLUSIONS: Patients with distal artery occlusion had a significantly higher rate of LAT compared to those with main trunk occlusion. Distal artery occlusion in CES therefore tends to result from fragmental embolization and is associated with a remnant LAT, with which there may be a concern of a risk of early recurrence.

Focal brain cooling suppresses spreading depolarization and reduces endothelial nitric oxide synthase expression in rats.

This study aimed to investigate the effects of focal brain cooling (FBC) on spreading depolarization (SD), which is associated with several neurological disorders. Although it has been studied from various aspects, no medication has been developed that can effectively control SD. As FBC can reduce neuronal damage and promote functional recovery in pathological conditions such as epilepsy, cerebral ischemia, and traumatic brain injury, it may also potentially suppress the onset and progression of SD. We created an experimental rat model of SD by administering 1 M potassium chloride (KCl) to the cortical surface. Changes in neuronal and vascular modalities were evaluated using multimodal recording, which simultaneously recorded brain temperature (BrT), wide range electrocorticogram, and two-dimensional cerebral blood flow. The rats were divided into two groups (cooling [CL] and non-cooling [NC]). Warm or cold saline was perfused on the surface of one hemisphere to maintain BrT at 37°C or 15°C in the NC and CL groups, respectively. Western blot analysis was performed to determine the effects of FBC on endothelial nitric oxide synthase (eNOS) expression. In the NC group, KCl administration triggered repetitive SDs (mean frequency = 11.57/h). In the CL group, FBC increased the duration of all KCl-induced events and gradually reduced their frequency. Additionally, eNOS expression decreased in the cooled brain regions compared to the non-cooled contralateral hemisphere. The results obtained by multimodal recording suggest that FBC suppresses SD and decreases eNOS expression. This study may contribute to developing new treatments for SD and related neurological disorders.

Multicenter prospective cohort study on volume management after subarachnoid hemorrhage: hemodynamic changes according to severity of subarachnoid hemorrhage and cerebral vasospasm.

BACKGROUND AND PURPOSE: Systemic circulation management has not been established for patients with poor grade aneurysmal subarachnoid hemorrhage (SAH) or delayed cerebral ischemia (DCI) after SAH. The aims of the study were to examine hemodynamic variables in these patients and to establish treatment strategies. METHODS: A multicenter prospective cohort study of hemodynamic variables from days 1 to 14 was performed using a transpulmonary thermodilution system (PiCCO Plus). Parameters were analyzed by Mann-Whitney test. Multivariate analysis was performed to identify parameters involved in onset of DCI. RESULTS: The subjects were 204 patients, including 138 with poor grade SAH (World Federation of Neurological Surgeons grades IV and V) and 52 who developed DCI. The extravascular lung water index, pulmonary vascular permeability index, and systemic vascular resistance index were significantly greater in patients with poor grade SAH compared with those with good grade SAH (World Federation of Neurological Surgeons I-III) on day 2 (P=0.049, P=0.039, and P=0.038). Cardiac index was significantly lower in patients with poor grade SAH on days 1 and 2 (P=0.027 and P=0.011). In patients with DCI, the global end-diastolic volume index was significantly lower than in those without DCI on days 3 to 5 (P=0.0053; P=0.048; and P=0.048). In multivariate analysis, median global end-diastolic volume index, cardiac index, and systemic vascular resistance index at an early stage of SAH (days 3-6) were independently related to onset of DCI (P=0.023, P=0.013, and P=0.003). CONCLUSIONS: Patients with poor grade SAH developed heart failure-like afterload mismatch at an early stage, and those with DCI had decreased global end-diastolic volume index (hypovolemia) in the early stage of SAH. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: UMIN000003794.

Cognitive outcome differences on the side of carotid artery stenting.

OBJECTIVE: The right and left sides of the brain play different roles in cognition. Therefore, the side of treatment should be taken into consideration when evaluating cognitive outcome following revascularization. Thus, we designed a study to evaluate changes in right hemisphere cognitive function in patients undergoing right carotid artery stentings (CAS) and left hemispheric cognitive function in patients undergoing left CAS. In addition, we studied CAS-related changes in regional cerebral blood flow to determine potential correlations with changes in cognitive function. METHODS: We performed a prospective assessment of 39 CAS patients, all of whom were right-handed. Patients with contralateral stenotic lesions were excluded. Twenty-one patients underwent CAS of the right internal carotid artery (Right CAS group) and 18 underwent CAS of the left internal carotid artery (Left CAS group). Neuropsychological testing was performed preoperatively and 6 months after endovascular treatment. Cerebral blood flow was determined by 123I-labeled N-isopropyl-p-iodoamphetamine single-photon emission computed tomography before and 6 months after CAS. RESULTS: In the Right CAS group, postoperative performance intelligence quotient score (91.1±18.2) was significantly improved compared with the preoperative score (84.9±16.7; P<.001). In the Left CAS group, postoperative verbal intelligence quotient score (104.0±18.8) was significantly higher than that before endovascular treatment (97.9±15.8; P<.005). Postoperative regional cerebral blood flow was not significantly different from that before endovascular treatment in either group. However, regional cerebrovascular reactivity of the treated side showed significant improvement after treatment. CONCLUSIONS: Amelioration of cognitive function may be dependent on the side of revascularization. Performance intelligence quotient improved after CAS in patients with severe carotid artery stenosis on the right side. Verbal intelligence quotient also improved on the left side after endovascular treatment. These effects seemed to involve improvement in regional cerebrovascular reactivity by CAS.

Seasonal variation in the incidence of aneurysmal subarachnoid hemorrhage associated with age and gender: 20-year results from the Yamaguchi cerebral aneurysm registry.

BACKGROUND: This study was a cerebral aneurysm registry study conducted in a region with few climatic differences. Based on data collected for over 20 years, seasonal variations and characteristics of subarachnoid hemorrhage (SAH) due to ruptured aneurysms were analyzed. METHODS: This study included 5,007 patients in the Yamaguchi Prefecture with aneurysmal SAH between 1986 and 2005. Incidence rates by month, sex, age, severity, and aneurysm site were analyzed. RESULTS: In women, seasonal variation was observed, in particular among those aged ≥50 years. Among those aged 50-69 years, the highest incidence was in October, and the nadir was in June (peak-to-trough ratio = 1.72). At age ≥70 years, this was slightly different, with the highest incidence in December and the nadir in July (peak-to-trough ratio = 1.48). However, there was no seasonal variation in men overall; it was limited to elderly men at age ≥70 years, with the highest incidence in January and the nadir in July (peak-to-trough ratio = 2.9). Aneurysm site and severity showed no relationship with seasonal variation. CONCLUSION: The present study shows seasonal variations in the onset of SAH. Seasonal variations in SAH differed depending on age and sex.

Cooling treatment transiently increases the permeability of brain capillary endothelial cells through translocation of claudin-5.

The blood-brain-barrier (BBB) is formed by different cell types, of which brain microvascular endothelial cells are major structural constituents. The goal of this study was to examine the effects of cooling on the permeability of the BBB with reference to tight junction formation of brain microendothelial cells. The sensorimotor cortex above the dura mater in adult male Wistar rats was focally cooled to a temperature of 5 °C for 1 h, then immunostaining for immunoglobulin G (IgG) was performed to evaluate the permeability of the BBB. Permeability produced by cooling was also evaluated in cultured murine brain endothelial cells (bEnd3) based on measurement of trans-epithelial electric resistance (TEER). Immunocytochemistry and Western blotting of proteins associated with tight junctions in bEnd3 were performed to determine protein distribution before and after cooling. After focal cooling of the rat brain cortex, diffuse immunostaining for IgG was observed primarily around the small vasculature and in the extracellular spaces of parenchyma of the cortex. In cultured bEnd3, TEER significantly decreased during cooling (15 °C) and recovered to normal levels after rewarming to 37 °C. Immunocytochemistry and Western blotting showed that claudin-5, a critical regulatory protein for tight junctions, was translocated from the membrane to the cytoplasm after cooling in cultured bEnd3 cells. These results suggest that focal brain cooling may open the BBB transiently through an effect on tight junctions of brain microendothelial cells, and that therapeutically this approach may allow control of BBB function and drug delivery through the BBB.

Cooling of the epileptic focus suppresses seizures with minimal influence on neurologic functions.

PURPOSE: Focal brain cooling is effective for suppression of epileptic seizures, but it is unclear if seizures can be suppressed without a substantial influence on normal neurologic function. To address the issue, a thermoelectrically driven cooling system was developed and applied in free-moving rat models of focal seizure and epilepsy. METHODS: Focal seizures limited to the unilateral forelimb were induced by local application of a penicillin G solution or cobalt powder to the unilateral sensorimotor cortex. A proportional integration and differentiation (PID)-controlled, thermoelectrically driven cooling device (weight of 11 g) and bipolar electrodes were chronically implanted on the eloquent area (on the epileptic focus) and the effects of cooling (20, 15, and 10°C) on electrocorticography, seizure frequency, and neurologic changes were investigated. KEY FINDINGS: Cooling was associated with a distinct reduction of the epileptic discharges. In both models, cooling of epileptic foci significantly improved both seizure frequency and neurologic functions from 20°C down to 15°C. Cooling to 10°C also suppressed seizures, but with no further improvement in neurologic function. Subsequent investigation of sensorimotor function revealed significant deterioration in foot-fault tests and the receptive field size at 15°C. SIGNIFICANCE: Despite the beneficial effects in ictal rats, sensorimotor functions deteriorated at 15°C, thereby suggesting a lower limit for the therapeutic temperature. These results provide important evidence of a therapeutic effect of temperatures from 20 to 15°C using an implantable, hypothermal device for focal epilepsy.

Preoperative prediction of outcome in 283 poor-grade patients with subarachnoid hemorrhage: a project of the Chugoku-Shikoku Division of the Japan Neurosurgical Society.

BACKGROUND: The management of patients with poor-grade subarachnoid hemorrhage (SAH) continues to be controversial. The objective of this study was to examine predictors of outcome of poor-grade SAH after surgical obliteration of the aneurysm. METHODS: The study was performed as a retrospective review of 283 patients with poor-grade SAH who underwent surgical obliteration of the aneurysm at multiple centers in Chugoku and Shikoku, Japan. RESULTS: A favorable outcome at discharge was achieved in 97 of the 283 patients (34.3%). Age (p < 0.001), World Federation of Neurosurgical Societies (WFNS) grade V at admission (p = 0.002), improvement in WFNS grade after admission (p = 0.002), Fisher grade (p = 0.039) and a low-density area (LDA) associated with vasospasm on computed tomography (CT; p < 0.001) showed a significant association with outcome. Further analysis of WFNS grades indicated that most patients who only improved to preoperative grade IV from grade V at admission did not have a favorable outcome. Multivariate analysis identified age (especially of > or =65 years; p < 0.001), WFNS grade V (p < 0.001) and LDA associated with vasospasm on CT (p < 0.001) as predictors of a poor outcome, and improvement in WFNS grade (p = 0.001) as a predictor of a favorable outcome after surgical obliteration of the aneurysm. CONCLUSIONS: Advanced age, WFNS grade V, improvement in WFNS grade, and LDA associated with vasospasm on CT were found to be independent predictors of clinical outcome, whereas rebleeding, early aneurysm surgery and treatment modality (surgical clipping or Guglielmi detachable coil embolization) were not independently associated with outcome in patients with poor-grade aneurysm.

Elevated concentrations of sphingosylphosphorylcholine in cerebrospinal fluid after subarachnoid hemorrhage: a possible role as a spasmogen.

This study investigates the role of sphingosylphosphorylcholine (SPC) in the mechanisms underlying cerebral vasospasm after subarachnoid hemorrhage (SAH). The levels of SPC were measured in cerebrospinal fluid (CSF) of patients with SAH and also in an experimental canine model. CSF samples were collected from 11 patients with SAH, and from dogs that had received an injection of SPC into the cisterna magna to examine SPC kinetics in the CSF. SPC was assayed using solid-phase extraction and triple quadrupole mass spectrometry. The SPC concentrations in SAH patients on days 3, 8, and 14 after the onset of SAH were significantly higher than those in normal CSF. In the canine model, rapid dilution of SPC in CSF was observed. In combination with data from previous studies, these results suggest that SPC is involved in the development of cerebral vasospasm. Rapid dilution of SPC in CSF suggests that SPC is released into CSF at higher concentrations than those measured in the present study.

Cholesterol primes vascular smooth muscle to induce Ca2 sensitization mediated by a sphingosylphosphorylcholine-Rho-kinase pathway: possible role for membrane raft.

Hypercholesterolemia is a major risk factor involved in abnormal cardiovascular events. Rho-kinase-mediated Ca(2+) sensitization of vascular smooth muscle (VSM) plays a critical role in vasospasm and hypertension. We recently identified sphingosylphosphorylcholine (SPC) and Src family tyrosine kinase (Src-TK) as upstream mediators for the Rho-kinase-mediated Ca(2+) sensitization. Here we report the strong linkage between cholesterol and the Ca(2+) sensitization of VSM mediated by a novel SPC/Src-TK/Rho-kinase pathway in both humans and rabbits. The extent of the sensitization correlated well with the total cholesterol or low-density lipoprotein cholesterol levels in serum. However, an inverse correlation with the serum level of high-density lipoprotein cholesterol was observed, and a correlation with other cardiovascular risk factors was nil. When cholesterol-lowering therapy was given to patients and rabbits with hypercholesterolemia, the SPC-induced contractions diminished. Depletion of VSM cholesterol by beta-cyclodextrin resulted in a loss of membrane caveolin-1, a marker of cholesterol-enriched lipid raft, and inhibited the SPC-induced Ca(2+) sensitization and translocation of Rho-kinase from cytosol to the cell membrane. Vasocontractions induced by membrane depolarization and by an adrenergic agonist were cholesterol-independent. Our data support the previously unreported concept that cholesterol potentiates the Ca(2+) sensitization of VSM mediated by a SPC/Src-TK/Rho-kinase pathway, and are also compatible with a role for cholesterol-enriched membrane microdomain, a lipid raft. This process may play an important role in the development of abnormal vascular contractions in patients with hypercholesterolemia.