Effects of Cervical Rotation Angle on Atherosclerotic Internal Carotid Artery Blood Flow: A Safety Study Using an Animal Model of Internal Carotid Atherosclerosis.

OBJECTIVE: The aim of this study was to investigate the effects of the cervical rotation angle (CRA) on atherosclerotic internal carotid artery blood flow (ICA-BF) in an animal model. METHODS: Thirty healthy New Zealand white rabbits were included in the study. Twenty of the 30 rabbits were chosen randomly to be the model rabbits, and the remaining 10 were chosen to be the normal rabbits. The model rabbits' left ICAs were treated by atherosclerosis modeling. The left ICAs of the model rabbits with atherosclerotic stenosis were chosen as the experimental group, and the right ICAs of the model rabbits without atherosclerotic stenosis were chosen as the control group. The left ICAs of the normal rabbits were chosen as the blank group. Using color duplex ultrasound, ICA-BF was measured in the artery contralateral to the direction of rotation in the positions of neutral (Pre-0°), 15°, 30°, 45°, 60°, 75°, 90°, and subsequent neutral (Post-0°). RESULTS: Statistically significant decreases were seen in ICA-BF after cervical spine rotation (from Pre-0° to 90°) in the control group only (P < .05). All the values of end-diastolic velocity in the experimental group were lower than those in the blank group at the same CRAs. The resistance index and pulsatility index of the experimental group were higher than those of the blank group except at 45° rotation. CONCLUSION: In our animal model, in the rabbits with hyperlipidemia but without atherosclerotic stenosis, CRA had the greatest impact on ICA-BF. Furthermore, at some of the same CRAs (especially neutral, 30°, and 60°), there were statistical differences in ICA-BF among the 3 groups.

Internal carotid artery aneurysm mimicking normal-tension glaucoma.

Differentiating glaucomatous from nonglaucomatous optic disc cupping remains challenging. We present a case of a 48-year-old woman with an internal carotid aneurysm of approximately 3.5 mm × 6.5 mm that mimicked normal-tension glaucoma. The patient had a 2-year history of low vision acuity in her left eye and frontal oppressive headache. Owing to the carotid aneurysm, she developed an asymmetric vertical cup-to-disc ratio above 0.2, and marked inferotemporal neuronal rim loss and pallor of the residual rim were noted in the left disc. She also developed a visual field defect with an arcuate scotoma in the left eye. The patient was referred to a neurosurgeon and underwent endovascular aneurysm occlusion. This case highlights the diagnostic importance of recognizing that many neurological defects remain underdiagnosed.

Internal carotid artery aneurysm mimicking normal-tension glaucoma / Aneurisma de carótida interna simulando glaucoma de pressão normal

ABSTRACT Differentiating glaucomatous from nonglaucomatous optic disc cupping remains challenging. We present a case of a 48-year-old woman with an internal carotid aneurysm of approximately 3.5 mm × 6.5 mm that mimicked normal-tension glaucoma. The patient had a 2-year history of low vision acuity in her left eye and frontal oppressive headache. Owing to the carotid aneurysm, she developed an asymmetric vertical cup-to-disc ratio above 0.2, and marked inferotemporal neuronal rim loss and pallor of the residual rim were noted in the left disc. She also developed a visual field defect with an arcuate scotoma in the left eye. The patient was referred to a neurosurgeon and underwent endovascular aneurysm occlusion. This case highlights the diagnostic importance of recognizing that many neurological defects remain underdiagnosed.

RESUMO diferenciação de escavações glaucomatosas e não glaucomatosas ainda permanece um desafio ainda nos dias de hoje. Nos descrevemos um caso de aneurisma de carótida interna medindo 3.5mm x 6.5mm que simulava um glaucoma de pressão normal. O caso é sobre uma paciente feminino de 48 anos com história de 2 anos de baixa acuidade visual no olho esquerdo e cefaléia frontal. Devido ao aneurisma de carótida a paciente desenvolveu uma assimetria de escavação vertical maior que 0.2 no olho esquerdo em relação ao direito com defeito localizado da camada de fibras nervosas temporal inferior. Ela também apresentava um defeito arqueado temporal superior a esquerda, cruzando a linha média vertical consistente. Após o diagnostico confirmado pela ressonância magnética funcional, a paciente foi enviada para o neurocirurgião para realização de uma oclusão endovascular do aneurisma. Esse caso nos alerta da importância de se lembrar que não apenas o glaucoma gera escavações suspeitas no disco óptico e que ainda muitos defeitos por causas neurológicas são subdiagnosticados.

Effects of face/head and whole body cooling during passive heat stress on human somatosensory processing.

We herein investigated the effects of face/head and whole body cooling during passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs) at C4' and Fz electrodes. Fourteen healthy subjects received a median nerve stimulation at the left wrist. SEPs were recorded at normothermic baseline (Rest), when esophageal temperature had increased by ~1.2°C (heat stress: HS) during passive heating, face/head cooling during passive heating (face/head cooling: FHC), and after HS (whole body cooling: WBC). The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Latency indicated speed of the subcortical and cortical somatosensory processing, while amplitude reflected the strength of neural activity. Blood flow in the internal and common carotid arteries (ICA and CCA, respectively) and psychological comfort were recorded in each session. Increases in esophageal temperature due to HS significantly decreased the amplitude of N60, psychological comfort, and ICA blood flow in the HS session, and also shortened the latencies of SEPs (all, P < 0.05). While esophageal temperature remained elevated, FHC recovered the peak amplitude of N60, psychological comfort, and ICA blood flow toward preheat baseline levels as well as WBC. However, the latencies of SEPs did not recover in the FHC and WBC sessions. These results suggest that impaired neural activity in cortical somatosensory processing during passive HS was recovered by FHC, whereas conduction velocity in the ascending somatosensory input was accelerated by increases in body temperature.

The Posterior Limb of the Internal Capsule as the Subcortical Transitional Zone of the Anterior and Posterior Circulations: Insights from Human 7T MRI.

BACKGROUND: In patients with cerebral infarction, identifying the distribution of infarction and the relevant artery is essential for ascertaining the underlying vascular pathophysiological mechanisms and preventing subsequent stroke. However, visualization of the basal perforating arteries (BPAs) has had limited success, and simultaneous viewing of background anatomical structures has only rarely been attempted in living human brains. Our study aimed at identifying the BPAs with 7T MRI and evaluating their distribution in the subcortical structures, thereby showing the clinical significance of the technique. METHODS: Twenty healthy subjects and 1 patient with cerebral infarction involving the posterior limb of the internal capsule (ICpost) and thalamus underwent 3-dimensional fast spoiled gradient-echo sequence as time-of-flight magnetic resonance angiography (MRA) at 7T with a submillimeter resolution. The MRA was modified to detect inflow signals from BPAs, while preserving the background anatomical signals. BPA stems and branches in the subcortical structures and their origins were identified on images, using partial maximum intensity projection in 3 dimensions. RESULTS: A branch of the left posterior cerebral artery (PCA) in the patient ran through both the infarcted thalamus and ICpost and was clearly the relevant artery. In 40 intact hemispheres in healthy subjects, 571 stems and 1,421 branches of BPAs were detected in the subcortical structures. No significant differences in the numbers of stems and branches were observed between the intact hemispheres. The numbers deviated even less across subjects. The distribution analysis showed that the subcortical structures of the telencephalon, such as the caudate nucleus, anterior limb of the internal capsule, and lenticular nucleus, were predominantly supplied by BPAs from the anterior circulation. In contrast, the thalamus, belonging to the diencephalon, was mostly fed by BPAs from the posterior circulation. However, compared with other subcortical structures, the ICpost, which marks the anatomical boundary between the telencephalon and the diencephalon, was supplied by BPAs with significantly more diverse origins. These BPAs originated from the internal carotid artery (23.1%), middle cerebral artery (38.5%), PCA (17.3%), and the posterior communicating artery (21.1%). CONCLUSIONS: The modified MRI method allowed the detection of the relevant BPA within the infarcted area in the stroke survivor as well as the BPAs in the subcortical structures of living human brains. Based on in vivo BPA distribution analyses, the ICpost is the transitional zone of the anterior and posterior cerebral circulations.

Hypothalamic, thalamic and hippocampal lesions in the mouse MCAO model: Potential involvement of deep cerebral arteries?

Intraluminal monofilament occlusion of the middle cerebral artery (MCAO) in mice is the most used rodent model to study the pathophysiology of stroke. However, this model often shows brain damage in regions not supplied by the MCA such as the hypothalamus, hippocampus and thalamus. Several studies have suggested some explanations on these localized infarcts. We aim to provide an alternative explanation which could allow each experimenter to better grasp the MCAO model. We propose that the MCA occlusion by the monofilament also occludes deep and small cerebral arteries arising directly from the internal carotid artery, proximally to the origin of MCA. Then, drawbacks and pitfalls of the MCAO model must be appreciated and the almost systematic risk of inducing lesions in some unwanted territories for neuroanatomical reasons, i.e. vascular connections between deep arteries and hypothalamic, thalamic and hippocampal areas in rodents has to be integrated.

Postoperative internal carotid artery restenosis after local anesthesia: presence of risk factors versus intraoperative shunt.

Published data suggest that the regional anesthetic technique used for carotid endarterectomy (CEA) increases the systolic arterial blood pressure and heart rate. At the same time local anesthesia reduced the shunt insertion rate. This study aimed to analyze risk factors and ischemic symptomatology in patients with postoperative internal carotid artery restenosis. The current retrospective study was undertaken to assess the results of CEA in 8000 patients who were operated during a five-year period in six regional cardiovascular centers. Carotid color coded flow imaging, medical history, clinical findings and atherosclerotic risk factors were analyzed. Among them, there were 33 patients (0.4%) with postoperative re-occlusion after CEA. The patients with restenosis were re-examined with carotid color coded flow imaging and data were compared with 33 consecutive patients with satisfactory postoperative findings to serve as a control group. In the restenosis group eight risk factors were analyzed (hypertension, smoking, hyperlipidemia, diabetes mellitus, history of stroke, transitory ischemic attack, heart attack and coronary disease), and compared with risk factors in control group. Study results suggested that early postoperative internal carotid artery restenosis was not caused by atherosclerosis risk factors but by intraoperative shunt usage.

Countervailing vascular effects of rosiglitazone in high cardiovascular risk mice: role of oxidative stress and PRMT-1.

In the present study, we tested the hypothesis that the PPARgamma (peroxisome-proliferator-activated receptor gamma) activator rosiglitazone improves vascular structure and function in aged hyperhomocysteinaemic MTHFR (methylene tetrahydrofolate reductase) gene heterozygous knockout (mthfr+/-) mice fed a HCD (high-cholesterol diet), a model of high cardiovascular risk. One-year-old mthfr+/- mice were fed or not HCD (6 mg x kg-1 of body weight x day-1) and treated or not with rosiglitazone (20 mg x kg-1 of body weight x day-1) for 90 days and compared with wild-type mice. Endothelium-dependent relaxation of carotid arteries was significantly impaired (-40%) only in rosiglitazone-treated HCD-fed mthfr+/- mice. Carotid M/L (media-to-lumen ratio) and CSA (cross-sectional area) were increased (2-fold) in mthfr+/- mice fed or not HCD compared with wild-type mice (P<0.05). Rosiglitazone reduced M/L and CSA only in mthfr+/- mice fed a normal diet. Superoxide production was increased in mthfr+/- mice fed HCD treated or not with rosiglitazone, whereas plasma nitrite was decreased by rosiglitazone in mice fed or not HCD. PRMT-1 (protein arginine methyltransferase-1), involved in synthesis of the NO (nitric oxide) synthase inhibitor ADMA (asymmetric omega-NG,NG-dimethylarginine), and ADMA were increased only in rosiglitazone-treated HCD-fed mthfr+/- mice. Rosiglitazone had both beneficial and deleterious vascular effects in this animal model of high cardiovascular risk: it prevented carotid remodelling, but impaired endothelial function in part through enhanced oxidative stress and increased ADMA production in mice at high cardiovascular risk.

Effective surgical treatment of the carotid sinus sindrome.

Elderly patients frequently suffer from dizziness and syncope; however, an underlying disease may not always be identified. Three patients aged 69, 71 and 56, respectively, experienced spells of dizziness and syncope. Massage of the carotid sinus demonstrated the presence of a carotid sinus syndrome (CSS), an abnormal baroreflex response of the carotid sinus that leads to asystole and extreme hypotension. Conventional treatment is generally by insertion of a pacemaker. These patients, however, were referred to the vascular surgery department of our hospital for removal of adventitial layers of proximal portions of the internal carotid artery. Recovery was uneventful; all three are now free of symptoms. CSS should be considered in the differential diagnosis of dizziness and syncope. Surgical denervation of the carotid artery is a valid treatment option, especially in the vasodepressive or mixed type of CSS.

Bilateral simultaneous central retinal artery occlusion following head injury.

PURPOSE: To report a case of bilateral simultaneous central retinal artery occlusion (CRAO) following head injury in a young 29-year-old man. METHODS: A 29-year-old man presented with head injury following road traffic accident. Posterior segment evaluation revealed CRAO in both eyes. RESULTS: The patient was treated for CRAO in the form of immediate ocular massage, paracentesis, intravenous mannitol and transdermal isosorbide dinitrate patch. Despite treatment the vision continued to be no perception of light. Systemic investigations were unremarkable. Color Doppler of carotid arteries showed plaque in left carotid bulb and thrombus in right internal carotid artery. CONCLUSION: Bilateral simultaneous CRAO following head trauma has not been reported earlier. Thorough ocular examination is recommended in all cases of head injury.

Relative changes in flow velocities in vasospasm after subarachnoid hemorrhage: a transcranial Doppler study.

INTRODUCTION: Transcranial Dopplers (TCDs) have been used to monitor cerebral blood flow velocities in subarachnoid hemorrhage (SAH).The purpose of our two-part study was to compare the reliability of relative increases in flow velocities with conventionally used absolute flow velocity indices and to correct for hyperemia-induced flow velocity change. METHODS: Part 1: Charts of 50 patients admitted to Hahnemann University Hospital with aneurismal SAH were reviewed. Mean middle cerebral artery maximum flow velocities (MCA-MFV) were reviewed for initial flow velocities (IFVs) and maximal flow velocities (MFVs) that were reached during hospital course. Correlating flow velocities (SFVs) were noted in patients who developed symptomatic vasospasm. MFV/IFV and SFV/IFV ratios were calculated to evaluate relative changes in flow velocity. Part 2: Correction for hyperemia was derived from Lindegaards Ratio using extracranial internal carotid artery (ICA) flow velocity ratio (corrected MCA-MFV/observed MCA-MFV = EC-ICAFV (day1)/observed EC-ICAFV). RESULTS: Part 1: All 10 patients who developed symptomatic vasospasm exhibited a twofold increase (SFV/IFV: >2) in flow velocities prior to developing symptomatic vasospasm, and 5 patients had a threefold increase (SFV/IFV: >3). Of the 40 patients who did not develop symptomatic vasospasm, 33 patients did not have a twofold increase in their flow velocities at any time. The positive predictive value for MFV/IFV greater than 3 (n = 6) and SFV/IFV greater than 3 (n = 5) was 100%. The negative predictive value for MFV/IFV less than 2 (n = 33) was 100%. Data using relative changes (twofold increase) in flow velocity was more sensitive (100 to 90%), specific (83 to 70%), and predictive (positive predictive value [PPV]: 59 to 45%; negative predictive value [NPV]: 100 to 97%) for symptomatic vasospasm than absolute flow velocity indices using MCA-MFV greater than 120 even in combination with Lindegaards Ratio (MCA/ICA greater than 3). Part 2: Correction for hyperemia by modifying Lindegaard's Index in the 32 patients where data was available improved the PPV of absolute flow velocities from 44 to 62%. In this population, the application of this equation while evaluating relative change in flow velocities improved PPV of twofold increase from 57 to 73%. CONCLUSION: Relative changes in flow velocities in patients with aneurysmal SAH correlated better with clinically significant vasospasm than absolute flow velocity indices. Correction for hyperemia improved predictive value of TCD in vasospasm.

Cervical artery dissection. A comparison of highly dynamic mechanisms: manipulation versus motor vehicle collision.

OBJECTIVE: To examine the similarities and dissimilarities between cervical chiropractic manipulative therapy and whiplash, and their respective relation to cervical artery dissection. DATA SOURCES: A literature synthesis used MEDLINE-PubMed and MANTIS literature searches. A total list of 99 relevant articles was generated. Additional references were collected from citations incorporated within the included articles. RESULTS: Both neck manipulation and motor vehicle collision events apply loads to the spinal column rapidly. While neck manipulation loads are slower to develop and displacements smaller, they may reach peak amplitudes on maximum effort comparable to those seen in low-velocity collision experiments. In contrast to reports that the vertebral artery experiences elongations exceeding its physiological range by up to 9.0 mm during simulated whiplash, strains incurred during cervical manipulative therapy have been reported to be approximately one ninth of those required for mechanical failure, comparable to forces encountered in the course of diagnostic range of motion examination. Additionally, long-lasting abnormalities of blood flow velocity within the vertebral artery have been reported in patients following common whiplash injuries, whereas no significant changes in vertebral artery peak flow velocity were observed following cervical chiropractic manipulative therapy. CONCLUSIONS: Perceived causation of reported cases of cervical artery dissection is more frequently attributed to chiropractic manipulative therapy procedures than to motor vehicle collision related injuries, even though the comparative biomechanical evidence makes such causation unlikely. The direct evidence suggests that the healthy vertebral artery is not at risk from properly performed chiropractic manipulative procedures.

A randomized, double-blind, placebo-controlled clinical trial of the Chinese herbal medicine "ba wei di huang wan" in the treatment of dementia.

OBJECTIVES: To evaluate whether a traditional Chinese herbal medicine, ba wei di huang wan (BDW), improves cognitive and physical functioning in dementia patients. DESIGN: An 8-week randomized, double-blind, placebo-controlled trial. SETTING: Long-term-care facility in Japan. PARTICIPANTS: Thirty-three patients with mild to severe dementia (7 men and 26 women; mean age +/- standard deviation=84.4 +/- 7.8) were recruited and enrolled from May 2002 through September 2002. INTERVENTION: Participants were randomly assigned to the active drug (BDW) group (n=16) or the placebo group (n=17) and treated for 8 weeks. MEASUREMENT: Cognitive function and activities of daily living (ADLs); palsatility index. RESULTS: After the trial, cognitive function as assessed using the Mini-Mental State Examination (MMSE) significantly improved from 13.5 +/- 8.5 to 16.3 +/- 7.7 (P<.01, 95% confidence interval (CI)=-4.1 to -1.4) in the BDW group. The ADL score in the Barthel Index also significantly changed, from 61.8 +/- 34.6 to 78.9 +/- 21.1 (P<.01, 95% CI=-26.2 to -7.9). In contrast, MMSE and Barthel Index scores of the placebo group showed no significant change. Eight weeks after the end of the administration, MMSE and Barthel Index scores of the BDW group declined to the baseline level. The pulsatility index in the internal carotid artery as measured using Doppler sonography significantly decreased in the BDW group (2.5 +/- 1.7 to 1.9 +/- 0.5, P<.05) but not in the placebo group. CONCLUSION: These results argue the benefits of BDW in the treatment of dementia.

[Benefits and effectiveness of recording somatosensory evoked potentials in surgery on the carotid artery]. / Nutzen und Effizienz der Ableitung somatisch evozierter Potenziale in der Karotischirurgie.

BACKGROUND: Operative treatment of high-grade carotid stenosis is an established procedure. The question whether a temporary - either selective or routine - shunt is needed, is a matter of controversy, and the decision is based on a number of available monitoring procedures. Within the framework of quality assurance based on the regular collection of our own patient data, carotid thromboendarterectomy (TEA) with recording of somatosensory evoked potentials (SEP) was analysed for its effectiveness. PATIENTS AND METHODS: Two non-randomised groups of patients were analysed retrospectively: Group I: 99 carotid TEAs with no recording of SEP (1.1.99-31.12.99); Group II: 139 carotid TEAs with SEP recording (1.1.01-31.12.01). These two groups were unselected in terms of procedure, as also with regard to age, sex, stage or degree of carotid stenosis or surgeon, and were homogeneously distributed. A comparison was made of anaesthesia and operating times, shunt rate and the outcome of the two groups. Additionally, the two subgroups surgery with no shunt, and surgery with shunt, and the subgroups thromboendarterectomy with patchplasty (TEA) and eversion endarterectomy (EEA), were analysed. RESULTS: A temporary shunt was employed in 41 (41.4 %) of the patients in Group I (no SEP recording) and in 16 (11.5 %) of those in Group II (SEP recording). The average operating time in Group II was 11.4 min shorter (p < 0.001) than in Group I. The average carotid clamping time in Group II was significantly reduced (by 4.2 min; p < 0.001), while the duration of anaesthesia prior to skin incision was increased by an average of 18.3 min (p < 0.001), and the overall duration of anaesthesia by an average of 15.8 min (p < 0.001). A comparison of the subgroups surgery with no shunt and surgery with shunt revealed - both in Group I and Group II - a significant prolongation of the anaesthesia time and operating time (p < 0.001). In both Groups I and II, the subgroup TEA revealed a significant prolongation of both the anaesthesia and operating times vis-à-vis EEA. The major stroke rate was 2.0 % in Group I and 1.4 % in Group II, and the minor stroke rate 3.0 in Group I and 3.6 % in Group II; no deaths were observed. CONCLUSIONS: A reduction in the shunt rate to 11 % (by means of SEP) significantly decreased the average operating time (incision - suture) and the clamping time, with identical outcome in Groups I and II. Despite a reduction in the average incision-suture time in Group II (with SEP recording), the average overall operating time (anaesthesia time) was significantly increased due to the greater technical effort required. Carotid TEA with a selective shunt as determined by SEP is a high-cost procedure with no demonstrable benefit. At a stroke rate < 5 % and a need for stratification into several groups in accordance with the AHA classification, it is not possible to achieve adequate patient recruitment for a randomised analysis of outcome of the individual monitoring procedures. Alternative procedures are the routine use of a shunt and operation under regional anaesthesia.

Prediction of cerebral ischemic tolerance during carotid cross-clamping by angiographic criteria.

OBJECTIVE: To evaluate the prognostic value of angiographic criteria and internal carotid artery (ICA) stump pressure for shunt placement in carotid surgery under local anaesthesia. DESIGN: Prospective clinical trial at a university hospital. MATERIALS AND METHODS: In 120 patients a cerebral angiography was initiated before undergoing carotid surgery. Seventy-five percent of the patients were neurologically asymptomatic, 13% had transient ischaemic attacks and 12% suffered from previous strokes. The operation was exclusively performed under local anaesthesia and prior to cross-clamping the ICA stump-pressure was measured. A shunt was inserted only if hemispheric symptoms or unconsciousness occurred independent of the angiographic findings or stump pressure. RESULTS: In 23% (27/120) a shunt became necessary and significantly (p<0.001) more often when there was a cross-flow towards the contralateral hemisphere (12/20=60%) or if the contralateral ICA was occluded (9/13=69%). The sensitivity for not needing a shunt in case of cross-flow towards the side of operation was 91% (52/57) whereas the specificity was 35% (22/63). ICA stump-pressure was significantly reduced in patients requiring a shunt (31 mmHg) compared to those not needing a shunt (53 mmHg) (p<0.001), but no definitive threshold value was found determining the need for shunting. Intraoperatively, no persistent neurological complication developed. CONCLUSIONS: Angiographic cross-flow was a good, but not perfect predictor for the need of an intraoperative shunt.

fMRI of the auditory cortex in patients with unilateral carotid artery steno-occlusive disease.

PURPOSE: To examine whether an internal carotid artery (ICA) steno-occlusive disease leads to a reduced blood oxygenation level dependent (BOLD)-signal change due to a decreased vasodilatory reserve capacity. MATERIALS AND METHODS: Patients suffering from unilateral ICA stenosis or occlusion were examined using functional magnetic resonance imaging (fMRI) of the auditory cortex with a bilateral stimulation applying a pulsed 1000 Hz sine-tone. RESULTS: Compared to control subjects, who showed symmetric bilateral BOLD-responses within the auditory cortex, the ICA patients revealed either a normal bilateral cortical activation pattern or a reduced cortical activation on the steno-occluded side. This latter decrease of BOLD-signal change might indicate a depressed vasomotor reserve capacity. The observed coincidence between this asymmetric reduction in BOLD-signal and ischemic borderzone lesions on the affected side in this subgroup of patients strongly supports this assumption. CONCLUSION: This study shows that fMRI of the auditory cortex appears to have clinical merit in the workup of cerebrovascular conditions.

Spontaneous hyperthermia and its mechanism in the intraluminal suture middle cerebral artery occlusion model of rats.

BACKGROUND AND PURPOSE: The intraluminal suture middle cerebral artery occlusion (MCAO) model is increasingly used in experimental stroke studies. The purposes of this study were to determine whether (1) spontaneous hyperthermia occurs after different periods of MCAO in this model, (2) hypothalamic injury contributes to hyperthermia, and (3) hyperthermia increases infarct volume after permanent MCAO. METHODS: Rats were subjected to 60, 90, and 120 minutes of transient MCAO (n=8 per group), permanent MCAO (n=8 per group, 5 groups), and permanent hypothalamic occlusion, in which an occluder was inserted 15 to 15.5 mm to block only the hypothalamic branch from the internal carotid artery (n=4) with the use of the intraluminal suture MCAO method. In one group undergoing permanent MCAO, the body temperature was maintained at 37 degrees C throughout the experiment. In another group (n=4) undergoing 90 minutes of temporary MCAO, diffusion- and perfusion-weighted imaging were performed to document the in vivo ischemic changes in the hypothalamus. Body temperature was measured hourly for 12 hours. At 24 hours (12 hours in 2 permanent MCAO groups), triphenyltetrazolium chloride staining was used to verify ischemic hypothalamic injury and to calculate corrected infarct volumes. RESULTS: Spontaneous hyperthermia (>39 degrees C) occurred in the 120-minute group, all permanent MCAO groups, and the hypothalamic occlusion group but not in the 60-minute or the 90-minute groups. Hypothalamic infarction was found in 1 rat each in the 60-minute and 90-minute groups, 6 of the 8 rats in the 120-minute group, 37 of the 40 rats in the permanent occlusion groups, and all 4 rats in the hypothalamic occlusion group. After 90 minutes of transient MCAO, the decreased cerebral blood flow and apparent diffusion coefficient values in the hypothalamic region during occlusion recovered fully 2 hours after reperfusion. The corrected infarct volumes were identical in all permanent occlusion groups. CONCLUSIONS: The intraluminal suture MCAO lasting for >/=2 hours induces spontaneous hyperthermia that is associated with hypothalamic injury, and delayed spontaneous hyperthermia does not increase infarct volume after permanent intraluminal suture MCAO.

Effect of adenosine on cerebral blood flow as evaluated by single-photon emission computed tomography in normal subjects and in patients with occlusive carotid disease. A comparison with acetazolamide.

BACKGROUND AND PURPOSE: Acetazolamide is commonly used with single-photon CT to assess the cerebrovascular reserve in patients with internal carotid artery stenosis or occlusion. In this study we wanted to evaluate the effects of adenosine, a well-known vasodilatatory compound with a short biological half-life, on brain circulation in humans and compare the results with those of acetazolamide. METHODS: Acetazolamide (1 g) and adenosine (140 micrograms/kg per minute) were injected intravenously on different days in 6 normal subjects and 6 patients: 4 with unilateral stenosis, 1 with bilateral stenosis, and 1 with complete occlusion of the internal carotid artery. Changes in regional cerebral blood flow relative to that of the cerebellum (cortico/cerebellar ratios) from resting conditions were evaluated by 99mTc-hexamethylpropyleneamine oxime and single-photon emission CT. RESULTS: The measured blood flow ratios increased significantly in the normal group 20 minutes after acetazolamide injection in several cortical and subcortical regions, as well as at the 4th minute of a 6-minute adenosine infusion. Regional cerebral blood flow ratio values were higher after adenosine than after acetazolamide in both cortical (frontal and parietal) and subcortical (thalamus and basal ganglia) regions. In 4 of the 6 patients the side-to-side asymmetry increased from the basal resting condition after the injection of acetazolamide and even more so after the injection of adenosine. CONCLUSIONS: Adenosine infusion causes vasodilation of cerebral arteries and can be used for the investigation of cerebrovascular perfusion capacity in patients with carotid occlusive disease. One advantage in the use of adenosine over acetazolamide is the possibility of interrupting the test with reversal of clinical symptoms or patient discomfort within a few minutes.