Shan Gao

In vivo high-resolution MR imaging of symptomatic and asymptomatic middle cerebral artery atherosclerotic stenosis

OBJECTIVEnRecently, the technique of high-resolution magnetic resonance imaging (HR-MRI) has been developed to depict intracranial artery wall. We aimed to compare the vessel wall properties between symptomatic and asymptomatic atherosclerotic middle cerebral arteries (MCA) using HR-MRI.nnnMETHODSnWe studied 26 patients with symptomatic and 35 patients with asymptomatic MCA stenosis. Routine cranial MRI, magnetic resonance angiography and HR-MRI were performed on each patient. The cross-sectional images of MCA wall on HR-MRI were compared between the two groups.nnnRESULTSnThe degree of MCA stenosis was similar between the two groups (67.9% vs 63.9%, P=0.327). On HR-MRI, eccentric plaques were observed in 26 (100%) symptomatic and 28 (80%) asymptomatic stenosis. In the remaining seven (20%) asymptomatic stenosis, only constrictive remodeling (vessel shrinkage) was observed. Compared with the asymptomatic group, symptomatic MCA stenosis had a larger wall area (P<0.001), greater remodeling ratio (P<0.001), higher prevalence of expansive remodeling (outward expansion of the vessel wall) (P=0.003) and lower prevalence of constrictive remodeling (P=0.008).nnnCONCLUSIONSnDifferent vessel wall properties on HR-MRI were observed between symptomatic and asymptomatic MCA stenosis. Further prospective studies are required to investigate whether HR-MRI is a helpful tool in stratifying stroke risk in patients with MCA atherosclerotic disease.

Atherosclerosis of middle cerebral artery: Evaluation with high-resolution MR imaging at 3 T

OBJECTIVEnThree-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) has been wildly used in the diagnosis of intracranial artery diseases, but it only shows the arterial lumen and does not delineate the vessel wall. The aim of this study was to assess whether high resolution cross sectional magnetic resonance imaging (HRMRI) could compensate the limitation of 3D TOF MRA in the atherosclerotic disease of middle cerebral artery (MCA).nnnMETHODSnFourty-eight suspected patients with atherosclerotic stenosis of MCA underwent 3D TOF MRA and HRMRI with a 3T scanner. The HRMRI was performed in 49 MCAs perpendicular to the M1 segment with T2-weighted imaging. Findings of HRMRI were compared with that of 3D MRA.nnnRESULTSnHRMRI displayed the artery wall clearly, and showed 37 abnormalities, including 20 plaques and 17 wall thickening. The inter-observer reproducibility was moderate for wall abnormalities with k=0.75 (95% CI 0.59-0.91), and excellent for plaques with k=0.91 (95% CI 0.80-1.03). 3D TOF MRA showed 34 stenoses at the M1 segment. Five normal MCAs on 3D TOF MRA had abnormal wall (3 plaques and 2 wall-thickening) on HRMRI. Two stenoses on 3D TOF MRA showed normal wall structure on HRMRI, indicating a possible negative remodeling phenomenon.nnnCONCLUSIONSnHigh-resolution MR imaging can clearly depict the wall structure of middle cerebral arteries. As a complementary method, HRMRI may compensate the limitation of 3D TOF MRA and help to detect atherosclerotic lesions not visualized by MRA.

Plaque Distribution of Stenotic Middle Cerebral Artery and Its Clinical Relevance

Background and Purpose— Microanatomy studies reveal that most penetrating branches of middle cerebral artery (MCA) arise from the dorsal–superior surface of the trunk. Using high-resolution MRI, we sought to explore the plaque distribution of MCA atherosclerosis and its clinical relevance in relation to the orifices of penetrating arteries. Methods— We retrospectively analyzed the imaging and clinical data of 86 patients with atherosclerotic MCA stenosis. On high-resolution MRI, plaques were categorized based on the involvement of the superior, inferior, ventral, or dorsal MCA wall. The relationship of plaque distribution and clinical presentation was analyzed. Results— A total of 92 stenotic MCAs (40 symptomatic and 52 asymptomatic) on 828 image slices were studied. Overall, of the 251 slices with identified plaques, plaques were more frequently located at the ventral (44.8%) and inferior (31.7%) wall as compared with the superior (14.3%) and dorsal wall (9.0%; P<0.001). Symptomatic MCA stenosis had more superior (P=0.016) and less inferior (P=0.023) wall plaques than asymptomatic stenosis. Within the group of symptomatic MCA stenosis, vessels with penetrating artery infarctions had more superior (P=0.001) but less ventral (P=0.038) and inferior (P=0.024) plaques than without penetrating artery infarctions. Conclusions— MCA plaques tend to locate opposite to the orifices of penetrating arterial branches. Further studies are required to investigate whether MCA plaque distribution is an independent determinant of stroke occurrence and its subtypes.

Implementation of a Structured Guideline–Based Program for the Secondary Prevention of Ischemic Stroke in China

Background and Purpose— High rates of ischemic stroke and poor adherence to secondary prevention measures are observed in the Chinese population. Methods— We used a national, multicenter, cluster-randomized controlled trial in which 47 hospitals were randomized to either a structured care program group (n=23) or a usual care group (n=24). The structured care program consisted of a specialist-administered, guideline-recommended pharmaceutical treatment and a lifestyle modification algorithm associated with written and Internet-accessed educational material for patients for the secondary prevention of ischemic stroke. The primary efficacy outcome was the proportion of patients who adhered to the recommended measures at 12-month postdischarge. This trial is registered with ClinicalTrial.gov (NCT00664846). Results— At 12 months, 1287 (72.1%) patients in the Standard Medical Management in Secondary Prevention of Ischemic Stroke in China (SMART) group and 1430 (72%) patients in the usual care group had completed the 12-month follow-up (P=0.342). Compared with the usual care group, those in the SMART group showed higher adherence to statins (56% versus 33%; P=0.006) but no difference in adherence to antiplatelet (81% versus 75%; P=0.088), antihypertensive (67% versus 69%; P=0.661), or diabetes mellitus drugs (73% versus 67%; P=0.297). No significant difference in the composite end point (new-onset ischemic stroke, hemorrhagic stroke, acute coronary syndrome, and all-cause death) was observed (3.56% versus 3.59%; P=0.921). Conclusions— The implementation of a program to improve adherence to secondary ischemic stroke prevention efforts in China is feasible, but these programs had only a limited impact on adherence and no impact on 1-year outcomes. Further development of a structured program to reduce vascular events after stroke is needed. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00664846.

Stroke risk and prognostic factors of asymptomatic middle cerebral artery atherosclerotic stenosis.

BACKGROUND AND PURPOSEnStroke risk of asymptomatic atherosclerotic middle cerebral artery (MCA) stenosis has not been well studied. This study was designed to investigate stroke risk and prognostic factors of asymptomatic atherosclerotic MCA stenosis.nnnMATERIALS AND METHODSnA total of 200 consecutive patients who visited the transcranial Doppler ultrasound (TCD) laboratory of our hospital and who met the following criteria were prospectively enrolled in this study: diagnosed as MCA stenosis due to atherosclerosis by TCD, age above 40 years old, no history of ischemic stroke or transient ischemic attack (TIA), no ipsilateral carotid artery stenosis. The mean follow-up time was 38.3 ± 9.9 (range 4 to 60) months.nnnRESULTSnThirteen patients were lost to follow up. Seven patients (3.8%) developed ischemic stroke or TIA during the follow-up period, with an occurrence rate of 0.5% in the first year and 1.6% in the second year. Three were in the blood supply region of diseased vessels, three were in the contralateral hemisphere and one case of TIA occurred in the posterior circulation. Univariate analysis showed that diabetes mellitus (DM) (X²=9.168, p=0.002) and carotid atherosclerotic plaque (X²=4.403, p=0.036) were associated with higher risk of stroke occurrence in this cohort.nnnCONCLUSIONSnThe stroke risk in patients with asymptomatic atherosclerotic MCA stenosis was low and remained stable during follow up. Higher risk of stroke occurrence is associated with DM and carotid atherosclerotic plaque.

Neurological Manifestations of Takayasu Arteritis

Objective To investigate the clinical neurological manifestations of Takayasu arteritis (TA). Methods A retrospective study was conducted with 63 consecutive TA cases admitted to Peking Union Medical College Hospital from January 2009 to May 2010. All the patients fulfilled the diagnostic criteria of TA by the American College of Rheumatology. Among the 63 TA patients, 27 with neurological manifestations were included in the present study. All the patients were evaluated using standardized neurological examination, sonography, computed tomography (CT) angiography, and cerebral CT or magnetic resonance imaging. Results Dizziness and visual disturbance were the most common symptoms, which occurred in 20 (74.1%) and 16 (59.3%) patients respectively. Another common symptom was headache, observed in 15 (55.6%) patients. Six (22.2%) patients had suffered from ischemic stroke; 7 (25.9%) patients had epileptic seizures. Two (7.4%) patients were diagnosed as reversible posterior encephalopathy syndrome (RPES) based on typical clinical and imaging manifestations. Conclusions Neurological manifestations are common symptoms in TA patients in the chronic phase, including dizziness, visual disturbance, headache, ischemic stroke, seizures, and some unusual ones such as RPES. We suggested RPES be included into the differential diagnosis of acute neurological changes in TA.

Disparate cardio-cerebral vascular modulation during standing in multiple system atrophy and Parkinson disease

PURPOSEnThe dynamic variance of cerebral blood flow velocity (CBFV), monitored by transcranial doppler (TCD), can reveal the integrated effects of cardio-cerebral vascular autoregulation. We investigated the characteristics of CBFV curve during active standing in multiple system atrophy (MSA), Parkinsons disease (PD) and healthy volunteers.nnnMETHODSnThe CBFV curve of middle cerebral arteries was recorded using TCD in 22 patients with probable MSA; 20 PD patients and 20 volunteers matched for age. All individuals started in a supine posture, followed by abrupt standing for 2 min before returning to supine. The features of CBFV curve were compared among the groups.nnnRESULTSnIn the healthy volunteers, the CBFV decreased following standing up but quickly rebounded and reached the same or greater level as the supine baseline. Afterwards, the CBFV decreased abruptly to a sustained level, lower than the supine baseline, forming a spike wave that appeared in CBFV curve. This spike wave was present in 5/22 of MSA, significantly less than PD patients (18/20) and volunteers (20/20) (P<0.001). The CBFV decrease after standing showed no significant difference between MSA than PD (9+/-7 vs. 6+/-3 cm/s, P=0.163).nnnCONCLUSIONSnThe different pattern of CBFV curves during active standing suggests MSA may possess cardio-cerebral vascular modulation different from PD. The clinical value of the CBFV curve in differentiating MSA from PD needs further investigation.

Clinical Reasoning: A 42-year-old man with severe headache, fever, and acute coma

A 42-year-old man underwent brain MRI at a local health facility for severe headache and was found to have a pituitary adenoma. Two days later, he presented to the emergency department of our hospital with high fever and sudden-onset coma. The patient had a history of intermittent moderate headache in the recent 8 months. No medical history of vascular risk factors was identified.

Supine-to-standing transcranial Doppler test in patients with multiple system atrophy

BACKGROUNDnSupine-to-standing test, a transcranial Doppler (TCD) based technique, has been recently developed to evaluate cardiovascular dysautonomia. We explored the value of supine-to-standing TCD test in predicting the course of multiple system atrophy (MSA) with orthostatic hypotension (OH).nnnMETHODSnBy monitoring the signals of middle cerebral artery during supine-to-standing posture changes, the trend curves of cerebral blood flow velocities, pulsatility index and resistance index were obtained from 38 MSA patients with OH and 31 healthy subjects. The correlation between TCD findings and the clinical outcome of the patients, which was determined by follow-up structured phone interview, was analyzed. Adverse outcome was defined if a patient died, was in bed-ridden state or had recurrent syncope (>1 per month).nnnRESULTSnTwo characteristic TCD findings were revealed in the MSA patients but not in the controls, i.e. a blunted cerebral blood flow velocity rebound after standing and/or sustained higher pulsatility index upon standing than supine baseline. Structured phone interview was completed in 31 of the 38 patients (mean follow-up time, 20xa0±xa011 months). While no subject had recurrent syncope before enrollment, 12 patients developed an adverse outcome during follow-up. The coexistence of two characteristic TCD findings predicted adverse outcomes with positive predictive value 66.7% and negative predictive value 87.5%.nnnCONCLUSIONSnSupine-to-standing TCD test is valuable in predicting the course of MSA with OH at early stage. We hypothesize baroreflex failure effects and paradoxical cerebral vasoconstriction in response to OH may account for the TCD findings in MSA patients.