Remote cortical dysfunction in aphasic stroke patients

We studied the effect of deep-seated left hemispheric lesions on cortical blood flow in 18 right-handed aphasic stroke patients. Regional cerebral blood flow was measured at rest and during the performance of a functional naming test using the two-dimensional xenon-133 inhalation method. Compared with 10 controls, at rest the patients showed regional cortical hypoperfusion in the left frontoparietal region. In the controls, activation patterns from the rest to the test condition involved mainly the left hemisphere areas. In the patients, a lack of blood flow change was observed in several areas that were usually hypoperfused at rest. However, in patients with slight verbal expression disorders there were obvious blood flow increases in other brain regions in both hemispheres. Such cortical functional reorganization and the presence of a remote cortical dysfunction could play a role in the pathophysiology of language disorders.     

Hemispheric specialization using SPECT and stimulation tasks in children with dysphasia and dystrophia

Developmental dysphasia, a severe childhood learning disorder, is thought to result from problems in hemispheric specialization involving both left and right cerebral hemispheres. Regional cerebral blood flow (rCBF) was measured at rest and during stimulation of both hemispheres independently: dichotic listening for the left, dichaptic palpation for the right. Eight right-handed boys with expressive dysphasia, aged 8 to 12 years, were investigated using SPECT and compared with eight right-handed age-matched boys with Duchenne muscular dystrophy with reading disorders but normal speech. rCBF values at rest were also compared with those of five right-handed age-matched normal boys. In the dichotic task, children with dysphasia differed from children with dystrophia by failure to increase rCBF in the left hemisphere, in Broca's area, but rCBF increased in the right hemisphere, in the region homologous to Broca's area. In the dichaptic task, rCBF increased bilaterally for children with dysphasia whereas in children with dystrophia rCBF increased only in the right hemisphere. At rest the physiological asymmetry was reversed in favor of the right hemisphere in all areas except Broca's area. Surprisingly, the same applied at rest and for all areas in children with dystrophia. These results confirm that functional specialization of both hemispheres is impaired in developmental dysphasia. Moreover, they suggest that learning disabilities associated with Duchenne muscular dystrophy could also be related to abnormal hemispheric specialization.     

Regional cerebral blood flow, white matter abnormalities, and cerebrospinal fluid hydrodynamics in patients with idiopathic adult hydrocephalus syndrome.

OBJECTIVES--(1) to evaluate regional cerebral blood flow (rCBF) with single photon emission computed tomography and 99mTc-hexamethylpropyleneamine oxime in patients with the idiopathic adult hydrocephalus syndrome (IAHS); (2) to examine regional cerebral blood flow (rCBF), gait, and psychometric functions before and after CSF removal (CSF tap test); (3) to assess abnormalities in subcortical white matter by MRI. METHODS--Thirty one patients fulfilling the criteria for IAHS (according to history and clinical and neuroradiological examination) were studied. Quantified gait measurements, psychometric testing, and rCBF before and after removal of CSF were obtained. Pressure of CSF and CSF outflow conductance were investigated with a constant pressure infusion method. Brain MRI was used to quantify the severity of white matter lesions and periventricular hyperintensities. In IAHS a widespread rCBF hypoperfusion pattern was depicted, with a caudal frontal and temporal grey matter and subcortical white matter reduction of rCBF as the dominant feature. Removal of CSF was not accompanied by a concomitant increase in rCBF. Significant white matter lesions were detected only in a minority of patients by MRI. An altered CSF hydrodynamic state with a higher CSF pressure and lower conductance was confirmed. IAHS is characterised by an abnormal CSF hydrodynamic state, associated with a widespread rCBF reduction with preference for subcortical white matter and frontal-temporal cortical regions. Furthermore in most patients MRI did not show white matter changes suggestive of a coexistent subcortical arteriosclerotic encephalopathy. At least in the idiopathic group of patients with AHS, measurements of rCBF before and after temporary relief of the CSF hydrodynamic disturbance will not provide additional information that would be helpful in the preoperative evaluation but is suggestive of a preserved autoregulation of rCBF.     

Platelet abnormalities associated with cerebral perfusion defects in cocaine dependence.

BACKGROUND: This study assessed whether reduced regional cerebral blood flow (rCBF; hypoperfusion) in cocaine-dependent (CD) patients is associated with platelet abnormalities and whether these platelet abnormalities predict improvement in hypoperfusion after 1 month of abstinence. METHODS: We correlated platelet number and aggregation with rCBF hypoperfusion in 54 CD patients at baseline and after a month of abstinence while taking either 325 mg aspirin or placebo. We measured rCBF by (SPECT) with (Tc-HMPAO). Platelet aggregation to adenosine diphosphate was compared at baseline and after treatment. RESULTS: At baseline the number of hypoperfused voxels positively correlated with higher platelet aggregation, and five brain regions (bilateral frontal, right insula, right cingulate, left temporal lobes) showed significantly more hypoperfusion in the high than low platelet aggregation group. After abstinence, hypoperfusion significantly improved regardless of treatment assignment, and greater platelet aggregation at baseline predicted greater improvement in hypoperfusion. After abstinence, only the cingulate continued to show more hypoperfusion in the high- than low-aggregation group. CONCLUSIONS: Because platelet function was related to hypoperfusion primarily in the distribution of the middle cerebral artery, where CD patients most commonly have strokes, more potent antiplatelet agents than aspirin might be effective.     

Interictal hyperperfusion observed in infants with cortical dysgenesis.

We investigated increases of interictal regional cerebral blood flow (rCBF) in patients with intractable epilepsy caused by cortical dysgenesis. Using single photon emission computed tomography, we measured interictal rCBF of epileptic foci in 24 patients with cortical dysgenesis who achieved Engel Class I or II outcomes at least 1 year after surgical intervention. The patients included 14 males and ten females, ranging in age from 2 months to 34 years (mean 6 years and 5 months). In the interictal period, dysplastic areas showed hyperperfusion in four patients (17%), hypoperfusion in 15 (62%), and isoperfusion patterns in five (21%). Interictal hyperperfusion was found in four infants aged 3-4 months; three with focal cortical dysplasia and one with hemimegalencephaly. Our results suggest that interictal hyperperfusion may indicate the presence of an active epileptic focus in infants with cortical dysgenesis, but not in older children or adults with the same disorder. Given the risk of misinterpreting the normal side as hypoperfused, the phenomenon of interictal hyperperfusion in the epileptogenic area should be taken into account when diagnosing pediatric epilepsy caused by cortical dysgenesis.     

Psychopathological and SPECT findings in never-treated schizophrenia

A total of 24 never-treated (i.e. drug-naive) actively psychotic schizophrenic patients, operationalized according to DSM-III-R, were examined in a pre-post-treatment design using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and ^99mTc-HMPAO-single photon emission computed tomography (SPECT) to assess regional cerebral blood flow (rCBF). The control subjects were 20 patients free of neurological and psychiatric symptoms. Before treatment there was only a slight hypofrontality, and hypoperfusion was observed in the left temporal superior region. After treatment, hypofrontality was reduced to one region and temporal hypoperfusion disappeared. Formal thought disorders were accompanied by increased rCBF in the bilateral frontal interior and left temporal superior regions. Delusions were associated with hypoperfusion in the anterior cingulate cortex. Negative symptoms showed no linkage to hypofrontality, either before or after treatment. Factor analysis showed delusions and hallucinations loading on different dimensions. The disorganized dimension correlated positively with all regions of interest, whereas these were negatively correlated with reality distortion.     

Speech Fluency in Aphasia: Regional Cerebral Blood Flow Correlates of Recovery Using Single-Photon Emission Computed Tomography

This study investigated the relationship between diminished regional cerebral blood flow (rCBF) and the recovery of fluent speech in aphasia. Single-photon emission computed tomographic brain scans using [¹²³I]N-isopropyl-p-iodoamphetamine were obtained from 14 nonfluent aphasic patients within 30 days of cerebral infarction. Measurements of speech fluency were acquired initially and at 3 months after infarction. Nearly all of the patients exhibited significant hypoperfusion to combinations of the anterior and posterior regions of the basal ganglion, the periventricular white matter, and the inferior frontal regions. Only the inferior frontal area was significantly associated with recovery of fluent speech. This region was hypoperfused in 4 of 5 patients with poor recovery while 8 of the 9 patients with good speech fluency recovery demonstrated normal rCBF to the inferior frontal region.     

Striatal dysfunction in attention deficit and hyperkinetic disorder

We have previously reported that periventricular structures are hypoperfused in attention deficit and hyperactivity disorder (ADHD). This study has expanded the number of patients, who were divided into two groups: six patients with pure ADHD, and 13 patients with ADHD in combination with other neurologic symptoms. By using xenon 133 inhalation and emission tomography, the regional cerebral blood flow distribution was determined and compared with a control group. Striatal regions were found to be hypoperfused and, by inference, hypofunctional in both groups. This hypoperfusion was statistically significant in the right striatum in ADHD, and in both striatal regions in ADHD with other neuropsychologic and neurologic symptoms. The primary sensory and sensorimotor cortical regions were highly perfused. Methylphenidate increased flow to striatal and posterior periventricular regions, and tended to decrease flow to primary sensory regions. Low striatal activity, partially reversible with methylphenidate, appears to be a cardinal feature in ADHD.     

Cerebral blood flow correlates of higher brain dysfunctions in corticobasal degeneration

To investigate clinicoanatomic correlations of higher brain dysfunctions in corticobasal degeneration, regional cerebral blood flow (rCBF) was semiquantitatively measured with single-photon emission computed tomography in 9 patients with corticobasal degeneration and 12 age-matched control subjects. The patients showed significant reductions of relative tracer uptake in widespread cortical areas, as well as the basal ganglia and thalamus. Interhemispheric difference of hypoperfusion was significant in the sensorimotor and posterior parietal cortices. Asymmetric limb apraxia and cortical sensory disturbance corresponded to either sensorimotor cortical or posterior parietal cortical hypoperfusion or both. Compared with the patients without dementia, those with dementia showed significant reductions of relative rCBF in the inferior prefrontal region in the more affected hemisphere. The unique correlation of cortical signs with regional hypoperfusion may be useful in distinguishing between corticobasal degeneration and other neurodegenerative diseases.     

Cerebral perfusion abnormalities in abstinent cocaine abusers: a perfusion MRI and SPECT study

Nuclear medicine studies found decreased regional cerebral blood flow (rCBF) in the cortex and deep gray matter of cocaine users. Perfusion magnetic resonance imaging (MRI), a non-radioactive technique, has not been applied to evaluate persistent rCBF abnormalities. Twenty-five abstinent cocaine users and 15 healthy subjects without a history of drug use were examined with perfusion MRI, using dynamic bolus-tracking, and single photon emission computed tomography (SPECT), using 133Xe-calibrated 99mTc-HMPAO. After coregistration of SPECT with MRI, the relative rCBF (from perfusion MRI and SPECT) and absolute rCBF (from SPECT) were determined in 10 brain regions in each hemisphere. There was a statistically significant interaction between drug use and brain region on SPECT alone (relative and absolute rCBF), and on SPECT and perfusion MRI combined, but not on perfusion MRI alone. There also was a significant interaction among gender, drug use, and brain region. Compared to the control subjects, cocaine users showed increased rCBF in the frontal white matter (+8.6%, P=0.02) and in the globus pallidus (+6.3%, P=0.05), and decreased rCBF in the putamen (-3.9%, P=0.04) and the temporal cortex (-2.4%, P=0.02). SPECT and perfusion MRI detect a regional pattern of rCBF abnormalities in cocaine users that is consistent across the two methods. The hypoperfusion in the cortex and deep gray matter of the cocaine users is consistent with previous results. The increased rCBF in the white matter of cocaine users may be due to the presence of reactive glia.     

Regional cerebral blood flow and neuropsychological functioning in early and late onset alcoholism

The aim of the study was to compare late and early onset alcoholism with regard to regional cerebral blood flow (rCBF) and neuropsychological functioning. Ten late onset and 13 early onset male alcoholics were included in the study, the criterion being the age of onset for alcohol abuse. Six healthy male volunteers were included as a control group. Regional measures of cortical cerebral blood flow were assessed using Tc-99m-HMPAO single photon emission computed tomography (SPECT) after a detoxification period. When compared with the control group, the early onset group showed reduced relative perfusion in the left superior frontal region, while relative perfusion in the late onset group was deficient in both right and left superior frontal regions. Both groups of alcoholic patients also displayed impairment in frontal lobe functions and non-verbal memory. The results of this study indicate that early onset alcoholism is associated with hypoperfusion in the left superior frontal region while the late onset subtype is characterized by uniformly hypoperfused left and right superior frontal regions. Additionally, both groups of alcoholic patients exhibit an almost identical pattern of neuropsychological abnormalities mainly related to frontal lobe functions and non-verbal memory. Collectively these findings support previous evidence suggesting a key role of frontal lobe pathology in understanding the neurobiology of alcoholism.     

Regional Cerebral Blood Flow in Patients with Alcohol-Related Dementia: A Spect Study

The purpose of this study was to investigate regional cerebral blood flow (rCBF) changes using 1110 MBq of Tc-99m ECD SPECT in alcohol-related dementia (ARD) patients. Twenty-five patients with ARD and 22 healthy control subjects were included in the study. Mini-Mental Status Examination was applied to the patients and controls. The ARD patients showed drastically reduced rCBF in the frontal cortices, basal ganglia, and thalami. The results indicate that ARD is associated with hypoperfusion in both cortical and subcortical regions. These findings support previous studies suggesting the association with both cortical and subcortical neuropathology in ARD patients.     

SPECT findings in Parkinson''s disease associated with dementia.

Dementia in Parkinson's disease is thought to be attributable not only to subcortical lesions but also to cortical alterations, especially frontal lobe dysfunction. To evaluate cortical function, the regional cerebral blood flow (rCBF) was estimated of 13 demented and 13 non-demented age matched patients with Parkinson's disease compared with that of 10 age matched controls using I-123 iodoamphetamine single photon emission tomography (IMP-SPECT). The rCBF of the nondemented Parkinson's patients showed no significant differences from that of the control subjects. In the demented patients, the bilateral frontal and parietal and left temporal regional blood flow was significantly less than in the controls. Four demented patients showed isolated frontal hypoperfusion, 8 showed fronto-parietal hypoperfusion, and 1 showed isolated parietal hypoperfusion. Frontal hypoperfusion was therefore present in 12 of the 13 demented patients, and this finding agrees with the frontal lobe dysfunction hypothesis. Parietal rCBF had a significant positive correlation with cortical functions such as calculation and language ability in the MMSE scores. The parietal and temporal reduction in rCBF probably reflects the presence of Alzheimer pathology, cortical Lewy body disease, or both.     

焦虑症患者单光子发射计算机断层研究

目的探讨焦虑障碍与局部脑功能改变的关系。方法对５３例焦虑症患者（分治疗组与未治疗组）和１５名正常对照者应用单光子发射计算机断层摄影（ＳＰＥＣＴ）测定局部脑血流（ｒＣＢＦ）灌注。结果焦虑症患者ｒＣＢＦ灌注异常率为９２５％（４９／５３），与对照组比较，治疗组、未治疗组病人的双侧额叶及颞叶ｒＣＢＦ灌注均有极显著下降，治疗组的左侧基底节下降也有显著差异。结论焦虑症患者额叶、颞叶功能显著降低并且与病程和药物治疗无关。提示额、颞叶功能降低是焦虑症患者的临床神经病理生理学的基本特征     

Study of Regional Cerebral Blood Flow in West Syndrome

Summary: Focal cortical disturbances are frequent sequelae in West syndrome (WS) even though it is a generalized epileptic syndrome. Functional neuroimaging was used to determine whether focal perfusion abnormalities exist at WS onset and change during evolution. We studied regional cerebral blood flow (rCBF) at different stages of WS. Mean CBF (mCBF) and rCBF were measured using SPECT (single photon emission computed tomography) and ¹³³Xe in 13 WS patients: at onset (20 cases), just after steroids (17 cases), and after a mean follow-up of 2 years (26 cases). At WS onset, interictal mCBF was increased as the result of foci of hyper- and hypoperfusion, which were, respectively, mainly located in the frontal and posterior cortex. Just after steroid therapy, mCBF decreased without any focal predominance. During follow-up, hypoperfused foci remained unchanged whereas the frontal hyperperfused foci decreased after spasm control. Our results show that focal abnormalities are present at WS onset. Focal hypoactivity could reflect a cortical lesion responsible for WS and focal hyperactivity could play a role in the persistence of generalized epilepsy.     

遗忘型轻度认知损害和非痴呆血管性认知损害的局部脑血流量

目的 探讨遗忘型轻度认知损害(aMCI)和非痴呆血管性认知损害(VCI-ND)的局部脑血流量(rCBF)改变的特征.方法 健康中老年人16名,aMCI组患者10例,VCI-ND组患者12例,年龄在50～80岁,教育程度均在初中毕业及以上,全部完成头颅CT或MRI检查.应用Xe-CT技术定量测定38例研究对象脑不同部位的rCBF.结果 (1)静息状态健康中老年人(NC)组脑不同部位的rCBF分布情况:由高到低分别为基底节核团(76.4±8.6)ml·100 g-1·min-1、皮质(48.0±7.1)ml·100 g-1·min-1和白质(20.5±1.7)ml·100 g-1·min-1.(2)NC组、aMCI组和VCI-ND组患者的rCBF表现比较:aMCI组颞、顶、枕叶的rCBF值呈一定趋势的减少,VCI-ND组额叶的rCBF值呈一定趋势的减少,而VCI-ND组rCBF下降最明显的部位集中在白质区域[(17.7±2.3)ml·100 g-1·min-1,F=5.740,P=0.002],从深度看覆盖了脑室旁白质和皮质下深部白质两部分,从长度看覆盖了白质的前后区域.3组基底节区核团包括尾状核、豆状核和丘脑的rCBF值比较差异无统计学意义.结论 aMCI和VCI-ND的rCBF值的差异反映了两者在病理机制方面的差异.     

新发病的特发性全面强直阵挛发作患者局部脑血流观察

目的 :探讨特发性全面强直阵挛发作 (generalizedtonicclonicseizure ,GTCS)癫患者发作间期局部脑血流 (rCBF)特征。方法 :用单光子发射计算机断层显像 ( 99Tcm ECD SPECT)技术对 2 0例新发病的特发性GTCS患者发作间期rCBF特征进行观察 ,以兴趣区(ROI)法作半定量分析。结果 :2 0例新发病的特发性GTCS患者发作间期rCBF异常率为 3 0 % ( 6例 ) ,主要表现为一侧丘脑区或基底节区的放射性稀疏。结论 :新发病的特发性GTCS患者的rCBF存在两种特征 :①正常的CBF ;②一侧丘脑区CBF降低 ,CBF降低的丘脑区可能为亚临床病灶     

Regional cerebral blood flow of patients with focal epilepsy studied using xenon enhanced CT brain scanning.

Stable xenon-enhanced X-ray computed tomography (XeCT) was used to measure the regional cerebral blood flow (rCBF) of 12 patients with drug resistant partial epilepsy and a marked unilateral focus on electroencephalography (EEG). Interictal mean rCBF of fixed regions of interest (ROIs) was reduced by 25% in the cortex of the epileptogenic cerebral lobe compared with the same regions on the contralateral side (p less than 0.02). Six control scans showed a mean side to side cortical difference in rCBF of 14%, whereas the epileptogenic focus was associated with a reduction in the cortical rCBF of greater than 30% in six out of the 12 patients. In an additional patient with partial epilepsy XeCT demonstrated significant focal hypoperfusion when interictal EEGs and conventional CT scans showed no abnormalities.     

Autism severity and temporal lobe functional abnormalities

Two independent studies have described bilateral temporal hypoperfusion in autistic children. Temporal regions are implicated in social perception, language, and "theory-of-mind," abilities that are impaired in autism. We investigated a putative relationship between cerebral blood flow (rCBF) measured at rest and clinical profile of 45 autistic children (Autism Diagnostic Interview-Revised [ADI-R] scores). A whole-brain covariance analysis was performed. Significant negative correlation was observed between rCBF and ADI-R score in the left superior temporal gyrus. The more severe the autistic syndrome, the more rCBF is low in this region, suggesting that left superior temporal hypoperfusion is related to autistic behavior severity.     

Cumulative white matter changes in the gerbil brain under chronic cerebral hypoperfusion

Summary An animal model of chronic brain hypoperfusion has been developed by applying coiled clips to the bilateral carotid artery of Mongorian gerbils. The brain tissue damage was neuropathologically studied after 1, 4, 8, and 12 weeks of hypoperfusion. The hippocampus, basal ganglia, and cerebral cortex of the chronically hypoperfused gerbil showed lesions with various severity which are probably due to ischemic episodes. In the cerebral white matter, however, two types of lesions were observed; one similar to those in the gray matter, and the other observed only in the white matter after more than an 8-week duration of brain hypoperfusion. The lesion specific to the white matter showed rarefaction and gliosis without locally associated ischemic changes. This type of the white matter lesion was never found in the gerbil brain before 8 weeks and, significantly, increased in number and size by 12 weeks post operation. The accumulation of the white matter lesions is characteristic in the gerbil with chronic hypoperfusion. The observed white matter-specific lesion resembles the histological changes in aged brain with cerebrovascular diseases.