Pattern of CBF in the Rehabilitation of Visuospatial Neglect

The CBF was assessed in seven patients before and after rehabilitation for visuospatial neglect. Two months of treatment produced an increased perfusion both in the right posterior and left anterior areas of the brain. However, only the left anterior CBF increase was correlated with the neglect disorders. The left anterior improvement in CBF was inversely correlated with right-left cerebellum asymmetry in pre-and post-treatment. The present data suggest the role of the frontal eye-fields in the mechanism of recovery of visual exploration in patients with severe neglect.     

Infarct of the anterior limb of the right internal capsule causing left motor neglect: case report and cerebral blood flow study

A sixty-nine year old hypertensive man had left motor neglect following an infarct of the anterior limb of the right internal capsule. He also had left auditory extinction on verbal dichotic listening and a sligh constructional apraxia. Regional cerebral blood flow (CBF) was measured at rest with Xenon 133 inhalation and was found to be slightly decreased in a diffuse fashion. Motor activation of the right hand resulted in an increase of CBF in the contralateral superior rolandic area, whereas no such increase was found during motor activation of the left hand. This lack of cortical CBF increase on contralateral motor activation is interpreted as a consequence of the failure of some corticosubcortical connexions involved in motor arousal. The specifically dynamic appearance of regional CBF abnormalities, i.e. during selective activation as opposed to rest measurements, is consistent with the functional character of neglect.     

Resting state cerebral blood flow and objective motor activity reveal basal ganglia dysfunction in schizophrenia

Reduced motor activity has been reported in schizophrenia and was associated with subtype, psychopathology and medication. Still, little is known about the neurobiology of motor retardation. To identify neural correlates of motor activity, resting state cerebral blood flow (CBF) was correlated with objective motor activity of the same day. Participants comprised 11 schizophrenia patients and 14 controls who underwent magnetic resonance imaging with arterial spin labeling and wrist actigraphy. Patients had reduced activity levels and reduced perfusion of the left parahippocampal gyrus, left middle temporal gyrus, right thalamus, and right prefrontal cortex. In controls, but not in schizophrenia, CBF was correlated with activity in the right thalamic ventral anterior (VA) nucleus, a key module within basal ganglia-cortical motor circuits. In contrast, only in schizophrenia patients positive correlations of CBF and motor activity were found in bilateral prefrontal areas and in the right rostral cingulate motor area (rCMA). Grey matter volume correlated with motor activity only in the left posterior cingulate cortex of the patients. The findings suggest that basal ganglia motor control is impaired in schizophrenia. In addition, CBF of cortical areas critical for motor control was associated with volitional motor behavior, which may be a compensatory mechanism for basal ganglia dysfunction.     

Unilateral spatial neglect due to a haemorrhagic contusion in the right frontal lobe

We report two cases of unilateral spatial neglect associated with an isolated right frontal lobe lesion. Case 1 was a 59-year-old, right-handed man, who developed a left hemiplegia, disorientation, and frontal lobe neglect associated with a haemorrhagic contusion following a head injury. Case 2 was a 55-year-old, right-handed man, who also developed disorientation and frontal lobe neglect secondary to a haemorrhagic contusion following a head injury.^99mTc HM-PAO SPECT revealed an isolated reduction in the regional cerebral blood flow (CBF) around the haematoma in the frontal lobe; blood flow to remaining parts of the brain was normal. Damage to the right frontal lobes of these patients was confirmed as being the cause of the unilateral spatial neglect in accordance with the results of CBF studies.     

Reduction of Cerebral Blood Flow in Chronic Schizophrenia: Relation to Age

Abstract: The effect of age on resting-state cerebral blood flow (CBF) was studied in 40 medicated patients with chronic schizophrenia aged 20 to 57 and 32 age- and sex-matched normal Controls, using the regional CBF with the xenon-133 inhalation technique. Global CBF (average of 16 cerebral regions) and the left prefrontal flow ratio (left prefrontal/global CBF) were significantly lower in schizophrenics aged 20–29 than in age-matched controls. Both global CBF and the left prefrontal flow ratio correlated with age in controls, but neither of such correlations was found in schizophrenics. Therefore, the CBF deficits in chronic schizophrenia appear to be unaffected by the aging process.     

Right motor neglect associated with dynamic aphasia, loss of drive and amnesia: case report and cerebral blood flow study.

A 30-year-old right-handed man had right motor neglect, amnesia, aphasia and loss of drive following bilateral thalamic and subthalamic infarctions. Serial resting cerebral blood flow (CBF) measurements with either Xenon 133 inhalation or positron emission tomography at 1, 8 and 10 months post-onset showed a widespread and long-lasting low CBF in the cortex. An additional CBF measurement, during motor tasks, showed a marked interhemispheric asymmetry in the pattern of activation: whereas left hand movement resulted in a CBF increase in contralateral superior rolandic and prerolandic areas, no significant regional CBF changes were seen during right hand movement, despite recovery from motor neglect. This loss of CBF increase in cortical motor and premotor areas during voluntary movement of the previously neglected side points to a disruption of cortico-subcortical pathways subserving motor activation. The pathophysiology of aphasia, loss of drive and amnesia as well as their relationships to motor neglect, may also be discussed on the basis of thalamo-cortical disconnections.     

A case of aphasia with speech disorders by infarction of the left caudate nucleus and putamen

An infarction involving the left putamen, caudate nucleus and the anterior limb of the internal capsule, resulted in aphasia with semantic paraphasias, verbal incoherence and verbal memory impairment. Cerebral blood flow (CBF) studies with 133Xe inhalation at 20 days post onset showed, on one hand, a bilateral lowering of cortical blood flow and on the other hand a left frontal-parietal hypoperfusion area. Spontaneous recovery occurred within 2 months. While the mean CBF became normal at 14 months post onset, a relative hypoperfusion area persisted on the anterior left hemispheric cortex. On the basis of these findings and current CBF and metabolic studies carried out in patients with subcortical lesions, the authors discuss the role of cortical and subcortical structures in subcortical aphasic syndromes. The importance of reciprocal connections between cortex, striatum and thalamus is stressed.     

Abnormal resting state corticolimbic blood flow in depressed unmedicated patients with major depression: a (15)O-H(2)O PET study

We investigated the differences in the resting state corticolimbic blood flow between 20 unmedicated depressed patients and 21 healthy comparisons. Resting state cerebral blood flow (CBF) was measured with H(2)(15)O PET. Anatomical MRI scans were performed on an Elscint 1.9 T Prestige system for PET-MRI coregistration. Significant changes in cerebral blood flow indicating neural activity were detected using an ROI-free image subtraction strategy. In addition, the resting blood flow in patients was correlated with the severity of depression as measured by HAM-D scores. Depressed patients showed decreases in blood flow in right anterior cingulate (Brodmann areas 24 and 32) and increased blood flow in left and right posterior cingulate (Brodmann areas 23, 29, 30), left parahippocampal gyrus (Brodmann area 36), and right caudate compared with healthy volunteers. The severity of depression was inversely correlated with the left middle and inferior frontal gyri (Brodmann areas 9 and 47) and right medial frontal gyrus (Brodmann area 10) and right anterior cingulate (Brodmann areas 24, 32) blood flow, and directly correlated with the right thalamus blood flow. These findings support previous reports of abnormalities in the resting state blood flow in the limbic-frontal structures in depressed patients compared to healthy volunteers.     

Evaluation of the effects of total sleep deprivation on cerebral blood flow using single photon emission computerized tomography.

HMPAO-single photon emission computerized tomography (SPECT) is a useful technique in studying cerebral blood flow (CBF). This method is suitable to evaluate the differences of CBF with reference to total sleep deprivation (TSD) within 24 h because of the short half-life of the radiopharmaceutical compound. In the present study, CBF before and after TSD was analysed in patients suffering from major depression. The morning before and after TSD, Tc-HMPAO-SPECT was performed in 20 patients. Hamilton Rating Scale for Depression scores and subjective ratings were obtained daily. Eleven patients responded to TSD; 9 were nonresponders. The main finding was a significant left temporal and mainly right parietal increase of CBF, which was observed in the responders only. CBF values and the severity of depression correlated inversely.     

Laterally directed arm movements and right unilateral neglect after left hemisphere damage.

Signs of unilateral neglect for events occurring in one hemispace most often result from right hemisphere lesions. Right unilateral neglect after left hemisphere damage is much rarer, and has received less attention. The present study explores the relationships between right unilateral neglect and asymmetries in producing laterally directed arm movements in the horizontal plane in left brain-damaged (LBD) patients. Participants produced right- or left-directed arm movements with their left arm in response to centrally located visual stimuli. Results showed that LBD patients with signs of right unilateral neglect were consistently slowed when producing arm movements toward the right (neglected) side, as compared to left-directed movements. Taking into account patients with and without signs of neglect, this directional asymmetry positively correlated with a reaction-time measure of perceptual spatial bias. These findings stand in contrast with previous results obtained with the same experimental paradigm in right brain-damaged patients, in whom a consistent slowing of leftward-directed movements was rare and apparently unrelated to the presence and severity of left neglect. These conflicting results are discussed with respect to the hypothesis that different mechanisms may underlie left and right unilateral neglect.     

Altered neurovascular coupling in thyroid-associated ophthalmopathy: A combined resting-state fMRI and arterial spin labeling study

Besides the well-documented ophthalmic manifestations, thyroid-associated ophthalmopathy (TAO) is believed to be related to emotional and psychological abnormalities. Given the previous neuroimaging evidence, we hypothesized that TAO patients would have altered neurovascular coupling associated with clinical-psychiatric disturbances. This study was to investigate neurovascular coupling changes in TAO by combining resting-state functional magnetic resonance imaging (rs-fMRI) and arterial spin labeling (ASL) techniques. Amplitude of low-frequency fluctuation (ALFF) was calculated from rs-fMRI, and cerebral blood flow (CBF) was computed from ASL in 37 TAO patients and 21 healthy controls (HCs). Global neurovascular coupling was assessed by across-voxel CBF-ALFF correlation, and regional neurovascular coupling was evaluated by CBF/ALFF ratio. Auxiliary analyses were performed using fractional ALFF (fALFF) and regional homogeneity (ReHo) as rs-fMRI measures. Compared with HCs, TAO patients showed significantly reduced global CBF-ALFF coupling. Moreover, TAO patients exhibited decreased CBF/ALFF ratio in the left lingual gyrus (LG)/fusiform gyrus (FFG), and increased CBF/ALFF ratio in the bilateral precuneus (PCu). In TAOs, CBF/ALFF ratio in the left LG/FFG was positively correlated with visual acuity, while CBF/ALFF ratio in the bilateral PCu was negatively correlated with Montreal Cognitive Assessment score. The auxiliary analyses showed trends of reduced global neurovascular coupling (i.e., CBF-fALFF correlation and CBF-ReHo correlation), as well as significant altered regional neurovascular coupling (i.e., CBF/fALFF ratio and CBF/ReHo ratio) in several brain regions. These findings indicated that TAO patients had altered neurovascular coupling in the visual and higher-order cognitive cortices. The neurovascular decoupling might be a possible neuropathological mechanism of TAO.     

Abnormal resting regional cerebral blood flow patterns and their correlates in schizophrenia

Regional cerebral blood flow (CBF) was measured under resting conditions in 108 right-handed schizophrenic inpatients and a matched group of normal controls with the xenon 133 inhalation technique. Forty-six patients were free of all medication for two weeks. There were no significant differences in CBF to the two hemispheres. The patients showed a comparatively reduced anteroposterior (AP) gradient for CBF. Though there were no differences in frontal flow, the patients had higher flow to several postcentral brain regions, bilaterally. Cerebral blood flow in the patients correlated inversely with age and positively with carbon dioxide level. Women had higher flow than men. Duration of the illness was the only significant predictor of the reduced AP gradient in patients. Higher left temporal and right parietal flow were found to be the best discriminators between patients and controls. Mean hemispheric flow to both hemispheres and several brain regions correlated with the total score and the item, unusual thought content, of the Brief Psychiatric Rating Scale. There were no differences in regional CBF between medicated and unmedicated patients.     

Good recovery in visual scanning in a patient with persistent anosognosia.

A patient with hemineglect disturbance (N.G.) due to a right hemispheric lesion was admitted to rehabilitative training which featured the use of procedures devised in a previous study (Pizzamiglio et al., 1990) both in a standard way and with the addition of optokinetic stimulation. This latter paradigm produces an automatic reaction which favors the spatial orienting of the patient toward his (left) neglected side. N.G. showed good recovery in visual scanning and, by the end of training, reached a level of recovery similar to other neglect patients. However, his recovery was particularly slow and no change was observed in his attitude toward the visual disturbance. The conclusion is reached that recovery in visual scanning also can be obtained in patients with persistent anosognosic disturbances. Stimulations such as the optokinetic condition which influence patients' behavior at an automatic level may play an important role in this recovery. CBF studies obtained before and after training showed a CBF improvement mainly in the right temporoparietal regions, behind the lesion, and in the left frontal cortex. The implications of these findings on various theoretical interpretations of the hemineglect disturbance are briefly discussed.     

Cerebral blood flow in the ventromedial prefrontal cortex correlates with treatment response to low-frequency right prefrontal repetitive transcranial magnetic stimulation in the treatment of depression

Aims: Low‐frequency right prefrontal repetitive transcranial magnetic stimulation (rTMS) is effective in treating depression, and its antidepressant effects have proven to correlate with decreases in cerebral blood flow (CBF) in the orbitofrontal cortex and subgenual cingulate cortex. However, a predictor of treatment response to low‐frequency right prefrontal rTMS in depression has not been identified yet. The aim of this study was to estimate regional CBF in the frontal regions and investigate the correlation with treatment response to low‐frequency right prefrontal rTMS in depression. Methods: We examined 26 depressed patients for the correlation between treatment response to rTMS and regional CBF in the frontal regions, by analyzing their brain scans with ^99mTc‐ethyl cysteinate dimer before rTMS treatment. CBF in 16 brain regions was estimated using fully automated region of interest analysis software. Two principal components were extracted from CBF in 16 brain regions by factor analysis with maximum likelihood method and Promax rotation with Kaiser normalization. Results: Sixteen brain regions were divided into two groups: dorsolateral prefrontal cortex (superior frontal, medial frontal, middle frontal, and inferior frontal regions) and ventromedial prefrontal cortex (anterior cingulate, subcallosal, orbital, and rectal regions). Treatment response to rTMS was not correlated with CBF in the dorsolateral prefrontal cortex, but it was correlated with CBF in the ventromedial prefrontal cortex. Conclusion: These findings suggest that CBF in the ventromedial prefrontal cortex may be a potential predictor of low‐frequency right prefrontal rTMS, and depressed patients with increased CBF in the ventromedial prefrontal cortex may show a better response.     

Diminished regional cerebral blood flow during the intercritical period in temporal lobe epilepsy

Hemisphere and regional cerebral blood flow (CBF) were determined during interictal periods by intravenous Xenon 133 in 43 patients considered to have "temporal" epilepsy and presenting complex partial attacks with altered consciousness and lateralized EEG anomalies predominant in the temporal region. Brain scans were normal in all cases. Three subgroups were differentiated according to EEG and polygraphic examinations during sleep; temporal epilepsy with left or right EEG anomalies, with asynchronous bilateral EEG anomalies, with alternating labile unilateral EEG anomalies. Measurements of CBF were compared with those of normal subjects (n = 13) of comparable age and with those of epileptic patients with cerebral lesions on CT scan (n = 4). In epileptics with left EEG anomalies CBF was diminished by about 25 p. 100 in the left temporal region and from 15 to 22 p. 100 in other regions of the ipsi- and contralateral hemisphere. In epileptics with right EEG anomalies CBF was diminished by 20 p. 100 in the right temporal region but not on the left. CBF in the third group was comparable to that of normal subjects. In epileptics with abnormal CT scans the reduction in CBF could be correlated with EEG and CT scan findings. Studies were also conducted to determine variations in reactivity to CO2 in the areas with reduced flow, during ictal and interictal periods. Results emphasize the value of CBF measurements for investigation of epileptic foci. The importance of areas of reduced blood flow as a parameter of severity and course is discussed, as well as their pathophysiological significance.     

Subjective experience of memory deficits related to clinical and neuroimaging findings

The aim of this study was to evaluate cognitive impairment, psychiatric symptoms and cerebral blood flow (CBF) patterns in middle-aged (35-64 years) and younger old patients (65-74 years) with subjective experience of memory deficits. The study group was heterogeneous with patients fulfilling criteria for dementia, as well as patients with mild cognitive impairment (MCI) and with non-verified cognitive impairment (non-MCI). Seventy per cent of the non-MCI patients reported long-lasting experiences of psychosocial stress tentatively causing the memory problems. The MCI patients were subdivided into two groups: MCI type 1 included patients with isolated memory impairment, while MCI type 2 included patients with memory impairment together with slight verbal and/or visuospatial impairments. CBF measurements comparing the two MCI groups with the non-MCI group were performed. The MCI type 2 showed reduced CBF in the left anterior medial temporal lobe as well as in parts of the posterior cingulate gyrus. The CBF pattern in MCI type 2 concurs with the pathophysiological process of Alzheimer's disease. The results indicate that it is important to make a subdivision of MCI patients regarding the presence of isolated memory impairments or memory impairments together with other slight cognitive deficits.     

Motor perseverative behavior on a line cancellation task.

OBJECTIVES: To study the behavioral and neuroanatomic characteristics of perseverative behavior encountered on a target cancellation task in patients with neglect. METHODS: Motor perseverative behavior during line cancellation task was evaluated retrospectively in 60 patients with left hemispatial neglect from right hemispheric stroke. RESULTS: More than 30% of the patients (21 of 60) showed perseveration, manifested as either repetitive cancellation of the same target (18/21) or cancelling extra lines created by the patients themselves (3/21). Neglect severity correlated positively with the frequency of perseverative errors. Perseveration was most prominent in the rightmost portion of the array. Anterior lesions or massive lesions involving anterior and posterior regions were more likely to be associated with motor perseveration than were lesions restricted to posterior areas. CONCLUSIONS: Although the mechanism of motor perseveration remains to be elucidated, our findings suggest that the combination of aberrant approach behaviors associated with frontal lobe injury and an attentional or intentional bias toward the rightsided targets might explain the behavior.     

Severity of neglect predicts accuracy of imitation in patients with right hemisphere lesions

Goldenberg [Goldenberg, G. (1996). Defective imitation of gestures in patients with damage in the left or right hemisphere. Journal of Neurology, Neurosurgery, and Psychiatry, 61, 176–180] proposed that the vulnerability of the imitation of meaningless gestures to right or left brain damage depends on the body parts that are involved in the gestures. Whereas imitation of hand postures was disturbed only in patients with left brain damage, imitation of finger postures was affected to similar degrees in left and right brain damage. Subsequent studies confirmed the selective vulnerability of hand postures to LBD but failed to replicate the severe disturbance of finger postures in RBD. In contrast to Goldenberg's studies, these studies excluded RBD patients with neglect. The present investigation aimed to explore the relationship between spatial neglect and imitation of finger postures in RBD patients.Presence and severity of spatial neglect and accuracy of imitation of hand and finger postures were tested in 50 RBD patients. Disturbance of imitation was much more severe for finger than hand postures and was tightly correlated with severity of neglect. The number of errors was higher for fingers which from the patient's perspective were located on the left side of the examiner's demonstrating hand but this spatial bias was not sufficient to explain all errors. Possible causes for non-lateralized errors could be a general narrowing of the focus of attention and reduced capacity for processing of visual information which have been postulated to be regular companions of the lateral displacement of attention in spatial neglect.     

Effect of schizophrenia on frontotemporal activity during word encoding and recognition: a PET cerebral blood flow study.

OBJECTIVE: Neuropsychological studies have shown that deficits in verbal episodic memory in schizophrenia occur primarily during encoding and retrieval stages of information processing. The current study used positron emission tomography to examine the effect of schizophrenia on change in cerebral blood flow (CBF) during these memory stages. METHOD: CBF was measured in 23 healthy comparison subjects and 23 patients with schizophrenia during four conditions: resting baseline, motor baseline, word encoding, and word recognition. The motor baseline was used as a reference that was subtracted from encoding and recognition conditions by using statistical parametric mapping. RESULTS: Patients' performance was similar to that of healthy comparison subjects. During word encoding, patients showed reduced activation of left prefrontal and superior temporal regions. Reduced left prefrontal activation in patients was also seen during word recognition, and additional differences were found in the left anterior cingulate, left mesial temporal lobe, and right thalamus. Although patients' performance was similar to that of healthy comparison subjects, left inferior prefrontal activation was associated with better performance only in the comparison subjects. CONCLUSIONS: Left frontotemporal activation during episodic encoding and retrieval, which is associated with better recognition in healthy people, is disrupted in schizophrenia despite relatively intact recognition performance and right prefrontal function. This may reflect impaired strategic use of semantic information to organize encoding and facilitate retrieval.