Objectives-In major cerebral arterial occlusive diseases, patients with inadequate blood supply relative to metabolic demand (misery perfusion) may be at increased risk for cerebral ischaemia. This study investigated whether patients showing misery perfusion on PET have a high risk of recurrent ischaemic stroke. Methods-The relation between the regional haemodynamic status of cerebral circulation and the subsequent risk of recurrent stroke was prospectively evaluated in 40 patients with symptomatic internal carotid or middle cerebral arterial occlusive diseases who underwent PET. Patients were divided into two haemodynamic categories according to the mean hemispheric value of oxygen extraction fraction in the hemisphere supplied by the artery with symptomatic disease: patients with normal oxygen extraction fraction and those with increased oxygen extraction fraction (misery perfusion). All patients were followed up for at least 12 months. Results-The one year incidence of ipsilateral ischaemic strokes for patients with normal oxygen extraction fraction and those with increased oxygen extraction fraction were two of 33 and four of seven patients respectively. A significantly higher incidence of ipsilateral strokes was found in patients with increased oxygen extraction fraction (Fisher's exact test; P = 0-005). In patients with increased oxygen extraction fraction, three of four strokes were watershed infarctions and the location of the infarction corresponded with the area of increased oxygen extraction fraction. Conclusion-These findings contradict conclusions of a previous study and suggest that patients with major cerebral arterial occlusive diseases and misery perfusion have a high risk for recurrent ischaemic stroke.(C Neurol Neurosurg Psychiatry 1996;61:18-25) Keywords: cerebrovascular disease; computed tomography; haemodynamics; stroke riskIn patients with major cerebral arterial occlusive disease, an inadequate blood supply relative to metabolic demand (misery perfusion)' may increase the risk of cerebral ischaemia, suggesting that identification and optimal treatment of patients with misery perfusion could help prevent stroke. However, it remains unclear whether patients with misery perfusion on PET have a high risk of ischaemic stroke, especially strokes of haemodynamic origin. Although case reports and retrospective studies have indicated that bypass surgery relieved patients with misery perfusion from abnormal haemodynamic state and recurring transient ischaemic attacks,'3' few studies have systematically investigated the relation between cerebral haemodynamics determined by PET and the subsequent risk of stroke. A previous longitudinal study did not find a relation between abnormal cerebral haemodynamics and the subsequent occurrence of stroke,5 but the data of the study were limited and not conclusive because of the few patients studied.2 To further investigate whether patients with misery perfusion have a high risk of recurrent ischaemic stroke, we prospectively followed up 40 medically tre...

Objectives: To explore the neural substrates corresponding to the perseverative errors in the Wisconsin Card Sorting Test (WCST). Methods: The study examined the correlations between the WCST performances and the SPECT measurements of regional cerebral blood flow (rCBF) in subjects with neurodegenerative dementia. Negative non-linear correlations between the rCBF and the two different types of the perseverative errors (''stuck-in-set'' and ''recurrent'' perseverative errors) were calculated on a voxel basis and volume-ofinterest basis in the mixed groups of 72 elderly and dementia patients. Results: The stuck-in-set perseverative error was associated with the reduced rCBF in the rostrodorsal prefrontal cortex, whereas the recurrent perseverative error was related to the left parietal activity but not to the prefrontal activity. Conclusions: These findings augment evidence that the rostrodorsal prefrontal cortex crucially mediates attentional set shifting, and suggest that the stuck-in-set perseverative errors would be a true pathognomonic sign of frontal dysfunction. Moreover, this study shows that the recurrent perseverative errors may not be associated closely with the prefrontal function, suggesting that this error and the stuckin-set error should be differentially estimated in the WCST.

In order to explore the factor structure of a modified version of the Wisconsin Card Sorting Test (mWCST) and to identify the dimensions of deficit in patients with Alzheimer’s disease (AD) and mild cognitive impairment (MCI), conventional mWCST scores in 55 AD patients, 17 MCI patients, and 22 controls were subjected to factor analysis. Three factors, perseveration, inefficient sorting, and nonperseverative error, were obtained. Perseveration score was significantly poorer in both AD and MCI than in controls. By contrast, the MCI group showed significantly poorer scores on the nonperseverative error factor than did the AD patients, and the controls yielded intermediate values between the two patient groups. The perseveration factor was significantly correlated with the other estimates of executive function. This study suggested that the many mWCST scores could be reduced to three major factors, and that the perseveration score may effectively represent an aspect of executive dysfunction in AD and MCI patients.

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Objective: To evaluate the possible relation between the rate of cognitive deterioration in patients with probable Alzheimer’s disease (AD) and the distribution pattern of neural dysfunction. Methods: The regional cerebral blood flow (rCBF) was measured in rapidly and slowly progressing groups of AD patients using single-photon emission computed tomography and was compared between the groups. While controlling for demographic and clinical factors that could be associated with the stage and prognosis of the illness, the deterioration rate of the Mini Mental State Examination (MMSE) score was significantly greater in the rapidly progressing group than that in the slowly progressing group. Results: The rCBF in the right posterodorsal, anterior and superior prefrontal cortices and the inferior parietal cortex was significantly lower in the rapidly progressing patients. Moreover, lower perfusion in these regions correlated significantly with rapid deterioration in the MMSE. Conclusions: These findings suggest that the rCBF values in these cortical regions could be useful in predicting which AD patients will show a relatively rapid cognitive decline.