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Forty-two patients with probable Alzheimer's disease (AD) and 18 elderly healthy controls underwent quantitative EEG (qEEG) and regional cerebral blood flow (rCBF; 133Xe clearance) examinations. Correlations were sought between relative qEEG band powers and percent rCBF values in a posterior temporoparietal region of interest in either hemisphere. Moreover, stepwise discriminant analysis was applied to study the accuracy of the two techniques in differentiating AD from healthy ageing. rCBF and qEEG were correlated with one another, especially in the right hemisphere (p values ranging from <0.001 to <0.01). Significant correlations were found between Mini Mental State Examination (MMSE) and relative power of both the 2- to 6-Hz and the 6.5- to 12-Hz bands on either side (p < 0.001), and between MMSE and left rCBF (p < 0.005), while the correlation with right rCBF was poorer (p < 0.02). The statistical procedure identified the right values of both examinations for the discriminant analysis. Sensitivity of qEEG and rCBF employed together was 88% and specificity 89%, with a total accuracy of 88.3%. The unrecognized patients (n = 5) were affected by mild AD (4 scoring 3 at the Global Deterioration Scale and 1 scoring 4). qEEG alone showed an accuracy of 77% in the whole group and of 69% in mild AD, and rCBF alone an accuracy of 75% in the whole group and of 71% in mild AD. It is concluded that qEEG and rCBF examinations employed together are accurate tools to differentiate AD from normal ageing, although a lower degree of accuracy is achieved in mildly demented patients.

Systemic Sclerosis (SSc) is a multisystem disease characterised by proliferation of vascular tissue, obliterative microvascular lesions and diffuse organ fibrosis. Despite widespread vascular disease, Central Nervous System complaints are only infrequently reported and it is uncertain whether they merely derive from systemic complications or whether they may be also caused by a primary vascular process within the brain. Regional cerebral blood flow (rCBF) was quantitatively measured by the 133Xenon clearance technique in twenty-seven consecutive SSc patients without relevant systemic complications and with different severity of vascular involvement, as staged by nailfold capillary videomicroscopy (NCV). Absolute, percent, and asymmetry rCBF values were compared (z-statistics) with age- and sex-matched healthy controls. Cerebral MRI and Mini-Mental State Examination (MMSE) were also performed. Doppler sonography of neck vessels and Transcranial Doppler sonography (TCD) were performed in patients presenting rCBF reduction. Cerebral hypoperfusion was found in the 52% of patients, i.e.: in 33% of patients with the 'early' NCV pattern, in 56% of patients with the 'active' pattern, and in 67% of patients with the 'late' NCV pattern. Thirty percent were the MRIs showing focal and/or diffuse signal abnormalities in the white matter of both hemispheres with the highest rate (44%) in the 'late' NCV pattern. MMSE disclosed mild dementia in one patient in the 'late' NCV group and some mistakes in 6 more patients, in the 'active' or 'late' NCV groups, whereas TCD failed to find significant stenosis of Willis' arteries. Cerebral hypoperfusion is shown for the first time in a substantial part of SSc patients without either neurological symptoms or relevant systemic complications. It is suggested that the rCBF reduction might be related to the systemic scleroderma microangiopathy although, probably due to the paucity of connective tissue in cerebral vessels, the vast majority of patients remains in a subclinical phase.

Objective: Comparative assessment of sensitivity and specificity of regional Cerebral Blood Flow (rCBF) by 133-Xenon inhalation and quantitative Electroencephalography (qEEG) in patients with Neuropsychiatric Systemic Lupus Erythematosus (NP-SLE)., Methods: Sixty-two combined rCBF and qEEG examinations were performed in fifty-two SLE patients. Group A: 27 SLE patients without NP-SLE; group B: 17 patients with florid (within 1 month) NP-SLE; group C: 12 patients previous NP-SLE examined in the remission phase (four patients of which already considered in group B). The study also included data deriving from two sets of examinations in ten patients who were observed twice, in different phases of the clinical course of NP-SLE., Results: In comparison to healthy controls, rCBF lower (p < .001) in group B only, whereas qEEG showed similar increases of both delta and theta relative powers together with a reduction of alpha relative power in groups A-C. As compared to group A, sensitivity and specificity in detecting cerebral abnormalities in group B were 76% and 78% for rCBF, and 59% and 44% for qEEG, respectively. In the ten patients examined twice, rCBF was consistent with clinical course in 90% of cases and qEEG in 60%., Conclusion: Total accuracy in detecting cerebral functional abnormalities during florid NP-SLE is better by rCBF than by qEEG. rCBF and, in selected cases, qEEG examinations are reliable markers of NP-SLE.

Spinal cord stimulation (SCS) has been shown to influence cerebral perfusion in both experimental models and humans. With the aim of further verifying such an effect, twelve patients had an epidural (cervical or dorsal) lead inserted percutaneously and underwent regional cerebral blood flow (rCBF) examinations (133-Xenon inhalation method) before and during SCS. Mean blood velocity (MBV) in the middle cerebral artery was also measured in seven cases by means of transcranial Doppler. In the patients with a cervical lead, a symmetrical increase in rCBF was found, mainly in the anterior regions (from +8% to +21%). MBV increased in four cervical lead implants (from +16% to +20%) and in one case with a dorsal lead (+15%). These results suggest that cerebral perfusion may increase in patients undergoing SCS through a cervical lead. Although the mechanism involved in the increase in rCBF remains to be clarified, frontal lobe functional activation by the ascending reticular pathways through the thalamo-cortical projections might be hypothesised.

Background and Purpose: Cerebral hypoperfusion has occasionally been reported during essential hypertension. We explored regional cerebral blood flow in a large series of neurologically asymptomatic hypertensive patients to determine relations among cerebral blood flow, concomitant main vascular risk factors, and the most common signs of end-organ damage., Methods: Regional cerebral blood flow was measured by the 133Xe inhalation method in 101 hypertensive patients without clinically apparent central nervous system involvement, including 39 mild to moderate untreated and 62 mild to severe treated patients., Results: Compared with age- and sex-matched normal control subjects, cerebral blood flow was significantly reduced in untreated hypertensive patients (P < .01) and to a lesser extent in treated patients (P = .047). Both regional and global cerebral blood flow reductions were observed in approximately one third of patients in both groups. Analysis of variance failed to show significant correlations between cerebral blood flow and total cholesterol concentration, mean arterial blood pressure, duration of disease, or the presence of retinopathy or left ventricular hypertrophy. In the treated group, the quality of control of hypertension significantly influenced both global cerebral blood flow (P = .007) and cerebrovascular resistance (P < .0001)., Conclusions: Focal or diffuse cerebral hypoperfusion is present even in neurologically asymptomatic hypertensive patients, especially when untreated; good control of blood pressure may preserve cerebral perfusion and reduce cerebrovascular resistance. Regional cerebral blood flow examination represents a relatively simple and low-cost technique to explore the perfusional condition of the brain, one of the main target organs of hypertensive disease.

Objective: To investigate both rCBF and cerebrovascular reactivity, evaluated as pre- and post-ACZ rCBF differences in a group of IDDM patients with differences in duration of disease and severity of complications., Research Design and Methods: rCBF was measured by the 133Xenon inhalation method in 20 IDDM patients and in 15 healthy control subjects before and after an intravenous injection of ACZ, a carbonic anhydrase inhibitor commonly used to assess cerebrovascular reactivity., Results: Basal global CBF (the mean of 32 regional values) was within the normal range in all patients but 1, who showed slight hyperperfusion; moreover, in 3 patients with long-lasting disease, some hypoperfused regions were found. ANOVA showed an inverse correlation between basal global CBF (P < 0.01) and duration of diabetes, but no correlation with Hb, MABP, serum glucose concentration, or GHb. Compared with control subjects, the percentage of global CBF increment after ACZ administration was significantly impaired in 4 patients and gave a borderline response in 2 patients; 4 of these poor ACZ responders had retinopathy, and 1 had suffered from a TIA. Duration of diabetes, Hb, MABP, serum glucose concentration, and GHb did not correlate with the percentage of post-ACZ global CBF changes, and did not differ among the 6 poor ACZ responders and the other diabetic patients or control subjects., Conclusions: These results confirm that global CBF is within the normal range in most IDDM patients, although it is significantly influenced by the duration of diabetes; pathophysiological correlates of the altered cerebrovascular reactivity need to be further investigated. rCBF measurements, before and after ACZ administration, seem to represent a safe and reliable tool for assessing cerebrovascular function in IDDM.

Background and Purpose: The aim of this study was to investigate regional cerebral blood flow parameters during the postacute phase of unilateral ischemic stroke and to correlate them with clinical data., Methods: Regional cerebral blood flow was measured in 187 patients in the stabilized phase of stroke by the xenon-133 inhalation method with 32 extracranial detectors. Thirty-eight patients were reexamined after a mean +/- SD time of 32 +/- 21.4 months., Results: The overall detection of hypoperfusion was 92.0%, with asymmetries as the most sensitive index, especially for patients with a lesser degree of neurological disability. Neurological disability score was strongly associated with regional cerebral blood flow in the affected hemisphere (p < 0.0001) and with asymmetries (p < 0.0001). The presence of carotid obstruction further decreased the regional cerebral blood flow in the affected hemisphere and significantly increased asymmetry (p < 0.0001). Subjects who had no hypoperfusion at absolute values analysis were more frequently free of carotid disease and had less severe disability than those who had bilateral or unilateral regional absolute cerebral blood flow reduction. In 38 patients without new cerebrovascular events, a significant (p = 0.005) reduction of hemispheric regional cerebral blood flow asymmetries was found on a follow-up examination., Conclusions: These data confirm the value of regional cerebral blood flow asymmetries in stroke detection and point out that important clinical information is also contained in absolute values analysis.

Ten judoka were examined at rest by EEG and regional Cerebral Blood Flow (rCBF) (133-Xenon inhalation method); in seven of them a syncope was induced by choking and EEG was recorded during the loss of consciousness while rCBF was measured immediately after recovery. Baseline EEG and rCBF examinations were normal. During choking, EEG showed diffuse 2-3 Hz. high voltage waves, predominantly in the anterior regions, then the EEG gradually recovered to normal. After choking, rCBF decreased in all but one subject, slightly in four and more markedly in two. Our findings suggest that there is no evidence of permanent CNS functional changes due to judo practice and choking. The variable rCBF features soon after choking-induced syncope may reflect a different timing of recovery from cerebral ischemia for each subject.

Regional cerebral blood flow (rCBF) asymmetries were studied in 189 subjects (96 males and 93 females) at rest with the 133Xenon inhalation method using a fixed detector system. rCBF asymmetries in the resting condition were very small, nevertheless a significant (p less than 0.001) effect for their topographical distribution was present, reflecting higher rCBF in the right fronto-temporal and left parieto-occipital regions. rCBF asymmetries were not correlated with age, and there were no significant differences between males and females. Asymmetries are therefore useful from a statistical point of view in detecting rCBF abnormalities in the resting condition: they are more stable than absolute values in normal subjects and no matching according to age or sex is required when statistical comparisons are performed.

An increase of regional cerebral blood flow (rCBF) has been shown to occur in man during spinal cord stimulation (SCS) by Hosobuchi (1986) and by Meglio et al. (1988) using the 133-Xenon wash-out technique. In this paper we report the effects of SCS on CBF as measured by two different techniques: 8 patients were studied with the 133-Xe method and 28 with the transcranial doppler sonography (TCD), in two cases both studies were performed. The aim of our study was to: 1-verify the effect of SCS on CBF, 2-compare observations made by two different methods, and 3-evaluate a possible correlation between the stimulated spinal segmental level and the modification of CBF. The results of our study confirm that SCS interacts with the mechanisms of regulation of CBF. The stimulation of different spinal cord levels in the same patient can produce different effects and such effects are reproducible. An increase of CBF is more likely to occur with the stimulation of the cervical spinal cord. In patients studied by both methods the sign of CBF changes induced by SCS was the same. Finally, in two patients the effect of SCS on CO2 autoregulation was studied with TCD. The results of such a study, although preliminary, suggest that CO2 and SCS have a competitive effect upon the mechanisms of regulation of CBF.

In a man with orthostatic and effort syncopes due to primary dysautonomia, we measured cerebral blood flow (CBF)--by the 133-Xenon inhalation method--in supine and in sitting positions, and after the i.v. administration of Acetazolamide, a potent cereal vasodilator. Heart rate (HR) and blood pressure (BP) were monitored over the 24 hours by a non-invasive device. The CBF was normal in supine position and significantly reduced when the patient was sitting. Despite che sympathetic denervation, good response to acetazolamide infusion was seen. BP changed with the position of the subject according to gravity, and HR was unresponsive to orthostatic and effort stimuli.

Ten male patients with brain ischaemia were studied. Regional cerebral blood flow (rCBF) was measured in the resting condition and 1 h after intravenous infusion of 1500 mg acetyl-L-carnitine. rCBF values were compared to those of a control population of the same age decade by a computer mapping system of our own design, which enables rapid visual inspection of cerebral blood flood values distribution and of statistical significance of differences. Beneficial effects of the drug were observed in at least four patients, especially in the affected hemisphere, in another four, rCBF elevations in the areas which were lowest on resting examination were observed, which was paralleled by reductions in surrounding zones. In two patients no modification of rCBF values after acetylcarnitine was seen.

Cerebral blood flow (CBF), measured by the non-invasive 133-Xenon inhalation method, plasma levels of ammonia (NH3) and free tryptophan (fTRP) were determined in 30 cirrhotic patients without overt encephalopathy. Psychometric evaluation detected subclinical hepatic encephalopathy (SHE) in 20 of them, and was normal in the other 10. A significant CBF difference (p less than 0.05) was found between the SHE and the non-SHE patients. fTRP levels were significantly (p less than 0.05) higher in patients with SHE than in those without SHE, and a significant negative correlation (p = 0.003) was found between CBF values and fTRP in the whole group of patients. NH3 did not differ in the two subgroups and did not correlate with CBF values. It is concluded that CBF could have some implications in SHE, although its relevance is still unclear. The negative correlation between CBF and fTRP prompts further investigation concerning the relationships between plasma fTRP, brain serotonin, cerebral metabolism and blood flow in the development of brain derangement during cirrhosis.

Regional CBF (rCBF) was evaluated by the 133Xe inhalation method in 60 neurologically normal patients (30 men and 30 women) and hemispheric and regional values were correlated with anxiety measurements collected by a self-rating questionnaire before and after the examination. Statistically significant negative correlations between rCBF and anxiety measures were found. rCBF reduction for high anxiety levels is in line with results previously reported by others and could be related to lower performance levels for moderately high anxiety scores as those reported in the present population. This could perhaps be explained by rearrangement of flow from cortical zones to deeper areas of the brain, classically known to be implicated in the control of emotions. However, these results should be interpreted cautiously, since they were obtained in patients and not in normal subjects.

Regional cerebral blood flow was measured by the 133-xenon inhalation method during resting in 38 healthy men and 38 healthy women matched pairwise for age in the range 18-72 years. The results showed 11% higher global flow level in the women in all ages. A similar and significant regression of flow by age was seen for both sexes. The regional flow distribution also showed some sex-related differences. Frontal regions showed an asymmetry in the men with higher values on the right side. The female flows were more symmetric. As a hypothesis, it is suggested that the higher flow level in women may be a systemic phenomenon. In fact, other authors have found a higher cardiac index in females. The sex differences in regional flow pattern might be due to differences in the functional organization of the cortex and/or to differences in the mental processes of the "resting" state.

Regional cerebral blood flow (CBF) was measured in 15 healthy young volunteers in psycho-sensorial rest by the 32 probes Xe133 inhalation system. The mean hemispheric values are in good agreement with those reported in literature and obtained with a limited number of probes. The regional values of the flow in the gray matter are higher in the basal-temporal and frontal regions. This regional pattern is not evident for the other considered parameters (flow in the white matter, mean flow, "weight" of the gray matter).

Regional cerebral blood flow was studied by means of the 133Xe inhalation method in 26 untreated and 10 treated patients with essential hypertension. The untreated subjects were divided into newly and previously diagnosed groups to assess the relation between regional cerebral blood flow and the duration of hypertension. The overall flow reduction was more marked in the frontal and temporal regions in the previously diagnosed group, and this was attributed to pathological changes in the district served by the middle cerebral artery. Regional temporal lobe impairment was also noted in the newly diagnosed and treated subjects. A significant correlation was found between regional cerebral blood flow and mean arterial blood pressure.

We retrospectively examined regional cerebral blood flow values in 78 patients in the stabilized phase of stroke to evaluate the consistency of lateralization compared with computed tomographic imaging. Examinations were performed using the xenon-133 inhalation technique, and the data were processed and displayed by a computer-assisted system of our own design that allows statistical analysis in real time and is suitable for clinical use. The consistency of lateralization correlated with computed tomographic findings was tested for absolute values, percent distribution, and asymmetries. The latter yielded the highest degree of sensitivity (in 83.3% of the patients the affected hemisphere was correctly identified). Absolute values showed at least one hypoperfused area in the affected hemisphere in 48.7% of the patients, and percent distribution did so in 57.7%. Furthermore, the combination of the three methods of data analysis yielded a sensitivity of 91%; the remaining 9% of the patients, however, exhibited some abnormalities of regional cerebral blood flow (bilateral or contralateral hypoperfusion). Although good agreement was found for lateralization by computed tomography and by the combined use of the three methods of analysis, a complete overlap between functional and structural examinations should not be expected. Problems concerning the sensitivity of the xenon-133 inhalation technique under conditions of low blood flow and the statistical analysis of regional cerebral blood flow data are discussed.

Cerebral blood flow (CBF), measured by the noninvasive xenon-133 inhalation method, EEG, and plasma levels of ammonia (NH3) and free tryptophan were determined in 18 hospitalized cirrhotic patients affected with subclinical hepatic encephalopathy, as diagnosed by the Kurtz test. CBF results were significantly lower (p less than 0.001) in the patients' group as compared with a sex- and age-matched normal control population, although seven patients had values in the normal range. NH3 was increased only in six, while free tryptophan was increased in all but two patients. A significant negative correlation (p = 0.02) between CBF and free tryptophan was found, even though it appears to be difficult to interpret. We suggest that CBF impairment in some cirrhotic patients with subclinical hepatic encephalopathy may be related to the systemic metabolic derangement caused by the liver disease; free tryptophan could have some implication in producing CBF reduction.

Seventeen patients with minor cerebral contusion were selected from a series of patients with head injuries of various severity, who had undergone repeat evaluations of the regional cerebral blood flow. The mean global flow (expressed as mean global initial slope index) on early examination was found to be significantly lower, compared with that recorded in healthy volunteers. A tendency towards the recovery of higher flow values was apparent in repeat evaluations that were performed several weeks after the injury. Interhemispheric asymmetries of flow were a common occurrence, with lower perfusion and reduced attenuation values on computed tomography scans being, however, in good agreement only in approximately half of the cases.