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To investigate the effect of the level of baseline cerebral blood flow (CBF) on local CBF augmentation by activation, we have used positron emission tomography to measure regional CBF (rCBF) in 12 normal volunteers with and without photic stimulation during hypocapnia, normocapnia, and hypercapnia. The increase in rCBF in the primary visual cortex by photic stimulation was 10.8 ± 3.1, 18.6 ± 9.3, and 19.5 ± 6.1 ml 100 ml−1 min−1 in hypo-, normo-, and hypercapnia, respectively. The increase was significantly smaller in hypocapnia than in normocapnia ( p < 0.005). The fractional CBF increase caused by the photic stimulation was the same in all breathing conditions. This result indicates that the magnitude of the CBF increase induced by neuronal activity correlates proportionally with the level of baseline CBF.

During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.

Concerning vasoreactivity of cerebellar blood flow (CeBF) in patients affected with crossed cerebellar diaschisis (CCD), several controversies have been reported. One is reduced asymmetry of CeBF after acetazolamide administration in 99mTc hexamethylpropyleneamine oxime single-photon emission-computed tomography, and the other is persistent asymmetry with alternation in PaCO2 using the 133Xe clearance method. The purpose of this study is to examine whether CeBF vasoreactivity in the side affected with CCD is the same as that in the unaffected side. We analyzed CeBF during hypocapnia, normocapnia, and hypercapnia performed in 27 patients with cerebrovascular disease (age range, 38 to 73 years; mean age, 62.0 +/- 8.5 years) affected by CCD. CeBF was measured using H2(15)O and positron emission tomography. The CeBF ratio of CCD-affected side to CCD-unaffected side was consistent during the perturbation of PaCO2. This ratio was 0.82 +/- 0.08 for PaCO2 elevation and 0.83 +/- 0.07 for PaCO2 lowering. Both were not significantly different from unity. The percent change of CeBF per millimeter of mercury PaCO2 change was uniform across affected and unaffected sides with CCD. These findings are consistent with our recent findings observed in activated cerebral tissue during photic stimulation.

Using positron emission tomography (PET), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMR02) were measured in 32 healthy volunteers aged from 27 to 67 years. In bilateral putamen, left supratemporal\ left infrafrontal and left parietal cortices, CMR02 showed a significant decline during aging. The age-related decline of CBF was seen only at the left superior temporal cortex. The mean CMR02 was significantly lower in the elder group (over 51 years old) than in the younger group (under 50 years old), whereas no significant difference in mean CBF between the two groups. The poor correlation of CBF to the age could be explained partly by the fact that CBF is easily influenced by the physiological, psychological and/or environmental factors. The age-related changes of CMR02 were more marked in the association cortices of the left hemisphere than in that of the right hemisphere.

We elicited isolated sleep paralysis (ISP) from normal subjects by a nocturnal sleep interruption schedule. On four experimental nights, 16 subjects had their sleep interrupted for 60 minutes by forced awakening at the time when 40 minutes of nonrapid eye movement (NREM) sleep had elapsed from the termination of rapid eye movement (REM) sleep in the first or third sleep cycle. This schedule produced a sleep onset REM period (SOREMP) after the interruption at a high rate of 71.9%. We succeeded in eliciting six episodes of ISP in the sleep interruptions performed (9.4%). All episodes of ISP except one occurred from SOREMP, indicating a close correlation between ISP and SOREMP. We recorded verbal reports about ISP experiences and recorded the polysomnogram (PSG) during ISP. All of the subjects with ISP experienced inability to move and were simultaneously aware of lying in the laboratory. All but one reported auditory/visual hallucinations and unpleasant emotions. PSG recordings during ISP were characterized by a REM/W stage dissociated state, i.e. abundant alpha electroencephalographs and persistence of muscle atonia shown by the tonic electromyogram. Judging from the PSG recordings, ISP differs from other dissociated states such as lucid dreaming, nocturnal panic attacks and REM sleep behavior disorders. We compare some of the sleep variables between ISP and non-ISP nights. We also discuss the similarities and differences between ISP and sleep paralysis in narcolepsy.

Study Objectives: To further investigate mechanisms of isolated sleep paralysis (ISP) in normal individuals, we experimentally elicited ISPs by facilitating sleep onset REM periods (SOREMP), a prerequisite of ISPs, and examined behavioral and psychological measurements relating to ISP appearances. Design: The multi-phasic sleep/wake schedule (MPS) began at approximately midnight and ended when net sleep reached 7.5 hours. Participants were awakened after every 5 min of REM sleep to obtain a maximum number of SOREMPs. Upon each awakening, mentation reports and subjective measurements were collected. Performance tests were then assigned. Setting: Sleep lab, Tokyo Metropolitan Institute for Neurosciences, Japan. Participants: Thirteen healthy Japanese students (10 males) with high self-reported frequencies of ISPs but no other narcolepsy-related symptoms. Measurements and results: From 184 sleep interruptions, 8 ISP episodes were obtained. In within participant comparisons between episodes with and without ISPs, the vigilance task (VT) reaction times were elevated before SOREMPs with ISPs. In between analyses (ISP vs non-ISP), the ISP group showed poorer performance, more complaints of physical, mental, and neurotic symptoms, increased subjective fatigue and increased stage 1 throughout the entire schedule. VT hit rates remained constant in the non-ISP group, but dropped in the later part of schedule in the ISP group. Subjective sleepiness dropped over time in the non-ISP group while it slightly increased in the ISP group. Conclusions: ISP is likely to appear as a phenotype of REM dissociation during SOREMP when participants with low tolerance for disrupted sleepwake rhythms are placed in this type of schedule.

The hypothesis that there is a strict relationship between dreams and a specific rapid eye movement (REM) sleep mechanism is controversial. Many researchers have recently denied this relationship, yet none of their studies have simultaneously controlled both sleep length and depth prior to non-REM (NREM) and REM sleep awakenings, due to the natural rigid order of the NREM--REM sleep cycle. The failure to control sleep length and depth prior to arousal has confounded interpretations of the REM-dreams relationship. We have hypothesised that different physiological mechanisms underlie dreaming during REM and NREM sleep, based on recent findings concerning the specificity of REM sleep for cognitive function. Using the Sleep Interruption Technique, we elicited sleep onset REM periods (SOREMP) from 13 normal subjects to collect SOREMP and sleep onset NREM (NREMP) dreams without the confounds described above. Regression analyses showed that SOREMP dream occurrences were significantly related to the amount of REM sleep, while NREMP dream occurrences were related to arousals from NREM sleep. Dream properties evaluated using the Dream Property Scale showed qualitative differences between SOREMP and NREMP dream reports. These results support our hypothesis and we have concluded that although 'dreaming' may occur during both REM and NREM periods as previous researchers have suggested, the dreams obtained from these distinct periods differ significantly in their quantitative and qualitative aspects and are likely to be produced by different mechanisms.

Objective : REM latency is usually 60–120 min, but under certain conditions, its latency may be less than 25 min, in which it is known as sleep onset REM period (SOREMP). In order to identify the factors responsible for the appearance of SOREMP, we used the nocturnal sleep interruption method to investigate whether REM propensity in normal nocturnal sleep, (i.e. circadian variations in REM sleep related to body temperature rhythm), could affect the rate of SOREMP appearance (SOREMP%). Materials and methods : After two adaptation and one baseline nights, we interrupted the nocturnal sleep, either in the second or the fourth cycle (early and late conditions, respectively) of 16 subjects and compared SOREMP% at the second sleep onset between these conditions by χ 2 test. Rectal temperature was measured. Results : SOREMP% was found to be 58.1% in the early condition and 87.5% in the late condition – a significant difference. Body temperature dropped at the second sleep onset in both conditions but the drops did not differ significantly. Conclusion : We concluded that SOREMP% was affected by circadian variations in REM propensity but SOREMP% and body temperature drop did not show a linear relationship. Further studies to discriminate the influence of circadian rhythm factors and slow wave sleep on SOREMP% are called for.

A questionnaire concerning their sleep-related lifestyle and mental health was mailed to people aged in their twenties to fifties living in the Fukushima (North East), Tokyo (Central, Metropolitan) and Okayama (West) areas of Japan. We classified the sleeping pattern of 3642 people (1702 men, 1940 women; mean age 41.3+/-10.67) by multivariational analyses (factor analysis and cluster analysis). They were classified into six groups and defined as 'poor sleeper group' (30.0%), 'good sleeper group' (28.3%), 'long sleeper group' (8.2%), 'short sleeper group' (18.5%), 'irregular sleeper group' (11.3%), and 'Delayed Sleep Phase Syndrome group' (3.7%) based on their characteristics of the factor pattern.

We investigated the relationship between a subject's self-rated lifestyle and their pattern of nocturnal rectal temperature. Fifty-five students participated in the study. Among several significant findings, irregularity and eveningness component of lifestyle (irregular and delayed sleep phase) showed a significant negative correlation with temperature at the morning rising time. Examination of the nocturnal temperature pattern revealed that rectal temperature stayed at its lowest level in the early morning hours in the subjects with irregular and eveningness-like lifestyles.

Fluid-attenuated inversion-recovery (FLAIR) sequences have been reported to provide high sensitivity to a wide range of central nervous system diseases. To our knowledge, however, FLAIR sequences have not been used to study patients with acute cerebral infarcts. We evaluated the usefulness of FLAIR sequences in this context. FLAIR sequences were acquired on a 0.5 T superconducting unit within 8 h of the onset in 19 patients (aged 26-80 years) with a total of 23 ischaemic lesions. The images were reviewed retrospectively by three neuroradiologists, and the FLAIR images were compared with T2-weighted fast spin-echo images. All but one of the ischaemic lesions involving grey matter was clearly demonstrated on FLAIR images as increased signal intensity in cortical or central grey matter. FLAIR images were particularly useful for detecting the hyperacute cortical infarcts within 3 h of onset, which were not readily detected on the spin-echo images. In 9 of 11 patients with complete proximal occlusion, the distal portion of the cerebral artery was visible as an area of high signal intensity on FLAIR images.

To evaluate fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) imaging in the detection of subacute and chronic subarachnoid hemorrhage.The authors performed 19 FLAIR MR imaging examinations at 0.5 T in 14 adult patients with subarachnoid hemorrhage 3-45 days after the ictus and 22 FLAIR examinations in 22 adult control subjects. The detection of subacute and chronic subarachnoid hemorrhage on FLAIR images was compared with the detection on conventional spin-echo MR and computed tomographic (CT) images.In the detection of subacute subarachnoid hemorrhage, FLAIR (100% detection) was significantly superior to T1-weighted imaging (36% detection, P.01), T2-weighted imaging (0% detection, P.02), and CT (45% detection, P.02 [Fisher exact test]). Although FLAIR imaging (63% detection) was superior in chronic subarachnoid hemorrhage detection, there were no statistically significant differences between modalities. FLAIR imaging demonstrated all subarachnoid hemorrhage areas as high-signal-intensity areas within 18 days and up to a maximum of 45 days after the ictus. In a blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in patients.FLAIR diagnostic images are superior to conventional MR or CT images in patients with subacute subarachnoid hemorrhage.

Cerebral blood flow (CBF), oxygen metabolism (CMRO2), and glucose metabolism (CMRGlc) were measured using positron emission tomography in five patients diagnosed as having mitochondrial encephalomyopathy. The molar ratio between the oxygen and glucose consumptions was reduced diffusely, as CMRO2 was markedly decreased and CMRGlc was slightly reduced. The CBF showed less changes. The CBF increase on hypercapnia was smaller than normal, though this was not significant. CBF with hypocapnia demonstrated a significant reduction compared with the normal. These results suggest that oxidative metabolism is impaired and anaerobic glycolysis relatively stimulated, due to a primary defect of mitochondrial function, and that mild lactic acidosis occurs in brain tissue because of impaired utilisation of pyruvate in the TCA cycle. As these findings appear to indicate directly a characteristic of this disease, such measurements may be a useful tool for assessment of the pathophysiology and for diagnosis of mitochondrial encephalomyopathy.

We evaluated whether PET with L-methyl-11C-methionine (11C-methionine) was clinically useful in distinguishing neoplastic from non-neoplastic intracerebral hematoma.We examined eight patients with neoplastic (n = 4) or non-neoplastic (n = 4) intracerebral hematomas between 5 and 68 days after the bleeding episode using PET with 11C-methionine (Met-PET).Carbon-11-methionine accumulated in the area surrounding the hematoma in both groups, except in one patient with an acute hypertensive hematoma. Between 22 and 45 days after the ictus, non-neoplastic hematomas showed increased 11C-methionine accumulation largely in accordance with the contrast-enhanced areas on CT or MR images; whereas between 14 and 68 days after bleeding, neoplastic hematomas showed increased 11C-methionine accumulation that extended beyond the contrast-enhanced areas on CT or MR images. The intensity of 11C-methionine accumulation in tumor tissue was greater than that in non-neoplastic hematomas.Preliminary results suggest that Met-PET can distinguish neoplastic from non-neoplastic hematomas on the basis of differences in lesion extent compared with CT or MR findings.

The purpose of our study was to compare the value of MR imaging with CT in the diagnosis of subarachnoid hemorrhage in the subacute and chronic stages (3 days after the hemorrhagic episode).We performed 42 MR examinations using a 0.5-T unit in 37 patients with subarachnoid hemorrhage caused by a ruptured aneurysm. Examinations were done 4-75 days after the ictus. We obtained 40 T1-weighted, 11 proton density-weighted, 15 T2-weighted, and 28 moderately T2-weighted images. CT was also performed in all patients within 24 hr of the MR examination. Confirmation of the presence of subarachnoid hemorrhage at the time of the MR examination was made by CSF examination using lumbar puncture or surgical findings.In the subacute and chronic stages, subarachnoid hemorrhage was seen as an area of high signal intensity on T1-weighted, proton density-weighted, T2-weighted, and moderately T2-weighted MR images in 63%, 90%, 25%, and 92% of cases, respectively. On CT scans, subarachnoid hemorrhage was seen as an area of high attenuation in only 46% of cases. Especially in the chronic stage, subarachnoid hemorrhage was seen as an area of high signal intensity more frequently by MR imaging than by CT (90% on T1-weighted images; 100% on proton density-weighted images; 25% on T2-weighted images; 100% on moderately T2-weighted images; and 10% on CT scans). High-signal-intensity subarachnoid hemorrhage was demonstrated by MR imaging until a maximum of 39 days after the ictus, whereas high-attenuation subarachnoid hemorrhage was demonstrated by CT until a maximum of 17 days after the ictus.Our findings show that MR imaging is superior to CT for the diagnosis of subacute and chronic subarachnoid hemorrhage. MR imaging is especially useful for the diagnosis of chronic subarachnoid hemorrhage.

To evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging sequences in the detection of acute subarachnoid hemorrhage (SAH).MR imaging with FLAIR sequences was performed with a 0.5-T superconducting unit in 20 patients (aged 30-72 years) with acute SAH due to a ruptured aneurysm and in 27 control subjects (aged 32-72 years). FLAIR images were obtained 2 hours to 2 days after ictus. Findings were evaluated and compared with computed tomographic (CT) findings.In all patients, acute SAH was clearly demonstrated as an area with signal intensity that was high relative to that of the normal cerebrospinal fluid and surrounding brain parenchyma at FLAIR imaging. This sequence was especially useful in demonstration of acute SAH in the posterior fossa, which was difficult to show at CT because of beam-hardening artifacts. In a double-blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in control subjects were confused with those acquired in patients.FLAIR sequences reliably provide diagnostic images in patients with acute SAH.

By means of a high resolution PET scanner, the regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), and metabolic rate of oxygen (rCMRO2) for major cerebral gyri and deep brain structures were studied in eleven normal volunteers during an eye-covered and ear-unplugged resting condition. Regional CBF was measured by the auto-radiographic method after intravenous administration of H2 15O. Regional OEF and rCMRO2 were measured by the single inhalation of15O2. With MR T1-weighted images as an anatomical reference, thirteen major cerebral gyri, caudate nucleus, lentiform nucleus, thalamus, midbrain, pons, cerebellum and vermis were defined on the CMRO2 images. Values were read by using circular regions of interest 16 mm in diameter. The posterior part of the cingulate gyri had the highest rCBF and rCMRO2 values among brain structures, followed by the lentiform nucleus, the cerebellum, the caudate nucleus, and the thalamus. Parahippocampal gyri had the lowest rCBF and rCMRO2 values amongthe cortical gyri.RegionalOEFforthepontinenuclei (0.34 ± 0.04), the midbrain (0.35 ± 0.05), the parahippocampal gyri (0.35 ± 0.04 for the right and 0.37 ± 0.05 for the left), and the thalami (0.37 ± 0.05 for the right and 0.36 ± 0.04 for the left) were significantly lower than the mean OEF for the cerebral cortices (0.42 ± 0.04) (p < 0.05 or less). The global CBF and CMRO2 were consistent with those obtained by the Kety-Schmidt method. Although several limitations to the quantification derived from an inadequate spacial resolution remain unsolved, the performance of the present PET scanner and the method for the quantification employed provide regional estimates of brain circulation and oxygen metabolism more acurately than the PET system and the steady state method previously used.

We report preliminary results applying fluid-attenuated inversion-recovery (FLAIR) sequences to three patients with acute subarachnoid hemorrhage. Acute subarachnoid hemorrhage could be clearly demonstrated as areas of high signal intensity on FLAIR sequences in all patients. These preliminary results suggest that with FLAIR sequences one could reliably diagnose acute subarachnoid hemorrhage.

Technetium-99m-HMPAO can be used to evaluate abnormal brain perfusion in the hyperacute stage of stroke.We investigated cerebral blood flow using 99mTc-HMPAO SPECT in 31 patients within 6 hr after the onset of cerebral infarction and analyzed the relationship between abnormal perfusion and morphological changes on follow-up CT scans. Patients were classified into an infarct group and a noninfarct group, and the lesions on SPECT images were divided into infarct and peri-infarct regions.Among a total of 30 infarct regions, three lesions studied at 1.5, 2.5 and 5 hr after the ictus showed local hyperperfusion suggestive of early postischemic hyperemia, while the other 27 lesions demonstrated local hypoperfusion. All of the peri-infarct regions showed moderate hypoperfusion. The noninfarct group consisted of five patients, four of whom showed no perfusion abnormalities. The lesion-to-contralateral radioactivity ratios for the infarct and peri-infarct regions were respectively 0.48 +/- 0.14 and 0.75 +/- 0.10 in the patients with hypoperfusion, while the right-to-left ratio in the noninfarct group was 0.97 +/- 0.10.This SPECT study of cerebral blood flow demonstrates that local hyperperfusion occurs in some infarcts even within 6 hr of onset and that infarcted and morphological viable brain can be distinguished by a lesion-to-contralateral radioactivity ratio of 0.6 within this time range.

Using magnetic resonance imaging, we reviewed 141 infratentorial infarcts in 81 consecutive cases: 65 infarcts were seen in the paramedian pons, while 18 in the posterior inferior cerebellar artery (PICA) territory and 17 in the watershed area between PICA and superior cerebellar artery. No comparable sign or symptom was observed for 44 (31.2%) infarcts, whereas 66 (46.8%) infarcts appeared symptomatic and 31 (22.0%) infarcts were regarded as equivocal mainly due to the coexisting supratentorial lesions or non-localizing symptoms. The frequent coexistence of basal ganglionic small infarcts in those with infratentorial small (15 mm) infarcts implicated their common pathogenetic background. The fact that atrial fibrillation was seen in 33.3% of those with large (15 mm) infarcts whereas it was seen in only 6.5% of those with small infarcts may suggest a cardiogenic embolism as a possible cause of infratentorial large infarcts. Major artery occlusive lesion was seen in 15 of 22 cases with cerebellar infarction, whereas no occlusive lesion was seen in the majority of cases with pontine small infarcts. With MR imaging, infratentorial infarcts were detected more frequently than in the previous studies based on X-ray CT, and they can be considered as a benign condition.

We interrupted the nocturnal sleep of human subjects for an hour and investigated the effect on body temperature (BT). The interruption elicited sleep onset rapid eye movement period (SOREMP). We compared the BT patterns obtained during nights with SOREMP at the second sleep onset (SOREMP nights) and those obtained during nights without SOREMPs (non-SOREMP nights) with those obtained during baseline nights. BT decreased markedly after sleep interruption on both SOREMP and non-SOREMP nights. It remained lower for 2 hours after the second sleep onset when compared with the corresponding period on the baseline nights. Consequently, the minimum BT was lower and the timing of the minimum was advanced when compared with baseline. The fall of BT after sleep interruption was not accompanied by any increase in slow wave sleep (SWS, stage 3 + 4) when compared with the baseline nights. Thus, we suggest that no direct relationship exists between the decrease of BT and the amount of SWS. On SOREMP nights, the fall of BT from lights-out to the second sleep onset was larger than on non-SOREMP nights. This lower body temperature at the second sleep onset may reflect the physiological background necessary for the appearance of SOREMPs.

Thirty-seven magnetic resonance (MR) examinations were performed at 0.5 T in 33 patients with subarachnoid hemorrhage (SAH) caused by a ruptured aneurysm. Images were obtained 2 hours to 75 days after the ictus. Twenty-four proton-density-weighted (long repetition time [TR], short echo time [TE]) images were obtained in the acute stage (72 hours after the ictus) of SAH; SAH was hyperintense to brain parenchyma and cerebrospinal fluid in all cases. The detectability of acute SAH on T1- (short TR, short TE) and T2- (long TR, long TE) weighted images was 36% and 50%, respectively. In the subacute and chronic stages (3 days after the ictus), the detectability of SAH on T1-, T2-, and proton-density-weighted images was 73%, 31%, and 83%, respectively. Although computed tomography is still the modality of choice for evaluating acute SAH, the authors emphasize that even acute SAH can be reliably demonstrated with MR imaging with the appropriate parameters.

IMP is a flow tracer due to a large first pass extraction fraction and high affinity in the brain, but significant clearance from the brain causes change of distribution when the scan start time is delayed. The purpose of the present study is to develop a new method to rapidly calculate a quantitative CBF image by taking into account for the clearance effects. A dynamic SPECT scan was performed on 5 subjects (4 patients with cerebral infarction and 1 normal volunteer) following slow intravenous infusion of 123I-IMP. The arterial input function was obtained by frequent blood sampling and by measuring an octanol extraction ratio for each sample. Firstly, non-linear least square fitting (NLS) was performed to investigate the tracer kinetics of 123I-IMP. The 3 compartment model analysis yielded negligibly small k3 (retaining rate constant) (0.0056 +/- 0.0128 (ml/ml/min)), and consistent k1 (transport rate constant) with those determined by 2 compartment model (2CM) analysis (r = 0.96, p0.001). In addition, k1 was consistent with CBF measured by 15O water PET technique. These observations suggested validity of using 2CM for describing the IMP tracer kinetics. Secondly, a weighted integration (WI) technique has been implemented to calculate rapidly images of CBF and partition coefficient (Vd). The WI technique yielded values of CBF (k1) and Vd (k1/k2). They were confirmed to be consistent with those determined by NLS technique (CBF; r = 0.99, p0.001, Vd; r = 0.99, p0.001), and calculated k1 agreed well with PET CBF (r = 0.91, p0.001). We observed changed Vd in infarcted patients. This supports an importance for calculating of Vd image. Vd image will provide additional clinical information because 123I-IMP binding mechanism may be related to cell viability.

A 29-yr-old woman was studied for 1 yr after acute carbon monoxide intoxication following an attempted suicide by inhalation of automobile exhaust fumes. The patient demonstrated impaired responsiveness to stimuli without any specific neurological deficits for 1 yr after carbon monoxide intoxication. Repeated brain magnetic resonance imaging consistently displayed only bilateral globus pallidus lesions, but no lesions in either deep white matter or cerebral cortex. Position emission tomography measurements of regional cerebral blood flow, and glucose utilization rate were made in this patient at 6 mo and 1 yr following carbon monoxide intoxication. Impairment of both blood flow and glucose metabolism were found not only in the basal ganglia but also in morphologically normal frontal cortex. The decrease in glucose utilization in the frontal cortex was greater than that in the basal ganglia. During the period of 6 mo to 1 yr, blood flow and glucose metabolism in the basal ganglia recovered to the normal range. In the frontal cortex, however, blood flow and glucose metabolism remained approximately 20% lower than the normal mean values. This prolonged dysfunction in the frontal cortex may therefore be responsible for the impaired responsiveness of the subject.

Magnetic resonance imaging of subarachnoid hemorrhage (SAH) due to aneurysm rupture was evaluated in relation to CT findings in nine patients. Six patients were studied within 3 days and the other three patients were studied 4 to 6 days from the ictus of SAH using a 0.5 Tesla superconducting unit. In all of the patients, hematoma in the subarachnoid space and ventricles was demonstrated by the proton density-weighted spin echo sequence, which showed that bloody cerebrospinal fluid (CSF) had a higher signal intensity than brain tissue or normal CSF. Magnetic resonance imaging was more sensitive in detecting SAH and more informative as to the site of the ruptured aneurysm than CT. Despite some limitations in applying it to patients with acute SAH, magnetic resonance imaging has clear advantages in the diagnosis of SAH.

We studied 15 patients clinically suspected to have recurrent brain tumor or radiation injury, using positron emission tomography (PET) with 18F-fluorodeoxyglucose (18FDG) and L-methyl-11C-methionine (11C-Met). PET with 11C-Met (Met-PET) clearly delineated the extent of recurrent brain tumor as focal areas of increased accumulation of 11C-Met, and was useful for early detection of recurrent brain tumor. PET with 18FDG (FDG-PET) showed focal 18FDG-hypermetabolism in one patient with malignant transformation of low grade glioma, and demonstrated its usefulness for evaluation of malignant transformation. 18FDG-hypometabolism was observed in all patients with radiation injury, but was also found in one patient with recurrent malignant brain tumor. 11C-Met uptake in 3 patients with radiation injury was similar to that of the normal cortical tissue. FDG-PET can be used to initially exclude recurrent brain tumor which is seen as 18FDG-hypermetabolism. The combined use of Met-PET in addition to FDG-PET can improve the accuracy of differentiation of recurrent brain tumor with 18FDG-hypometabolism from radiation injury.

A rare case of multiple medullary venous malformations in the right cerebral hemisphere is reported. The literature review yielded only one case of multiple medullary venous malformations. Computed tomography scan showed multiple calcified lesions with linear contrast enhancement representing abnormal dilated vessels and mild atrophic change of the right cerebral hemisphere. Single-photon emission computed tomography using N-isopropyl-p-(123I) iodoamphetamine demonstrated decreased cerebral blood flow in the right cerebral hemisphere.

The changes of cerebral blood flow (CBF) and metabolism of normal brain tissue after surgery, radiation, and chemotherapy in brain tumor patients were measured by positron emission tomography (PET). The subjects consisted of 6 men and 3 women, and were from 11 to 62 years old. Those were four patients with glioblastomas, one patient with malignant oligodendroglioma, one patient with astrocytoma grade II, one patient with astrocytoma grade III, one patient with pontine glioma, one patient with pineal germinoma. Seven patients were operated and pathohistologically diagnosed. Two patients with pineal germinoma and pontine glioma were not operated and radiologically diagnosed. Of 7 operated patients, first PET was performed before operation in 3 patients, and from 10 to 16 days after operation in 4 patients. Following first PET, the patients were treated with irradiation (1 case), or with both irradiation and chemotherapy (8 cases). The total radiation dose for tumor was from 59 to 61 Gy distributed in a period of 6-8 weeks. Whole brain irradiation was performed up to 30 or 40 Gy, with a remaining dosimetry (20-30 Gy focused on the tumor field. Chemotherapy consisted of intravenous administration of ACNU and oral administration of FT-207. Second PET was performed 1 month after therapy (9 cases), and third PET was performed from 4 to 24 months after therapy (6 cases). Fourth PET was performed in 2 patients (22 and 35 months after therapy), and fifth PET was performed in one patient (35 months after therapy).(ABSTRACT TRUNCATED AT 250 WORDS)

Ten patients with low grade glioma were examined with positron emission tomography (PET) using 11C-methyl-L-methionine (11C-Met). In 4 cases, follow-up study was performed after radiation therapy. 11C-Met uptake index was calculated by sequential arterial blood sampling and PET image on 45 minutes after injection. The tumor was clearly seen in the images, and uptake index in the tumor lesion was higher than that in the normal cortex. The uptake of 11C-Met was observed in a recurrent lesion that was confirmed by operation. 11C-Met uptake indices were decreased in the tumor lesions after radiation therapy. From these results PET with 11C-Met is a useful clinical tool for diagnosis of low grade gliomas.

To investigate changes in cerebral circulation and oxygen metabolism during aging, regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), regional cerebral metabolic rate of oxygen (rCMRO2) and regional cerebral blood volume (rCBV) were measured using the 15O labelled gas inhalation technique and a multi-slice positron emission tomograph (PET) in 22 healthy volunteers, aged from 26 to 64 years old. The measurements were performed with subjects at rest, without sensory deprivation. The values of rCBF, rOEF, rCMRO2 and rCBV in more than 40 anatomical structures of the brain were evaluated by studying a large series of scans in each region of interest after the functional PET image had been anatomically identified using x-ray computed tomographic images corresponding to the PET. In mean gray values, only CMRO2 showed significant reduction with age. rCMRO2 significantly decreased with age only in the supratentrium, and much more in the left hemisphere. Especially remarkable was rCMRO2 reduction in the left caudate region. Both CBF and OEF were variable and less age-dependent. It was concluded that CMRO2 could be reflecting healthy brain aging most properly.

The present study investigated some differences between ‘morning’ and ‘evening’ types in life habits, particularly concerning meals, ingestion of caffeine and alcohol, and smoking. The Life Habits Inventory and the Japanese version of Home and Östberg Morningness-Eveningness Questionnaire were administered to approximately 1500 students, and data on life habits of the morning types were compared with those of the evening types. Significant differences between these types were found in frequency of night meals, smoking, and ingestion of caffeine and alcohol. Although significant differences were not found for mealtimes, 34.8% of the evening types typically did not eat breakfast. These differences were discussed from viewpoint of chronopharmacology and personality.

This article is a survey study, followed by an experimental study, examining the differences of sleep-wake habits and sleep electroencephalographic (EEG) variables between morning and evening type subjects (Ss). In the survey study, the Japanese version of the Horne and Ostberg Morningness-Eveningness Questionnaire and Life Habits Inventory (LHI) were administered to approximately 1,500 university students. The survey results showed that the two types were significantly different from each other in terms of retiring and arising time, sleep latency, mood on arising, nap, adequate amount of sleep, number of times of staying awake all night, and variability in bedtime, arising time, and sleep length. These results suggested that evening type Ss had more irregular and/or flexible sleep-wake habits than morning type Ss. In the experimental study, 10 morning and 11 evening type Ss were selected from the population included in the survey study, and polysomnograms were obtained. The results showed that only in rapid eye movement (REM) latency did morning type Ss significantly differ from evening type Ss. REM latency might be related to personality factors, particularly to neuroticism and anxiety.

Forty-four normal male students, aged 18-23 years were studied. After adaptation and baseline night (BN), 3 or 4 consecutive nights were interrupted by a forced awakening (10-90 min) once a night (ENs). Subjects (Ss) were awakened after they had slept for the first sleep cycle plus 20 min of NREM sleep in the 2nd cycle. The REM latencies following return to sleep showed a bimodal distribution separated by 25-30 min. The ENs were divided into 2 clusters: SOREMP (sleep onset REM period) and non-SOREMP nights. After interruption, the 2nd and the 3rd REM durations increased on non-SOREMP nights compared to SOREMP nights. We plotted, separately for SOREMP and non-SOREMP nights, the fluctuation of REM episode probability (FRP) at successive points in time. We examined the correspondence of FRPs derived from the sleep-independent, the sleep-dependent, and the reset hypotheses, with FRP of intact BN. On both SOREMP and non-SOREMP nights, none of the 3 models corresponded with BN. Thus, we suggest that, for both SOREMP and non-SOREMP nights, intervening wakefulness cancels the pre-awakening REM rhythm, and a new REM rhythm starts with or without SOREMP. We discuss factors influencing the rate of SOREMP occurrence (SOREMP %), such as circadian effect, individual differences, length of interruption, and pre-awakening NREM duration.

In four patients highly suspected of having delayed radiation necrosis of the brain, regional cerebral blood flow and metabolism were studied by using positron emission tomography (PET) with the 15O-labelled gases, 18F-fluorodeoxyglucose (18FDG). All four patients showed marked decreases in glucose and oxygen consumption in the lesion with that suspected pathology in comparison with those in normal brain parenchyma. Two of them were histologically proved to have radiation injuries (one was radiation necrosis and another was early delayed reactions). But one patient was histologically proved to have a recurrent tumor. Although metabolic study with PET using 18FDG is generally an excellent procedure for differentiation between radiation injuries and recurrent brain tumor, these results imply that in some cases the differential diagnosis is difficult even with 18FDG. The present study demonstrated considerably more pronounced reduction in the metabolism than the decrease of the blood flow in the lesion with radiation necrosis. This result would indicate that the primary effect causing the radiation necrosis is a direct effect of irradiation on neural tissue rather than the capillary damage.

The oxygen extraction fraction (OEF) at maximally vasodilated tissue in patients with chronic cerebrovascular disease was evaluated using positron emission tomography. The vascular responsiveness to changes in PaCO2 was measured by the H215O autoradiographic method. It was correlated with the resting-state OEF, as estimated using the 15O steady-state method. The subjects comprised 15 patients with unilateral or bilateral occlusion and stenosis of the internal carotid artery or middle cerebral artery or moyamoya disease. In hypercapnia, the scattergram between the OEF and the vascular responsiveness to changes in PaCO2 revealed a significant negative correlation in 11 of 19 studies on these patients, and the OEF at the zero cross point of the regression line with a vascular responsiveness of 0 was 0.53 ± 0.08 (n = 11). This OEF in the resting state corresponds to exhaustion of the capacity for vasodilation. The vasodilatory capacity is discussed in relation to the lower limit of autoregulation.

Among about 1000 male college students, 6 short and 5 long sleepers were finally selected on the basis of their responses to a sleep habit questionnaire. The subjects slept in the laboratory for 6 consecutive nights. On nights, 4, 5, and 6, deliberate sleep interruption was performed during the second sleep cycle. During interruption, subjects were asked to perform 3 different kinds of tasks on each of the 3 nights. Stage REM latencies after interruption were distributed bimodally with peaks at sleep onset after the interruption (sleep onset REM period: SOREMP) and 50–60 min later (non-SOREMP). SOREMPs were observed only in the sleep of short sleepers. Short sleepers showed a shorter sleep latency and a greater amount of stage REM in the 2nd and the 3rd sleep cycle of their baseline sleep record than did long sleepers. These characteristics of short sleepers' sleep and sleep interruptions probably affected the occurrence of SOREMPs. The mean duration of SOREMPs was significantly shorter than that of non-SOREMPs.

In Japan, a set of experiences called kanashibari is considered identical with isolated sleep paralysis. We investigated this phenomenon by means of a questionnaire administered to 635 college students (390 men and 245 women). Of all subjects, about 40% had experienced at least one episode of kanashibari [subjects of K(+)]. Therefore, isolated sleep paralysis is apparently a more common phenomenon than is usually appreciated. About half of the subjects of K(+) reported that they had been under "physical or psychological stress" or in a "disturbed sleep and wakefulness cycle" immediately before the episode. Many subjects of K(+) experienced the first episode in adolescence. In the distribution of age of first attack, the peak occurred at an earlier age in women subjects than in men subjects. These findings suggest that two factors influence the occurrence of the phenomenon. One is exogenous physical or psychological load and the other is endogenous biological development.

Using positron computed tomography (PCT) and the 15O labeled gas steady-state inhalation technique, regional cerebral blood flow (rCBF), cerebral oxygen consumption (rCMRO2), and oxygen extraction fraction (rOEF) can be measured quantitatively in humans. We quantitatively examined the relationship between focal ischemic lesions and intact regions as detected by X-ray CT in such areas as the territory of the contralateral middle cerebral artery (MCA), thalami, pons, and cerebellar hemispheres. Twenty-three PCT measurements in 13 patients with unilateral ischemic infarction in the MCA territory as detected by X-ray CT were performed. Remote effects from cerebral infarction of the MCA territory were observed in the contralateral MCA territory, ipsilateral thalamus, brainstem, and contralateral cerebellar hemisphere. Slight depression of rCBF and rCMRO2 was also observed in the contralateral thalamus and ipsilateral cerebral hemisphere; rOEF was normal in these areas. Though the depression of rCBF and rCMRO2 due to remote effects was detected in all periods, it was mildly observed 0 to 6 days after onset. The reduction of rCBF and rCMRO2 due to remote effects was less than the morphological as well as the functional threshold. The phenomenon is probably caused by neuronal deactivation, and the regions with depressed blood flow and metabolism may be in a "resting" state.

The criteria of the cerebrovascular Moyamoya disease is defined by the characteristic findings of its cerebral angiograms, as follows; 1) The internal carotid siphon is narrowed or obstructed bilaterally. 2) The "Moyamoya vessels" are observed at the base of the brain or the basal ganglionic regions. 3) Main trunks of the cerebral arteries such as the anterior, the middle, and/or the posterior cerebral arteries are often not or poorly visualized. 4) Its etiology is unknown. It has been known that the occlusion of the internal carotid fork with Moyamoya vessels is not infrequently seen in patients with tuberculous meningitis, sickle cell anemia, head trauma, and so on. In the definition of the disease, patients with known etiology and/or unilateral occlusion in the carotid fork must be excluded. However, the cases who cannot fulfil its criteria of the cerebrovascular Moyamoya disease, but have its characteristic Moyamoya vessels and collateral pathways have been reported. We investigated the findings of cerebral computed tomograms in 13 patients who did not fulfil the criteria of the cerebrovascular Moyamoya disease, but revealed the Moyamoya vessels. The subjects are 5 males and 8 females, ranging 15 to 70 years old. The past histories of 9 patients among them revealed hypertension, radiation therapy for pituitary adenoma, head trauma, aplastic anemia, and the Raynaud phenomenon. By angiographic evaluations, occlusions in the unilateral carotid forks were seen in 7 patients, and stenoses in those were in 5 patients. One patient showed only a severe stenosis in the horizontal portion of the middle cerebral artery.(ABSTRACT TRUNCATED AT 250 WORDS)

We investigated cerebral blood flow and metabolism, and cerebral vascular response in 9 patients with cerebrovascular Moyamoya disease or unilateral Moyamoya phenomenon using positron emission tomography (PET). The subjects consisted of 5 men and 4 women, and were from 9 to 60 years old. Five patients had bilateral occlusion in the carotid fork with Moyamoya vessels (fulfilled the criteria of cerebrovascular Moyamoya disease), and four patients had unilateral Moyamoya phenomenon. The PET scanner used was the HEADTOME III, of which spatial resolution in clinical use was 10 mm full width at half-maximum (FWHM) in the image plane. Cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) were measured in resting state by the 15O-labelled gases steady state method in every patient and 22 normal controls (17 men and 5 women, and from 26 to 64 years old). Consecutively cerebral vascular responses were measured by H215O autoradiographic method in resting state, hypercapnia, hypocapnia, and hypertension. Forced hypercapnia, hypocapnia, and hypertension were achieved by 7% CO2 inhalation, hyperventilation, and venous infusion of angiotensin II, respectively. CMRO2 of the whole brain was significantly lower in patients than in normal controls (p less than 0.05), and CBV of the lentiform nucleus significantly increased in patients (p less than 0.01). This reflected Moyamoya vessels in the basal ganglionic regions. In 3 of 5 patients with bilateral Moyamoya vessels, CBF and CMRO2 in the symptomatic cerebral hemisphere were lower than that in the nonsymptomatic hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

The radioisotope distribution following intravenous injection of 99mTc-labeled hexamethylpropyleneamine oxime (HM-PAO) in the brain was measured by single photon emission computed tomography (SPECT) and corrected for the nonlinearity caused by differences in net extraction. The “linearization” correction was based on a three compartment model, and it required a region of reference to normalize the SPECT image in terms of regional cerebral blood flow distribution. Two different regions of reference, the cerebellum and the whole brain, were tested. The uncorrected and corrected HM-PAO images were compared with cerebral blood flow (CBF) image measured by the C15O2 inhalation steady state method and positron emission tomography (PET). The relationship between uncorrected HM-PAO and PET–CBF showed a correlation coefficient of 0.85 but tended to saturate at high CBF values, whereas it was improved to 0.93 after the “linearization” correction. The whole-brain normalization worked just as well as normalization using the cerebellum. This study constitutes a validation of the “linearization” correction and it suggests that after linearization the HM-PAO image may be scaled to absolute CBF by employing a global hemispheric CBF value as measured by the nontomographic 133Xe clearance method.

Using positron emission tomography, the regional cerebral blood flow (CBF), oxygen extraction fraction (OEF) and oxygen consumption (CMRO2) were studied in 21 patients with hypertensive intracerebral hematomas. The study showed a very localized decrease of CBF and CMRO2 around a hematoma, and revealed in two cases (9.1%) distinct luxury perfusion around it. There was diffuse reduction of CBF with increased OEF in hematomas larger than 4.5 cm in diameter. The results suggested that surgical evacuation should be considered for hematomas with a diameter exceeding 4.5 cm.

Using dynamic positron emission tomographic (PET) scans, kinetic rate constants in the (18F) fluorodeoxyglucose (18FDG) model and glucose consumption rate were measured in human brain tumors. In the tumor tissue, all rate constants were higher on the average in the glioma grade IV and the non-glial tumor groups. The k*3 showed wide deviation in the glioma grade IV group. Discrepancy was found between the k*3 and the glucose consumption rate in several cases. The k*1 correlated with the neovascularity in tumors confirmed at angiography. Analysis of the rate constants might be useful for interpreting tumor nature and predicting its malignancy.