Masahiko Hiroki

Tortuosity of the white matter medullary arterioles is related to the severity of hypertension.

Background: The clinical implication of the tortuosity of white matter medullary arterioles has never been clarified precisely. We quantitatively investigated the relationship between such vascular tortuosity and the severity of hypertension (HT), which was graded according to the WHO classification. Methods: Forty-seven autopsied brains with age-adjusted stages of HT were evaluated. The largest tortuosity diameter and the largest vascular diameter in the same tortuous lesion were measured by light microscopic observation at the level of the corona radiata and centrum semiovale. A maximum ratio of these diameters was calculated for each patient. Results: Maximum ratios were found in almost all arterioles and were significantly increased according to the HT stages. Conclusions: Arteriolar tortuosity in the hemispheric white matter may reflect the severity of HT and be an indicator of hypertensive small vessel disease of the brain.

Linear Hyperintensity Objects on Magnetic Resonance Imaging Related to Hypertension

Linear hyperintensity lesions, which are sometimes recognized in the cerebral white matter on T2-weighted magnetic resonance (MR) images, have never been studied from the clinical viewpoint. We refer to these lesions as linear hyperintensity objects (LHOs) and have investigated them quantitatively. Twenty-six consecutive patients underwent routine 1.5-Tesla MR imaging. LHOs were found in 24 patients. We measured the width and number of LHOs at the upper corona radiata level on T2-weighted images (repetition time: 4,500.0 ms, echo time: 96.0 ms) using a scale loupe. The diameters were significantly correlated with the stages of hypertension (WHO classification). The LHOs may associated with the dilated perivascular spaces of cortical medullary arteries and may become an indicator for hypertensive small vessel disease.

Central Retinal Artery Doppler Flow Parameters Reflect the Severity of Cerebral Small-Vessel Disease

Background and Purpose— We investigated the usefulness of central retinal artery (CRA) Doppler flowmetry in patients with cerebral small-vessel disease (SVD). Methods— CRA Doppler flowmetry was performed in 103 SVD patients who underwent MRI. Sixty-four adjusted control subjects were also registered. We assessed average CRA flow parameter values for both eyes with the clinical and MRI findings. Results— Each Doppler flowmetry was performed within 5 minutes. Patients with SVD had significantly lower end-diastolic and mean velocities of the CRA than control subjects; they also had higher pulsatility and resistive indexes. Multivariate analysis showed that the number of small infarcts was an independent predictor of peak systolic and mean velocities. Grade of periventricular hyperintensities was an additional independent predictor of peak systolic and mean velocities, whereas the number of small infarcts was predictive of end-diastolic velocity. Conclusions— Flow parameters may be useful for the quantitative assessment of SVD severity.

Neural mechanism of propofol anesthesia in severe depression: a positron emission tomographic study.

Background The precise neural mechanisms of propofol anesthesia in humans are still unknown. The authors examined the acute effects of propofol on regional cerebral blood flow (rCBF) using positron emission tomography in patients with severe depression. Methods In six severely depressed patients (mean age, 55.0 yr) scheduled for electroconvulsive therapy, anesthetic levels were monitored by electroencephalography, and rCBF was serially quantified in the awake, sedated, and anesthetized states. The authors used high-resolution positron emission tomography with 15O-labeled water and statistical parametric mapping 99 for imaging and analysis of the data. Results Global cerebral blood flow showed sharp decreases from the awake level during the administration of propofol, decreasing 26.8% in the sedated state and 54.4% in the anesthetized state. Moreover, a dose effect was seen in both parietal cortices and the left lateral prefrontal region with larger regions of relative decrease in rCBF at higher propofol doses. At the higher dose, the values of rCBF in the pulvinar nucleus of the thalamus, the pontine tegmentum, and the cerebellar cortex were also affected. Meanwhile, there were few changes of relative rCBF in the basal frontal lobes during both sedated and anesthetized states. Conclusions As in earlier studies using normal subjects, pronounced suppression in rCBF in the brain stem reticular formation, the thalamus, and the parietal association cortex occurred even in severely depressed patients. However, previously reported decreases in rCBF in the basal frontal lobe were absent in depressed patients.

Link between Linear Hyperintensity Objects in Cerebral White Matter and Hypertensive Intracerebral Hemorrhage

Background: We retrospectively studied the relationship between linear hyperintensity objects (LHOs) on T2-weighted magnetic resonance images (MRI) in the cerebral white matter and the occurrence of hypertensive intracerebral hemorrhage (HIH). Methods: Forty-nine hypertensive patients with a fixed imaging condition MRI were classified into three groups: HIH (n = 17), ischemic stroke due to hypertensive vasculopathy (n = 19), and hypertension only (n = 13). After assessing clinical and radiological background information among these groups and the reliability of LHO measurements, polynomial logistic regression analysis was used to identify the factors relating to HIH. Results: HIH had a significantly higher LHO number (p = 0.002) and larger diameter (p = 0.007). The LHO number showed an excellent interrater (ĸ = 0.91, 95% CI = 0.87–0.94, SEM = 6.2%) and intrarater reliability (ĸ = 0.95, 95% CI= 0.92–0.97, SEM = 4.8%), and was the most significant independent indicator of HIH (OR = 1.29, 95% CI = 1.05–1.60, p = 0.017). The number of microbleeds was an additional indicator (OR = 3.73, 95% CI = 1.10–12.65, p = 0.034). Conclusions: LHOs are closely linked to HIH. A prospective, longitudinal study is needed to clarify whether LHOs can predict HIH.

Functional neuroanatomy of human non-rapid eye movement sleep: A study using a positron emission tomography

Abstract In order to clarify the neural correlates and brain functions during non-rapid eye movement (NREM) sleep, regional cerebral blood flow (rCBF) were measured using positron emission tomography (PET) in healthy male subjects. During light NREM sleep, the rCBF in the midbrain, in contrast to that in the pons and thalamic nuclei, did not decrease when compared to that during wakefulness, while rCBF decreased in the left medial frontal gyrus, left inferior frontal gyrus, and left inferior parietal gyrus of the neocortex. During deep NREM sleep, the rCBF in the midbrain tegmentum decreased and there was a marked and bilateral decrease in the rCBF in all neocortical regions except for the peri-rolandic areas and the occipital lobe. Thus, the activity of the midbrain reticular formation may be maintained during light NREM sleep. Furthermore, selective deactivation of heteromodal association cortices including those related to language, may occur during NREM sleep, which supports the recent theory that sleep is a local, use-dependent process of the brain.

Paraparesis due to capsular hemorrhages

To the Editor: Takaya et al.1 report on a patient with paraparesis with bilateral capsular hemorrhages. In order to fit the space allowed to the text for Neuro Images , the clinical details are scant. Although the lesions shown in the CT scan could impinge upon the internal capsule, they are centered in the lateral thalamic region and the suprathalamic white matter on both sides. Lesions in this location have caused a motor syndrome consisting of inability to walk without sensory loss, due to impairment of postural reflexes and a misperception of the vertical axis (thalamic astasia).2,3⇓ Unilateral lesions do occur, but simultaneous bilateral lesions are rare. I would …