Biomedical subjects

Yasuhiro Hasegawa

Publications and source records attributed to Yasuhiro Hasegawa.

23 records · Page 2Linked to original sources

PubMed2002

Acetazolamide challenge test using semiquantitative 123 I-IMP SPECT for detection of cerebral misery perfusion.

The accuracy of the acetazolamide (ACZ) challenge test using semiquantitative SPECT in detecting Stage II hemodynamic failure, i.e. cerebral misery perfusion, in patients so diagnosed with PET has yet to be determined. This study was carried out in 53 patients who had a unilateral occlusion or severe stenosis of their cerebral artery. Asymmetry index (AI) was used to determine relative CBF distribution on each SPECT image. DeltaAI (regional vasodilatory capacity) values were compared with the values of several PET parameters. We also repeated SPECT and PET studies in 15 patients after a mean interval of 2.6 years from entry. The correlation between changes in DeltaAI and PET data were examined. The DeltaAI value closely correlated with the ipsilateral OEF value (r=-0.64, p<0.001). Sensitivity-specificity curve analysis revealed that the optimal cut-off value for detecting Stage II hemodynamic failure was -13.5% of DeltaAI, at which point the diagnostic accuracy was 82%. In follow-up studies, changes in DeltaAI correlated significantly with changes in OEF values (r=-0.68, p<0.01). Semiquantitative SPECT examination with ACZ challenge detects Stage II hemodynamic failure with a diagnostic accuracy of 82%. An improvement in reduced vasodilatory capacity as determined by SPECT coincides with a reduction in OEF values.

Acetazolamide↗

PubMed2002

Unique profile of spreading depression in a primate model.

Spreading depression (SD) is considered to play a role in pathologic conditions of humans such as in the evolution of ischemic brain injury and migraine aura. Because many studies have demonstrated spreading hypoperfusion in patients with migraine and persistent hypoperfusion in nonprimate animal models of SD, these changes in cerebral blood flow (CBF) were regarded as an epiphenomenon of SD. However, there is no direct evidence of the occurrence of SD in primates. The authors attempted to elicit SD by applying 3.3 mol/L potassium chloride to the cerebral cortex of nine male cynomolgus monkeys. The CBF was monitored by positron emission tomography in five animals. Propagated direct-current shifts were found by the two neighboring microelectrodes only in one animal. The direct-current wave propagated at a speed of 4 mm/min and its amplitude was 20 mV, being consistent with the SD findings. Except in one animal with 6 SD episodes, SD waves were recorded infrequently at the rostral site (none in three animals, once in three, and twice in two). Focal hyperemia accompanied SD. Neither spreading hypoperfusion nor persistent hypoperfusion was found. These unique features of SD in primates raise a doubt as to whether the role of SD in nonprimate animals is the same as that in stroke and migraine in humans.

Animals↗

PubMedDate not supplied

Pathogenesis and diagnosis of delayed vertebral collapse resulting from osteoporotic spinal fracture.

BACKGROUND CONTEXT: In recent years there have been an increasing number of reports on surgical cases involving delayed neurological deficits caused by vertebral collapse after osteoporotic vertebral fracture. PURPOSE: We do not yet know which patients are most susceptible to delayed vertebral collapse and subsequent neurological deficits, or whether this pathological condition can be prevented or predicted. In this study, we investigated the mechanism of progression and radiographic features characteristic of this disease, and we report here the predictive or risk factors for delayed osteoporotic vertebral collapse. STUDY DESIGN: Retrospectively, we investigated the pathogenesis and diagnosis of delayed vertebral collapse with neurological deficit resulting from osteoporosis. PATIENT SAMPLE: A total of 28 patients (7 men and 21 women) with neurological deficits resulting from vertebral collapse caused by osteoporotic vertebral fractures were the subjects for this study. OUTCOME MEASURES: Comparisons and investigations about clinical features and radiographic findings between the patient group of delayed vertebral collapse with neurological deficits and the group of osteoporotic spinal fracture with no neurological deficits. METHODS: The following factors were examined: the cause of injury; the length of time from injury, or the onset of pain, to the onset of neurological symptoms; radiographic findings obtained during the above period; the clinical course of vertebral fracture on plain X-ray films; time of appearance of the intravertebral cleft, and its localization and changes. RESULTS: Six patients were hospitalized and prescribed a period of 2 weeks of bed rest followed by the fitting of a corset; seven outpatients were corseted but not prescribed bed rest; 15 patients were given medication only at an outpatient clinic. At radiography, intravertebral clefts were detected in 22 patients (79%) during the period from the appearance of pain to the onset of neurological deficit. In 14 patients (50%) who were radiographed every 1 to 2 weeks from the injury to the onset of neurological symptoms, the course of progression to collapse of the vertebral body could be observed. CONCLUSION: Initial correct diagnosis and immobilization are important in preventing the delayed collapse with neurological deficit. The presence of an intravertebral cleft and instability of the affected vertebra represent risk factors for vertebral collapse with neurological deficit, requiring careful observation.

Aged↗

PubMedDate not supplied

Smoking-induced olfactory dysfunction in chronic sinusitis and assessment of brief University of Pennsylvania Smell Identification Test and T&T methods.

BACKGROUND: To evaluate the outcome of smell activity after endoscopic sinus surgery in chronic sinusitis, it is important to verify evidence of smoking-induced olfactory dysfunction. METHODS: In both the preoperative and the postoperative stages, the 5-odorant T&T olfactometer (T&T5) and the 40-item University of Pennsylvania Smell Identification Test (UPSIT40) were administered to 100 patients (84 men and 16 women; mean age, 49.5 years; range, 21-75 years) who underwent surgery for chronic sinusitis. Additionally, as more simplified measures, we adopted a 3-odorant T&T (T&T3) and a 12-item UPSIT (UPSIT12), and then compared findings with those of each original method. RESULTS: (1) Obvious correlations of scores were noticed both between T&T5 and T&T3 and between UPSIT40 and UPSIT12 (r = 0.964 and 0.893, respectively), (2) significant changes in postoperative scores were observed on all four measurements (p < 0.0001), (3) smoking-induced hyposmia was noticeable in older subjects but not in younger subjects, and (4) the correlations of postoperative scores and the age of smoker or the smoking dose was significant (UPSIT40, r = 0.825 or 0.642; UPSIT12, r = 0.666 or 0.428; T&T5, r = 0.447 or 0.476; T&T3, r = 0.457 or 0.500, respectively). CONCLUSION: The abbreviated measures of T&T3 and UPSIT12 could be available enough to assess the effect of surgical intervention on olfaction, while the original UPSIT40 was considered to be the most sensitive among the four methods tested here for examining the impact of smoking on olfaction.

Adult↗

PubMedDate not supplied

Highly diffusion-sensitized tensor imaging of unilateral cerebral arterial occlusive disease.

BACKGROUND AND PURPOSE: Selective neuronal death is a well-recognized histopathologic sequel to moderate ischemic brain damage. However, radiologic visualization of these changes has not been established, even with diffusion tensor imaging (DTI). We sought to determine whether DTI with b values > or =1900 s/mm(2) reveals occult diffusion abnormalities in patients with cerebral arterial occlusive disease. METHODS: Six patients (five men, one woman; mean age +/- standard deviation, 66 +/- 8 years) with unilateral internal carotid or middle cerebral arterial occlusive disease but not parenchymal T2 hyperintensity underwent 3T fast DTI with b < or = 1300 s/mm(2) and slow DTI with b > or = 1900 s/mm(2). We postprocessed mean diffusibility and fractional anisotropy (FA) images from the fast and slow DTI datasets. Standardized asymmetry indices (AIs) were used to identify regional asymmetries. Diagnostic accuracy among the DTI modalities was assessed by means of receiver operating characteristic analysis. RESULTS: In hemispheres ipsilateral to occluded vessel, AIs were significantly elevated on fast mean-diffusibility images of white matter at the levels of the internal capsule (95% confidence interval [CI]: 1.00, 1.09; P = .045) and corona radiata (95% CI: 1.01, 1.12; P = .034). AIs were significantly decreased on slow FA images at the internal capsule (95% CI: 0.84, 0.98; P = .018) and white matter at the internal capsule level (95% CI: 0.92, 1.00, P = .043). The slow FA map had the highest accuracy (89.8%) for detecting the hemisphere ipsilateral to arterial occlusion. CONCLUSION: Slow FA maps acquired by using DTI with high b values are useful for visualizing ischemic brain damage in apparently normal WM.

Aged↗