Yasuyuki Iguchi

The Jikei University School of Medicine, Edo, Tōkyō, Japan

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Publications (173)452.2 Total impact

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    ABSTRACT: Background and purpose: Hyperintense vessels (HV) detected on fluid-attenuated inversion recovery (FLAIR) in patients with acute ischemic stroke (AIS) indicate cerebral hypoperfusion. However, the clinical meaning of changes in HV is yet to be clarified. Here, we investigated serial changes to HV in patients with AIS who received tissue plasminogen activator (t-PA) therapy. Methods: We studied t-PA patients presenting with HV on FLAIR in the middle cerebral artery territory. Patients underwent brain MRI 1 h before and after t-PA infusion. HV scores (range 1-7) were evaluated according to Alberta Stroke Program Early Computed Tomography Score territories, and then by subtracting HV scores at 1 h after t-PA infusion from those on admission, with a result of >1 defined as decrease in HV score (DHV). Patients were divided into 2 groups based on the presence or absence of DHV. Multivariate logistic regression analysis was conducted to identify variables independently associated with good outcome (modified Rankin Scale score at 90 days after stroke onset of 0-1). Results: A total of 118 consecutive patients were enrolled (73 men; mean age 76 ± 9.7; median initial National Institutes of Health Stroke Scale (NIHSS) 13; median initial HV score 5), of whom 52 (44%) had DHV. Patients with DHV showed a significantly lower NIHSS time course (p < 0.001) and significantly smaller infarct volume time course (p < 0.001) compared to those without DHV. Multivariate analysis showed that DHV was independently associated with good outcome (OR 3.89; 95% CI 1.55-9.77; p < 0.01). The sensitivity and specificity of DHV for good outcome were 70 and 68%, respectively. Conclusion: A DHV on FLAIR predicts good outcome in patients receiving t-PA.
    No preview · Article · Jan 2016 · Cerebrovascular Diseases
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    Preview · Article · Nov 2015
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    ABSTRACT: Purpose: Vertebral artery hypoplasia (VAH) is a common congenital anatomical variation. In previous reports, it was unclear whether VAH was an independent risk factor for posterior circulation ischemia. The purpose of this study was to evaluate the impact of VAH on posterior circulation ischemia. Methods: Subjects were patients with acute ischemic stroke who underwent brain magnetic resonance imaging (MRI) and carotid ultrasonography. Diagnostic criteria for VAH were as follows: (1) Vertebral artery (VA) diameter less than 2.5 mm; (2) VA diameter less than 3.0 mm and a difference in length equal to or greater than 1:1.7; (3) VA diameter less than 3.0 mm, peak systolic velocity less than 40 cm/second, and resistance index value greater than .75. The patients were categorized by the location of the ischemic stroke on MRI as follows: lesion in posterior circulation (P group), lesion in anterior circulation (A group), and multiple lesions in both the anterior and posterior circulations (AP group). Results: We evaluated 129 consecutive patients. VAH was seen in 39, and VA occlusion was found in 15. The prevalence of VAH in the P group (44.4%) was significantly higher than that in the A + AP group (24.7%, P = .034). Multivariate regression analysis showed that large-artery atherosclerosis (odds ratio, 6.3; 95% confidence interval [CI], 1.3-30.1), posterior circulation ischemia (odds ratio, 12.0; 95% CI, 2.8-51.2), and VAH (odds ratio, 4.2; 95% CI, 1.2-15.0) were independent factors related to VA occlusion. Conclusion: VAH was an independent factor related to VA occlusion. Therefore, VAH likely plays a role in posterior circulation ischemia.
    No preview · Article · Nov 2015 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
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    Y Kuroiwa · K. Nishioka · S. Yokota · T. Hirai · K. Fujino · Y. Iguchi

    Preview · Article · Nov 2015
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    S. Mochio · H. Matsuno · S. Miyagawa · C. Toyoda · H. Oka · Y. Iguchi

    Preview · Article · Oct 2015
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    ABSTRACT: A 30-year-old man presented with headache, left hemiparesis, and uncal herniation. Magnetic resonance imaging showed acute infarction in the right middle cerebral artery (MCA). Lifesaving craniotomy proceeded because of the uncal herniation. Assessment of brain tissue led to a diagnosis of MCA dissection. His skin biopsy showed ultrastructural abnormalities of dermal connective tissue. This is the unique case that dissection was diagnosed from both a biopsy specimen of the MCA and the dermal connective tissue. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Aug 2015 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
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    ABSTRACT: A 73-year-old woman was admitted with severe burning pain, hyperesthesia, and weakness in the right lower extremity. The patient had undergone radio- and chemotherapy after surgery for cervical cancer 17 years earlier. We diagnosed radiation-induced lumbosacral plexopathy because of conduction block in the deep peroneal nerve and myokymic discharge in the tibialis anterior muscle. Pelvic computed tomography and magnetic resonance imaging ruled out recurrent tumor and nerve-compressing lesions. Although radiation-induced lumbosacral plexopathy is usually characterized by lower motor neuron syndrome, we report a rare case presenting with severe pain and hyperesthesia.
    Full-text · Article · Jul 2015
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    ABSTRACT: Carotid duplex ultrasonography (CUS) has been used to identify reversed vertebral artery flow (RVAF) at the extracranial cervical artery in some patients with subclavian steal syndrome. However, the characteristics of intracranial RVAF as evaluated by transcranial color flow imaging (TC-CFI), which can examine intracranial hemodynamics in a real-time and noninvasive fashion, remain unclear. The goal of this study was to analyze the prevalence of intracranial RVAF and its associated clinical characteristics. Subjects were consecutive patients who underwent TC-CFI and CUS. We evaluated blood flow in both intracranial vertebral arteries (VAs) from the suboccipital echo window using TC-CFI. RVAF was defined as a flow signal directed toward the probe. We calculated the prevalence of intracranial RVAF in our subjects. Then, we investigated vascular condition (ie, site of lesion, stenosis, occlusion, and dissection) using magnetic resonance angiography, computed tomography angiography , and CUS in patients with intracranial RVAF. Seven hundred twenty patients (508 men; median age, 73 years) were included in this study from September 2007 to March 2013. Intracranial RVAF was seen in 12 patients (1.7%; 11 men; median age, 61 years). Among the 12 patients with intracranial RVAF, 8 patients (67%) had ischemia of the vertebrobasilar territory with distal VA occlusion, according to CUS. Of those patients, 6 (75%) had dissection of the VA. TC-CFI detected intracranial RVAF in 1.7% of consecutive examinations in our facility. In vertebrobasilar territory stroke patients with intracranial RVAF, VA dissection may contribute to the development of stroke. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Jun 2015 · Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association
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    Shinji Miyagawa · Ayumi Arai · Hidetaka Mitsumura · Yasuyuki Iguchi
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    ABSTRACT: A patient started anticoagulation for secondary prevention of stroke, achieving a prothrombin time-international normalized ratio within the optimal therapeutic range. The patient subsequently complained of pain in the left thigh on hospital day 25, and ultrasonography showed a large intramuscular hematoma in the left hamstring. The intramuscular hematoma gradually reduced without surgical intervention. Ultrasound examination plays an important role in precisely diagnosing intramuscular hematoma and monitoring changes in hematoma size.
    Preview · Article · Jun 2015
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    ABSTRACT: This study aimed to examine whether the volume of the olfactory bulbs and tracts (OB & T) on magnetic resonance imaging (MRI) is useful for differentiating Parkinson's disease (PD) from PD-related disorders. The study group comprised 13 patients with PD, 11 with multiple system atrophy (MSA), five with progressive supranuclear palsy, and five with corticobasal degeneration (PSP/CBD). All patients were evaluated using the odor stick identification test for Japanese (OSIT-J), (123)I-meta-iodobenzylguanidine (MIBG) scintigraphy, and brain MRI. OB & T areas on 1-mm-thick coronal images were measured and summed for volumes. We examined relationships between olfactory function and volume, and cardiovascular dysautonomia. We defined the cut-off values for OSIT-J score or MIBG uptake and OB & T volume to discriminate PD from PD-related disorders and calculated the proportional rate of PD in four categorized groups. OB & T volume was smaller in PD than in MSA or PSP/CBD (p < 0.05 each). The cut-off for detecting PD patients was OSIT-J score <8, heart/mediastinum ratio <1.6, and OB & T volume <270 mm(3). In the group with OSIT-J score <8 and OB & T volume <270 mm(3), the proportion of PD patients among all patients with PD-related disorders was 91%. The rate of probable PD gradually increased as OSIT-J score and OB & T volume decreased (p < 0.001). Although preliminary, these data obtained from a combined morphological and functional evaluation of OB or cardiovascular dysautonomia could be useful for further differential of PD and other PD-related disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · May 2015 · Parkinsonism & Related Disorders
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    ABSTRACT: Little is known about the ill effects of concurrent obstructive sleep apnea (OSA) on the symptoms of myasthenia gravis (MG). We report a case of generalized MG with OSA in which MG symptoms improved dramatically following initiation of continuous positive airway pressure (CPAP) therapy. A 42-year-old man was admitted with generalized MG. He was found to be snoring loudly during sleep and then diagnosed with OSA by polysomnography. CPAP therapy contributed to immediate improvements in not only apnea-hypopnea index (70.6 to 20.9), but also the MG-specific activities of daily living scale (10 to 1) and quantitative MG scale (21 to 8). We suggest that when an MG patient is obese and suspected to have sleep problems, examinations to detect OSA should be conducted. If OSA is diagnosed, CPAP therapy may also improve the MG symptoms of the patient.This article is protected by copyright. All rights reserved.
    No preview · Article · Apr 2015
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    ABSTRACT: Case presentationAn 86-year-old, right-handed man was admitted to our hospital 3 h after onset of a disturbance of consciousness. He had a history of hypertension. His blood pressure was 170/106 mmHg, and heart rate was 96 beats/min with a regular rhythm. Neurological examination revealed a disturbance of consciousness, aphasia, and right unilateral spatial neglect. His muscle strength was weak on his right side. The total National Institute of Health stroke scale score on admission was 16. Laboratory data showed that the D-dimer was 5.2 μg/mL (normal, 1a). DWI also indicated subacute (and apparently asymptomatic) infarctions in the right occipital lobe and cerebellum (Fig. 1b, c). Acute stroke was diagnosed, and intravenous (IV) recombinant tissue plasminogen activator (rt-PA) therapy was started 4.2 h after symptom onset. ...
    Full-text · Article · Mar 2015 · Neurological Sciences
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    ABSTRACT: For safe and efficient sonothrombolysis therapies, accurate estimation of ultrasound transmittance through the human skull is essential. The present study clarifies uncertainty surrounding this transmittance and experimentally verifies the equalization of transmittance through the modulation of ultrasound frequency. By changing three factors (ultrasound frequency, the thickness of a bone-phantom plate, and the distance between a transducer and a bone-phantom plate), we measured the intensity of ultrasound passing through the plate. Two activating methods, sinusoidal waves at 500kHz and modulated waves, were compared. When we changed (1) the distance between a transducer and a bone-phantom plate and (2) the thickness of the bone-phantom plate, ultrasound transmittance through the plates substantially fluctuated. The substantial fluctuation in transmittance was observed also for a cut piece of human temporal skull bone. This fluctuation significantly declined for the modulated wave. In conclusion, modulation of ultrasound frequency can equalize the transmittance with an approximately 30-65% fluctuation drop and an approximately 40% fluctuation drop for a bone-phantom plate and for a cut piece of skull bone, respectively. By using modulated waves, we can develop safer and more effective sonothrombolysis therapies. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Feb 2015 · Ultrasonics
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    ABSTRACT: Since the administration of intravenous tissue plasminogen activator (IV t-PA)was approved in 1995, stroke care has changed dramatically with a highly time-dependent aspect. Among 698 cases with first-ever and recurrent cerebral infarction, thrombolysis was administered for only 5% of these patients and for only 16% of patients admitted within 3 hours of onset. To broaden the eligibility of patients for IV t-PA, stroke symptom awareness for the general populace, secure patient transportation by ambulance supported by emergency medical services, and telemedicine are needed to minimize the duration from symptom onset to hospital arrival and decrease the time to physical examination on admission. In the stroke center itself, appropriate identification of hyper-acute cerebral infarction by stroke specialists appears likely to also increase the number of candidates for IV t-PA. Finally, endovascular therapy and sonothrombolysis in combination with IV t-PA should play an important role in improving the recanalization rate and long-term outcome. © 2015 Japanese Congress of Neurological Surgeons. All rights reserved.
    Full-text · Article · Jan 2015 · Japanese Journal of Neurosurgery
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    ABSTRACT: An 85-year-old woman came to our hospital due to an inability to live independently from a decline in her activities of daily living. Neurologically, she showed no focal signs, but multiple acute ischemic lesions were evident in the posterior circulation on magnetic resonance imaging. Occlusion of the right intracranial vertebral artery (VA) and stenosis of the left intracranial VA were detected on magnetic resonance angiography (MRA). Carotid duplex ultrasonography (CUS) showed a flow pattern with occlusion of the right VA before the branching of the posterior inferior cerebellar artery. Based upon antegrade flow in the right intracranial VA as evaluated on transcranial color flow imaging, the distal VA territory might have been maintained via collateral flow. With antiplatelet therapy and intravenous injection of argatroban, the patient’s activity gradually improved to the same level as before admission. Recanalization of the right VA was seen on MRA and CUS at 14 days after admission. Reduced cerebellar blood flow due to VA occlusion was thought to be associated with the mechanism affecting her activity levels. Follow-up ultrasonography was useful for evaluating changes in intracranial hemodynamics in this patient who demonstrated neurological improvement.
    No preview · Article · Jan 2015 · Neurosonology
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    ABSTRACT: Background The goal of this study was to investigate the relationship between white matter lesions on magnetic resonance imaging and flow parameters in the middle cerebral artery (MCA) measured by transcranial color flow imaging. Methods Patients with acute ischemic stroke or transient ischemic attack were included. The relationship between severities of periventricular hyperintensity (PVH) and ultrasonographic parameters in the MCA was investigated. The frequency of PVH was calculated for different categories according to the presence or absence of 2 considerable parameters according to the value of area under the receiver operating characteristic curve. Results MCA flow was successfully measured in 203 temporal windows among 124 patients. After determining the cutoff value of end-diastolic velocity (EDV) and pulsatility index (PI) for the presence of PVH, 4 different categories were established: Category A, EDV more than 40 cm/second and PI less than .7; Category B, EDV more than 40 cm/second and PI more than .7; Category C, EDV less than 40 cm/second and PI less than .7; and Category D, EDV less than 40 cm/second and PI more than .7. The prevalence of PVH gradually increased along with category (P < .01). Conclusions The evaluation of MCA parameters using the combination of PI and EDV may be useful for the prediction of PVH.
    No preview · Article · Oct 2014 · Journal of Stroke and Cerebrovascular Diseases
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    ABSTRACT: Objective: The usefulness of conventional magnetic resonance imaging (C-MRI) for diagnosing amyotrophic lateral sclerosis (ALS) remains controversial. The aim of this study was to investigate the utility of C-MRI in identifying ALS, specifically the association between corticospinal tract (CST) hyperintensity on C-MRI and clinical characteristics in patients with ALS. Methods: Between June 2008 and April 2012, we retrospectively enrolled consecutive patients diagnosed with sporadic ALS who underwent C-MRI. Patients with ALS were classified as definite-phase ALS (D-ALS) and indefinite-phase ALS (ID-ALS). We focused on the hyperintensity of T2-weighted images in the CST in patients with ALS. Based on the MRI results, we divided patients into two groups: a positive CST group showing CST hyperintensity; and a negative CST group with no such findings. Clinical characteristics of the two groups were compared. Results: Seventeen patients (median age, 62 years; 8 women, 9 men) were enrolled in this study, with D-ALS in eight (47%) and ID-ALS in nine (53%). Eight patients (47%) showed CST positivity. The rate of CST positivity was higher in patients with D-ALS (75%) than in patients with ID-ALS (22%, p=0.03). Conclusions: CST positivity appears significantly increased in D-ALS patients. C-MRI can play an important role in diagnosing ALS.
    No preview · Article · Oct 2014 · Clinical Neurology and Neurosurgery
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    ABSTRACT: A 49-year-old man with a 16-year history of adult-onset X-linked adrenoleukodystrophy (X-ALD) was admitted because of aspiration pneumonia. He was comatose with obvious akinesia and positive plantar reflexes. Magnetic resonance imaging (MRI) on admission showed abnormal intensities in the middle cerebellar peduncles, pons and internal capsule (Fig.1).This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2014
  • Yasuyuki Iguchi · Hideki Mitsumura · Teppei Komatsu

    No preview · Article · Aug 2014 · Nihon Naika Gakkai Zasshi
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    ABSTRACT: A 76-year-old woman was admitted to our hospital because of convulsions that developed after a 1-month history of progressive right-leg palsy. MRI showed thickening of the meninges with gadolinium enhancement in the left parietal lobe and it revealed pia-subarachnoid space pattern. A lumbar puncture was performed, and cerebrospinal fluid analysis revealed no abnormality. Her serum adenosine deaminase level was elevated (28.7 IU/l). The results of serum cultures were normal. To differentially diagnose collagen disease, infection, malignancy, and inflammation of uncommon causes, we conducted brain and meningeal biopsies on the 15th hospital day. Histopathological examination of the brain tissue showed mainly necrosis and inflammation. There was severe pachymeningeal thickening without necrosis. Although it was difficult to reach a definitive diagnosis, a tissue sample taken from under the leptomeninges tested positive for mycobacterium on Ziehl-Neelsen staining. The results of polymerase chain reaction for mycobacterium were negative in the meningeal tissue. The patient received anti-tuberculous drugs, anti-nontuberculous mycobacteriosis drugs, and corticosteroids to treat Mycobacterium tuberculosis and nontuberculous mycobacterium. After starting treatment, the findings on magnetic resonance imaging improved dramatically, and no convulsions occurred during hospitalization. She was discharged on the 153rd hospital day without any neurological deficit. Because previous studies have reported that isolated mycobacterium meningitis is a diagnostically challenging condition, brain and meningeal biopsies should be considered in patients with gadolinium enhancement in the meninges.
    No preview · Article · Mar 2014

Publication Stats

2k Citations
452.20 Total Impact Points


  • 2013-2015
    • The Jikei University School of Medicine
      • Division of Neurology
      Edo, Tōkyō, Japan
  • 2005-2013
    • Kawasaki Medical University
      • • Department of Stroke Medicine
      • • Department of Neurology
      Kurasiki, Okayama, Japan
  • 2006
    • Yokohama Brain and Stroke Center
      Yokohama, Kanagawa, Japan
  • 2004
    • University of Houston
      Houston, Texas, United States