Mitsuhiro Hara

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (49)90.13 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To image cerebral neural activity in ischemic areas, we proposed a novel technique to analyze spontaneous neuromagnetic fields based on standardized low-resolution brain electromagnetic tomography modified for a quantifiable method (sLORETA-qm). Using a 160-channel whole-head-type magnetoencephalographic system, cerebral magnetic fields were obtained pre- and postoperatively from 5 patients with unilateral internal carotid artery occlusive disease and 16 age-matched healthy volunteers. For quantitative imaging, voxel-based time-averaged intensities of slow waves in 4 frequency bands (0.3-2 Hz, 2-4 Hz, 4-6 Hz and 6-8 Hz) were obtained by the proposed technique based on sLORETA-qm. Positron emission tomography with (15)O gas inhalation ((15)O-PET) was also performed in these patients to evaluate cerebral blood flow and metabolism. In all 5 patients, slow waves in every frequency band were distributed in the area of cerebrovascular insufficiency, as confirmed by (15)O-PET preoperatively. In 4 patients, slow-wave intensities in theta bands (4-6 Hz, 6-8 Hz) decreased postoperatively along with improvements in cerebral blood flow and metabolism, whereas delta bands (0.3-2 Hz, 2-4 Hz) showed no significant differences between pre- and postoperatively. One patient with deterioration of cerebral infarction after surgery showed marked increases in slow-wave intensities in delta bands (0.3-2 Hz, 2-4 Hz) postoperatively, with distribution close to the infarct region. The proposed quantitative imaging of spontaneous neuromagnetic fields enabled clear visualization and alternations of cerebral neural conditions in the ischemic area. This technique may offer a novel, non-invasive method for identifying cerebral ischemia, although further studies in a larger number of patients are warranted.
    NeuroImage 08/2009; 49(1):488-97. DOI:10.1016/j.neuroimage.2009.07.039 · 6.36 Impact Factor
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    ABSTRACT: The objective of this retrospective study is to analyze whether preoperative functional imaging studies using FDG-PET and MEG enable prediction of postoperative seizure outcomes. Thirty-six patients with intractable temporal lobe epilepsy were studied. Asymmetry index of tCMRgluc (PET-AI) and the equivalent current dipole intensity of first response of SEF (SEF-AI) were determined preoperatively using (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and magnetoencephalography (MEG), respectively. Seizure outcomes were evaluated according to the classification proposed by the International League Against Epilepsy (ILAE) at least 24 months after resection of epileptic focuses. Twelve healthy volunteers were included in this study to determine the normal value. Quantitative analysis revealed mean PET-AI in the patients was 5.4+/-5.2% (significantly different from normal controls); mean SEF-AI was 25.2+/-20.6% (not significantly different). PET-AI was positive (indicative of epileptic focus) in 29 of 36 patients (80.6%), while SEF-AI was positive in 17 of 36 patients (47.2%). Although no significant correlation between PET-AI and SEF-AI was noted (r=0.43), concordant asymmetry in both PET-AI and SEF-AI was significantly associated with better seizure outcome than discordant or paradoxical asymmetry of both factors (p<0.01). The results suggest that quantitative analysis of tCMRgluc with SEF may be helpful in characterizing the preoperative epileptogenic condition and predicting postoperative seizure outcome in patients with temporal lobe epilepsy, although a constellation of developmental brain abnormalities and environmental factors that together produce epilepsy need to be further explored.
    Seizure 06/2008; 18(1):1-6. DOI:10.1016/j.seizure.2008.05.004 · 1.82 Impact Factor
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    ABSTRACT: RCAS1, one of the tumor cell surface antigens, is strongly expressed in aggressive tumors. RCAS1 suppresses the in vitro growth of immune effector cells. We investigated the expression of RCAS1 in 57 gliomas using immunohistochemistry. Furthermore, we examined the association of the RCAS1 expression with the infiltration of tumor infiltrating lymphocyte (TIL). RCAS1 overexpression was significantly correlated with high histological grade and poor prognosis. Reduced infiltration and increased apoptosis of TILs was observed in RCAS1-positive regions. Apoptotsis of TILs appeared to be induced by RCAS1. RCAS1 expression in gliomas may play roles in tumor progression and tumor immune escape.
    Cancer Letters 03/2007; 246(1-2):182-9. DOI:10.1016/j.canlet.2006.02.021 · 5.62 Impact Factor
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    ABSTRACT: Surgical procedures for cerebral hemispherotomy may be broadly divided into those using a lateral and those using a vertical approach. However, careful study of surgical procedures using the lateral approach described in the literature shows differences in the approach to the ventricles. We discuss the application of transventricular hemispherotomy as a technique which provides relatively easy ventricular access for cerebral hemispherotomy. Transventricular hemispherotomy was successfully performed in a 36-year-old woman who was diagnosed with intractable epilepsy due to Sturge-Weber disease, and in a 25-year-old man who had developed intractable post-traumatic seizures after suffering cerebral contusion in a traffic accident as a child. These patients had no seizures or complications after surgery, and both patients have been weaned from antiepileptic drugs. The transventricular approach, as compared with other lateral approaches described in the literature, provides easy access to the ventricular cavity. Transventricular hemispherotomy proved to be a useful approach that allowed the following four common steps in cerebral hemispherotomy to be performed safely: (i) interruption of the internal capsule and corona radiata; (ii) resection of the medial temporal structures; (iii) transventricular corpus callosotomy; and (iv) disruption of the frontal horizontal fibers.
    Journal of Clinical Neuroscience 03/2007; 14(2):171-5. DOI:10.1016/j.jocn.2005.11.051 · 1.38 Impact Factor
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    ABSTRACT: Experimental spinal cord injury (SCI) with focal spinal tissue scarring was studied to better understand the progressive post-traumatic myelomalacia (PPM). Using a stereotactic device, the authors developed an acute compression of spinal cord at Th-10 in the adult rat. In Group A, the rat thoracic spinal cord was compressed epidurally with preservation of local cerebrospinal fluid (CSF) dynamics. In Group B (spinal tissue scarring), the rat thoracic spinal cord was compressed directly after disruption of meninges of dura mater and arachnoid membrane, followed by gelatine sponge sealing. All rats were maintained for 12 weeks after injury. Imaging analysis revealed the significant increase of cystic cavitation in the contused spinal cord in Group B compared with Group A. Anterograde axonal tracing demonstrated that the labeled corticospinal axons had extended axonal sprouting into the nearby gray matter and displayed prominent dieback at the rostral interface of the spinal cord lesion in both groups. No significant difference in motor and sensory functions between the two groups was noted. The new experimental model of PPM formation was devised. Spinal tissue scarring at the injury site may cause a tethering effect on the spinal cord, which may lead to significant alteration of the spinal cord parenchyma. Although the devastating effect of PPM on motor and sensory functions is still not resolved completely, the results in the present study suggest the importance of careful analysis in the treatment of PPM after SCI.
    Neurological Research 01/2007; 28(8):802-6. DOI:10.1179/016164106X110355 · 1.44 Impact Factor
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    Takehiro Uda · Kenji Ohata · Toshihiro Takami · Mitsuhiro Hara
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    ABSTRACT: We present a rare case of skull base chordoma of extraosseous intradural type that presented as acute intratumoral hemorrhage. Surgical removal of the tumor was accomplished using a skull base approach.
    Neurology India 10/2006; 54(3):306-7. DOI:10.4103/0028-3886.27162 · 1.23 Impact Factor
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    ABSTRACT: Transsylvian selective amygdalohippocampectomy (TSA) is an operative technique designed to spare unaffected brain tissue during surgical treatment for mesial temporal lobe epilepsy. In contrast to standard anterior temporal lobectomy (ATL), the advantages of TSA with respect to postoperative cognitive outcome are equivocal. We compared cognitive function before and after surgery in 49 patients with unilateral mesial temporal lobe seizures who underwent either ATL (n=17) or TSA (n=32). All patients received neuropsychological testing before and 1 year after surgery. The intelligence quotient (IQ) increased postoperatively in both surgical groups. Memory evaluation in the ATL group revealed a postoperative decline in nonverbal memory after right-sided resection and a postoperative decline in verbal memory after left-sided resection. In the TSA group, there was a slight postoperative decline only in verbal memory after left-sided resection, but other memory function was well preserved. In particular, there was significant postoperative improvement in verbal memory after right-sided resection. Overall, memory function was better preserved in the TSA group than in the ATL group.
    Epilepsy & Behavior 09/2006; 9(1):95-100. DOI:10.1016/j.yebeh.2006.04.017 · 2.26 Impact Factor
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    ABSTRACT: We report three cases with ventral cervical intramedullary cavernous angiomas. An anterolateral partial vertebrectomy was performed to surgically approach and successfully resect these lesions. All three patients presented with numbness in the upper extremities and investigation revealed a cavernous angioma on the ventral aspect of the spinal cord in each case. The lesion was exposed by an anterolateral partial vertebrectomy in all cases. Postoperative stabilization was achieved by using autografted iliac bone in all patients. In two patients, locking screws and plates were also used. Complete resection of the cavernous angioma was performed in all patients. There was symptomatic relief in all cases, and there was no postoperative morbidity. Anterolateral partial vertebrectomy provides direct exposure and is probably an ideal approach for selected cases with ventrally located intramedullary cavernous angiomas.
    Neurosurgery 08/2006; 59(1 Suppl 1):ONS58-63; discussion ONS58-63. DOI:10.1227/01.NEU.0000219930.65161.AD · 3.62 Impact Factor
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    Toshihiro Takami · Kenji Ohata · Akimasa Nishio · Mitsuhiro Hara
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    ABSTRACT: The histological features of arterialized medullary vein (MV) in spinal dural arteriovenous fistulas (SDAVF) were studied in five consecutive patients who presented with progressive congestive myelopathy. Retrograde venous filling on preoperative angiography was recognized as being severe in 3 cases and moderate in 2 cases. Direct intradural interruption of the arterialized MV was performed in all patients. The arterialized MV was sampled and examined histologically to determine the percentage of the hyperplasia of venous wall (hypertrophic ratio). Histological examination of arterialized MV showed that hypertrophic alteration of venous wall structure was due to hyperplasia of elastic fibers, ranging from 41 to 82%. Patients with angiographically severe venous hypertension tended to have a higher hypertrophic ratio than patients with moderate venous hypertension. Our observations support the clinical concept that long-standing arterial stress in the spinal venous circulation causes histological alterations of spinal vascular structure associated with the progression of venous hypertension. We suggested that possibly the histological parameter can be used for predicting neurological recovery after occlusion of the fistulas.
    Neurology India 07/2006; 54(2):202-4. · 1.23 Impact Factor
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    ABSTRACT: In the management of skull base chordomas, surgical treatment is essential to achieve long-term control. A petroclival chordoma growing laterally in the skull base is one of the most challenging tumors for neurosurgeons. We have treated petroclival chordomas based on the principle of maximal surgical resection of the tumor with minimal morbidity. Lateral skull base approaches were used to approach petroclival chordomas in eight patients. The surgical procedure involved removal of soft tumor tissue and extensive drilling of adjacent bony structures. Gross total resection of the tumor was achieved in six patients. Subtotal resection in the remaining two patients was associated with acceptable morbidity. In cases of petroclival chordomas, lateral skull base approaches can be used as a primary procedure, although those approaches may be associated with high rates of morbidity and mortality.
    Skull Base Surgery 06/2006; 16(2):85-94. DOI:10.1055/s-2006-934109 · 0.60 Impact Factor
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    ABSTRACT: A 25-year-old man presented with intractable post-traumatic seizures after suffering cerebral contusion in a traffic accident at age 5 years. Cerebral hemispherotomy was performed to transect the neuronal fibers to interrupt connections between seizure foci in wide areas of the brain, and to minimize the resected brain parenchyma. His seizures resolved and behavioral disorders improved, which had been impaired since age 8 years. Increased glucose metabolism in the normal frontal lobe detected by interictal fluorodeoxyglucose-positron emission tomography was correlated with the improvements in behavioral disorders. These findings suggest that the effects of seizures may be reversible in brain areas connected with, but remote from, the epileptogenic cortex.
    Neurologia medico-chirurgica 05/2006; 46(4):182-5. DOI:10.2176/nmc.46.182 · 0.72 Impact Factor
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    ABSTRACT: The authors evaluated their surgical experience over 20 years with 14 treated falcotentorial meningiomas. In the past 20 years, 14 patients with falcotentorial junction meningiomas were surgically treated. There were seven men and seven women, whose ages ranged from 34 to 79 years. On the basis of neuroimaging studies, the authors analyzed the influence of the anatomical relationship of the tumor to the vein of Galen, patency of the vein of Galen, tumor size, and the signal intensities on the magnetic resonance images to determine possible difficulties that might be encountered during surgery and to prognosticate the outcome of surgery. Depending on the relationship with the vein of Galen, tumors were labeled as either a superior or an inferior type. All tumors were resected via an occipital transtentorial approach. The surgical outcome in eight patients was excellent; in the remaining six patients, it was fair. Of the prognostic factors, tumor location especially seemed to be the most important (p < 0.01, Fisher exact test). The outcome associated with the inferior type of tumor was significantly less optimal probably due to the relationship to the deep veins and the brainstem. In this series, the occlusion of deep veins did not significantly influence outcome. . Classification of the tumor location by preoperative neuroimaging studies can be helpful in estimating the surgical difficulty that might be encountered in treating the falcotentorial junction meningioma.
    Journal of Neurosurgery 02/2006; 104(1):47-53. DOI:10.3171/jns.2006.104.1.47 · 3.74 Impact Factor
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    ABSTRACT: The uptake of L-methyl-11C-methionine (MET) by gliomas is greater than that by intact tissue, making methionine very useful for evaluation of tumor extent. If the degree of malignancy of brain tumors can be evaluated by MET-PET, the usefulness of MET-PET as a means of diagnosing brain tumors will increase. We performed this study on 67 glioma patients between 3 and 69 years of age (36 males and 31 females). Tumors included diffuse astrocytoma, anaplastic astrocytoma, glioblastoma, ependymoma, oligodendroglioma, medulloblastoma, dysembryoplastic neuroepithelial tumor, choroid plexus papilloma, central neurocytoma, optic glioma, gliomatosis cerebri, pleomorphic xanthoastrocytoma, and ganglioglioma. Tumor activity and degree of malignancy were evaluated using Ki-67LI (LI: labeling index) and Kaplan-Meier survival curves. The correlations between methionine uptake and tumor proliferation (tumor versus contralateral gray matter ratio (T/N) and Ki-67LI) were determined for the group of all subjects. The existence of significant correlations between T/N and Ki-67LI and between SUV and Ki-67LI was determined for astrocytic tumors. Receiver operating characteristics (ROC) analysis of T/N and standardized uptake value (SUV) was performed for the group of astrocytic tumors. We also determined the ROC cut-off levels to ensure high accuracy of the analysis. For the 67 cases of glioma, the degree of accumulation was variable. Ki-67LI differed significantly between the high-grade group and low-grade group at T/N levels between 1.5 and 1.8 on analysis using tumor proliferative potential (p = 0.019-0.031). The prognosis differed significantly between the high-grade and low-grade groups when T/N was in the range of 1.6-1.8 (p = 0.028-0.032). The accuracy thus calculated was highest (85.7%) when T/N was 1.5 as determined by ROC analysis. When analysis was confined to cases of astrocytic tumor, a correlation was noted between methionine accumulation and Ki-67LI. For the astrocytic tumors, T/N ratio seemed to be more useful as a diagnostic indicator than SUV. The cut-off level of T/N ratio for distinction between high-grade and low-grade astrocytoma appears to lie between 1.5 and 1.6.
    Annals of Nuclear Medicine 01/2006; 19(8):677-83. DOI:10.1007/BF02985116 · 1.68 Impact Factor
  • Surgery for Cerebral Stroke 01/2006; 34(1):59-63. DOI:10.2335/scs.34.59
  • Surgery for Cerebral Stroke 01/2006; 34(3):199-205. DOI:10.2335/scs.34.199
  • Nippon rinsho. Japanese journal of clinical medicine 10/2005; 63 Suppl 9:263-70.
  • Takeo Goto · Kenji Ohata · Mitsuhiro Hara
    Nippon rinsho. Japanese journal of clinical medicine 10/2005; 63 Suppl 9:341-6.
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    Hiromichi Nakabayashi · Mitsuhiro Hara · Keiji Shimuzu
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    ABSTRACT: Cathepsin B, one of the lysosomal cysteine proteases, has been related to tumor invasiveness. Cystatin C is the strongest inhibitor of cathepsin B. Knowledge of its participation in the progression of gliomas is limited. We investigated the expression of cystatin C and its association with the clinicopathologic features of 57 gliomas. Cystatin C and cathepsin B expressions were evaluated by immunohistochemical methods and by semiquantitative real-time polymerase chain reaction analysis for the corresponding messenger RNA. Disease-free survival was analyzed by the Kaplan-Meier method. Tumors with low cystatin C protein expression and high cathepsin B protein expression were significantly more likely to be of high grade, and this pattern was significantly correlated with high Ki-67 LI and tumor recurrence. Depressed expression of cystatin C messenger RNA in glioblastomas compared with low-grade astrocytomas was demonstrated. Multivariate analysis demonstrated high tumor grade, high Ki-67 labeling index, high cathepsin B expression, and low cystatin C expression correlated significantly with shorter disease-free survival. These results suggest that gliomas in patients with an unfavorable clinical outcome are characterized by depressed expression of cystatin C. Evaluation of cystatin C expression in gliomas provides useful clinical information, especially as a prognostic indicator.
    Human Pathlogy 10/2005; 36(9):1008-15. DOI:10.1016/j.humpath.2005.06.021 · 2.77 Impact Factor
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    ABSTRACT: We report two rare cases of progressive congestive myelopathy caused by dural arteriovenous fistulae (DAVF) at the foramen magnum. The first, a 69-year-old male with a 2-year history of progressive myelopathy, had symptoms unrecognized due to a past history that included spinal caries and congenital dislocation of the hip. The second, a 60-year-old male, had a recurrence of the myelopathy three months after endovascular occlusion of the DAVF feeding artery. Both patients were successfully treated by direct microsurgical interruption of the arterialized medullary vein with functional and radiological improvement. The clinical manifestations of DAVF at the foramen magnum are nonspecific, mimicking those of cervical spondylotic myelopathy or cervical neoplasm. Accurate and early diagnosis followed by complete obliteration of the fistula is mandatory to avoid permanent neurological deficit.
    Journal of Clinical Neuroscience 07/2005; 12(5):580-3. DOI:10.1016/j.jocn.2005.02.003 · 1.38 Impact Factor
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    ABSTRACT: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary disease characterized by recurrent transient ischemic attacks (TIA) and strokes, and vascular dementia caused by point mutations of the Notch 3 gene. Here, we report a Japanese CADASIL case who displayed limited dementia and had the Notch 3 R141C mutation. The relationship between pathogenesis and the mutation site in Notch 3 is discussed based on the case presented here.
    Nō to shinkei = Brain and nerve 06/2005; 57(5):415-8.

Publication Stats

630 Citations
90.13 Total Impact Points


  • 2001–2009
    • Osaka City University
      • Department of Neurosurgery
      Ōsaka, Ōsaka, Japan
    • Kanazawa Institute of Technology
      Kanazawa, Ishikawa, Japan
  • 2002
    • Tsukazaki Hospital
      Himezi, Hyōgo, Japan