Biomedical subjects

Hideo Hamada

Publications and source records attributed to Hideo Hamada.

At least 19 recordsLinked to original sources

PubMed2006

Transparent endoscopic sheath and rigid-rod endoscope used in endoscopic third ventriculostomy for hydrocephalus in the presence of deformed ventricular anatomy.

OBJECT: Endoscopic third ventriculostomy (ETV) has been widely performed for the treatment of noncommunicating hydrocephalus. In cases of hydrocephalus in conjunction with deformed and complex ventricular anatomy, it is preferable to use a rigid-rod endoscope for ETV, because the excellent visibility provided by this instrument yields a smooth and correct orientation in the ventricle. The authors report on ETV procedures in which they used a transparent endoscopic sheath that has a common channel in which a rigid-rod endoscope and an instrument can be inserted. METHODS: In 15 cases of noncommunicating hydrocephalus, a transparent endoscopic sheath and a rigid endoscope were used for ETV. In 11 of the 15 patients, the diameter of the foramen of Monro and the width of the third ventricle were greater than 5 mm, and thus a transparent endoscopic sheath and a rigid endoscope could be smoothly introduced through the foramen of Monro and an ETV successfully performed. Four patients had congenital or acquired narrowing of the foramen of Monro and an anatomically deformed ventricular system. In three of the patients, opening of the narrowed foramen and an ETV were successfully performed using the transparent endoscopic sheath under direct visualization through the rigid-rod endoscope. CONCLUSIONS: A transparent endoscopic sheath increases safety by offering a corridor to the third ventricle. It also provides excellent visibility without troublesome bleeding from tissues surrounding the foramen of Monro during endoscopic procedures in which a rigid endoscope is used.

Adolescent↗

PubMed2005

Huge arachnoid cyst incorporating choroid plexus.

BACKGROUND: We report a rare case of arachnoid cyst incorporating choroid plexus. This 7-month-old girl presented with macrocrania. Magnetic resonance (MR) imaging disclosed a cystic lesion arising from the left prepontine cistern extending to the left middle cranial fossa. METHODS: First, we performed resection of the membrane microscopically and obtained an adequate reduction of the cystic size. However, 4 months after the first operation, the cyst was enlarged again, and bulging of the portion of the craniotomy was noted. Thus, we performed neuroendoscopic transcortical ventriculo-cyst-cysternostomy and confirmed the choroid plexus inside of the arachnoid cyst. DISCUSSION: Postoperative course was uneventful. This is the first reported case of choroid plexus within an arachnoid cyst, determined neuroendoscopically.

Arachnoid Cysts↗

PubMed2005

Endoscopic biopsy interpretation difficulties in a congenital diffuse intracranial teratoma.

INTRODUCTION: Congenital brain tumours are a rare entity that is nowadays often already recognised during pregnancy by ultrasound (US) and magnetic resonance (MR). Even though the definitive diagnosis is usually achieved by means of histological studies, in some cases the diagnosis may remain uncertain because of the malformative origin of this type of tumour. CASE REPORT: We describe a patient with a diffuse congenital intracranial mass diagnosed by intrauterine US and foetal MR performed to further evaluate the lesion and the associated foetal hydrocephalus. After delivery by caesarean section, an endoscopic biopsy was performed. Several specimens were obtained and resulted in the diagnosis of primitive neuroectodermal tumour (PNET). Despite polychemotherapy, the tumour continued to enlarge and the patient died at 2 months of age. Post-mortem histological examination of the intracranial mass showed a diffuse intracranial teratoma. CONCLUSION: Endoscopic biopsy specimen examination resulted in a diagnosis that was not confirmed by post-mortem findings. The scarce differentiation of teratoma components and their high variability in histomorphology as well as the huge size of the tumoral mass may limit the interpretation of endoscopic biopsy specimens, even when multiple and obtained from different areas.

Biopsy↗

PubMed2005

Endoscopic aqueductal stenting via the fourth ventricle under navigating system guidance: technical note.

OBJECTIVE: We report three patients with symptomatic isolated fourth ventricle after ventriculoperitoneal shunt placement for hydrocephalus associated with ventricular hemorrhage. All three patients were treated successfully with our new method of endoscopic aqueductal stenting under navigating system guidance. METHODS: A therapeutic rigid endoscope was inserted through the thin cerebellar hemisphere, and endoscopic aqueductal stenting was performed via the enlarged fourth ventricle under navigating system guidance. RESULTS: All three patients underwent successful procedures with good outcomes. CONCLUSION: Our method of aqueductal stenting is a reasonable choice for initial treatment of patients with isolated fourth ventricle, and it entails less invasive neurosurgery.

Cerebral Aqueduct↗

PubMed2005

Multiple epidermoid cysts located in the pineal and extracranial regions treated by neuroendoscopy.

A 22-year-old woman presented with a rare case of multiple epidermoid cysts located in the pineal and extracranial regions. Magnetic resonance (MR) imaging showed a lesion in the pineal region as hypointense on the T(1)-weighted image and hyperintense on the T(2)-weighted image, without enhancement. Neuroendoscopic treatment was performed under a diagnosis of pineal cyst. However, the cyst wall was too thick to perforate, although third ventriculostomy was performed. Diffusion-weighted MR imaging demonstrated the lesions in the pineal and extracranial regions as marked hyperintensity. The diagnosis was epidermoid cyst. Subsequently, neuroendoscopic treatment of the pineal epidermoid cyst was performed. Careful preoperative diagnosis of epidermoid cysts based on diffusion-weighted MR imaging is required.

Adult↗

PubMed2005

Decrease in platelet count as an independent risk factor for symptomatic vasospasm following aneurysmal subarachnoid hemorrhage.

OBJECT: Increased platelet consumption is expected in patients with cerebral vasospasm, according to data from clinical and experimental studies. The authors investigated sequential changes in platelet counts in patients with subarachnoid hemorrhage (SAH) and the difference in platelet consumption between patients with and those without symptomatic vasospasm (SV). Variables related to platelet count as well as other clinical and radiological variables were analyzed as independent predictors of SV. METHODS: One hundred consecutive patients who had undergone surgery within 48 hours after SAH onset were entered in the study. Clinical and radiological variables and blood cell counts, including red blood cells, white blood cells, and platelets, after SAH were retrospectively examined. Twenty of these variables were entered into univariatete and multivariate analyses to determine predictors for SV. After SAH, the platelet count decreased to a minimum and then increased rapidly to levels greater than those recorded on admission. This change was specific to SAH, and platelet consumption was more severe in patients with SV than in those without. There were three independent predictors of SV: a ratio of the lowest platelet count and the admission count greater than 0.7 (odds ratio [OR] 0.322, 95% confidence interval [CI] 0.124-0.834, p = 0.0196) and a history of hypertension (OR 0.338, 95% CI 0.126-0.906, p = 0.0311) were negatively significant (that is, decreases the occurrence of SV), and a Fisher Grade 3 (OR 4.42, 95% CI 1.48-13.2, p = 0.0077) was positively significant (that is, increases the occurrence of SV). CONCLUSIONS: The association between a decrease in platelet count and the occurrence of SV indicates the important role of platelets in the pathophysiology of vasospasm following SAH.

Adult↗

PubMed2005

[Selection of surgical approach for quadrigeminal cistern arachnoid cyst].

Preoperative magnetic resonance imaging of 4 cases of quadrigeminal cistern arachnoid cyst were retrospectively reviewed and patterns of extension to surrounding cisterns from the quadrigeminal cistern were examined. Relationship between patterns of extension to surrounding cisterns and selected surgical approach were evaluated. In 2 cases, the cyst extended anteriorly and compressed the quadrigeminal plate. These two cases had hydrocephalus due to aqueductal stenosis. The anteroirly extending cyst was treated with endoscopic ventriculocystocisternostomy via the lateral and third ventricles. In one case, the cyst extended superiorly to the velum interpositum cistern, and was treated with endoscopic ventriculocystocisternostomy via the lateral ventricle. In one case, the cyst extended laterally to the ambient cistern and compressed the posterior horn of the lateral ventricle. This case had loculated hydrocephalus of the inferior horn. The laterally extending cyst was treated with resection of the wall of the arachnoid cyst via an infratentorial supracerebellar approach assisted by endoscope. All cysts were successfully treated. Injury of the foramen of Monro occurred during a procedure using a flexible endoscope in a case with an anterior extending cyst. Exact analysis of the preoperative imaging and selection of appropriate surgical approach are key factors for successful treatment of a quadrigeminal cistern arachnoid cyst.

Adult↗

PubMed2004

Huge arachnoid cyst in the posterior fossa: controversial discussion for selection of the surgical approach.

CASE REPORT: We report a case of a huge posterior fossa arachnoid cyst with hydrocephalus. This 15-month-old girl presented with macrocrania and psychomotor retardation. Magnetic resonance (MR) imaging demonstrated ventriculomegaly and a huge cystic lesion in the posterior fossa. A membranectomy was performed microscopically and the patient had a good postoperative course. OUTCOME: Magnetic resonance imaging 1 year after the operation revealed adequate reduction in the size of the ventricle and cyst. Progressive macrocrania discontinued and normal development was obtained.

Arachnoid Cysts↗

PubMed2004

Tension pneumocephalus after a neuroendoscopic procedure--case report.

A 60-year-old female presented with gait disturbance, urinary incontinence, and recent memory disturbance. Computed tomography and magnetic resonance imaging revealed a partially calcified mass lesion without enhancement in the left caudate head and mild ventriculomegaly. She underwent endoscopic tumor biopsy. The histological diagnosis was astrocytoma grade 2. After the endoscopic procedure she presented with prolonged consciousness disturbance caused by tension pneumocephalus. Tension pneumocephalus is one of the potential complications of neuroendoscopic procedures.

Astrocytoma↗

PubMed2004

Isolated third and fourth ventricles associated with neurosarcoidosis successfully treated by neuroendoscopy--case report.

A 48-year-old woman presented with a unique case of isolated third and fourth ventricles associated with neurosarcoidosis, manifesting as upward gaze palsy. She had a past history of surgery for intracranial sarcoid granuloma 10 years previously and placement of a ventriculoperitoneal shunt 3 years later. Magnetic resonance imaging revealed isolated third and fourth ventricles. Endoscopic plasty of the right foramen of Monro, fenestration of the septum pellucidum, and revision of the ventriculoperitoneal shunt were performed. Postoperatively the size of the third and fourth ventricles was reduced, and the upward gaze palsy resolved. Endoscopic treatment is less invasive and effective for the treatment of multiple septum formation in the ventricular system.

Female↗

PubMed2003

A case of occult intrasacral meningocele presented with atypical bowel symptoms.

CASE REPORT: We report a case of an occult intrasacral meningocele. An 11-year-old boy presented with atypical bowel symptoms, severe constipation, and stool incontinence. Magnetic resonance (MR) imaging disclosed an intrasacral cyst containing cerebrospinal fluid (CSF). We diagnosed an occult intrasacral meningocele and performed perforation of the cyst and closure of the fistula. The patient was free from constipation and stool incontinence after the operation. DISCUSSION: We discuss the clinical features and neuroradiological findings of this rare condition.

Child↗

PubMed2003

Development-associated myristoylated alanine-rich C kinase substrate phosphorylation in rat brain.

OBJECT: In neuronal cells, myristoylated alanine-rich C kinase substrate (MARCKS), localized to particular areas of the synaptic membrane, is active during brain development. The destination of phosphorylated MARCKS is thought to be the cytoplasm where it is probably inactive. We compared MARCKS phosphorylation in the brains of embryonic, perinatal, and adult rats to determine its possible involvement in neurogenesis. METHODS: We prepared crude and partially purified extracts from various brain regions of rats aged between embryonic day 14 (E14) and 7 weeks after birth and assayed them for MARCKS phosphorylation by immunochemical methods. The isotypes of protein kinase C (PKC) were immunochemically identified in crude brain extracts from embryonic and postnatal rats. Despite negligible MARCKS phosphorylation, E16 brain extracts contained both MARCKS and PKCgamma, delta, epsilon, and lambda. MARCKS and polypeptides were clearly phosphorylated (49 and 45 kDa, respectively) in brain extracts purified on a DE52 column. Embryonic brain extracts manifested a high-molecular-weight activity capable of suppressing polypeptide phosphorylation. This activity was markedly decreased on the day of birth and almost undetectable in the brains of 9-day-old rats. CONCLUSIONS: The embryonic rat brain appears to contain a protein(s) that suppresses the phosphorylation of other proteins including MARCKS. We posit that this inhibitory activity represents a factor(s) that plays a role in the regulation of neurogenesis beginning on the day on which MARCKS appears in the embryonic brain.

Animals↗

PubMed2003

A rare case of dysembryoplastic neuroepithelial tumour in occipital lobe presenting with only headache.

We report an unusual case of dysembryoplastic neuroepithelial tumour (DNT) located in the occipital lobe presenting with only headache. A 31 year old woman presented with headache. She had no history of epilepsy and neurological examination revealed no abnormal findings. Computed tomography (CT) scanning revealed a multilobulated mass lesion with calcification in the right occipital lobe. Magnetic resonance (MR) imaging demonstrated a heterogeneously enhanced mass with hypointense signals on T1- and hyperintense signals on T2-weighted images. The lesion was totally resected and histopathologically diagnosed as DNT. Physicians must bear in mind that DNT may occur in the occipital lobe and present with only mass effect.

Adult↗

PubMed2003

In vitro and in vivo growth inhibition of human malignant astrocytoma cells by the farnesyltransferase inhibitor B1620.

p21-Ras, the protein product of the proto-oncogene Ras is overactivated in malignant astrocytomas despite the absence of mutation. It is known that p21-Ras participates in signaling events from membrane tyrosine kinase receptors and a variety of intracellular biochemical pathways to downstream targets. Signal transduction inhibition by targeting against Ras is now thought to be a promising therapeutic strategy for malignant astrocytomas. This study demonstrates that Ras pathway inactivation by a farnesyltransferase inhibitor, B1620, effectively inhibits in vitro and in vivo growth of human astrocytoma cells, although normal human astrocytes (NHA) derived from fetal brain are resistant to B1620. Anti-proliferative effect of B1620 on in vitro growth of astrocytoma cells was examined by MTT assays and soft agar colony formation assay. B1620 inhibited anchorage-dependent growth of six astrocytoma cell lines with a median effective dose (IC50) ranging from 2.0 to 20.7 microM. However, growth of NHA was not significantly affected by B1620 even at the concentration of 100 microM. All astrocytoma cells showed apoptotic figures after Hoechst 33258 staining, when treated for 5 days at each IC50 concentration against B1620. Anchorage-independent growth of these astrocytoma cell lines was inhibited at a much lower concentration than that of anchorage-dependent growth. Daily treatment of U87 xenograft-bearing athymic mice with B1620 at 100 or 50 mg kg(-1) resulted in significant inhibition of tumor growth. A histological study of the B1620-treated tumor tissue showed decreased vascularity with numerous TUNEL-positive apoptotic cells. These results suggest that the mechanism of the growth-inhibitory effect of B1620 is anti-angiogenesis, apoptosis induction and reversion of the transformed phenotype. The potential clinical use of B1620 could be expanded to malignant astrocytomas.

Alkyl and Aryl Transferases↗

PubMed2003

Independent predictors of late hydrocephalus in patients with aneurysmal subarachnoid hemorrhage--analysis by multivariate logistic regression model.

OBJECT: We determined independent variables contributing to the development of late hydrocephalus after subarachnoid hemorrhage (SAH). METHODS: A total of 114 consecutive patients who underwent surgery for aneurysms within 72 h after SAH were studied. Thirty-nine patients underwent ventriculoperitoneal shunt (VPS) placement (14 patients within 30 days and 25 patients more than 30 days after onset). Univariate and multivariate analyses were performed to assess relationships among various variables and shunt placement. RESULTS: Three variables were found to be independently associated with VPS patients: (1) the rate of SAH clearance; (2) the duration of external cerebrospinal fluid drainage, and (3) presence of neurological deficits 2 weeks after surgery, which indicates brain damage mainly caused by intraoperative manipulation and cerebral vasospasm. CONCLUSION: As in previous reports, intraoperative clot removal and duration of external CSF drainage were found to be closely related to the incidence of hydrocephalus. Brain damage due to intraoperative manipulation and cerebral vasospasm is seemed to be involved in the occurrence of late hydrocephalus in this study.

Adult↗

PubMed2003

Neuroendoscopic septostomy for isolated lateral ventricle.

The clinical features and endoscopic findings were investigated in 20 patients with isolated lateral ventricle treated by neuroendoscopic septostomy to establish cerebrospinal fluid communication and open an isolated ventricular compartment. The endoscopic procedure was incomplete because of thickened septum pellucidum and insufficient working space in two adults with postmeningitic hydrocephalus. Two children underwent second septostomy. In all other cases, results were good and there were no complications related to endoscopic procedures. Endoscopic septostomy is less invasive and has few complications. Intraoperative navigation and the biportal approach may be required in difficult cases with multiple septum formation and severe postmeningitic hydrocephalus. Adequate stomal size is required in high-risk groups including children under 2 years of age.

Aged↗

PubMed2003

Independent predictors of recurrence of chronic subdural hematoma: results of multivariate analysis performed using a logistic regression model.

OBJECT: The authors attempted to determine independent predictors that contribute to the recurrence of chronic subdural hematoma (CSDH). METHODS: A total of 105 consecutive patients who underwent surgery for CSDH were included in this study. Eleven patients underwent a repeated operation because the CSDH recurred. Univariate and multivariate analyses were performed to assess the relationships among various variables and CSDH recurrence. Finally, four variables were found to be independently associated with the recurrence of CSDH: 1) absence of a multiplicity of hematoma cavities on CT scans; 2) presence of a history of seizure; 3) width of the hematoma; and 4) absence of a history of diabetes mellitus (DM). CONCLUSIONS: As previously reported, the width of the hematoma is related to the incidence of CSDH recurrence. In this study, the lack of a multiplicity of hematoma cavities was the favorite predictor of CSDH recurrence. In addition, histories of seizure and no past DM are closely related to the incidence of CSDH recurrence.

Adult↗

PubMed2002

Contribution of basic residues of the A helix of heparin cofactor II to heparin- or dermatan sulfate-mediated thrombin inhibition.

Inhibition of thrombin by heparin cofactor II (HCII) is accelerated 1000-fold by heparin or dermatan sulfate. To investigate the contribution of basic residues of the A helix of HCII to this activation, we constructed amino acid substitutions (K101Q, R103L, and R106L) by site-directed mutagenesis. K101Q greatly reduced heparin cofactor activity and required a more than 10-fold higher concentration of dermatan sulfate to accelerate thrombin inhibition compared with wild-type recombinant HCII. Thrombin inhibition by R106L was not significantly stimulated by dermatan sulfate. These results provide evidence that basic residues of the A helix of HCII (Lys(101) and Arg(106)) are necessary for heparin- or dermatan sulfate-accelerated thrombin inhibition.

Amino Acid Sequence↗