Biomedical subjects

Masaru Yamada

Publications and source records attributed to Masaru Yamada.

12 recordsLinked to original sources

PubMed2006

Efficacy of a direct puncture approach for anterior circulation aneurysms using a newly developed guiding catheter - especially for geriatric patients.

BACKGROUND: Endovascular surgery is being increasingly used as an alternative to craniotomy clipping surgery, especially for aged patients and complicated cases. However, tortuous atherosclerotic arteries sometimes interfere with advancement of catheters so that direct puncture may be necessary. Short guiding catheters for use with this approach have been newly developed, as discussed in this article. METHODS: One hundred twenty three anterior circulation aneurysms in 121 patients were consecutively treated by endovascular coil embolization, of which 42 (34%) were older than 70 years. RESULTS: With 21 aneurysms, coil embolization via the transfemoral approach failed, but all could be successfully treated with the direct puncture approach with minor complications such as 1 transient ischemic attack and 1 nonsymptomatic minor leakage. In the aged patients, the direct puncture approach with short guiding catheter resulted in complete obliteration of aneurysms in 20 (71%) of 28 with follow-up angiography. CONCLUSION: Direct puncture using newly developed short guiding catheters is an alternative to femoral approaches for patients with anterior circulation aneurysm with tortuous arteries and obvious atherosclerotic change at bifurcations of the common carotid artery.

Adult↗

PubMed2006

Technetium-99m ethyl cysteinate dimer dynamic and static single photon emission computed tomography in crossed cerebellar diaschisis.

A 69-year-old man with a past history of right middle cerebral artery (MCA) occlusion had cerebral single photon emission computed tomography (SPECT) with technetium-99m ethyl cysteinate dimer (Tc-99m ECD). Dynamic SPECT in the super-early phase revealed normal uptake in the left cerebellum and hypoactivity in the right MCA territory. Conventional static SPECT revealed decreased cerebral blood flow in the right MCA territory and the left cerebellum, indicating crossed cerebellar diaschisis. Our SPECT studies revealed decreased retention of Tc-99m ECD in the cerebellum manifested as crossed cerebellar diaschisis.

Aged↗

PubMed2006

Subcutaneous pneumocele associated with ventriculoperitoneal shunt migration into the mechanically occluded colon - case report.

A 62-year-old man presented with shunt failure manifesting as consciousness disturbance 4 years after placement of a ventriculoperitoneal shunt for subarachnoid hemorrhage. Physical examination found subcutaneous pneumocele around the peritoneal catheter extending from the abdomen to the neck. He had undergone pelvic radiation therapy for bladder cancer 2 years before. The peritoneal catheter was removed from the cervical region, and external ventricular drainage and a descending colon stoma for ileus release were positioned. The cerebrospinal fluid was clear and yielded no cultures. No inflammatory changes were seen. He developed carcinomatous peritonitis and died 4 months later. Retrograde colon gas reflux due to catheter perforation into the colon occluded by metastatic sigmoid cancer was probably the cause. Fragility of the wall of colon associated with the prior abdominal radiation therapy might have been a contributing factor. Subcutaneous pneumocele around the peritoneal catheter, i.e. pneumocele within the fibrous sheath surrounding the catheter, is a differential diagnosis to cerebrospinal fluid collection in patients with subcutaneous swelling around the catheter.

Carcinoma↗

PubMed2006

Stereotactic radiosurgery as adjuvant treatment for residual solitary fibrous tumor. Case report.

This 50-year-old woman presented with headache and visual disturbance. Neuroimaging results demonstrated a well-demarcated tumor attached to the falx cerebri near the transverse sinus, and the lesion was subtotally removed. Based on histological and immunohistochemical evaluation, a solitary fibrous tumor (SFT) was diagnosed. During the next 32 months, the size of the residual tumor increased slightly at the transverse sinus. Stereotactic radiosurgery (SRS) was performed as an adjuvant treatment. Over the course of the next 4 years the tumor decreased in size. The authors suggest that SRS constitutes good adjuvant treatment for regrowing residual SFTs not amenable to reoperation.

Brain Neoplasms↗

PubMed2006

Endovascular surgery for very small ruptured intracranial aneurysms. Technical note.

Application of endovascular surgery for very small aneurysms is controversial because of technical difficulties and high complication rates. The aim in the present study was to assess treatment results in a series of such lesions at one institution. Since 1997, endovascular surgery has been advocated for very small ruptured aneurysms (< 3 mm in maximum diameter) that fulfill the criterion of a fundus/neck ratio greater than 1.5. Twenty-one patients were treated, for whom the World Federation of Neurosurgical Societies classification before treatment was Grade I in 10, Grade II in two, Grade III in two, Grade IV in five, and Grade V in two. The aneurysm location was the internal carotid artery in four, the anterior communicating artery in 11, the middle cerebral artery in one, and the vertebrobasilar system in five. In all patients, endovascular surgery was performed using Guglielmi detachable coils after induction of general anesthesia. Initially, the presumed volume of the lesions was calculated for each aneurysm. Thereafter, the appropriate coil length was decided according to the volume embolization ratio, as 30 to 40%. In all attempts to obliterate aneurysms a single coil was used. All aneurysms were completely obliterated as confirmed by postembolization angiography, without procedure-related complications. During the follow-up period only one patient needed additional coil embolization for a growing aneurysm. Final outcomes were good recovery in 15 patients, moderate disability in five, and severe disability in one. Appropriate selection of patients and coils, and use of sophisticated techniques allow a good outcome for patients with very small aneurysms.

Adult↗

PubMed2006

[Vancomycin-resistant Enterococcal meningitis in patients with ventriculoperitoneal shunt: two cases report and review of the literature].

Enterococcal meningitis often occurs in patients with head trauma, cerebrospinal fluid leakage, or shunt devices. Herein, we describe two patients, a 12-year-old boy and a 57-year-old man, who developed meningitis due to vancomycin-resistant Enterococcus (VRE) gallinarum. Both of them had a ventriculoperitoneal shunt for hydrocephalus. The meningitis in one patient was due to fecal transmission of VRE derived from the gut and in the other from prolonged use of vancomycin. In addition, both patients were immunocompromised due to radiotherapy and steroid therapy. The mechanism of developing resistancy and the management of VRE meningitis is discussed.

Child↗

PubMed2005

[Clinical features and outcomes in patients with asymptomatic moyamoya disease--from the results of nation-wide questionnaire survey].

After induction of noninvasive diagnostic tools, asymptomatic moyamoya disease is occasionally being diagnosed. However, there is no epidemiological or clinical data concerning this condition because of its rarity. To elucidate clinical features and outcomes in patients with asymptomatic moyamoya disease we conducted a nation-wide questionnaire survey. Questionnaires were sent to 88 neurosurgical institutes in 1994 and we received answers from 66 institutions (75% recovery). Diagnosis of moyamoya disease is based on the guidelines established by the research committee on moyamoya disease of the Ministry of Health and Welfare, Japan. Thirty three asymptomatic moyamoya disease patients were collected (11 male, 22 female) and divided into 2 groups; group 1 defined as patients without any symptoms, and group 2 as patients who did not show any symptoms except headache. 80% of group 1 patients were adults, whereas in group 2, children and adults were equally distributed. Follow-up periods were 3 years and 8 months on average. Among conservatively treated 28 patients, 2 patients died from suspected bleeding (mortality 7%) and 4 patients with TIAs resulted in good outcome. Among surgically treated 5 patients, 1 patient showed poor outcome due to post-operative infarction. Other 26 patients showed excellent outcome. Natural course of asymptomatic moyamoya disease seemed benign, but mortality from bleeding is not negligible. A prospective study of asymptomatic moyamoya disease is necessary to clarify its natural course and appropriate management strategy.

Adolescent↗

PubMed2005

[Aplasia of the right internal carotid artery presenting with callosal hemorrhage: case report and review of the literature].

A 73-year-old woman without a history of cerebral ischemia suffered from sudden onset headache. Brain computed tomography (CT) showed intracerebral hemorrhage in the corpus callosum with intraventricular hemorrhage and thin subarachnoid hemorrhage in the basal cistern. Cerebral angiography showed narrowing of the right internal carotid artery just distal to its origin in the neck and abrupt occlusion just after branching of the ophthalmic artery with moyamoya-like vessels. The right A2 segment showed irregular dilatation and stenosis. The right middle cerebral artery was supplied from the basilar artery via the right posterior communicating artery. There was neither aneurysm nor arteriovenous malformation. Thin-slice bone-window CT of the skull base revealed hypoplasia of the right carotid canal. Aplasia of the right internal carotid artery was diagnosed. The origin of the hemorrhage was thought to be the irregularly opacified right A2 segment, which had been subjected to long-standing hemodynamic stress as collateral vessel.

Aged↗

PubMed2005

[Infected and calcified chronic subdural hematoma presenting an attitude of acute hematoma on MRI: case report].

We report a case of calcified chronic subdural hematoma with unusual magnetic resonance imaging (MRI) findings. A 50-year-old male with no marked medical history presented with fever for two weeks. Computed tomography (CT) revealed a thick, calcified subdural hematoma of low-iso mixed density. MRI showed characteristic signals of hematoma in the acute stage. Total removal of the hematoma by craniotomy was performed after rapid deterioration of consciousness. At surgery, a muddy hematoma and a small amount of pus were seen within the calcified capsule. Diagnosis of infected and calcified chronic subdural hematoma was established. His symptoms were resolved completely within the following few months. As the mechanisms of delayed signal sequence of hematoma on MRI, we speculate existence of tissue hypoxia associated with infection and paramagnetic effects of free radicals and ions associated with inflammation, necrosis and calcification.

Calcinosis↗

PubMed2004

Intracranial vertebral artery dissection with subarachnoid hemorrhage: clinical characteristics and outcomes in conservatively treated patients.

OBJECT: Intracranial vertebral artery (VA) dissection with subarachnoid hemorrhage is notorious for frequent rebleeding and a poor prognosis. Nevertheless, some patients survive with a good final outcome. The factors associated with the prognosis of this disease are not fully understood and appropriate treatment strategies continue to be debated. The authors retrospectively evaluated the clinical features of conservatively treated patients to elucidate the relationship between the clinical and angiographic characteristics of the disease and final outcomes. METHODS: This study includes 24 patients who were treated by conservative methods between 1990 and 2000. Conservative treatment was chosen because of delayed diagnosis, poor clinical condition, or anatomical features such as bilateral lesions and contralateral VA hypoplasia. Of nine patients with an admission Hunt and Kosnik Grade I or II, eight had good outcomes (mean follow-up period 8 years and 4 months). All 15 patients with Grade III, IV, or V died and in 10 of these the cause of death was rebleeding. Among the 24 patients, 14 suffered a total of 35 rebleeding episodes; in 10 (71.4%) of these 14 patients rebleeding occurred within 6 hours and in 13 (93%) within 24 hours. Compared with the survivors, there was a female preponderance (0.022) among patients who died. These patients also had significantly shorter intervals between onset and hospital admission (p = 0.0067), a higher admission Hunt and Kosnik grade (p = 0.0001), a higher incidence of prehospitalization (p = 0.0296) and postadmission (p = 0.0029) rebleeding episodes, and a higher incidence of angiographically confirmed pearl-and-string structure of the lesion (p = 0.0049). CONCLUSIONS: In our series of preselected patients, poor admission neurological grade, rebleeding episode(s), and lesions with a pearl-and-string structure were predictive of poor outcomes. Our findings indicate that patients with these characteristics may be candidates for aggressive attempts to prevent rebleeding during the acute stage. Patients without these characteristics may be good candidates for conservative treatment, especially those who survive the acute phase without rebleeding.

Acute-Phase Reaction↗

PubMed2003

Dissecting aneurysm of the intracranial vertebral artery associated with proximal focal degeneration of the elastica: a comparative pathological study of the vertebral artery in patients with and without aneurysms.

BACKGROUND: The pathogenesis underlying intracranial dissecting aneurysms remains unclear. We performed a detailed study using vertebral artery specimens obtained at autopsy from patients with and without aneurysms to identify the primary abnormality resulting in weakness of the elastica. We compared our observations with those made in specimens manifesting the normal atherosclerotic process. METHODS: Using histologic methods, we examined intracranial vertebral artery specimens from two autopsied aneurysm patients and 13 autopsied control cases to compare the state of atherosclerosis and the weakness of the elastica at this aneurysm predilection site. RESULTS: Case 1: A 54-year-old woman with 2 dissecting aneurysms of the bilateral vertebral arteries (VA) who died from recurrent subarachnoid hemorrhage (SAH). Case 2: A 53-year-old woman who died from SAH. Microscopically, all 3 vertebral aneurysms were typical transmural dissecting aneurysms. They manifested areas of focal, severe degeneration of the elastic lamina and calcification at VA sites proximal to the aneurysms. These lesions could be differentiated from secondary changes attributable to the aneurysms because of their separate location only proximal to the site of aneurysmal rupture. Atherosclerotic changes were minimal in both cases. In the controls, the degenerative state of the elastic lamina of the VA reflected an atherosclerotic process. CONCLUSIONS: We postulate that focal degeneration of elastic tissue not involved in the atherosclerotic process was the vasculopathy resulting in aneurysm formation in our SAH cases.

Aortic Dissection↗

PubMed2003

Chronic cerebral venous hypertension model in rats.

Although cerebral venous hypertension is known as an important determinant factor for clinical manifestation and outcome in patients with dural arteriovenous malformation (AVM), the pathophysiology of that condition is not well understood. We have created a chronic rat model by cervical arteriovenous fistularization with jugular vein occlusion and examined effect of cerebral venous hypertension on cerebral blood flow regulation. This model may be suitable for investigating mechanisms of cerebrovascular alteration after venous hypertension.

Animals↗