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Biomedical subjects

S Wakai

Publications and source records attributed to S Wakai.

At least 73 records · Page 4Linked to original sources
PubMed1998

External hydrocephalus after aneurysm surgery: paradoxical response to ventricular shunting.

OBJECT: The authors sought to investigate the mechanisms and pathophysiological effects of subdural fluid collection after surgery for aneurysmal subarachnoid hemorrhage (SAH). METHODS: The authors retrospectively analyzed the medical records of 76 patients who had undergone craniotomy. The patients included 55 with aneurysmal SAH (SAH group) and 21 with unruptured aneurysms (non-SAH group) who were used as controls. Subdural fluid collection was more common in the SAH than in the non-SAH group (38% compared with 14%, p < 0.05). Although older patients appeared to be at greater risk for subdural fluid collection in both groups (p < 0.05), this condition developed even in relatively young patients with SAH. In the SAH group most subdural fluid collection was associated with ventricular dilation (81%), and a significant correlation was seen between fluid collection and the need for subsequent shunt placement (48% compared with 21%, p < 0.05). These results point to an association between hydrodynamic dysfunction and subdural fluid collection. The course of patients with subdural fluid collection varied from spontaneous resolution to normal-pressure hydrocephalus. Seven patients with persistent subdural collections underwent shunt placement (ventriculoperitoneal [VP] shunt in six and lumboperitoneal in one), which resulted in resolution of fluid collection in all seven. CONCLUSIONS: The results indicate that for most patients in the SAH group, subdural fluid collection represented "external hydrocephalus" rather than simple "subdural hygroma." Decreased absorption of cerebrospinal fluid because of SAH and surgically created tears in the arachnoid membrane communicating with the subdural space were factors in the development of external hydrocephalus. The authors believe that differentiating external hydrocephalus from subdural hygroma is extremely important, because VP shunt placement can be used to treat the former but could worsen the latter.

Absorption↗
PubMed1998

[Recurring intradiploic epidermoid cyst of the skull: a case report].

We report a case of a 65-year-old man with intradipolic epidermoid cyst of the frontal bone. The patient presented with headache and swelling of the forehead. Skull x-ray showed massive destruction of the frontal bone. Magnetic resonance imaging (MRI) revealed an epidural mass without any encroachment of the dura mater. The cystic tumor was removed followed by cranipolasty with methylmethacrylate. Four years later, the tumor recurred in the same region. At the second surgery the bony defect was again replaced with methylemthacrylate plate. Four years after the second operation, the tumor reemerged with some subcutaneous fluid retention. At the third surgery, the remaining tumor capsule was removed as much as possible except for that part which adhered to the superior sagittal sinus. The authors discuss the relationship of tumor recurrence with utilization of methylmethacrylate for cranioplasty in this type of tumor.

Bone Cements↗
PubMed1998

[Relationship between glomerular epithelial cell injury and proteinuria in IgA nephropathy].

The present study was designed to elucidate whether glomerular epithelial cell (GEC) injury is associated with the mechanism of proteinuria in biopsy-proven IgA nephropathy (IgAN). Twenty-four IgAN patients were divided into 4 groups based on their grade of proteinuria. Light microscopic examination revealed that GEC injury appeared prior to glomerular lesions such as sclerosis, crescent and adhesion. Reduced glomerular expression of C3b receptor (CR1), an indicator of GEC injury, was detected initially at the portion of damaged GEC and around the lesions of sclerosis, crescent and adhesion. CR1 expression eventually disappeared in the group IV patients who had nephrotic range proteinuria. Moreover, the grade of proteinuria in IgAN patients was associated with GEC injury and reduced glomerular expression of CR1. Taken together, GEC injury might be an important pathological finding which appears initially in the glomeruli, suggesting that GEC injury is a predictor of proteinuria in IgAN patients.

Adolescent↗
PubMed1997

Significance of pupillary reactivity in poor-grade aneurysm patients as a prognostic factor and an indication for active treatment.

Sixty-eight patients with subarachnoid haemorrhage (SAH) who were admitted in a comatose state were studied to determine the factors influencing mortality and to seek criteria for case management. Overall, the functional recovery (good recovery or moderate disability) rate was 33%, with a mortality rate of 50%. Bilaterally unreactive pupils on admission was a powerful predictor of death (p < 0.0001): outcome of these patients was poor regardless of any treatment modalities with a mortality rate of 91% (20/22). Initial poor motor response (abnormal flexion, extension, or nil) was also significantly related with death (p < 0.05). However, motor response was a less powerful predictor than pupillary reactivity. Motor response often altered spontaneously during the 12 h after admission, whereas pupillary reactivity tended to be stable. Initial reactive pupils were shown to be an indicator of spontaneous improvement of motor response. These findings indicate that pupillary reactivity may be a reliable predictor of outcome in poor-grade SAH patients.

Adult↗
PubMed1997

Unruptured intracranial vertebral artery dissection. Clinical course and serial radiographic imagings.

BACKGROUND AND PURPOSE: Intracranial vertebral artery dissection is an increasingly recognized cause of stroke. However, little is known about its natural history and clinical manifestations, and appropriate management protocol has not yet been established. This study was performed to clarify its clinical course and determine the best management protocol. METHODS: This study is a retrospective clinical and radiographic review of 11 patients with 13 lesions who presented between 1990 and 1996. Patients with a history of trauma and those who presented with subarachnoid hemorrhage were excluded. The 11 patients comprised seven men and four women, who ranged in age from 34 to 71 years, with a mean age of 47 years. Ten patients presented with ischemic symptoms. RESULTS: Although recurrent ischemic attacks were observed in two patients, most (90%) subsequently made a good recovery and returned to their previous lifestyle. Five arteries showed the typical "string sign" or "pearl and string sign" on initial angiography. They changed in the follow-up examinations, which demonstrated either resolution of the stenosis or progression to complete occlusion. In contrast, the angiographic signs of complete occlusion (three arteries) or aneurysmal dilatation without luminal stenosis (four arteries) remained unchanged during the observation period of 5 months to 2.5 years. MRI was a sensitive tool for diagnosing intracranial vertebral artery dissection; intramural thrombus and intimal flap were the two major findings. MR angiography was also useful for demonstrating abnormalities of the arterial signal column such as pseudolumen or aneurysmal dilatation. CONCLUSIONS: The natural history of unruptured intracranial vertebral artery dissection seems relatively benign, with a high probability (62%) of spontaneous angiographic cure. Some persistent aneurysmal dilatation may be amenable to intravascular coil embolization.

Adult↗
PubMed1997

Early fatal rebleeding from a cerebellar cavernous malformation--case report.

A 25-year-old female patient presented with hemorrhage from a cerebellar cavernous malformation manifesting as headache and vomiting. She died of massive rebleeding within 1 week of the previous hemorrhage. The natural history of cavernous malformations was considered relatively benign, with significant hemorrhage being uncommon. The present case suggests that emergency surgery should be performed for patients with unstable clinical conditions and/or those with a significant mass effect in the cerebellum or the brainstem.

Adult↗
PubMed1997

Global health care and neurosurgeons.

The contributions that neurosurgeons can make to global health are discussed in the context of the author's clinical and research experience, his views on priorities and equity in research and economic development, and the state of health care in developed and developing countries. Ideas for establishing a new paradigm of health care for all are proposed, as well as more general interventions on behalf of human rights and peace. Neurosurgeons, other medical professionals, and those who are concerned about these global issues are urged to work in concert to remove inequalities in health care both locally and globally.

Delivery of Health Care↗
PubMed1997

Correlation between venous stump pressure and brain damage after cortical vein occlusion: an experimental study.

A canine model of cortical vein occlusion was used to evaluate whether data obtained from monitoring venous stump pressure could help predict cerebral infarction after venous obstruction. Following bilateral parasagittal craniotomy, the cortical vein in each hemisphere was temporarily occluded and the increase in pressure was directly measured. Permanent venous obstruction was subsequently produced, and parenchymal brain damage 24 hours later was classified as: Stage 0, no parenchymal damage; Stage I, mild edema; Stage II, moderate parenchymal edema and/or ischemic changes in neurons; and Stage III, moderate-to-severe hemorrhage. The histological stages correlated closely with the rise in venous pressure: mean pressure increases (+/- standard deviation) were 5.5 +/- 2.9 mm Hg in hemispheres graded as Stage 0 (12 hemispheres), 7.7 +/- 3.2 mm Hg in those graded as Stage I (five), 11.2 +/- 4.1 mm Hg in those classed as Stage II (five), and 16.4 +/- 5 in those categorized as Stage III (seven). There were significant differences between Stages 0 and II (p < 0.01) and between Stages 0 and III (p < 0.001). Disruption of the blood-brain barrier as indicated by extravasation of Evans blue dye correlated well with the pressure increment. These results may indicate the threshold for injury after cortical venous occlusion. Venous stump pressure measurements obtained during a test occlusion may be a useful adjunct in predicting brain damage and may be helpful for intraoperative vessel selection for venous resection.

Animals↗