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T Ohwada

Publications and source records attributed to T Ohwada.

140 records · Page 8Linked to original sources
PubMed1977

[A case of spontaneous 3rd ventriculostomy (author's transl)].

We have reported a rare case of spontaneous 3rd ventriculostomy with spontaneous arrest of obstructive hydrocephalus. A 41 year old man, who had had an intermittent headache for about a year, was admitted to the department of neurosurgery Kitasato University with chief complaints of sudden onset of severe headache, vomiting and disturbance of consciousness. At the time of admission, 30 minutes after the onset of symptoms, the positive neurological findings were delirious state of consciousness, miotic pupils with sluggish reaction to light, mild hemiparesis on the left site and slight nucnal rigidity. He lapsed into coma after two hours, however he gradually relieved from these symptoms since the forth hospital day. Cerebrospinal fluid was bloody. Radiograms of the skull revealed decalcification of posterior clinoid process and postero-inferior displacement of pineal calcification. Brain scanning and vertebral angiography demonstrated tumor stain in the posterior portion of the 3rd ventricle. Dimer-X ventriculography revealed the obstruction of posterior portion of the 3rd ventricle and the leakage of Dimer-X through the floor of the 3rd ventricle into the intrasellar subarchnoid space. The patient died after about one year from the onset of symptoms. Any signs of increased intracranial pressure had not been noticed since the forth hospital day; At autopsy we confirmed the posterior portion of the 3rd ventricle was obstructed by tumor. In the floor of the 3rd ventricle there was a round opening which was patient and measured about 3 mm in diameter. Microscopic examination of the tumor showed an oligodendroglioma. Neoplastic cells partially infiltrated into the surface facing to the 3rd ventricle and slight gliosis was observed around the site of rupture. The surface along the subarachnoid space was lined with pia-aracnoid membrane except at the site of rupture. In the past literatures only 6 cases of spontaneous 3rd ventriculostomy have been reported. Three cases were observed spontaneous arrest of obstructive hydrocephalus. Our case is the first reported case of spontaneous 3rd ventriculostomy through the floor of the 3rd ventriculostomy through the floor of the 3rd ventricle. We suggested the pathogenesis of spontaneous 3rd ventriculostomy is a result of destruction at normally weak points of 3rd ventricle (ex. anterior, posterior wall and floor of 3rd ventricle), which has the reultant internal hydrocephalus caused by recurrent obstruction of C.S.F. pathway or long-standing obstructive hydrocephalus.

Adult↗
PubMed1976

[Bilateral traumatic abducens nerve palsy without skull fracture or intracranial hematoma-a report of 3 cases and consideration of the mechanism of injury (author's transl)].

Three cases of bilateral traumatic abducens nerve palsy were presented and the mechanism of damage to the abducens nerve was discussed in relation to the analysis of traumatic force at the time of impact and topographical anatomy of the abducens nerve in detail. Case 1. A 70 year old man sustained a traffic accident with one hour loss of consciousness. Physical examination revealed a contused area on the medial side of his right forehead. Neurological examination revealed bilateral abducens nerve palsy (Fig. 1). There were no ther cranial nerve abnormalities. Roentgenograms of the skull, including views of the base and orbit showed no fracture. At follow up examination 12 months later, bilateral Duane's retraction syndrome could be noticed with slight increase in size of the pupil on each side of lateral gaze (Fig. 2). Case 2. A 32 year old women sustained a traffic accident with 31 days of loss of consciousness. At the time of admission, bilateral abducens nerve palsy and slight left hemiparesis were noticed in semicomatose condition. Right carotid angiogtam showed no evidence of intracranial hematoma. One month later, the right eye began to abduct and 2 months later, the left eye began to abduct. Three months after the injury, bilateral abducens nerve palsy could no longer be demonstrated. No retraction syndrome was observed during this period. Case 3. A 3 year old boy sustained a traffic accident with 32 days of loss of consciousness. At the time of admission, neurological examination showed bilateral abducens palsy and left sided decerebrate posture in comatose condition. At the time of discharge 3 months after admission, bilateral abducens palsy, right hemiataxia, left spastic hemiparesis and scanning speach were noticed. Three months later, right eye began to abduct and 4 months later, the left eye began to abduct. At follow up examination 6 months later, there was no evidence of abducens nerve palsy. Topographical details of anatomy of the abducens nerve are shown in Fig. 3, 4. It is greatly speculated that both abducens nerves are streched by the lineal accerelated force on mid sagittal plane at the time of impact, then the apex of petrous pyramid acts as the fulculum, so that the abducens nerves are compressed, contused and streched at this point (Fig. 5-a). The authors pointed out that the abducens nerve are impossible to be damaged at the petroclinoid ligament (Grüber's lig.) by the upward movement of the brainstem, because the abducens nerve is fixed downward below this ligament by the dura and apex of the petrous pyramid (Fig. 4-b, c). One case showed bilateral acquired retraction syndrome with slight increase in size of the pupil on each side of lateral gaze, the fact greatly suggesting that the sympathetic nerve have intimate relationship to the miss direction during the recovery stage of abducens nerve palsy.

Abducens Nerve↗
PubMed1976

[Paratrigeminal epidermoid originated in the meckel's cave (author's transl)].

We have reported a case of paratrigeminal epidermoid originated in the Meckel's cave. A 30 years old man was admitted to the department of neurosurgery with chief complaints of continuous right facial pain and numbness of entire right side of the face of three years duration. The positive neurological findings were hypesthesia over the distribution of the right trigeminal nerve, absence of the right corneal reflex and nystagmus on left lateral gaze. Caloric response was absent on the right side, however the audiogram showed normal. Cerebrospinal fluid examination was within normal limit. Electromyography showed giant spike in the right masseter and temporal muscles. Radiogram of the skull revealed a bone-destroying lesion over the medial florr of the right middle fossa involving the apex of the petrous bone (Fig 1). Right carotid angiography showed straightening and forward displacement of C4- C5 portion of the carotid siphon in the lateral view, and vertebral angiography showed displacement of basilar artery to the left side, upward displacement of the right posterior cerebral and superior cerebellar artery in the frontal view (Fig. 2, 3). At the time of operation, an epidermoid was identified in the Meckel's cave and totally removed microsurgically. Small amount of the tumor extending into the posterior fossa was also removed (Fig. 4, 5, 6, 7). Postoperative course was uneventfull except for an episode of headache and high fever of short duration, suggesting the signs of meningial irritation. Two months postoperativelly patient was relived of facial pain and was discharged with sensory impairment of the right trigeminal nerve distribution. Only 11 cases of paratrigeminal epidermoid, including the cases localized in the Meckel's cave have been reported in the past literatures (Table 1). In this paper we have discussed about the symptomatology and clinical data of paratrigeminal epidermoid and compared with those of trigeminal neurinoma, and meningioma originated in the same region. We would like to emphasize that the importance of differentiating the idiopathic trigeminal neuralgia from the paratrigeminal epidermoid, if the initial symptom of this tumor were tic douloureux. The total removal of epidermoid with capsule is essential treatment following the early diagnosis, however the attempt of total removal is sometimes difficult because of the relationship between the origin, size and extension of this kind of tumor to other important brain structures. And if some of the tumor is left behind at the time of operation, cholesterin meningitis is an important complication.

Adult↗
PubMedDate not supplied

Reanalysis of unruptured intracranial aneurysm management: effect of a new international study on the threshold probabilities.

OBJECTIVE: This report updates previous clinical decision analysis for patients with unruptured intracranial aneurysm (UN-AN) based on newly published data and discusses the role of reanalysis in individual decision making. METHODS: The authors employed probabilities for the natural history of UN-AN and results of preventive surgery based on the report by the International Study of Unruptured Intracranial Aneurysms. Probabilistic sensitivity analysis with Monte Carlo simulation and traditional n-way sensitivity analyses were used to assess the uncertainty of clinical decisions. RESULTS: The baseline decision in favor of preventive surgery is reversed by new data from the international study. Probabilistic sensitivity analyses revealed several populations showing heterogeneity in terms of strategy selection. One- and two-way sensitivity analyses detected two important factors for decision making: annual rupture rate and utility for knowingly living with UN-AN. CONCLUSIONS: Annual UN-AN rupture rate and the utility for knowingly living with UN-AN are key factors when deciding on a therapeutic strategy. Also, updating published decision analyses can improve clinical decision making by integrating clinical judgment and newly available clinical data.

Adult↗
PubMedDate not supplied

Management of unruptured intracranial aneurysm in Japan: a Markovian decision analysis with utility measurements based on the Glasgow Outcome Scale.

The purpose of this study was to analyze the management of individual patients with unruptured intracranial aneurysms (UN-ANs) using a decision-analytic approach. Transition probabilities among Glasgow Outcome Scale (GOS) categories were estimated from the published literature and data from patients who had been treated at Kitasato University Hospital. Utilities were obtained from 140 health providers based principally on the GOS. Baseline analysis for a healthy 40-year-old man with an anterior UN-AN less than 10 mm in diameter showed that the quality-adjusted life expectancies for preventive operation and follow-up were 15.34 and 14.66 years, respectively. For a follow-up strategy to be preferred, the annual rupture rate had to be as low as 0.9%. These results were sustained through extensive sensitivity analysis. The results support preventive operation for UN-ANs, and identify problems that can be clarified with a well-designed stratified clinical trial.

Adult↗
PubMedDate not supplied

Midazolam for continuous sedation in Japanese patients in the critical care setting: phase II study.

This prospective, phase II study was carried out to evaluate the efficacy and safety of midazolam as a sedative agent in nine critically ill Japanese patients without coma who had been admitted to an intensive care unit. An adequate level of sedation (sedative score [SS] 4-6) was induced by midazolam 0.14 - 0.39 mg/kg and maintained with a dose range of 0.08 - 0.24 mg/kg per h. One patient was excluded from the efficacy analysis since optimum sedation was not maintained by continuous infusion. The percentage of time during which SS 5 was achieved varied among the patients. The most frequent adverse events were hypotension, partial pressure of carbon dioxide elevation and premature ventricular contraction. Population pharmacokinetic analysis suggested that lower drug clearance rates were correlated with the presence of complications. The 50% of effective concentration values of SS 5, estimated by logistic regression analysis, varied greatly (mean, 251 ng/ml). In conclusion, midazolam infusion achieved successful sedation in this critical care setting. The optimum dose differed among the patients, however, and was influenced by the presence of complications.

Adult↗
PubMedDate not supplied

Pathophysiologic assessment of stagnating arteries after removal of arteriovenous malformations.

PURPOSE: To assess the hemodynamics and pathophysiology of stagnating arteries after removal of arteriovenous malformations (AVMs). SUBJECTS: 50 patients with supratentorial pial AVMs underwent pre- and postoperative angiographic studies. RESULTS: The following characteristics were found to correlate with stagnating arteries: 1) advanced patient age, 2) large AVM size, 3) markedly dilated feeders, 4) early postoperative angiograms, and 5) delayed restoration of feeding artery diameter. CONCLUSIONS: The rate of blood flow in the former feeding arteries, expressed as v x pi x r2 (v = mean velocity, r = vessel radius), suddenly decreases after removal of AVMs. When dilatation persists postoperatively in these arteries the flow velocity decreases and stagnation takes place. Delayed postoperative restoration of feeding artery diameter may be caused by a decrease of elasticity due to long-standing hemodynamic stresses, and by increased postoperative vascular resistance of these arteries.

Adolescent↗