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Biomedical subjects

K Kamada

Publications and source records attributed to K Kamada.

At least 109 records · Page 6Linked to original sources
PubMed1993

Identification of central sulcus by using somatosensory evoked magnetic fields and brain surface MR images: three dimensional projection analysis.

We present a novel non-invasive technique for identification of the central sulcus on the brain surface by using three-dimensional magnetic resonance imaging (3D-MRI) in combination with somatosensory evoked magnetic fields (SEFs). The central sulcus was supposed anatomically on the brain surface by using 3D-MRI. On the other hand, the primary somatosensory area is determined by using SEF data with median nerve stimulation. Superimposition of the SEFs of the 25 ms response onto the brain surface MR images clearly demonstrated the dipole source located in the gyral fold just behind the supposed central sulcus in all subjects analyzed. Three-dimensional reconstruction of the brain surface image data facilitated visualizing the precise anatomical localization of the magnetic field activities from any angle and measuring the distance from the source to any point of interest. The potential clinical application of this technique is discussed.

Adult↗
PubMed1993

Longitudinal changes in proton magnetic resonance spectroscopy in cerebral infarction.

BACKGROUND AND PURPOSE: Proton magnetic resonance spectroscopy has revealed changes in lactate and N-acetyl-aspartate in acute cerebral infarction. However, the details of these drastic changes and subsequent chronic changes have not been clarified. The purpose of this study was to disclose longitudinal changes in spectra seen in proton magnetic resonance spectroscopy. METHODS: Six patients with completed cerebral infarction were examined longitudinally with localized proton magnetic resonance spectroscopy. RESULTS: (1) In the acute stage (within 2 days after onset), two drastic changes were observed: N-acetyl-aspartate decreased rapidly and severely within 2 days after onset, and lactate increased immediately and reached a high level in the acute stage after onset. (2) In the chronic stage (more than 1 month after onset), two features were observed: lactate, which had increased in the acute stage, remained high for more than 1 month, and other signals such as those of N-acetyl-aspartate, choline, and phosphocreatine/creatine decreased dramatically. CONCLUSIONS: These results suggest that N-acetyl-aspartate and lactate as revealed by proton magnetic resonance spectroscopy can be useful indicators of the ischemic damage to the brain in clinical cases of cerebral infarction.

Adult↗
PubMed1993

Functional neurosurgical simulation with brain surface magnetic resonance images and magnetoencephalography.

We present a novel noninvasive technique for functional neurosurgical simulation combining three-dimensional magnetic resonance imaging of the brain surface with somatosensory evoked magnetic fields (SEFs) in a case of subcortical brain tumor. The preoperative analysis using this technique revealed that the central sulcus was located between the SEF source projected onto the brain surface and the tumor. At the time of surgery, the central sulcus was clearly identified by phase reversal of the cortical recordings of somatosensory evoked potentials. The actual cortical anatomy and the maximum somatosensory evoked potential location showed excellent agreement with the preoperative analysis of the brain surface magnetic resonance images and the SEF source. The subcortical tumor, which was barely identifiable without reliable functional cortical anatomy, was easily found in the motor area, just before the somatosensory evoked potential (and SEF) source. The potential clinical application of this technique is discussed.

Brain Mapping↗
PubMed1993

Dissecting aneurysm of the posterior inferior cerebellar artery--case report.

A 29-year-old male presented with a dissecting aneurysm of the left posterior inferior cerebellar artery manifesting as left lateral medullary syndrome due to brainstem ischemia. Extirpation of the aneurysm and anastomosis of the occipital artery to the posterior inferior cerebellar artery were performed simultaneously. The dissecting aneurysm was confirmed by histological examination of the surgical specimen.

Adult↗
PubMed1993

[Study of diffusion weighted magnetic resonance imaging in Wilson's disease].

We analyzed diffusion weighted magnetic resonance images (diffusion MRI) of the basal ganglia, which were obtained from four patients with Wilson's disease, and compared them with the images from ten age-matched normal individuals. In all patients, T2-MRI of the basal ganglia disclosed low or iso-signals, but diffusion MRI revealed abnormal high signals in some areas of the basal ganglia in each case. Pathological changes except for copper and/or iron deposits are difficult to estimate by T2-MRI because the low signal on T2-MRI emphatically reflects the deposits, while the abnormal high signal on diffusion MRI is thought to reflect parenchymal lesions such as cell loss, demyelination and/or increase of the extracellular fluid. From our results, we confirmed that diffusion MRI was very useful for estimating parenchymal lesions with metal deposits.

Adult↗
PubMed1993

[A case with pyramidal tract lesion suggesting Wallerian degeneration--analysis with diffusion coefficient].

We reported a 55-year-old man, whose T2-weighted MR images disclosed abnormal high signal band along the left pyramidal tract 6 months after cerebral infarction of the left centrum semiovale. Brain CT revealed low intensity areas in the centrum semiovale, the posterior limb of the internal capsule on left side. On T2-weighted MR images, there were an irregular high signal area on the left centrum semiovale, a high signal band from the left centrum semiovale to the medullary pyramid, and a high signal band from the left centrum semiovale to the cerebral cortex. These lesions were observed as high signal areas on proton weighted images and low signal areas on T1-weighted MR images. Diffusion coefficient perpendicular to the pyramidal tract in the patient, which was calculated from diffusion weighted images at the posterior limb of the internal capsule, was higher than that in normal individuals. Diffusion anisotropy at the lesion, which is the rate between the diffusion coefficient parallel and perpendicular to nerve fiber, was higher than that of normal individuals. These data suggested that the lesion had demyelinating process, which was consistent with the pathology at stage 2 of the Wallerian degeneration.

Cerebral Infarction↗
PubMed1993

[Diffusion weighted magnetic resonance imaging in multiple cerebral infarction].

Serial examination of magnetic resonance images (MRI) for two months were carried out on two cases of multiple cerebral infarction during the acute stage. The T2-weighted MR images at the onset of the infarction showed both acute (new) and chronic (old) lesions appearing as high signal area. While on the diffusion weighted images only an acute lesion was detected as a high signal area with good contrast. The diffusion coefficient of the acute lesion was lower than that of normal white matter. Diffusion coefficient of the chronic lesions were higher than that of normal white matter. Therefore, on the apparent diffusion coefficient mapping images (ADC images) only an acute lesion appeared as a low signal area. The examination of diffusion images was very useful for distinguishing an acute lesion from a chronic lesion during the acute stage of multiple infarction. The diffusion weighted images after 4 weeks from the onset showed the diffusion coefficient of the "acute" lesion to be the same level of normal white matter. And after 8 weeks from the onset, increased to a level higher than that of normal white matter to the same level of the "chronic" lesion.

Aged↗
PubMed1993

[Intraoperative monitoring for spinal cord tumor by spinal cord evoked potential following unilateral spinal cord stimulation].

We described our experiences with intraoperative spinal cord monitoring in 6 cases of spinal cord tumor. During the operation, spinal cord evoked potential following unilateral spinal cord stimulation was recorded from subdural monitoring electrodes. This series included two cases of intradural extramedullary tumor (one case each of neurinoma and of meningioma) and four cases of intramedullary tumor (2 cases of cavernous angioma, one case each of ependymoma, and of glioblastoma multiforme). Before the removal of the tumor, the spinal cord evoked potential showed lower amplitude or no response on the more affected side in all 6 cases. During the operation, the different intraoperative changes were shown on each side. The authors think that the detection of unilateral damage to the spinal cord is possible in spinal cord evoked potential using unilateral spinal cord stimulation.

Adult↗
PubMed1993

[Syringomyelia secondary to adhesive arachnoiditis: clinical profiles and efficacy of shunt operations].

The authors report nine cases of syringomyelia secondary to adhesive arachnoiditis treated in our institute from 1982 to 1991. Neurological signs, radiological features, and results of surgical treatment were reviewed. Common initial manifestations in association with syringomyelia were spastic paraparesis in 8 patients (88.9%), regional sensory loss in 4 (44.4%), neurogenic bladder in 4 (44.4%), and somatic pain in 2 (22.2%). All the neurological symptoms or signs progressed gradually for years. All the patients were treated with various modes of shunt operations, including syringo-peritoneal shunt in seven patients, syringo-subarachnoid shunt in one, and ventriculo-peritoneal shunt in one, respectively. Three patients who failed to resolve their major complaints after the first surgery further received syringo-peritoneal shunts. Postsurgical follow-up periods ranged from 18 months to 10 years. Serial MR imaging revealed a significant reduction of the size of syringomyelia in 8 of 9 patients. However only 6 patients showed certain improvement of neurological deficits. Three patients who failed to improve clearly had a long (beyond 15 years) history of syringomyelia before the first surgical treatment. A total of 11 syringo-peritoneal shunts were done in 8 patients of whom 5 patients improved neurologically. It was noticed that 4 of 5 successful syringo-peritoneal shunts were placed in the caudal level of the syrinx. In conclusion, syringo-peritoneal shunt may be at present an optimal mode of surgical management for syringomyelia secondary to adhesive arachnoiditis. In addition, we would like to recommend that follow-up serial MR imaging be done for patients having adhesive arachnoiditis in order to detect syringomyelia as early as possible.

Arachnoiditis↗
PubMed1992

Prostaglandin E1 and carbon dioxide reactivity during cerebral aneurysm surgery.

The purpose of this study was to evaluate the effect of prostaglandin E1 (PGE1) on CO2 reactivity during cerebral aneurysm surgery in 37 patients under neuroleptoanaesthesia (NLA). The patients were divided into two groups based on the timing of surgery (A: late surgery B: early surgery). In the early surgery group, aneurysm surgery was performed within three days of subarachnoid haemorrhage (SAH) and in the late surgery group surgery was performed more than four days after SAH. Presurgical neurological status was worse in the early surgery group than in the late surgery group (P less than 0.01). Local cerebral blood flow (LCBF) measurements were made using a thermal gradient blood flow meter. Hypotension was induced by PGE1 administration at an initial dose of 0.1 micrograms.kg-1.min-1 and adjusted to maintain the mean arterial pressure (MAP) at about 70 mmHg. The CO2 reactivity was calculated by the % change in LCBF divided by the change in PaCO2 (% delta LCBF/delta PaCO2 (%.mmHg-1)). LCBF, heart rate and mean arterial blood pressure were measured during and after PGE1 infusion. Carbon dioxide reactivity was measured before, during and after PGE1 administration. The LCBF did not change throughout the study but CO2 reactivity was greater in Group A (before hypotension: 2.74 +/- 0.85 %.mmHg-1, during hypotension: 2.54 +/- 0.73 % .mmHg-1, after hypotension: 2.59 +/- 1.17 %.mmHg-1) than in group B (before hypotension: 1.54 +/- 0.57%.mmHg-1, during hypotension: 1.56 +/- 0.59 %.mmHg-1, after hypotension: 1.49 +/- 0.42%.mmHg-1) (P less than 0.01). Outcome which was graded by Glasgow Outcome Scale at discharge, was better in Group A (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Carbon dioxide reactivity during prostaglandin E1 induced hypotension for cerebral aneurysm surgery.

The cerebral vasomotor reactivity to carbon dioxide was studied, using a thermal gradient blood flow meter in 43 patients with intracranial cerebral aneurysm under deliberate hypotension induced by prostaglandin E1 (PGE1) infusion. The patients were divided into three groups according to the neurological status. Patients in Groups A and B had subarachnoid haemorrhage due to ruptured cerebral aneurysms. Group A consisted of 23 patients with a neurological grade of I-II and Group B consisted of 11 patients with a grade of III-V. Nine patients with non-ruptured cerebral aneurysm served as controls (Group C). After the dura was opened, local cerebral blood flow (LCBF) was measured. The PGE1 was started with an initial dose of 0.1 microgram.-kg-1.min-1 and the dose was adjusted to maintain MAP at about 70 mmHg. The LCBF and carbon dioxide (CO2) reactivity were estimated during and after PGE1 administration. The LCBF did not change among groups throughout the study period. Carbon dioxide reactivity was estimated as follows: absolute; delta LCBF/delta PaCO2, and relative; % delta LCBF/delta PaCO2 after changing PaCO2 by increasing minute ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Local cerebral blood flow and its CO2 reactivity in the ischemic cerebrovascular diseases before and after bypass].

We evaluated the effects of the STA-MCA anastomosis on local cerebral blood flow (LCBF) and CO2 cerebrovascular reactivity (CVR) in ischemic cerebrovascular diseases (CVD). [Patients and Methods] We examined the LCBF and CVR of 21 patients with ischemic CVD subjected standard STA-MCA anastomosis. During surgery, LCBF was continuously measured using the thermal diffusion method sometimes in a state of decreased PaCO2 (median: 7.2mmHg) before and after bypass. CVR was represented as % delta LCBF/delta CO2. [Results] 1) In the control group (with non-ruptured aneurysm, n = 7), LCBF was 58.6 +/- 14.1 ml/100g/min and % delta LCBF/delta CO2 was 4.68 +/- 1.68%/mmHg. 2) Before bypass, LCBF was 46.7 +/- 10.3ml/100g/min. It was significantly (p < 0.05) lower than control level. After bypass, LCBF increased significantly (p < 0.05) to 62.0 +/- 14.3 ml/100g/min. 3) Before bypass, % delta LCBF/delta CO2 was -1.36 +/- 4.34%/mmHg. In the 14 cases (66.7%), % delta LCBF/delta CO2 was below the 0%/mmHg (inverse steal effect). 4) After bypass, it increased to 0.08 +/- 2.73%/mmHg. 11 cases (52.4%) showed % delta LCBF/delta CO2 was above the 0%/mmHg. 5) In the group with a preoperative % delta LCBF/delta CO2 of less than 0%/mmHg, preoperative LCBF was 43.6 +/- 9.3 ml/100g/min, which was significantly low (p < 0.01) compared to that in the group with higher % delta LCBF/delta CO2. After bypass, LCBF and % delta LCBF/delta CO2 remarkably increased in the group with % delta LCBF/delta CO2 below 0%/mmHg. [Conclusion] Before bypass, LCBF was low and CVR was severely disturbed. In the 14 cases % delta LCBF/delta CO2 was below 0%/mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[New surgical technique for anterior cervical fusion; surgical technique for anterior cervical fusion utilizing autogenous bone graft from the cervical vertebrae].

Since April, 1990, the authors have been reporting a surgical technique for anterior cervical fusion utilizing autogenous bone graft from the cervical vertebrae. This series included 53 patients (40 males and 13 females). The age ranged from 24 to 72 years with a mean of 49 years. There were 42 cases of cervical disc disease, and 11 cases of cervical disc disease with ossification of the posterior longitudinal ligament (OPLL). The patient was out of bed within two days and treated in a soft collar for 3 months. In all patients, the symptoms improved postoperatively. Postoperative X-ray showed slight anterior angulation deformity in 3 out of 53 cases (6%). The advantages of our surgical technique are as follows: 1) There are no problems related to the iliac donor site 2) The removal of posterior spur and localized OPLL is safely and easily performed.

Adult↗
PubMed1992

[Spontaneous peripelvic extravasation after the operation of rectal cancer, treated by indwelling the ureteral stent: report of three cases].

Three cases of spontaneous peripelvic extravasation after the operation of rectal cancer are reported. In case 1, a 65-year-old female complained of left flank pain one month after high-anterior resection for rectal cancer. Drip infusion pyelography (DIP) and retrograde pyelography (RP) showed extravasation from the left renal pelvis. The ureteral stent was indwelled, and the extravasation showed remission. In case 2, a 55-year-old female complained of left lumbago 6 months after Miles' operation for rectal cancer. DIP showed extravasation from the left renal pelvis. The same findings were confirmed on the repeated DIP after 10 days. The ureteral stent was indwelled, and the extravasation was cured. In case 3, a 69-year-old male complained of left flank pain and left abdominal tumor 10 months after Miles' operation for rectal cancer. DIP and RP showed extravasation from the right renal pelvis, and computed tomographic (CT) scan showed urinoma formation. Drainage of the urinoma was performed and the ureteral stent was indwelled. The urinoma and the extravasation was cured. We emphasized the usefulness of indwelling the ureteral stent for the conservative management of spontaneous peripelvic extravasation caused by a malignant tumor, and a discussion of the relevant literature follows.

Aged↗
PubMed1992

[Anatomical analysis of the sources of somatosensory evoked fields (SEFs) using 3D-MRI].

We have recorded short latency somatosensory evoked magnetic fields (SEFs) to left median nerve stimulation in three healthy subjects. The locations of the deduced dipole sources were projected onto the 3-Dimensional magnetic resonance imaging (3D-MRI) of the individual subjects providing an anatomical localization. We found that the deduced sources were located at the primary sensorimotor hand area on the posterior surface of the central sulcus, at an average depth of 26mm (11mm) from the scalp (brain surface). This technique that combined MEG with 3D-MRI was able to precisely determine source locations and analyze the relationships between dipole sources and brain structures. By using this technique, we can confirm functional anatomy of the brain noninvasively, and obtain much useful information preoperatively and during operation.

Adult↗
PubMed1992

[Intraoperative monitoring of facial electromyographic responses during neurovascular decompressive surgery for hemifacial spasm].

UNLABELLED: In this paper, we reported our experience of intraoperative facial electromyographic recordings obtained during microvascular decompression for hemifacial spasm. MATERIALS AND METHODS: Intraoperative electromyographic recordings from the mentalis muscle during stimulation of the temporal branch of the facial nerve has been attempted in 31 patients. No muscle relaxants were used except for those before intubation. Of 31 patients, 22 were female and 9 were male. The age on admission ranged from 31 to 60 years with a mean of 54 years. RESULTS: 1. Abnormal response appeared with a latency of about 10 msec after stimulation. This response disappeared in 30 out of 31 patients at the end of operation. In 4 patients, the abnormal response disappeared prior to decompression of the nerve. 2. 30 patients in whom the abnormal response disappeared were free of spasm immediately after surgery. Hemifacial spasm has been relieved in 28 patients with a follow up period of 6 months to 2 years and 7 months. The remaining two patients had mild spasm. The one patient in whom the abnormal response did not disappear had persistent hemifacial spasm. CONCLUSION: The authors think that intraoperative facial electromyographic recording is useful to identify the blood vessel that is causing the spasm and to ensure that decompression of the nerve has been accomplished.

Adult↗
PubMed1991

Local cerebral blood flow with prostaglandin E1 or trimethaphan during cerebral aneurysm clip ligation.

This study was performed to examine changes in local cerebral blood flow during hypotensive anaesthesia with either prostaglandin E1 (PGE1) or trimethaphan (TMP). Local cerebral blood flow (LCBF), mean blood pressure (MBP), heart rate (HR), and hourly urine output (UO) were studied in 51 patients undergoing cerebral aneurysm surgery with neuroleptanalgesia (NLA). The incidence of vasospasm after aneurysm surgery, and outcome (Glasgow Outcome Scale) at discharge were evaluated. Measurements of LCBF were made using a thermal gradient blood flow meter. The dose of PGE1 or TMP was adjusted to maintain MBP at about 70 mmHg, and LCBF was studied during and after PGE1 or TMP administration. Hypotensive drugs were discontinued at the completion of aneurysm clipping. After starting PGE1 or TMP, MBP decreased immediately, but HR did not change in either group. The LCBF decreased 30 min after the start of TMP administration and increased immediately after its discontinuation, whereas PGE1 did not affect LCBF. Urine output increased during PGE1 administration but was unchanged during TMP. Neither drug affected surgical outcome or the incidence of vasospasm. These results suggest that PGE1 may be preferable to trimethaphan for hypotensive anaesthesia in cerebral aneurysm surgery because LCBF is maintained.

Adult↗