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Biomedical subjects

Yoichi Katayama

Publications and source records attributed to Yoichi Katayama.

At least 55 records · Page 3Linked to original sources
PubMed2004

Evoked-cerebral blood oxygenation changes in false-negative activations in BOLD contrast functional MRI of patients with brain tumors.

Blood oxygenation level dependent contrast functional MRI (BOLD-fMRI) has been used to define the functional cortices of the brain in preoperative planning for tumor removal. However, some studies have demonstrated false-negative activations in such patients. We compared the evoked-cerebral blood oxygenation (CBO) changes measured by near-infrared spectroscopy (NIRS) and activation mapping of BOLD-fMRI in 12 patients with brain tumors who had no paresis of the upper extremities. On the nonlesion side, NIRS demonstrated a decrease in deoxyhemoglobin (Deoxy-Hb) with increases in oxyhemoglobin (Oxy-Hb) and total hemoglobin (Total-Hb) during a contralateral hand grasping task in the primary sensorimotor cortex (PSMC) of all patients. On the lesion side, NIRS revealed a decrease in Deoxy-Hb in five patients (Deoxy-decrease group), and an increase in Deoxy-Hb in seven patients (Deoxy-increase group); the Oxy-Hb and Total-Hb were increased during activation in both groups, indicating the occurrence of rCBF increases in response to neuronal activation. BOLD-fMRI demonstrated clear activation areas in the PSMC on the nonlesion side of all patients and on the lesion side of the Deoxy-decrease group. However, in the Deoxy-increase group, BOLD-fMRI revealed only a small activation area or no activation on the lesion side. Intraoperative brain mapping identified the PSMC on the lesion side that was not demonstrated by BOLD-fMRI. The false-negative activations might have been caused by the atypical evoked-CBO changes (i.e. increases in Deoxy-Hb) and the software employed to calculate the activation maps, which does not regard an increase of Deoxy-Hb (i.e., a decrease in BOLD-fMRI signal) as neuronal activation.

Adult↗
PubMed2004

Intraoperative monitoring of the corticospinal motor evoked potential (D-wave): clinical index for postoperative motor function and functional recovery.

The corticospinal motor evoked potential was investigated as a monitoring index of motor function to perform maximal resection of brain tumors located around the motor cortex in 37 patients with glioma. Tumor resections were performed under general anesthesia with muscle relaxant and completely controlled ventilation. No special arrangements for anesthesia were required. Direct cortical stimulation revealed that if one electrode was placed on the posterior half of the precentral gyrus, the D-wave could be recorded even when using an electrode separation of 10 mm, and the amplitude was larger with anodic rather than cathodic stimulation. Monitoring of the D-wave enabled the function of the corticospinal tract to be evaluated selectively. Postoperative persistent motor disturbance remained in six patients who had a decrease of over 30% in amplitude of the D-wave during tumor resection. A decrease of less than 30% may indicate postoperative preservation of motor function, including transient motor disturbance with subsequent complete recovery. Intraoperative monitoring of the D-wave is suitable for open cranial surgery with general anesthesia, can detect the primary motor cortex, and allow maximal resection of brain tumors located around the motor cortex.

Brain Neoplasms↗
PubMed2004

Metastatic pituitary tumor from renal cell carcinoma treated by fractionated stereotactic radiotherapy--case report.

A 63-year-old man presented with rapidly progressive visual field deficit and hypopituitarism including diabetes insipidus, 8 years after treatment for a renal cell carcinoma. Neuroimaging studies revealed a dumbbell-shaped pituitary mass that had destroyed the sellar floor and abutted against the optic apparatus. Fractionated stereotactic radiotherapy (SRT), employing computer-image integration techniques and a frame that could be relocated to facilitate a fractionated dosing scheme, was carried out under a plan for reducing the treatment risk to the optic apparatus. Three months later, the patient exhibited marked improvement in the visual field deficit and visual acuity concomitant with a reduction in tumor volume. Magnetic resonance imaging of the sellar region confirmed striking shrinkage of the metastasis. His neurological status remained stable at 12 months after the SRT with no complications. Fractionated SRT appears to be effective for preserving or improving the residual vision in patients with visual loss secondary to metastatic tumor of the pituitary gland, and may result in a longer and better quality of life.

Bone Neoplasms↗
PubMed2004

Deep brain stimulation for the treatment of parkinsonian, essential, and poststroke tremor: a suitable stimulation method and changes in effective stimulation intensity.

OBJECT: The tremor-suppression effect resulting from long-term stimulation of the thalamic nucleus ventralis intermedius (Vim) and the nucleus ventralis oralis posterior (Vop) was examined in the treatment of parkinsonian, essential, and poststroke tremor. METHODS: After identifying the accurate anterior border of the nucleus ventrocaudalis (Vc), deep brain stimulation (DBS) electrodes with four contacts were inserted into the Vim-Vop region at an angle of between 40 and 50 degrees from the horizontal plane of the anterior commissure-posterior commissure line. Two distal contacts were placed on the Vim side and two proximal contacts on the Vop side. The best sites of stimulation and parameters of bipolar stimulation were selected in each case and follow-up examinations were conducted for at least 2 years. In all 15 cases of parkinsonian tremor (18 sides) and in 14 of 15 cases of essential tremor (24 of 25 sides), cathodal stimulation of the Vim side with anodal stimulation of the Vop side was determined to be the best choice to suppress the tremor. In poststroke tremor, however, six of 12 cases (six of 12 sides) were selected for cathodal stimulation of the Vop side with anodal stimulation of the Vim side. The average stimulation intensity 1 month after initiation of DBS was 1.61 V in cases of parkinsonian tremor, 1.99 V in cases of essential tremor, and 2.39 V in cases of poststroke tremor. A comparison of stimulation intensities required at 1 and 24 months after initiation of DBS revealed that the lowest effective stimulation intensity increased 24.2% in cases of parkinsonian tremor, 21% in cases of poststroke tremor, and 46.9% in cases of essential tremor. Suppression of tremor was achieved in all cases (42 cases, 55 sides) during a period of 2 years. Nevertheless, two cases of poststroke tremor required dual-lead stimulation at the unilateral Vim-Vop region from the start of DBS, and two cases of essential tremor and one case of poststroke tremor required a stimulation intensity that was high enough to evoke unpleasant paresthesia and slight motor contraction during the follow-up period. CONCLUSIONS: Effective stimulation sites and stimulation intensities differ in different kinds of tremor; Vim and Vop stimulation is necessary in many cases. Interactions of the Vim and Vop under the control of interconnected areas of the motor circuitry may play an important role in both the development and DBS-induced suppression of tremor.

Adult↗
PubMed2004

Impact of stereotactic hematoma evacuation on activities of daily living during the chronic period following spontaneous putaminal hemorrhage: a randomized study.

OBJECT: Stereotactic evacuation of hematoma has been reported to reduce the incidence of mortality and to improve functional outcome in patients with spontaneous putaminal hemorrhage. Stereotactic evacuation of hematoma has not been widely accepted as a standard therapy, however, because its effect on functional outcome has been regarded as marginal and there have been no randomized trials with sufficient statistical power to quantify the benefits of this procedure. The authors reassessed the value of stereotactic evacuation of hematoma by analyzing its impact on activities of living during the chronic period following spontaneous putaminal hemorrhage in a randomized study. METHODS: Four hundred ninety patients were entered into the study. The severity of their hemorrhages was graded neurologically on admission (neurological grades: 1, eyes are open; 2, eyes are closed but open to weak stimuli; 3, eyes are closed but open to strong stimuli; 4, eyes do not open but extremities move to stimuli; and 5, eyes do not open and extremities do not move to stimuli). Patients with Grade 2 and those with Grade 3 were randomized into two groups with different treatment protocols (Group I, stereotactic evacuation of the hematoma; and Group II, conservative treatment). Patients assigned neurological Grade 4 or 5 were excluded from the study because a large-scale retrospective study in Japan revealed that surgical treatment in patients assigned to these neurological grades does not improve functional outcome. Among the 490 patients, 242 were randomized strictly. This patient population comprised 148 men and 94 women ranging in age from 38 to 80 years (mean 60.5 years). Compared with Group II, Group I treatment resulted in a lower mortality rate and better recovery to functional independence in patients with neurological Grade 3. In patients with Grade 2, Group I treatment contributed to a better recovery of functional outcome and a lower mortality rate, but the difference was not significant. Multivariate analysis confirmed that stereotactic evacuation of the hematoma was contributory to a better recovery in functional outcome. CONCLUSIONS: Stereotactic evacuation of hematoma is clearly of value in selected patients with spontaneous putuminal hemorrhage, whose eyes are closed but will open in response to strong stimuli (neurological Grade 3) on admission.

Activities of Daily Living↗
PubMed2004

Decreases of blood oxygenation level--dependent signal in the activated motor cortex during functional recovery after resection of a glioma.

The present case demonstrates that the blood oxygenation level-dependent (BOLD) signal intensity can decrease in the activated motor cortex on the lesion side (left) of a patient with a left frontal glioma during functional recovery after surgery. Near-infrared spectroscopy revealed that the decrease of BOLD signal was associated with increases of cerebral blood volume and deoxyhemoglobin concentrations in the cerebral vessels. This implies that the interpretation of results obtained by functional MR imaging in patients with brain disorders must take into consideration such atypically evoked cerebral blood oxygenation changes, which do not increase the BOLD signals.

Adult↗
PubMed2004

[Indication of surgical therapy for Parkinson's disease].

We review the current status of surgical treatment of Parkinson's disease (PD). The advantages of deep brain stimulation (DBS) over ablative surgery include reversibility and controllability of stimulation. In addition, DBS carries a smaller risk of side effects, especially when employed bilaterally. DBS of the thalamus is useful to control tremor which is unresponsive to medication. DBS of the globus pallidus internus (GPi) or the subthalamic nucleus (STN) is useful to control wearing off of motor symptoms which is difficult to manage with medication alone. DBS of STN and GPi improves motor function mainly during the off-period. DBS of STN attenuates levodopa-induced dyskinesia through reduction of dopa requirement, whereas DBS of GPi attenuates dopa-induced dyskinesia directly. DBS of STN is also useful to control symptoms of PD in patients who are intolerant to dopa. However, DBS of either STN or GPi cannot reverse advanced symptoms of PD, which are unresponsive to dopa.

Humans↗
PubMed2003

Prophylactic management of excessive natriuresis with hydrocortisone for efficient hypervolemic therapy after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Hyponatremia caused by excessive natriuresis is common in patients with aneurysmal subarachnoid hemorrhage (SAH). Natriuresis decreases the total blood volume through osmotic diuresis and increases the risk of symptomatic cerebral vasospasm. In such patients, hypervolemic therapy is difficult to achieve without causing hyponatremia because sodium replacement provokes further natriuresis and osmotic diuresis. We examined the effects of hydrocortisone, which promotes sodium retention, in patients with SAH. METHODS: Twenty-eight SAH patients were randomized into 2 groups after direct surgery: group 1 patients without hydrocortisone treatment (n=14) and group 2 patients with hydrocortisone treatment (1200 mg/d for 10 days; n=14). Both groups underwent hypervolemic therapy by aggressive sodium and water replacement. The goal of the hypervolemic therapy was to maintain the serum sodium level >140 mEq/L and the central venous pressure (CVP) within 8 to 12 cm H2O. RESULTS: Group 2 demonstrated a lower sodium excretion (P<0.05) and higher serum sodium level (P<0.05) compared with group 1. Hyponatremia developed in 6 patients (43%) in group 1 and 0 patients in group 2 (P<0.05). Group 2 also demonstrated a lower urine volume, lower infusion volume (P<0.05) required for hypervolemic therapy, and higher CVP (P<0.05). Failure to maintain CVP was observed in 12 patients (86%) in group 1 and 3 patients (21%) in group 2 (P<0.05). Hydrocortisone caused no serious side effects. CONCLUSIONS: Hydrocortisone clearly attenuates excessive natriuresis. Prophylactic hydrocortisone administration appears to have a therapeutic value in inducing hypervolemia efficiently after SAH.

Adult↗
PubMed2003

Deregulation of the TP53/p14ARF tumor suppressor pathway in low-grade diffuse astrocytomas and its influence on clinical course.

PURPOSE: The chromosome 9p21 region harbors three tumor suppressor genes, p14(ARF), p15(INK4b), and p16(INK4a), all of which can be targets for hypermethylation-associated inactivation in low-grade gliomas. p16(INK4a) and p15(INK4b) are critically involved in the RB1 pathway, whereas p14(ARF) acts as an upstream regulator of the TP53 pathway. The role of each tumor suppressor pathway in low-grade diffuse astrocytomas and their relationships with clinical behavior remain to be elucidated. EXPERIMENTAL DESIGN: We assessed the alterations of the RB1/CDK4/p16(INK4a)/p15(INK4b) and the TP53/MDM2/p14(ARF) pathways in 46 WHO grade II astrocytomas and analyzed their impact on prognosis. RESULTS: The TP53/MDM2/p14(ARF) pathway was altered in 32 of 46 cases (70%) by either TP53 mutation (25 cases) or p14(ARF) methylation (9 cases). The RB1/CDK4/p16(INK4a)/p15(INK4b) pathway was disrupted in 6 of 46 cases (13%) by either RB1 methylation (1 case), p16(INK4a) methylation (3 cases), or p15(INK4b) methylation or homozygous deletion (3 cases). Generally speaking, individual tumors thus tended to display alteration of only one component from both pathways. Any independently analyzed genetic alteration failed to provide statistically prognostic information. The alternate or simultaneous presence of TP53 mutation and p14(ARF) methylation emerged as a univariate predictor of a shorter progression-free survival (P = 0.0456) but was not statistically significant when age and extent of surgery were included in the analysis. CONCLUSIONS: Alternative disruption of the TP53/p14(ARF) pathway represents a frequent event in low-grade diffuse astrocytomas and correlates with an unfavorable clinical course. However, its value is unlikely to include prognostic utility that is independent of other conventional prognostic factors.

Adult↗
PubMed2003

Treatment of low-grade diffuse astrocytomas by surgery and human fibroblast interferon without radiation therapy.

Low-grade diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. However, a substantial proportion undergoes dedifferentiation to a more malignant phenotype. Considerable controversy exists as to the best therapeutic management for patients with such tumors. Over the past decade, we have applied human fibroblast interferon (HFIF) therapy without radiation therapy to low-grade astrocytomas. We investigated 28 patients with WHO grade II astrocytomas of the cerebral hemispheres treated by surgery plus HFIF therapy. The overall response rate to the HFIF therapy was 36%. All side-effects of HFIF were transient, tolerable and manageable. The 5-year progression free survival and overall survival probabilities were 65% and 96%, respectively. Although our data from small cohort of patients may have modest value, our results suggest that HFIF may be useful in treating low-grade diffuse astrocytomas.

Adolescent↗
PubMed2003

Long-term remission of primary central nervous system lymphoma by intensified methotrexate chemotherapy.

High-dose (1-3.5 g/m2) methotrexate (MTX) followed by whole-brain radiation therapy (WBRT) has consistently improved length of survival in primary central nervous system lymphoma (PCNSL), but the prognosis remains dismal. To optimize and enhance the dose intensity of MTX, we applied MTX at 8 g/m2 to 20 patients with PCNSL. In an effort to lower the risk of neurotoxic treatment sequelae, the WBRT dose was reduced to 30 Gy in cases of complete remission after MTX therapy. Further, omission of WBRT and administration of stereotactic radiotherapy (SRT) were undertaken in 3 older patients. The overall response rate to the MTX therapy was 83%. The median progression free survival (PFS) was 54 months with a median overall survival (OS) of 57 months. Achieving a complete response after MTX therapy was significantly associated with a longer PFS. Late neurotoxicity was encountered in 4 (50%) of 8 patients who were aged 60 years or older and received WBRT, but in none of 12 patients who were aged less than 60 years or avoided WBRT. All older patients who underwent SRT sustained complete remission without a dementing disease. Intensifying the MTX dosage to 8 g/m2 appears more promising in comparison to results reported with MTX doses of 1-3.5 g/m2. In younger patients, the establishment of complete remission by intensified MTX therapy and subsequent WBRT with a relatively lower dose could promise durable tumor remission with an acceptable neurotoxicity. In older patients, WBRT should be avoided to sustain a meaningful survival, and SRT may provide a valid strategy in terms of enhancing local disease control without undue risk.

Adult↗
PubMed2003

Telomerase activity in pituitary adenomas: significance of telomerase expression in predicting pituitary adenoma recurrence.

Clinical and histopathological evaluations are inadequate for assessing biological aggressiveness and regrowth potential in benign pituitary adenomas. To develop reliable and prognostically informative means of predicting behavior remains an intractable problem. Telomerase, a reverse transcriptase that extends telomere length, may facilitate tumorigenesis and tumor immortality. In the present study, we investigated the telomerase activity of pituitary adenomas, and attempted to assess the value of telomerase expression for predicting their clinical course. In total, 31 (30 patients) benign pituitary adenoma samples including 8 recurrent adenomas were studied. Telomerase expression was evaluated by polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay and telomerase activity levels were quantitated by improved PCR enzyme-linked immunosorbent assay (ELISA). The data were analyzed in relation to clinical course which was reviewed at 4-5.5 years (median follow-up time, 52.5 months) after surgery. The relative values of the telomerase expression for predicting the clinical course were compared with the MIB-1 antigen-based proliferative cell index (PCI) and p53 immunoreactivity which have recently been suggested to correlate with aggressive behavior in pituitary adenomas. Overall, telomerase expression was detected in 13% of the adenomas (4 tumor tissues, 3 patients). These adenomas comprised large, invasive, and functioning adenomas. The number of telomerase-positive adenomas was small; however, the PCI was higher in cases with telomerase expression (4 tumor tissues; mean, 4.2 +/- 2.4%) than in those without it (27 tumor tissues; 1.4 +/- 1.3%) (p = 0.01). One tumor with detectable telomerase expression, which did not undergo additional pharmacological or radiotherapeutic intervention after first surgery, recurred rapidly despite gross total surgical resection, although the PCI of both the primary and recurrent adenomas was not high. Detection of telomerase expression may represent an additional useful means of identifying aggressive behavior, complementing the histopathological evaluation of benign-appearing pituitary adenomas.

Adenoma↗
PubMed2003

Promoter hypermethylation of the DNA repair gene O6-methylguanine-DNA methyltransferase is an independent predictor of shortened progression free survival in patients with low-grade diffuse astrocytomas.

The O6-methylguanine-DNA methyltransferase (MGMT) plays a major role in repairing DNA damage from alkylating agents. In several human neoplasms including low-grade diffuse astrocytomas, promoter hypermethylation of MGMT has been shown to correlate with an increased frequency of p53 mutation. In the present study, we analyzed MGMT promoter methylation by the methylation-specific PCR in 49 newly diagnosed WHO grade II astrocytomas and evaluated its clinical usefulness. MGMT promoter methylation was found in 21 (43%) of the 49 tumors. A tight correlation existed between MGMT methylation and p53 protein accumulation (P=0.0424). The presence of MGMT methylation was significantly associated with a shorter progression free survival (PFS) on both univariate analysis (P=0.0014) and multivariate analysis (P=0.0081). It was a more powerful determinant of the PFS than age, sex, performance status, proliferative activity, or p53 expression, and was independent of the extent of surgery. In terms of the overall survival, MGMT methylation demonstrated a prognostic utility in the univariate analysis but not in the multivariate analysis. The present findings indicate that aberrant methylation of the MGMT promoter independently augurs for an unfavorable clinical course in patients with low-grade diffuse astrocytomas. Since the presence of MGMT methylation is expected to predict an increased sensitivity to alkylating chemotherapeutic agents, earlier chemotherapy could serve to improve an unfavorable natural history in tumors with MGMT methylation.

Adult↗
PubMed2003

Motor cortex stimulation in patients with post-stroke pain: conscious somatosensory response and pain control.

We analyzed the conscious sensory responses to cortical stimulation of 31 patients with post-stroke pain who underwent motor cortex stimulation (MCS) therapy. During surgery for electrode placement, a sensory response (tingle projected to a localized peripheral area) was elicited by high-frequency stimulation (50 Hz) in 23 (84%) from the somatosensory cortex, and in 16 (52%) from the motor cortex without muscle contraction. Unpleasant painful sensation was induced or their original pain was exacerbated in 12 patients (39%) when the somatosensory cortex was stimulated and in two (6%) when the motor cortex was stimulated. Somatosensory responses were induced in eight (25%) even by low-frequency stimulation (1-2 Hz) of the motor cortex at an intensity below the threshold for muscle contraction. In contrast, among 20 nonpain patients who underwent a similar procedure for cortical mapping in epilepsy or brain tumor surgery, a sensory response was produced by high-frequency stimulation in only eight (40%; p < 0.02) from the somatosensory cortex and four (20%; p < 0.03) from the motor cortex. Pain sensation was not induced by stimulation of the somatosensory cortex (p < 0.002) or motor cortex in any of these patients. In addition, none of these patients reported a sensory response to low-frequency stimulation. In both of the two post-stroke pain patients who reported abnormal pain sensation in response to stimulation of the motor cortex, MCS failed to control their post-stroke pain. These findings imply that the sensitivity of the perceptual system even to activity of the motor cortex is heightened in post-stroke pain patients, which can sometimes hinder pain control by MCS.

Consciousness↗
PubMed2003

Reduction of infarction volume by bolus injection of pamiteplase, a modified tissue plasminogen activator with a longer half-life.

Using a rat model of thromboembolic stroke we evaluated whether or not fibrinolysis by bolus injection of pamiteplase, a modified tissue plasminogen activator (tPA) with a longer half-life, reduces infarction volume. Infarction volume was significantly reduced by the early administration of pamiteplase at 2 h after the onset of ischemia. Hemorrhagic infarction was observed only in 3 of 10 rats (30%) treated at 6 h. Thus, bolus injection of pamiteplase can reduce infarction volume suppressing the incidence of hemorrhage.

Acute Disease↗
PubMed2003

Evaluation of extracranial-intracranial arterial bypass function by using near-infrared spectroscopy.

OBJECT: It has been reported that extracranial-intracranial (EC-IC) arterial bypass surgery can be useful in preventing stroke in patients with hemodynamic compromise. Little is yet known, however, regarding the extent to which the bypass contributes to maintaining adequate cerebral blood oxygenation (CBO) and its temporal changes following surgery. The authors evaluated bypass function repeatedly by using near-infrared spectroscopy (NIRS) after surgery. METHODS: The authors investigated 30 patients who had undergone EC-IC bypass surgery. Single-photon emission computerized tomography revealed a decrease in regional cerebral blood flow (rCBF) and a lowered rCBF response to acetazolamide. Changes in CBO were evaluated in the sensorimotor cortex during compression of the anastomosed superficial temporal artery (STA). When decreases in oxyhemoglobin (HbO2) and total hemoglobin (Hb) concentrations were observed, the bypass was considered to have maintained CBO in the sensorimotor cortex given that decreases in HbO2 and total Hb indicate cerebral ischemic changes. The bypass maintained CBO immediately after surgery in 36.7% of patients (Group I, 11 patients) and at some time after surgery, mostly within 1 year, in 43.3% of patients (Group II, 13 patients); however, it did not maintain it throughout the follow-up period in 20% of patients (Group III, six patients). Note that the preoperative rCBF in patients in Groups I and II was lower than that in patients in Group III (p < 0.004). In fact, the preoperative rCBF predicted whether a bypass would maintain CBO at a cutoff value of 24.5 to 25 ml/100 g/min. Among Groups I and II, 18 patients demonstrated an increase in deoxyhemoglobin during STA compression. The preoperative rCBF in these cases was lower than that in the six remaining patients (p < 0.006). Note that the preoperative rCBF predicted the postoperative deoxyhemoglobin response at a cutoff value of 22.2 to 24 ml/100 g/min. CONCLUSIONS: The EC-IC bypass surgery can maintain CBO immediately after surgery or gradually within 1 year when the preoperative rCBF is below 24.5 to 25 ml/100 g/min. Furthermore, bypass flow plays a critical role in maintaining an adequate CBO when preoperative rCBF is below 22.2 to 24 ml/100 g/min.

Acetazolamide↗