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F Shichijo

Publications and source records attributed to F Shichijo.

13 recordsLinked to original sources
PubMed1991

Artificial neural networks for source localization in the human brain.

Source localization in the brain remains an ill-posed problem unless further constraints about the type of sources and the head model are imposed. Human head is modeled in various ways depending critically on the computing power available and/or the required level of accuracy. Sophisticated and truly representative models may yield more accurate results in general, but at the cost of prohibitively long computer times and huge memory requirements. In conventional source localization techniques, solution source parameters are taken as those which minimize an index of performance, defined relative to the model-generated and clinically measured voltages. We propose the use of a neural network in the place of commonly employed minimization algorithms such as the Simplex Method and the Marquardt algorithm, which are iterative and time consuming. With the aid of the error-backpropagation technique, a neural network is trained to compute source parameters, starting from a voltage set measured on the scalp. Here we describe the methods of training the neural network and investigate its localization accuracy. Based on the results of extensive studies, we conclude that neural networks are highly feasible as source localizers. A trained neural network's independence of localization speed from the head model, and the rapid localization ability, makes it possible to employ the most complex head model with the ease of the simplest model. No initial parameters need to be guessed in order to start the calculation, implying a possible automation of the entire localization process. One may train the network on experimental data, if available, thereby possibly doing away with head models.

Brain↗
PubMed1991

[Surgical treatment of hypertensive cerebellar hemorrhage; stereotactic aspiration surgery vs suboccipital craniectomy].

Patients with severe types of hypertensive cerebellar hemorrhage have been treated usually by suboccipital craniectomy and hematoma evacuation. However, since 1981, we have treated such patients with stereotactic aspiration surgery. The purpose of this study was to evaluate the prognosis of patients treated by stereotactic aspiration surgery for cerebellar hemorrhage in comparison with those who underwent suboccipital craniectomy. Between May 1976 and December 1989, 246 patients with hypertensive cerebellar hemorrhage were admitted to our university hospital and affiliated hospitals. The patients were classified into four categories according to the grading of hypertensive cerebellar hemorrhage proposed by Matsumoto in 1982; benign, moderate, severe, and fulminant. Then we decided the most appropriate therapy according to this grading. Fifty-nine patients (24.0%) underwent suboccipital craniectomy and 38 (15.4%) underwent stereotactic aspiration surgery. There was no significant difference in the postoperative outcome between suboccipital craniectomy and stereotactic aspiration surgery in the overall study. However prognosis of the fulminant type was significantly better with stereotactic aspiration surgery than with suboccipital craniectomy. Possible reasons for this include: 1) All patients of this type who underwent aspiration surgery had this procedure within 12 hours after the onset of cerebellar hemorrhage. 2) The hematoma volume of most patients of this type who had aspiration surgery was under 30ml. 3) The age of all patients of this type with aspiration surgery was under 70 years old. In conclusion, we suggest that aspiration surgery for hypertensive cerebellar hemorrhage is indicated for all patients with moderate, severe and fulminant types of hemorrhage.

Cerebellar Diseases↗
PubMed1990

Spinal sensory and motor tract activation after epidural electrical stimulation in the cat.

Somatosensory evoked potentials (SEPs) after peripheral nerve stimulation and motor evoked potentials (MEPs) after transcranial stimulation have been routinely used as monitors of the viability of pathways in the posterior and anterior spinal cord, respectively, in patients undergoing spinal cord surgery. To assess total spinal cord function, both of these procedures must be performed simultaneously, which is both cumbersome and technically difficult. The objectives of this study were to demonstrate both sensory and motor spinal tract activation after epidural electrical stimulation of the cat spinal cord. Thirty-seven adult mongrel cats were anesthetized with ketamine, intubated, and maintained with Ethrane and nitrous oxide. Stimulating electrodes were placed over the right dorsolateral spinal cord epidurally at T7 after a laminectomy. Recording electrodes were placed over the right L3 spinal cord epidurally, on the right L7 dorsal and ventral nerve roots, on the right and left sciatic nerves in the popliteal fossa, and in the right gastrocnemius muscle. After epidural stimulation of the spinal cord at T11, distinct reproducible potentials were recorded at each site. Activity in the L7 dorsal root implicated activation of spinal sensory tracts. Activity in the L7 ventral root and in the gastrocnemius implicated activation of spinal motoneurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Analysis of premovement components of movement-related cortical potentials in patients with Parkinson's disease or brain tumors.

We have recorded movement-related cortical potentials (MRCPs) preceding voluntary finger extension in patients with Parkinson's disease and in patients with brain tumors that may involve the motor system. Three components of potential shifts preceding the voluntary movement were identified in all subjects. There were no differences between the healthy subjects and those with Parkinson's disease, or between pre- and postoperative recordings from the same parkinsonian patients in terms of onset latencies and gradients of these potential shifts. There was no evidence of MRCPs from the depth electroencephalogram recorded from the thalamic ventrolateral (VL) nucleus. After removal of the cerebellar dentate nucleus along with a tumor, MRCPs were still identified. After removal of tumors from the supplementary motor cortex and frontal association cortex, a part of the MRCPs preceding the voluntary movement was absent. The generation of MRCPs was considered not to be greatly affected by the cerebellar system because: (1) no MRCPs were detected from the thalamic VL nucleus, which is the relay nucleus of the dentato-rubro-thalamic pathway, believed to be related to voluntary movement; (2) destruction of the VL nucleus did not cause any changes in the MRCPs recorded at other sites, and (3) the MRCPs did not disappear when the dentate nucleus, an output system, was excised.

Adult↗
PubMed1990

Computed tomography controlled aspiration surgery for hypertensive intracerebral hemorrhage. Experience of more than 400 cases.

To overcome the disadvantages of conventional surgery, we developed our own method of computed tomography controlled stereotactic aspiration surgery for hypertensive intracerebral hemorrhage. A new ultrasonic surgical aspirator was also developed to facilitate aspiration of a dense clot in the acute stage. Between 1980 and 1988, 437 patients with hypertensive intracerebral hemorrhage underwent aspiration surgery. Computed tomography controlled stereotactic aspiration surgery can be performed in hematomas of any site or any stage with minimal tissue damage, even in aged patients. Aspiration surgery led to a favorable clinical experience and outcome, especially in the acute stage.

Activities of Daily Living↗
PubMed1988

[Surgical treatment for hypertensive cerebellar hemorrhage--indication and characteristics of stereotaxic aspiration surgery].

From May 1976, through May 1985, eighty-nine patients with hypertensive cerebellar hemorrhage were admitted to our university hospital and affiliated hospitals. The age at onset ranged from 42 to 86 years, with a mean of 65.1 years. Thirty-one of these patients underwent conservative treatment, 20 were given ventricular drainage, 23 underwent suboccipital craniectomy and 15 underwent stereotaxic aspiration surgery. The patients were classified into four categories according to the grading of hypertensive cerebellar hemorrhage proposed by Matsumoto in 1982. Twenty-two cases were of benign type, 20 were moderate type, 30 were severe type, and 17 were fulminant type. The 22 benign type cases showed good recovery (ADL 1 or ADL 2), whereas the mortality rate of severe type cases was 26.7%, and that of fulminant type cases was 70.6%. The site and extension of hematoma were identified by CT. Fourty cases (45.0%) were confined to the left hemisphere, and 19 (21.3%) were localized in the vermis. When the hematoma volume was more than 15 ml, surgical evacuation of the hematoma was considered. Since 1981, stereotaxic aspiration surgery has been performed in cases of hypertensive cerebellar hemorrhage with a mean patient age of 66.9 years, ranging from 51 to 82 years. Patients treated have consisted of 2 with moderate type hemorrhage, 10 with severe type, and 3 with fulminant type, with an overall surgical mortality rate of 33.3%. However, the outcome of fulminant type hemorrhage has remained ADL 2 or ADL 3. The benefits of this type of surgery are that it is not only indicated as an emergency treatment for patients who are aged or at high risk, but that it can be also performed for fulminant type hemorrhage.

Aged↗
PubMed1987

CT-controlled stereotactic aspiration in hypertensive brain hemorrhage. Six-month postoperative outcome.

CT-guided stereotactic aspiration surgery for the evacuation of hypertensive brain hemorrhage (HBH) has been introduced recently. From December, 1980, to April, 1986, we used aspiration surgery in 375 cases of HBH. The 6-month postoperative outcome of aspiration surgery for acute basal-ganglionic hemorrhage was compared with that after conventional surgery of all Japan and those after conservative treatment. In basal-ganglionic hemorrhage, aspiration surgery led to a favorable clinical experience and outcome, providing the possibility of a new avenue of surgical treatment of HBH.

Cerebral Hemorrhage↗
PubMed1985

Computer tomography-controlled stereotactic surgery.

In computed tomography (CT)-controlled stereotactic surgery, the coordinate system of the CT scanner is applied to determine the target depth and direction as well as for readjustment of final probe direction. This method can be used for all types of stereotactic surgery for the brain.

Cerebral Hemorrhage↗
PubMed1985

[CT-controlled stereotactic operation of hypertensive intracerebral hemorrhage--1. Theoretical principles and the operative procedures].

In recent years, the CT-guided stereotactic operations have been applied to evacuation of intracerebral hematomas or cystic lesions, the biopsy of deep seated brain tumors, and brachytherapy of brain tumors. However, most of these operations utilized stereotactic guide-frame for determination of the coordinates of the target point. In this paper, an operative method for the stereotactic surgery using coordinate system of CT apparatus itself is presented as a novel method with the principles and the actual operative procedures. It may be called as "CT-controlled stereotactic operation" because the surgery should be performed under intraoperative use of CT scanning. The apparatus is composed with two parts: head holder and needle holder, which were reformed MATSUMOTO's stereotactic apparatus with a more wider separation of the two parts. The principles of the aiming of the target are as follows. Values of coordinates of the target point of Xt, Yt, and Zt will be obtained from the CT scan preoperatively. Zt is set to Zero, then values of coordinates of aiming needle are obtained in two points, N1 (X1, Y1, Z1) and N2 (X2, Y2, Z2). Value of coordinates of the X0 and Y0, namely falling points of the needle direction in the plane of XY, will be calculated with the values of X1, Y1, X2, Y2, Z1 and Z2 by a formula. Direction of the needle is corrected until the values of X0 and Y0 are equal to that of Xt and Yt before insertion of the needle.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1985

[CT-controlled stereotactic operations for hypertensive intracerebral hemorrhage Part 2: Cases with small hematomas in the thalamus and the basal ganglia].

Theoretical principles and actual operative procedures of "CT-controlled stereotactic operations," which was invented by us, have been reported in the previous paper of part 1. In this paper, it is reported 9 cases, 5 of putaminal hemorrhage and 4 of thalamic hemorrhage, who underwent CT-controlled stereotactic operations for evacuation of their small hematomas. Eight patients were male and one patient was female. The age of patients ranged from 42 to 75 years, with a mean age of 62.7 years and there were 3 patients of over 70 years old. And there were 2 patients with poor general condition preoperatively; one had the implantation of pacemaker because of Adams-Stokes syndrome 5 years ago and the other had total gastrectomy because of gastric neoplasm 1 month ago. Eight cases were in acute stage within three days after the onset. Mean operative timing was 14.6 hrs. after the onset. It was very interesting that three cases, 2 of putaminal and 1 of thalamic hemorrhage, had recovered dramatically by this surgery, just like the course after the hematoma evacuation in cases of chronic subdural hematoma. Namely their hemiparesis are decreased remarkably within a few hours after hematoma evacuation. Practically this surgery has minimum risk with simple procedures. The hematoma evacuation can be done easily with high accuracy of stereotaxy. From our experience, potential usefulness of this surgery was positively suggested in the surgical treatment for small ganglionic hematomas as well as thalamic hematomas.

Adult↗
PubMed1984

Long-term follow-up review of cases of Parkinson's disease after unilateral or bilateral thalamotomy.

Follow-up reviews were carried out on 86 of 103 patients with Parkinson's disease who underwent unilateral or bilateral ventrolateral (VL) thalamotomy in the period from 1964 to 1969. Of these 86 patients, 64 received unilateral surgery, and 22 bilateral surgery. The follow-up periods were at least 10 years from the operation (from the second intervention in cases with bilateral procedures). In the group that received unilateral surgery, no progression after surgery was seen in three of six patients classified preoperatively in Grade I (Hoehn and Yahr's Grade 1), nine of 20 patients in Grade IIa (Hoehn and Yahr's Grade 2), 13 of 23 patients in Grade IIb (Hoehn and Yahr's Grade 3), and six of 15 patients in Grade III (Hoehn and Yahr's Grade 4). In the group that received bilateral surgery, one of three patients in Grade I and one of 11 patients in Grade IIa before the second intervention maintained continuous full social activities for over 10 years after the second surgery without any medication. In addition, eight of 11 patients classified preoperatively in Grade IIa and five of eight patients in Grade IIb seemed to show no progression after the second operation; four of 22 patients stopped taking their medication because of improvement in their symptoms. No patient who received bilateral surgery had progression of the disease to death. Observations suggested the efficacy of thalamic surgery, not only for improvement of motor symptoms but also for reducing progression of the disease, although no control study was made. Thalamotomy is still used to treat Parkinson's disease as an alternative to current medical treatments, such as L-dopa therapy.

Adult↗