Biomedical subjects

I Koyanagi

Publications and source records attributed to I Koyanagi.

At least 19 recordsLinked to original sources

PubMed1999

Pediatric syringomyelia with chiari malformation: its clinical characteristics and surgical outcomes.

BACKGROUND: Most reports regarding pediatric syringomyelia have focused not only on Chiari malformation, but also on spinal dysraphism. However, the clinical characteristics of syringomyelia with spinal dysraphism are quite different from those of syringomyelia due to Chiari Type I malformation. The objectives of this study were to identify clinical characteristics of pediatric syringomyelia and to determine whether surgery prevents or corrects the scoliosis associated with syringomyelia. METHODS: We reviewed the records of 16 pediatric patients with syringomyelia and Chiari Type I malformation. The patients' ages ranged from 3 to 15 years, with mean age of 9.8 years. None of the patients had spinal dysraphism. RESULTS: Nystagmus was observed in 2 of the 16 patients, motor weakness in 8 patients, sensory disturbance in 10 patients, and scoliosis in 13 patients. As the initial surgical procedure, foramen magnum decompression (FMD) was performed in seven patients and syringo-subarachnoid (S-S) shunting in nine patients. The motor function improved in 7 of the 8 affected patients, and the sensory disturbance improved in 9 of the 10 affected patients. The magnetic resonance images obtained after the surgery revealed marked decrease of the syrinx size in all patients. Of the 13 patients with scoliosis, 5 showed improvement, 5 stabilization, and 3 deterioration. CONCLUSIONS: Compared with adolescent and adult syringomyelia, pediatric syringomyelia shows a much lower incidence of sensory disturbance and pain, but quite a high incidence of scoliosis. Surgery is effective in improving or stabilizing scoliosis in these patients.

Adolescent↗

PubMed1999

Syringo-subarachnoid shunt for syringomyelia using partial hemilaminectomy.

Syringo-subarachnoid shunt (S-S shunt) is one of the established surgical procedures for syringomyelia. However, this procedure requires a laminectomy which may lead to spinal column complications. We present a modified form of S-S shunt using a partial hemilaminectomy; a S-S shunt is placed via the dorsal root entry zone into the anterior subarachnoid space which is considered to be an ideal site for the drainage of the syrinx fluid. This technique will decrease the incidence of neuronal and spinal complications after surgery and avoid subarachnoid adhesions around the shunt tube. Between 1992 and 1997, a total of 24 patients with syringomyelia have been treated with this surgical procedure without any complications. Collapse of the syrinx was achieved in all cases. The authors believe that the procedure is an effective surgical treatment for syringomyelia and can be applied safely to adolescent and child cases.

Adolescent↗

PubMed1999

Autoradiographic [3H]nimodipine distribution after experimental spinal cord injury in rats.

Because of its potential for augmentation of blood flow and protection of neurons after neurological insult, nimodipine has been investigated as a treatment of spinal cord injury (SCI). The results have been inconsistent, possibly because of poor delivery of nimodipine to the injured spinal cord. The following study was designed to determine the delivery of nimodipine to the injured spinal cord. It was also hoped that information about the temporal and spatial pattern of binding of nimodipine after SCI might further elucidate the relationship between calcium channel activation and injury. Fourteen female Wistar rats were divided into three groups: control (n = 3), 30 min post-SCI (n = 6); and 4 h post-SCI (n = 5). The injury was produced by acute clip compression for 1 min at T1. [3H]Nimodipine was administered 5 min after laminectomy in the control group, and at the above-specified times after injury in the SCI groups. The drug was then allowed to equilibrate for 30 min before the animals were killed. The spatial patterns and concentrations of [3H]nimodipine in various segments of the spinal cord were autoradiographically determined. The highest concentrations of [3H]nimodipine were at the injury site after SCI. Also, the mean [3H]nimodipine concentrations in all sites in each animal were higher in the injury groups than in the control group (p < 0.05). This study indicates that delivery of this agent to the injured cord is possible, and provides evidence of widespread Ca2+ channel activation in the first 4 h after injury.

Animals↗

PubMed1999

Analysis of optical signals evoked by peripheral nerve stimulation in rat somatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation.

The origins of reflected light changes associated with neuronal activity (optical signals) were investigated in rat somatosensory cortex with optical imaging, microspectrophotometry, and laser-Doppler flowmetry, and dynamic changes in local hemoglobin concentration and oxygenation were focused on. Functional activation was carried out by 2-second, 5-Hz electrical stimulation of the hind limb under chloralose anesthesia. These measurements were performed at the contralateral parietal cortex through a thinned skull. Regional cortical blood flow (rCBF) started to rise 1.5 seconds after the stimulus onset, peaked at 3.5 seconds (26.7% +/- 9.7% increase over baseline), and returned to near baseline by 10 seconds. Optical signal responses at 577, 586, and 805 nm showed a monophasic increase in absorbance coincident with the increase in rCBF; however, the signal responses at 605 and 760 nm were biphasic (an early increase and late decrease in absorbance) and microanatomically heterogeneous. The spectral changes of absorbance indicated that the concentrations of both total hemoglobin and oxyhemoglobin increased together with rCBF; deoxyhemoglobin, increased slightly but distinctly (P = 0.016 at 1.0 seconds, P = 0.00038 at 1.5 seconds) just before rCBF increases, then decreased. The authors conclude that activity-related optical signals are greatly associated with a moment-to-moment adjustment of rCBF and metabolism to neuronal activity.

Animals↗

PubMed1999

Anterior approach to intramedullary hemangioblastoma: case report.

OBJECTIVE AND IMPORTANCE: Intramedullary spinal cord tumors are generally operated on by using the posterior approach. However, the posterior approach may not be suitable for a tumor in the anterior part of the spinal cord. In this report, we describe a case of a cervical intramedullary tumor that was successfully removed by using the anterior approach. CLINICAL PRESENTATION: A 48-year-old woman presented with lower cranial nerve disturbance and motor weakness of the upper extremities. Magnetic resonance imaging revealed a large extensive syrinx and an intramedullary enhanced tumor at the C6 level. The tumor was located at the left of the anterior part of the spinal cord. INTERVENTION: Based on these findings, the anterior approach was used in performing a corpectomy of C5 and C6. The tumor was highly vascular and was resected without resulting in any operative deficits. The pathological diagnosis was hemangioblastoma. CONCLUSION: The present case suggests that the anterior approach is an important option among surgical approaches to the intramedullary tumor in cases in which the tumors are small in size and are located in the anterior part of the cervical cord.

Cervical Vertebrae↗

PubMed1999

[Clinical reference values for laboratory hematology tests calculated using the iterative truncation method with correction: Part 2, Reference values for white blood cell (WBC) count, WBC differential including segmented neutrophil, band neutrophil, lymphocyte, monocyte, eosinophil, basophil, platelet count and mean platelet volume].

Age and sex dependent differences in the clinical reference values for white blood cell(WBC) count, WBC differential including segmented neutrophils(SEG), band neutrophils(BAND), lymphocytes (LYMPH), monocytes(MONO), eosinophils(EOSINO), basophils(BASO), platelet count(PLT) and mean platelet volume(MPV) were calculated by the iterative truncation method with correction(Usui's method) using the result from tests on 6,300 patient specimens obtained at Kyoto University Hospital. WBC counts exhibited log-normal distribution in all age either in male and female. PLT counts and MPV showed normal or log-normal distribution. WBC differential (SEG, BAND, LYMPH, MONO, EOSINO, BASO) usually showed log-normal distribution. As to the reference value for WBC, high limit values gradually decreased in the age range of 5-14 year old in males and females. After 15 year old, it gradually increased and reached adult's level. Low limit values for WBC gradually decreased with age both in males and females. The reference value for SEG showed similar change to WBC. The reference value for LYMPH gradually decreased age both in males and females. The reference values for BAND, MONO, EOSINO, BASO were generated by the percentile method instead of the iterative truncation method because of the strong deviation in the distribution pattern. BAND, MONO and BASO values were very stable for all ages in males and females. High limit values for EOSINO in the age range of 5-10 year old in males and females remained constant, and gradually decreased in 10-20 year old, and were stable at ages above 20 year old. PLT counts gradually decreased with age, and the MPV remained constant in all age populations both in male and female.

Adolescent↗

PubMed1998

A split cord malformation.

This report describes a case of split cord malformation without a septum. A 2-year-old boy presented with a 3-month history of neurogenic bladder. MRI did not show any apparent abnormality around the conus medullaris. However, CT myelography clearly demonstrated the presence of a split filum terminale. The patient underwent laminectomy of L1-5 laminas and untethering of the split filum terminale. CT myelography was superior to MRI in diagnosing split cord malformation in this case. As MRI is currently regarded as the superior imaging modality, this reported case may have been missed because the pathology was not apparent on MRI.

Cauda Equina↗

PubMed1998

Spinal intrathecal actinomycosis: a case report.

BACKGROUND: Actinomycosis of the central nervous system is a rare disease that most frequently forms cerebral abscesses. In the present report, we describe an extremely rare case of spinal intrathecal actinomycosis. CASE PRESENTATION: A 33-year-old man presented with high fever followed by back pain and paraparesis. Magnetic resonance imaging (MRI) with gadolinium-diethylene-triamine penta-acetic acid (Gd-DTPA) enhancement (Gd-MRI) displayed an irregularly enhanced mass lesion at the thoraco-lumbar junction that mimicked an intramedullary tumor with exophytic growth. Surgical exploration 7 months after the onset of the high fever revealed intrathecal granulation tissue with small abscess formation. Another surgical exploration was carried out 2 months after the first operation because the patient developed progressive paraparesis and showed an intrathecal ring-like enhancement that was detected with Gd-MRI. Actinomyces organisms were finally identified histologically in the surgical specimen. CONCLUSIONS: The clinical course and serial changes of Gd-MRI findings are important considerations when this rare and infectious spinal lesion is suspected.

Abscess↗

PubMed1998

Spontaneous shrinkage of lumbosacral lipoma in conjunction with a general decrease in body fat: case report.

OBJECTIVE AND IMPORTANCE: We describe a rare case of a lumbosacral lipoma that shrank spontaneously in parallel to a general loss of body fat. Although early prophylactic surgery is generally recommended for lumbosacral lipomas, the observation made in this case may provide an important implication regarding the conservative management of this disorder. CLINICAL PRESENTATION: A 9-year-old male patient with a subcutaneous lipoma at the sacral level was found to have a lumbosacral lipoma in the spinal canal and tethered spinal cord, as revealed by magnetic resonance imaging. The patient showed no neurological or urological deficits, except for a mild pes cavus deformity. INTERVENTION: Follow-up magnetic resonance imaging performed 4 years later revealed a significant decrease in the size of the lumbosacral lipoma. The patient became very thin and showed no neurological deterioration during the follow-up period. The shrinkage of the lipoma was considered to be in association with the general loss of body fat. CONCLUSION: The control of body weight may be an important factor in the conservative management of patients with lumbosacral spinal lipomas.

Child↗

PubMed1998

Magnetic resonance imaging findings in ossification of the posterior longitudinal ligament of the cervical spine.

OBJECT: Because of the lack of magnetic resonance (MR) signal from cortical bones, MR imaging is inadequate for diagnosing ossified lesions in the spinal canal. However, MR imaging provides important information on spinal cord morphology and associated soft-tissue abnormality. The purpose of this study is to determine the role of MR imaging in the diagnosis and treatment of patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. METHODS: The authors reviewed MR imaging findings in 42 patients with cervical OPLL who were examined with a superconducting MR imaging system. The types of OPLL reviewed included eight cases of continuous, 21 cases of segmental, and 13 cases of the mixed type. All patients were treated surgically either by anterior (26 cases) or posterior decompression (16 cases). CONCLUSIONS: The T1-weighted images clearly demonstrated the spinal cord deformity caused by OPLL. Associated disc protrusion was found to be present at the maximum compression level in 60% of the patients in this series. The highest incidence of disc protrusion (81%) was found in patients with segmental OPLL. Intramedullary hyperintensity on T2*-weighted imaging was noted in 18 patients (43%). The neurological deficits observed in these 18 patients were significantly more severe than those observed in the other 24 patients. Postoperative MR imaging revealed improvement in the spinal cord deformity, although the intramedullary hyperintensity was still observed in most cases. The present study demonstrates the importance of associated disc protrusion in the development of myelopathy in patients with cervical OPLL. Magnetic resonance imaging findings may be used to help determine the actual levels of spinal cord compression and to suggest the method of surgical treatment.

Adult↗

PubMed1997

Laboratory diagnosis of anemia and related diseases using multivariate analysis.

To establish a simple computer program for the laboratory diagnosis of anemia and related diseases, multivariate analyses were applied to the results of routine hematological laboratory tests obtained from 48 patients and 51 healthy volunteers. The patients studied were limited to those who had not been treated hematologically by the time of their first visit to our hospital, and their first data obtained in our laboratory were analyzed. Final diagnoses were aplastic anemia (AA) in 21, myelodysplastic syndrome (MDS) in 14, iron deficiency anemia (IDA) in 3, polycytemia vera (PV)in 3, and idiopathic thrombocytopenic purpura (ITP) in 7. Eight parameters, WBC, RBC, Hb, Ht, MCV, MCH, MCHC, and PLT, were transformed to normal distribution and then applied to principal component analysis to evaluate their independence. Very close relationships were observed between Ht and Hb, and between MCV and MCH. One each of these pairs was selected by discriminant analysis and two sets, RBC, MCH, Hb, PLT, and WBC, and RBC, MCV, Ht, PLT, and WBC, were obtained. Two canonical components gave good discrimination of these five diseases and also of normal subjects. When disease prediction was made using this analysis, 37 of 48 patients (77.1%) were predicted correctly, and furthermore, when two disease predictions were allowed, all patients were diagnosed properly. Some overlaps were observed in this two-dimensional coordinate system, especially of AA and MDS, and also with normal subjects. To improve the system further, the additional parameters of age and sex were added to construct a three-dimensional analysis which resulted in much clearer discrimination. The whole procedure described is being developed with subjects who are not taking medication. Subsequently, the general application of this analytical procedure should be limited to only those not on medications. In conclusion, this is in essence a demonstration project; however, this trial of laboratory diagnosis using routine hematological laboratory results appears to be promising. Further extension of the study by increasing numbers of patients and disorders studied, including secondary anemias, will allow the design of diagnostic software for use with personal computers at the sites of primary care.

Adult↗

PubMed1997

Surgical treatment of syringomyelia associated with spinal dysraphism.

Clinical and radiological features of syringomyelia in 15 patients with spinal dysraphism are reported. There were 8 patients with occult spinal dysraphism (lumbosacral lipoma) and 7 with spina bifida aperta (meningomyelocele). Syringomyelia with spinal dysraphism can be radiologically divided into two types according to the dysraphic state. The syrinx in the patients with occult spinal dysraphism occurred immediately rostral to the lipoma and was localized to the lower thoracic to lumbar levels, while in the meningomyelocele patients the syrinx extended from the cervical to the thoracic level. Large syrinx formation was recognized in 1 of the 7 occult spinal dysraphism cases and 3 of the 8 meningomyelocele cases. For syringomyelia with occult spinal dysraphism, 4 patients underwent syringo-subarachnoid shunting (S-S shunt, 2 cases) or syringostomy (2 cases) during an untethering operation. In the case of meningomyelocele, S-S shunts were placed in 2 patients. Collapse of the syrinx was achieved in all 6 patients who underwent S-S shunting or syringostomy. Decreased size of the syrinx was also noted in 3 occult spinal dysraphism patients who underwent untethering operations alone. In conclusion, a large syrinx in the case of spinal dysraphism should be surgically treated. S-S shunting is effective in both types of syringomyelia. Foramen magnum decompression may be an alternative method of surgical treatment for syringomyelia in patients with meningomyelocele.

Child↗

PubMed1997

Surgical treatment supposed natural history of the tethered cord with occult spinal dysraphism.

We retrospectively evaluated the pre- and postoperative course of 34 tethered cord patients with occult spinal dysraphism in an attempt to infer the natural history of this disorder and to determine the effectiveness of the surgical treatment. There were 32 cases with lumbosacral lipoma and 2 with tight filum terminale. The age at surgery ranged from 1 month to 47 years old. Eight patients, aged 1 month to 4 years old, were asymptomatic; 26 had neurogenic bladder (26 cases) or motor problems affecting the legs (8 cases). None of the patients older than 5 years of age were asymptomatic. Untethering of the spinal cord was performed in all cases. The postoperative follow-up period ranged from 5 months to 11 years. During these periods, 7 (88%) of the 8 asymptomatic patients remained neurologically intact, 6 (23%) of the 26 symptomatic patients showed improved symptoms, and 15 patients (58%) remained unchanged. These results indicate that the neurological symptoms will appear progressively in the tethered cord patients, and that prophylactic surgery should be considered as early as possible.

Adolescent↗

PubMed1997

Effect of a single huge dose of methylprednisolone on blood flow, evoked potentials, and histology after acute spinal cord injury in the rat.

Effects of a single, huge dose of methylprednisolone on post-traumatic spinal cord blood flow (SCBF), evoked potentials and histological changes were studied in a rat model of spinal cord injury. The purpose of this study was to assess the optimal dose of methylprednisolone for the treatment of rat spinal cord injury. Twenty-five male Wistar rats were subjected to an acute clip compression injury at 51 g for 1 min at C8-T1, and then received an intravenous bolus injection of one of the following 30 min after injury: vehicle, 30, 60, 120 or 240 mg kg-1 methylprednisolone. SCBF was measured at the injury site and an adjacent area with the hydrogen clearance technique. Sensory evoked potentials following sciatic stimulation were recorded from the somatosensory and cerebellar cortices. Descending volleys were recorded from T9-10 spinal cord following cerebellar stimulation. SCBF and evoked potential recordings were repeated until perfusion-fixation at 4 h after injury. After injury, SCBF at both levels significantly dropped, and all evoked potentials disappeared in all animals. None of the doses of methylprednisolone improved post-traumatic SCBF, or evoked potentials. Quantitative histological assessment of the injured cords revealed no significant differences in hemorrhages or cavitation in the spinal cord among the treatment groups. This study showed that a single huge dose of methylprednisolone from 30 to 240 mg kg-1 had no beneficial effects on the traumatized rat spinal cord in the acute stage.

Acute Disease↗

PubMed1997

Bone window computed tomography for detection of dural defect associated with cervical ossified posterior longitudinal ligament.

Anterior decompression of a cervical ossified posterior longitudinal ligament (OPLL) which involves the dura mater occasionally results in a postoperative cerebrospinal fluid fistula. Bone window computed tomography (CT) was carried out to detect dural defects in 21 patients with cervical OPLL. Twelve of 21 patients had double-layer OPLL, and nine had single-layer OPLL. Dural defects were present in 10 of the 12 patients with double-layer OPLL compared with only one of the nine patients with single-layer OPLL. In addition, greater stenosis of the spinal canal by the OPLL was also associated with dural defect. Preoperative bone window CT can indicate likely locations of dural defect in patients with OPLL.

Adult↗

PubMed1997

Vascular mechanisms in the pathophysiology of human spinal cord injury.

Vascular injury plays an important role in the primary and secondary injury mechanisms that cause damage to the acutely traumatized spinal cord. To understand the pathophysiology of human spinal cord injury, the authors investigated the vascular system in three uninjured human spinal cords using silicone rubber microangiography and analyzed the histological findings related to vascular injury in nine acutely traumatized human spinal cords obtained at autopsy. The interval from spinal cord injury to death ranged from 20 minutes to 9 months. The microangiograms of the uninjured human cervical cords demonstrated new information about the sulcal arterial system and the pial arteries. The centrifugal sulcal arterial system was found to supply all of the anterior gray matter, the anterior half of the posterior gray matter, approximately the inner half of the anterior and lateral white columns, and the anterior half of the posterior white columns. Traumatized spinal cord specimens in the acute stage (3-5 days postinjury) showed severe hemorrhages predominantly in the gray matter, but also in the white matter. The white matter surrounding the hemorrhagic gray matter showed a variety of lesions, including decreased staining, disrupted myelin, and axonal and periaxonal swelling. The white matter lesions extended far from the injury site, especially in the posterior columns. There was no evidence of complete occlusion of any of the larger arteries, including the anterior and posterior spinal arteries and the sulcal arteries. However, occluded intramedullary veins were identified in the degenerated posterior white columns. In the chronic stage (3-9 months postinjury), the injured segments showed major tissue loss with large cavitations, whereas both rostral and caudal remote sites showed well-demarcated necrotic areas indicative of infarction mainly in the posterior white columns. Obstruction of small intramedullary arteries and veins by the initial mechanical stress or secondary injury mechanisms most likely produced these extensive white matter lesions. Our studies implicate damage to the anterior sulcal arteries in causing the hemorrhagic necrosis and subsequent central myelomalacia at the injury site in acute spinal cord injury in humans.

Acute Disease↗

PubMed1996

The effects of cortical stimulation, anesthesia and recording site on somatosensory evoked potentials in the rat.

The purpose of this study was to standardize the method of spinal cord monitoring with evoked potentials in the rat. Seventeen male Wistar rats were anesthetized with alpha-chloralose and urethane. Somatosensory evoked potential (SEP) and cerebellar evoked potential (CEP) following sciatic nerve stimulation were mapped at different time points after induction of anesthesia. SEP peaks at latencies of 13-18 ms (P13, N18) were localized to an extremely small area over the sensory cortex. In contrasts, a negative peak of the SEP at 11 ms (N11) and the CEP were widely distributed over the cerebral or cerebellar surface. Anesthesia significantly influenced the cortical components of the SEP. In 10 rats, MEP or posterior fossa evoked potential (PFEP) following stimulation of the sensorimotor or cerebellar cortices respectively, were recorded at T9. Stimulation of different points produced little change on the waveforms of the MEP or PFEP. Successive recordings of MEP and SEP revealed that the P13-N18 complex of the SEP was markedly suppressed after MEP recordings were made. In conclusion, this study identified several factors which alter SEP waveforms in the rat including location of recording, anesthesia and sequence with respect to MEP recording. MEP by stimulation of the same sensory cortex as SEP recordings should not be used for concurrent monitoring, since cortical stimulation will change the waveforms of the SEP.

Anesthesia↗

PubMed1996

[Clinical study of intraspinal neoplasms in children].

The authors report a series of 10 children under 15 years of age with primary intraspinal neoplasm who underwent surgical resection from 1981 to 1994. The tumors consisted of 4 intramedullary tumors (myxopapillary ependymoma, pilocytic astrocytoma, subpial liporna, cavernous angioma), 2 intradural extramedullary tumors (2 neurinomas), and 4 extradural tumors (ganglioneuroma, chordoma, osteochondroma, rhabdomyosarcoma). The initial symptoms in these patients were gait disturbance (50%), weakness of lower extremities (50%), pain (40%), weakness of upper extremities (10%), and tetraparesis (10%). The neurological findings on admission in these patients revealed motor paresis (90%), sensory disturbance (60%), abnormality of deep tendon reflex (60%), pathological reflex (30%), neurogenic bladder (30%), and Lasegue's sign (10%). All patients were treated surgically; laminectoy was performed in 8 patients, laminoplasty in one patient, and transoral approach in one patient. Five patients (50%) underwent a grossly total resection, 3 (30%) had a subtotal resection, and 2 (20%) had a partial resection. Mean follow-up period was 5.6 years. One (10%) patient died due to recurrence and dissemination of the tumor at eight months after surgery in a case of rhabdomyosarcoma. 9 (90%) have had no recurrent tumor and have improved neurologically. In 4 patients (40%) spinal deformity developed, and 2 patients required operative treatment for the spinal deformity. We emphasized the advantage of laminoplasty to prevent postoperative spinal deformity in children.

Adolescent↗