E Urasaki

University of Occupational and Environmental Health, Kitakyūshū, Fukuoka, Japan

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Publications (36)20.22 Total impact

  • N. Akamatsu · S. Tsuji · E. Urasaki

    No preview · Article · Oct 2007 · Clinical Neurophysiology
  • N. Akamatsu · T. Uozumi · E. Urasaki · S. Tsuji

    No preview · Article · Sep 2006 · Clinical Neurophysiology
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    ABSTRACT: To evaluate the focal nature of the early and late inhibition of corticospinal neurons demonstrated by a paired-pulse stimulation paradigm. We performed paired-electric pulse stimulation studies using subdural electrodes implanted in 4 patients with intractable partial epilepsy. Inhibition of motor evoked potentials in the first dorsal interosseous muscle was obtained by paired-pulse stimulation of the hand motor cortex (M1) with a subthreshold conditioning stimulus at conditioning-test intervals between 1 and 6ms. This early inhibition was abolished when the conditioning stimulus was moved to the sensory cortex (S1) or the arm M1. The inhibition was also produced by paired-pulse stimulation of the hand M1 with a suprathreshold conditioning stimulus between 50 and 300ms in all 3 patients. This late inhibition was still recognized when moving the conditioning stimulus to the hand S1 only in one of 3 patients. The early inhibition arises from very small areas in the M1 and is little mediated by neuronal circuits in the S1. On the other hand, the focal nature of the late inhibition is complicated and it arises mainly from the M1 but the S1 may be related to the generation of the late inhibition in some cases.
    No preview · Article · Aug 2002 · Clinical Neurophysiology
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    ABSTRACT: To examine high frequency oscillations (HFOs) of somatosensory evoked potentials (SEPs) recorded directly from subdural electrodes to investigate the relationship between the primary somatosensory cortex and HFOs. SEPs were recorded directly from subdural electrodes previously implanted in 3 patients for clinical evaluation prior to surgical treatment of intractable epilepsy. The primary sensory cortex (area 3b) was proposed as the source of somatosensory HFOs, because the distribution of HFOs recorded from the subdural electrodes agreed with the distribution of the N20-P20 components of the somatosensory evoked potential. The somatosensory HFOs showed a strictly somatotopic source arrangement. There was a polarity inversion of the prophase component and also the N20-P20 component of HFOs across the central sulcus. However, the phase was synchronized in the latter part of the HFOs. We propose that the origins of the early and latter parts of HFOs are different, and that there was a clear somatotopy.
    No preview · Article · Jan 2002 · Clinical Neurophysiology
  • T Genmoto · E Urasaki · A Yokota · N Akamatsu · A Aoki · S Tuji
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    ABSTRACT: Here we report a case of bitemporal epilepsy that was well controlled after unilateral temporal lobectomy. The patient was a 31-year-old woman, who was born in an asphyxia state and had a history of a febrile convulsion. Complex partial seizure(CPS) preceded by abdominal aura appeared at the age of three. Despite anticonvulsant medication, the seizures gradually increased in frequency and sometimes developed into secondary generalized convulsions. Her scalp electroencephalogram(EEG) showed interictal spikes and seizure activities arising from the bilateral temporal lobes. No apparent lateralities in regard to the size or blood flow at the hippocampus were detected by MRI and SPECT studies. Intracranial EEG monitoring revealed that 80% of the clinical seizures originated from the left mesial temporal lobe, which was the non-dominant side for speech and memory functions as demonstrated by Wada test. Therefore, we performed a left temporal lobectomy that resulted in the complete disappearance of CPS. The present case exemplified the usefulness of intracranial EEG monitoring to clarify the dominant epileptic focus for surgery.
    No preview · Article · Dec 2000 · Nō to shinkei = Brain and nerve
  • E Urasaki

    No preview · Article · Feb 1999 · Electroencephalography and clinical neurophysiology. Supplement
  • H Ohta · Y Kinoshita · M Hashimoto · H Yamada · E Urasaki · A Yokota
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    ABSTRACT: A 54-year-old female, who had been treated for aplastic anemia by metenolone acetate since 1981, developed a sudden unconsciousness in September 1995. On admission, she was drowny, CT showed a subarachnoid hemorrhage (SAH) in the right Sylvian fissure. Angiography demonstrated a complete occlusion of the superior sagittal sinus. The SAH was assumed to be originated from rupture of the right Sylvian vein, which was irregularly dilated on angiography. The dural sinus thrombosis was thought to be caused by a long term use of metenolone acetate, and it was discontinued. But her platelet count dropped due to the aggravation of aplastic anemia, and she developed repeated hemorrhagic infarction. An active anticoagulant therapy for the dural sinus thrombosis was thought to be inappropriate because she had the aplastic anemia and the hemorrhagic infarction recurred. We have successfully treated this case by mild anticoagulant therapy with nafamostat mesilate (Futhan).
    No preview · Article · Sep 1998 · Nō to shinkei = Brain and nerve
  • H Yasukouchi · S.-I. Wada · E Urasaki · A Yokota
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    ABSTRACT: To estimate the effects of night work on the human cognitive function, P300 event related potentials (ERPs) evoked with an auditory "oddball" paradigm were recorded for 17 nurses (mean age 27.4 +/- 6.1 years; range 21-41 years) for 3 epochs; after a night of work, after a day of work and on a holiday, and for 12 elderly security guards (mean age 62.8 +/- 2.2 years; range 60-67 years) for 2 epochs; after a night of work and on a holiday. The Stress Arousal Check List (SACL) was used for all the subjects just prior to the P300 ERP recording to determine the extent of stress and the arousal grades. Fourteen of the nurses were in their twenties (mean age 24.9 +/- 2.6 years; range 21-29 years), and 3 (39.0 +/- 2.6) were older (36, 40 and 41 years). The 14 nurses were classed as the young group. All the security guards were classed as the elderly group. In the young group, the stress grade scores increased significantly (P < 0.05) and the arousal grades decreased significantly (P < 0.01) after night work as compared to the holiday values. Although statistically not significant, the amplitude of the P300 component tended to decrease after night work, whereas the latency was very stable for these 2 epochs. The P300 latencies of the 3 older nurses were as stable as those of the young group, but their amplitudes were significantly reduced after night work as compared with the holiday amplitudes (P < 0.05). In contrast, the 12 elderly security guards showed no statistically significant changes in the scores for the stress and arousal grades between the 2 epochs, after night work and holiday. Latency prolongation however, was statistically significant (P < 0.01) after night work. The P300 amplitudes for many of the elderly security guards also tended to decrease after night work, but were not statistically significant. The P300 amplitude is considered to reflect the amount of attentional resources and the latency to reflect the time needed for the cognitive process, indicating that the elderly security guards experiences slowing of the cognitive process in night work. Our results suggest that the effect of night work on the cognitive function is greater for elderly than for young workers. We conclude that P300 can be used to evaluate changes in the human cognitive function produced by night or rotating shift work and that the results provide useful information with which to plan shift schedules on the basis of worker age.
    No preview · Article · Jan 1996 · Journal of UOEH
  • E Urasaki · M Momota · E Tsuru · A Yokota
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    ABSTRACT: We report subdural extension of a recurrent intracranial germinoma, producing human chorionic gonadotrophin
    No preview · Article · Dec 1995 · Neuroradiology
  • T Tokimura · E Urasaki · S Wada · H Yasukouchi
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    ABSTRACT: To evaluate the clinical utility of somatosensory evoked potentials elicited by stimulation of the paraspinal region (PS-SEPs), waveform characteristics and scalp topography were studied in 23 normal controls. PS-SEPs were recorded in 22 patients with spinal lesions, and the relation between the abnormal PS-SEPs and clinico-radiological findings was investigated. 1) The normal control study showed clear waveforms on the scalp elicited by stimulation of the paraspinal region from C7 to the L2 spinous process level, with both bilateral and unilateral stimulation. The latency of PS-SEPs was gradually decreased when stimulation was moved in the caudo-rostral direction. 2) The normal range of spinal conduction time and conduction velocity was wide. The conduction velocity resulting from stimulation of the lumbar region tended to be slower than that from stimulation of the thoracic region, perhaps due to the difference in the length of the peripheral cutaneous nerves. 3) There was no correlation between the height and the latency of PS-SEPs. 4) Amplitudes of PS-SEPs after unilateral stimulation of the C7 and Th5 spinous levels were larger on the scalp contralateral to the side of stimulation. These findings were similar to SEPs elicited by median nerve stimulation. There was no significant amplitude laterality of PS-SEPs when the Th10 and L2 spinous levels were stimulated. Posterior tibial nerve SEPs showed a larger amplitude at the scalp ipsilateral to the side of stimulation than at the contralateral side. All these findings suggest that the cortical generator sites of PS-SEPs elicited by C7 and Th5 stimulation are located near the hand area, and those from Th10 and L2 stimulation are between the hand and the foot area. 5) Unilateral stimulation disclosed a clear laterality of sensory disturbance that was obscure when only bilateral stimulation was employed. PS-SEPs showed a high degree of abnormality when the patient had deep sensory disturbance. Generally, abnormal PS-SEPs were found caudal to the clinical sensory level, and a few cases showed abnormal PS-SEPs rostral to the sensory level. The latter might indicate that PS-SEPs detected subclinical sensory disturbance. It was therefore concluded that PS-SEPs are a useful tool for the objective evaluation of sensory disturbance, especially in cases of thoracic lesion, because conventional SEP studies, utilizing non-cephalic references do not provide clear identification of abnormal sensory levels along the thoracic spinal cord.
    No preview · Article · Apr 1994 · Journal of UOEH
  • S. Wada · E. Urasaki · T. Tokimura · H. Yasukouchi · A. Yokota

    No preview · Article · Aug 1993 · Electroencephalography and Clinical Neurophysiology
  • E Urasaki · S Wada · A Yokota · T Tokimura · H Yasukouchi
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    ABSTRACT: To identify the origin of short latency somatosensory evoked potentials (SSEPs) to posterior tibial nerve stimulation, direct recordings were made from the cervical cord, the ventricular system and the frontal subcortex during 8 neurosurgical operations. The origin of each component of SSEPs was also studied in 7 selected patients with various lesions in the central nervous system. In addition, SSEPs to median nerve stimulation were investigated in 4 of 8 surgical cases and all 7 cases of the lesion study group. Bilateral posterior tibial nerve stimulation in 10 normal subjects showed spinal N28 on the skin of the posterior neck and far-field P30 and N33 components followed by a cortical P38 component at the scalp. Direct recordings made to the mid-brain through the medulla oblongata showed a negative potential with gradually increasing latency. The peak of the negativity in the vicinity of the dorsal column nucleus showed almost the same latency as that of the scalp far-field P30, and positivity with a stationary peak was found above the dorsal column nucleus. Above the mid-pons, there was a stationary negativity with no latency shift, showing the same peak latency as that of scalp N33. The spatiotemporal distributions of P30 and N33 to posterior tibial nerve stimulation were analogous to those of P14 and N18 by median nerve stimulation. Transesophageal and direct cervical cord recordings showed that the spinal N13 phase to median nerve stimulation was reversed between the dorsal and ventral sides of the cervical cord. No such reversal occurred for the spinal N28 potential. Clinical lesion studies showed that changes in P30 and P14, and in N33 and N18 correlated with one another: that is, 1) prolongation of latency of N33 was also observed for N18; 2) absence of P30 was paralleled by the absence of P14. These data suggest that spinal N28 originates from ascending activity such as a dorsal column volley, and scalp P30 comes from activity near the dorsal column nucleus, which is similar to the P14 component of median nerve stimulation. The origin of N33 is thought to be similar to N18 from median nerve stimulation, which originates from brainstem activity below the thalamus.
    No preview · Article · Jul 1993 · Journal of UOEH
  • S Wada · E Urasaki · C Kadoya · S Matsuoka · M Mohri
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    ABSTRACT: Hyperbaric chamber dives at 19 ATA with helium-oxygen were performed at the Japan Marine Science Technology Center, Yokosuka, from January 31 to February 2 in 1990. During simulated underwater experiments, event-related potentials were recorded in 2 divers for assessment of the cognitive function. Although the P300 amplitude of the potentials did not show any significant change, its latency was clearly prolongated and this prolongation continued to when the decompression reached to 70 m below sea level. These findings indicated that the hyperbaric environment corresponding to 180 m below sea level or less must cause some cognitive dysfunctions and that P300 is useful for early detection of those dysfunctions or HPNS.
    No preview · Article · Jul 1991 · Journal of UOEH
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    ABSTRACT: A clinical lesion study and intraoperative epidural recordings were made to test the origin and clinical significance of the spinal N13 and P13 of somatosensory evoked potentials (SEP) that follow median nerve stimulation. Intraoperatively, the respective peak latencies of spinal P13 and N13 coincided with those of the N1 component of the dorsal cord potential and its phase reversed positivity. On both the ventral and dorsal sides of the cervical epidural space, maximal amplitude was at the C5 vertebral level to which nerve input from the C6 dermatome is the main contributor. The modality of sensory impairment in the hand dermatome was examined in selected patients with cervical lesions, who showed such normal conventional SEP components as Erb N9, far-field P9, P11, P14, N18 and cortical N20, with or without loss of spinal N13. Statistically, the loss of spinal N13 was associated with decrease of pain sensation in the C6 dermatome. This was interpreted as being due to damage to the central grey matter of the cord, including the dorsal horn. Our results suggest the spinal N13 and P13 originate from the same source in the C6 spinal cord segment and that they are good indicators for the detection of centromedullary cervical cord damage.
    No preview · Article · Dec 1990 · Journal of Neurology

    No preview · Article · Jan 1990 · Electroencephalography and Clinical Neurophysiology

    No preview · Article · Jan 1990 · Electroencephalography and Clinical Neurophysiology
  • E Urasaki · T Soejima · A Yokota · S Matsuoka
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    ABSTRACT: A case of asymptomatic syringomyelia associated with tentorial meningioma is reported. A 53-year-old female was admitted to our hospital with the complaints of headache, decrease of bilateral visual acuity and gait disturbance. Neurological examination revealed no abnormality except for bilateral papilledema and left cerebellar sign. Motor and sensory systems were also intact. CT and MRI scans showed a left tentorial mass lesion, cervical syringomyelia and left tonsillar herniation. A relationship between the fourth ventricle and syringomyelia was not clearly identified. The tumor was totally removed and a histological diagnosis of fibroblastic meningioma was made. Postoperative radiological examination showed a diminishing of syringomyelia with the improved tonsillar herniation. Association of syringomyelia with brain tumor was reviewed, and its pathogenesis was discussed.
    No preview · Article · Nov 1989 · No shinkei geka. Neurological surgery
  • Y Ito · A Fukumura · E Urasaki · Y Ushio
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    ABSTRACT: A 41-year-old man noticed colorless cutaneous nodules all over his body at the age of 24. Recently the nodules increased markedly in number and several large nodules were removed at the dermatological clinic of our hospital. The histological diagnosis of the nodules was neurofibroma. He was then referred to our neurosurgical clinic for neurological examinations to rule out involvement of the central nervous system. He showed no abnormality in neurological examination except for hyper-reflexia of the left patellar tendon reflex and occasional right leg weakness. Cranial CT scan and EEG were normal. Mental examination and routine laboratory studies were also normal. Vertebral scoliosis from C6 to T3 level, enlargement of the bilateral vertebral foramen at the level of T2 to T4, vertebral dysplasia of the C6 and T3, and the scalloping of the vertebral posterior margin of the T2 to T4 were seen in the plain X-ray films and tomography of the upper thoracic and cervical spine. The myelography and metrizamide CT scan showed multiple diverticular dilation of CSF space at the level of T1 to T4. This extended through the enlarged vertebral foramina to the chest cavity forming a dumb-bell shape. Spinal cord was normal and there was no tumor in the spinal canal. Dural ectasia and vertebral body scalloping were more clearly shown by magnetic resonance imaging (M.R.I). Dural ectasia accompanying von Recklinghausen's disease is rare and no MRI findings have been reported. Therefore, we reported this case and mainly discussed roentgenological findings and MRI of dural ectasia and other spinal abnormalities.
    No preview · Article · Jan 1989 · No shinkei geka. Neurological surgery
  • E Urasaki · A Fukumura · Y Itho · Y Itoyama · M Yamada · Y Ushio · S Wada · A Yokota
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    ABSTRACT: In the diagnosis of brain death, it is generally accepted that respiratory function has to be absent, however, spinal reflexes can be preserved. We presented a patient who showed a complex movements of upper limbs (Lazarus' sign) and respiratory like movement during the apnea test for the determination of brain death. This 72-year old female admitted to our hospital in a semicomatous state due to severe subarachnoid and ventricular hemorrhage. Her conscious level suddenly deteriorated to deep coma because of second hemorrhage on the same day. She became apnea and no brain stem reflexes elicited. Three days later, electrophysiological examination revealed a flat recording of electroencephalography, absence of auditory evoked potentials and no response of blink reflex. Short latency somatosensory evoked potentials obtained by median nerve stimulation showed the presence of Erb's N9 and spinal N13-P 13 components originating from cervical dorsal horn, however, the scalp P13 generated by cervico-medullary junction was absent. This patient fulfilled all other criteria for brain death. Four days after, an apnea test was performed. Spontaneous movements of both upper limbs were observed starting between 7 and 8 minutes after disconnecting the intubation tube from the ventilator. Both arms flexed at the elbow, abducted and elevated from the bed. Then, both hands were brought up to chest. Wrist and fingers were in a neutral position (Lazarus' sign). Simultaneously, shallow and irregular respiration like movements were recognized. These movements ceased immediately after connecting the respirator. These two types of movements were reproducible except for in the final test. Blood pressure gradually decreased, and cardiac arrest occurred one hour after.(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · Jan 1989 · Nō to shinkei = Brain and nerve
  • E Urasaki · A Fukumura · Y Itho · Y Itoyama · M Yamada · Y Ushio · S Wada · A Yokota
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    ABSTRACT: Using non-cephalic reference and by median nerve stimulation, P 13 component and N 13 component are recorded on the scalp (scalp P 13) and the posterior neck (spinal N 13), respectively, in the short latency somatosensory evoked potentials (SSEP). The purpose of this study is to disclose the origin, characteristics and clinical significance of these two components. Ten healthy volunteers served for normal subjects. Ten patients with pontine lesion or brain death were studied. The effect of barbiturate was also studied in additional 5 patients during anesthesia for cranioplastic surgeries. Electrical stimuli of 0.2 msec square wave pulse were used in routine examination. To confirm the effects of stimulation frequency, 3, 6, 9, 12, 15, 18, 21, 24 and 27 Hz were also used in normal subjects. Recording electrodes were placed in the following sites. (1) Scalp electrode at the Shagass' point contralateral to the stimulated side (Par.). (2) Posterior neck electrode on the spinous process of the fifth cervical vertebrae (Cv5), (3) Anterior neck electrode on the thyroidal cartilage (Ant. C). (4) Erb's electrode just above the mid-clavicular point ipsilateral to the stimulation. Erb's electrode contra-lateral side of stimulation was used as a reference. Spinal N 13 on posterior neck reversed its polarity into P 13 (spinal P 13) on the anterior cervical electrode. A study with different stimulus rates revealed that the latency of scalp P 13 significantly prolonged at 24 Hz stimulation. On the other hand, the latency of spinal N 13-P 13 easily prolonged even at 18 Hz. This suggested that spinal N 13-P 13 were generated polysynaptically.(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · Dec 1988 · Nō to shinkei = Brain and nerve