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Biomedical subjects

H Shibasaki

Publications and source records attributed to H Shibasaki.

At least 235 records · Page 13Linked to original sources
PubMed1994

Optimisation of botulinum treatment for cervical and axial dystonias: experience with a Japanese type A toxin.

Twenty two patients with cervical and axial dystonias were treated with Japanese type A botulinum toxin. Injections were given repeatedly at intervals of 28-30 days to carefully chosen muscles with increased activities, with a maximum dose per session of 300 units. The maximum improvements in subjective and objective ratings were obtained only after repeated injections. No anti-toxin antibodies were detected; nor did any muscle fail to respond to the toxin. During the treatment, previously "silent" muscles were activated to reproduce the original abnormal posture, as if driven by a central motor programme. This resistance to treatment was overcome by injecting the toxin into newly activated muscles. Repeated injections are thus required to override central mechanisms in dystonias or to maximise drug delivery to large muscles. Antibody development may be controlled by the use of a less immunogenic toxin.

Adolescent↗
PubMed1994

[Intractable epilepsy--neurophysiological evaluation and indication for surgical treatment].

Medically intractable epilepsy, defined as the clinical attacks occurring at least once a month in spite of appropriate antiepileptic drug treatments, is one of the commonest disorders in the clinical neurology. Since surgical treatment of epilepsy is successful in selected patients, it is most important to delineate the epileptogenic focus and functions of adjacent cortical areas as precisely as possible. Recent advances in electrophysiology, magnetoencephalography, magnetic resonance imaging (MRI), functional imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) have enabled us to elucidate the epileptogenic focus noninvasively without involving the conventional invasive EEG recording techniques. We evaluated 37 patients with intractable partial seizures by using prolonged video/EEG monitoring with sphenoidal or T1/T2 electrodes. MRI, ictal and interictal SPECT for blood flow measurement and interictal FDG-PET for glucose metabolism. Among 20 patients with intractable epilepsy who had a single ictal focus, PET, ictal SPECT and MRI findings were correlated with the ictal EEG finding with the concordance rate of 100, 86 and 75%, respectively. If all of those findings were convergent upon a single focus, then the surgical treatment with intraoperative corticography is most likely effective without employing any invasive recording. If those findings were divergent, then the invasive evaluation will be indicated.

Adolescent↗
PubMed1994

Sleep bruxism as a manifestation of subclinical rapid eye movement sleep behavior disorder.

A 59-year-old man with temporomandibular joint pain/dysfunction syndrome presented with a long history of nocturnal bruxism. All-night polysomnographic recordings with video monitoring showed episodes of teeth grinding or clenching occurring exclusively during rapid eye movement (REM) sleep, which were often associated with movements of the hands and fingers and/or brief vocalization. Throughout REM sleep, there was excessive phasic chin electromyographic twitching, without increased tone, and also excessive phasic electromyographic twitching in multiple muscle sites. The patient maintained a normal nonrapid eye movement-REM cycle, but showed increased REM density. Polysomnographic characteristics suggested that there may be a common pathophysiology in a certain type of sleep bruxism and the REM sleep behavior disorder. Sleep bruxism seen in this case is concluded to be a manifestation of subclinical REM sleep behavior disorder.

Bruxism↗
PubMed1994

[Ictal electroencephalographic findings and clinical seizure types in postencephalitic epilepsy].

A prolonged video/electroencephalogram (EEG) monitoring was performed in two patients with intractable epilepsy after adult onset acute encephalitis. Clinically both patients were thought to have a localized epileptogenic focus because of the single stereotyped clinical seizures by history in two patients, and a well localized lesion shown by MRI in one patient. The video/EEG monitoring, however, revealed multiple EEG foci ictally as well as interictally in both patients. Moreover, both patients were found to have at least two different patterns of clinical seizures. In patients with adult onset postencephalitic epilepsy, therefore, it is necessary and important to evaluate enough number of seizures by prolonged video/EEG monitoring even if seizures are clinically stereotyped by history and localized lesions are present on brain imaging.

Acute Disease↗
PubMed1994

Brain perfusion SPECT with 99mTc-bicisate: comparison with PET measurement and linearization based on permeability-surface area product model.

To characterize a recently introduced cerebral perfusion tracer, 99mTc-bicisate, single photon emission computed tomography (SPECT) images of 99mTc-bicisate were compared with CBF images obtained by positron emission tomography (PET) using the 15O steady-state method in 10 cases of cerebrovascular disease and dementia. 99mTc-Bicisate SPECT and PET CBF images showed a similar distribution pattern except for two cases with subacute stroke, in which 99mTc-bicisate showed less uptake than CBF in the infarcted area where oxygen metabolism was severely diminished. Comparison of 99mTc-bicisate uptake and CBF in the other eight cases showed less contrast between high- and low-flow regions in 99mTc-bicisate SPECT. Although the SPECT count ratio of cerebral structures to cerebellum showed a good correlation with CBF ratio, it gradually deviated from the linear relationship in the high-flow range. Assuming this nonlinear relationship is due to the limited extraction of the tracer, we estimated the permeability-surface area product (PS) value by a nonlinear least-squares curve-fitting procedure. The correction of the nonlinear relationship using the estimated PS value and a table lookup method resulted in an excellent linear relationship between corrected SPECT counts and CBF.

Adult↗
PubMed1993

MR imaging findings of tremors associated with lesions in cerebellar outflow tracts: report of two cases.

Two cases with severe tremors were studied by means of electromyograms using surface electrodes and also by magnetic resonance (MR) imaging. The first case was associated with multiple sclerosis and demonstrated a severe postural cerebellar tremor and an alternate activation of antagonist muscles in the right arm. The second case, with hemorrhage in the brainstem, demonstrated a severe tremor at rest and mixed synchronous and alternating activation of antagonist muscles in the left forearm. MR imaging studies localized lesions possibly responsible for these tremors. In the first case a lesion was located in the superior cerebellar peduncle just under the decussation, and in the second case a lesion was found between the red nucleus and the thalamus, with possible involvement of both the cerebellothalamic and nigrostriatal pathways. The first case accords with the theory that a lesion located in the dentate nucleus and its projection can cause severe postural cerebellar tremor. The lesion demonstrated in the second case may be responsible for "cerebellar tremor at rest" or "static (resting) cerebellar tremor."

Adult↗
PubMed1993

Scalp topography of somatosensory evoked potentials following median and posterior tibial nerve stimulation in Down's syndrome.

The scalp topography of somatosensory evoked potentials (SEPs) following stimulation of the median and posterior tibial nerve of 39 patients with Down's syndrome was compared with that of age-matched normal controls using significance probability mapping (SPM). The maximal area of each potential in Down's syndrome was similar to that in normal controls, but the scalp distribution was wider. The amplitudes of all components, except the N45 and P59 potentials of the posterior tibial nerve SEPs, were greater in Down's syndrome, and the t values calculated by SPM were significantly greater. However, the difference of SEP maps between Down's patients and aged controls (over 65 years) was much smaller than that between Down's patients and age-matched controls. Therefore, we conclude that the generator sources and generating mechanisms of SEPs in Down's syndrome are not different from those of normal control, however SEP potentials in Down's syndrome are remarkably enhanced, resulting in a wider distribution, probably due to accelerated aging in Down's patients.

Adolescent↗
PubMed1993

Enhanced negative slope of cortical potentials before sequential as compared with simultaneous extensions of two fingers.

Cortical potentials preceding voluntary sequential extension of the right middle finger followed by the index finger were compared with those preceding voluntary simultaneous extension of the two fingers in 7 right-handed subjects who were trained to make the total duration of the EMG discharges approximately the same between the two movements. The negative slope with the sequential movement started earlier and was larger, especially at the vertex and also at the bilateral precentral areas, as compared with the simultaneous movement. There was no difference in the Bereitschaftspotential amplitude between the two movements. It was postulated that a greater and earlier activation of the supplementary motor areas as well as the primary hand sensorimotor areas is associated, both bilaterally, with the execution of the unilateral sequential movement.

Adult↗
PubMed1993

A cortical slow potential is larger before an isolated movement of a single finger than simultaneous movement of two fingers.

Movement-related cortical potentials (MRCPs) preceding voluntary, self-paced, simultaneous extension of the middle and index fingers (two finger movement) were compared with those preceding extension of the index or middle finger alone (single finger movement) of the right hand in 7 right-handed normal subjects. It was meant to double the number of muscles involved in the two finger movement as compared with the single finger movement and to activate only the motor cortex involving the movement of distal joints. The NS' (negative slope) amplitude with the isolated middle finger movement was significantly larger at the precentral area contralateral to the movement as compared with the two finger movement. The NS' amplitude with the index finger movement was also larger than that with the two finger movement at the contralateral precentral area, but the difference was not significant. It is postulated that greater activation of the primary hand sensorimotor area (HSMA) contralateral to the movement might be necessary for the isolated movement of a single finger than for the two finger movement, although a smaller area of HSMA is expected to be activated in the former than in the latter. The NS' may be related to central motor control processes independent of muscle mass activated. As the single finger movement is considered to be more discrete and fine as compared with the simultaneous two finger movement, it is concluded that the HSMA plays an especially important role in discrete and fine finger movement.

Adult↗
PubMed1993

Method for single-trial recording of somatosensory evoked potentials.

Evoked potentials (EPs) in response to stimuli are recorded from a human scalp contaminated with noise. To improve the signal-to-noise ratio, averaging methods have been widely used for the recorded data. However, when the waveforms of EP for each stimulus are not identical, the average waveform of the EP deteriorates. Variation of the EP waveform to each stimulus itself is important information for the EP. In this paper, a recording method for single somatosensory evoked potential (SEP) waveform is proposed, in which three kinds of band-pass filters were selectively used during three specific time sectors for each interstimulus interval. For the late section of the interval, an EEG waveform prediction method was applied to eliminate contaminated alpha rhythm components. By using the proposed method, we were successful in detecting the single SEP waveform.

Adult↗
PubMed1993

Movement-related potentials associated with single and repetitive movements recorded from human supplementary motor area.

To clarify the differences of movement-related potentials (MRPs) between single and repetitive movements, MRPs with finger movements were recorded from subdural electrodes chronically implanted on the supplementary motor area (SMA) in 2 patients, and MRPs with foot movements were recorded simultaneously from the SMA and the primary motor foot area in 1 patient. Repetitive movements did not elicit larger pre-movement potentials in the SMA as compared with single movements in all 3 patients. In the negative motor area, where electrical stimulation elicited inhibitory responses of voluntary movements and which is located at the rostral part of the SMA, pre-movement potentials to either single or repetitive movements were of approximately equal amplitude in 1 out of 3 patients. It is, therefore, most likely that the SMA plays an equally significant role in preparation for single and repetive voluntary movements.

Adult↗
PubMed1993

Vibration-evoked sensory nerve action potentials derived from Pacinian corpuscles.

To evaluate sensory response to natural stimuli, we developed a method to record sensory nerve action potentials evoked by high-frequency vibratory stimulation. Trains of 250 Hz sinusoidal indentations with a duration of 100 msec were applied to the finger tip at a rate of 3 Hz. The responses were obtained with surface electrodes placed over the median and ulnar nerves at the wrist. Averaged wave forms consisted of two components: an initial diphasic or triphasic potential and the following low amplitude trains of discharges phase-locked to vibratory stimuli. Anesthesia of the skin at the stimulation site or tourniquet-induced ischemia of the limb eventually diminished both components. Neither of them therefore represented artifacts from electrode movement or electromagnetic field intrinsic to the stimulator. Various kinds of mechanoreceptors may contribute to the first component. Pacinian corpuscles probably give rise to the second component as the only skin receptors that can respond to high-frequency vibratory stimuli of 250 Hz. This method helps examine neural coding of the receptor and the peripheral nerve fiber mediating vibration sense.

Action Potentials↗
PubMed1993

Both primary motor cortex and supplementary motor area play an important role in complex finger movement.

In order to clarify the roles played by the primary motor cortex and the supplementary motor area in the execution of complex sequential and simple repetitive finger movements, regional cerebral blood flow (rCBF) was measured with PET using 15O-labelled water in five normal subjects. The PET data of each individual subject co-registered to his own MRI, was analysed. Compared with the resting condition, the mean rCBF was markedly increased in the contralateral sensorimotor cortex (M1-S1) and moderately increased in the contralateral cingulate gyrus and putamen in both the simple and complex motor tasks. During the complex motor task, in addition to the above, the mean rCBF was markedly increased in the supplementary motor area and the contralateral premotor area, and moderately increased in the ipsilateral M1-S1 and cerebellum. In the supplementary motor area, there was a moderate rCBF increase also during the simple task. However, comparison of the mean rCBF increase against the resting condition between the two tasks revealed a greater increase during the complex task than in the other only in the supplementary motor area and the ipsilateral M1-S1. Thus, in agreement with our previous electrophysiological findings, not only the supplementary motor area but also the M1-S1 seems to play an important role in the execution of complex sequential finger movements.

Adult↗
PubMed1993

Effects of acupuncture on somatosensory evoked potentials: a review.

Although acupuncture has a long history of analgesic effects, the mechanisms underlying its effects are still unclear. Somatosensory evoked potential (SEP) methodology has been adopted in the research of acupuncture since the 1970s. In research on the effects of acupuncture on the conventional SEP, variable results have been observed, and two different opinions concerning the presence or absence of acupuncture effects on the conventional SEP are discussed. Since the conventional SEP is mediated mainly by fast conducting sensory nerve fibers, the conventional SEP methodology, especially that for recording short-latency SEP, may be inadequate for studying acupuncture mechanisms. In the case of the long-latency cortical SEP, there are too few data available to judge the effects of acupuncture analgesia (AA). Studies on the effects of AA on pain SEPs demonstrated that AA has a suppressive effect on amplitude of the pain SEP (and affecting the latency as well in some experiments) in both animals and humans, being accompanied by increased pain threshold. Thus, acupuncture seems to have analgesic effects that are probably related to activation of the antinociceptive system, and application of the pain SEP methodology to the study of mechanisms of AA may be promising.

Acupuncture Analgesia↗
PubMed1993

Progressive degeneration of motor nerve terminals in GAD mutant mouse with hereditary sensory axonopathy.

The evolution of motor nerve degeneration was examined in gracile axonal dystrophy (GAD) mutant mice, which develop initial sensory ataxia and subsequent motor paresis. Using the anterior gracilis (AG) muscle, which is innervated at two discrete and well-separated endplate zones, we demonstrated that axonal degeneration occurred first at motor nerve terminals in the distal endplate zone, and then extended gradually from the distal to the more proximal parts of affected axons in the intra-muscular nerve trunk. In contrast to the degeneration in the distal zone, active degeneration was less marked in the proximal endplate zone and, furthermore, most terminal axons had begun to produce regenerating sprouts. Ventral horn cells were histologically normal, even at advanced stages. These results indicate that, as previously observed in sensory nerves, dying back degeneration progresses later in the lower motor neuron system, even within one muscle. The mechanism(s) influencing the activation of axonal regeneration are discussed. This mutant mouse will be a useful model for the study of regenerating phenomena in dying back degeneration of genetically compromised motor neurons, as well as for the study of the pathogenesis of hereditary sensory and motor neuropathies in man.

Acetylcholinesterase↗
PubMed1993

Auditory event-related potentials in patients with systemic lupus erythematosus.

We studied auditory event-related potentials (ERPs) in 17 patients with systemic lupus erythematosus (SLE). Latencies of N100 and P200 components were normal in all patients, whereas the latencies of target P300 and nontarget P300 components were significantly prolonged in SLE patients with and without cognitive dysfunction. The P300 component of ERPs can be applied to evaluate the cognitive aspects of central nervous system manifestations in SLE patients.

Adult↗
PubMed1993

[Chronic herpes simplex encephalitis initially presenting with persistent myoclonus].

A 59-year-old female patient with atypical chronic herpes simplex encephalitis was reported. Initial symptom was persistent myoclonus involving the trunk and limb muscles, and later lateral gaze palsy to the left side, cerebellar ataxia, consciousness disturbance and other brainstem symptoms including absence of corneal and gag reflex and vocal cord palsy developed. The patient was successfully treated with high dose of acyclovir. Electroencephalogram was normal in the initial stage but later showed diffuse slow waves. Although CT scan and MRI showed no abnormal finding in the cerebral cortex, brainstem lesion was observed on PD weighted image of MRI. Lumbar puncture yielded a clear cerebrospinal fluid, with slightly elevated protein, increased lymphocytes, and elevated titer of herpes simplex virus type I. The serological data, albumin ratio (10.3), antibody index (12.3) and antibody ratio (7.1) were consistent with herpes simplex encephalitis. Ten days' administration of acyclovir, 1,200 mg a day and repeated three times, was prominently effective for the myoclonus and consciousness disturbance. A diagnosis of chronic herpes simplex encephalitis initially presenting with brainstem encephalitis was made. Judging from the clinical and EEG findings, the brainstem lesion was initially thought to be a cause of myoclonus in this case. However, somatosensory evoked potential (SPE) of both upper and lower extremities revealed enlarged amplitude (giant SEP), and long loop reflex was enhanced (C-reflex) on the left. Giant SEP and C-reflex imply cerebral cortex as the origin of the myoclonus. Brainstem inflammatory lesion might have involved the ascending inhibitory system, thus disinhibiting the cortical sensorimotor area and causing cortical myoclonus.

Chronic Disease↗