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Nagako Murase

Publications and source records attributed to Nagako Murase.

14 recordsLinked to original sources
PubMed2006

Stereotactic surgery for subthalamic nucleus stimulation under general anesthesia: a retrospective evaluation of Japanese patients with Parkinson's disease.

We compared retrospectively the outcome of bilateral subthalamic nucleus (STN) stimulation in 15 patients with Parkinson's disease who underwent the procedure under general anesthesia (GA) with that achieved in 10 patients under local anesthesia (LA). At 3 months postoperatively, all cardinal parkinsonian motor symptoms, evaluated on Unified Parkinson's Disease Rating Scale were significantly improved compared to preoperative baselines in both groups. The administration of GA did not adversely affect postoperative improvements in motor and daily activity scores, except for off-medication bradykinesia. Our results suggest that GA compares favorably with LA in surgical procedure for bilateral STN stimulation.

Aged↗
PubMed2006

Alleviation of camptocormia by bilateral subthalamic nucleus stimulation in a patient with Parkinson's disease.

Camptocormia, known also as "bent spine syndrome", is characterized by involuntary truncal flexion of the thoraco-lumbar spine that appears in the sitting or standing position. Although Parkinson's disease (PD) is the most frequent etiologic factor, this postural disorder responds poorly to levodopa or other medications. We report a PD patient in whom chronic bilateral subthalamic nucleus stimulation produced a striking alleviation of camptocormia.

Aged↗
PubMed2006

Effect of repetitive transcranial magnetic stimulation applied over the premotor cortex on somatosensory-evoked potentials and regional cerebral blood flow.

Somatosensory-evoked potentials (SEPs) are attenuated by movement. This phenomenon of 'gating' reflects sensorimotor integration for motor control. The frontal N30 component after median nerve stimulation was shown to be reduced in amplitude prior to hand movement. To investigate the mechanism of this sensory gating, we recorded median SEPs immediately before and after application of monophasic very low-frequency (0.2 Hz) repetitive transcranial magnetic stimulation (rTMS) of 250 stimuli over motor cortex (MC), premotor cortex (PMC), or supplementary motor area (SMA) in 9 healthy volunteers. The stimulus intensity for MC or PMC was set 85% of the resting motor threshold for the hand muscle, and that for SMA was at the active motor threshold for the leg muscle. SEPs showed significant increases in amplitudes of the frontal N30 component after PMC stimulation, but not after SMA or MC stimulation. Low-frequency (1 Hz) biphasic stimulation over PMC showed no significant N30 changes in 6 out of 9 subjects tested, indicating the effect being specific for 0.2 Hz monophasic stimulation. To examine the functional anatomy of the N30 change, single photon emission computed tomography was performed immediately before and after monophasic 0.2 Hz rTMS over PMC in all the 9 subjects. Regional cerebral blood flow showed significant increases mainly in PMC and prefrontal cortex, indicating the involvement of these cortical areas in sensory input gating for motor control.

Adult↗
PubMed2006

Complete suppression of paroxysmal nonkinesigenic dyskinesia by globus pallidus internus pallidal stimulation.

Stereotactic functional surgery is being explored as potential therapies for medically intractable paroxysmal dyskinesias (PxD). We report on a 59-year-old man in whom stimulation of globus pallidus internus produced immediate and sustained relief of paroxysmal non-kinesigenic dyskinesia secondary to a rotator cuff tears on the left shoulder. Our finding strongly suggests that altered function of neuronal circuits of the basal ganglia underlies the manifestation of PxD.

Chorea↗
PubMed2006

Impact of bilateral pallidal stimulation on DYT1-generalized dystonia in Japanese patients.

Early-onset generalized dystonia attributable to a DYT1 gene mutation is a hyperkinetic movement disorder that responds poorly to pharmacotherapy. In this video brief, we show that continuous bilateral stimulation of the globus pallidus internus produced sustained and marked improvements in the motor symptoms and functional disabilities of Japanese patients with DYT1-generalized dystonia.

Adolescent↗
PubMed2005

Transcallosal inhibition in chronic subcortical stroke.

Movements of the paretic hand in patients with chronic subcortical stroke are associated with high interhemispheric inhibition (IHI) targeting the motor cortex in the lesioned hemisphere relative to healthy controls. The purpose of this investigation was to determine whether this abnormality also involves IHI operating during movements of the non-paretic hand. Here, we studied IHI in the process of generation of voluntary index finger movements by the paretic and non-paretic hands in a simple reaction time paradigm in a group of patients with chronic subcortical stroke. With movements of the non-paretic index finger, IHI targeting the contralateral primary motor cortex ((c)M1) decreased progressively to turn into facilitation at around movement onset, similar to healthy controls. In contrast, movements of the paretic index finger resulted in significantly deeper inhibition at all premovement timings relative to the non-paretic hand. In conclusion, these results document a deeper premovement IHI with paretic than non-paretic hand movements of patients with chronic subcortical stroke, a possible mechanism underlying deficits in motor control.

Adult↗
PubMed2005

Abnormal sensory gating in basal ganglia disorders.

Basal ganglia encompass four to five distinct loops to allow parallel processing of information. Among them, the most intensively studied is the motor loop, which includes two distinct direct and indirect pathways. The direct pathway exerts facilitatory influence upon the motor cortex, whereas the indirect pathway exerts an inhibitory effect. Overall, this dual system provides a center(excitatory)-surround-(inhibitory) mechanism to focus its effect on selected cortical neurons, and several lines of evidence suggest that this center-surround mechanism is used to focus the output on a specific group of muscles required for performing a specific task. This operation is made possible through opening the sensory channel for the expected sensory feed-back afferents during movement. Thus, one of the important functions of basal ganglia seems to be the gating of sensory input for motor control. Dystonia may be caused by a mismatch between sensory input versus motor output, and parkinsonism may be viewed as a disorder of gain control of this sensorimotor integration.

Animals↗
PubMed2004

Subthreshold low-frequency repetitive transcranial magnetic stimulation over the premotor cortex modulates writer's cramp.

Writer's cramp, or focal hand dystonia, is characterized by involuntary coactivation of antagonist or unnecessary muscles while writing or performing other tasks. Although the mechanism underlying this muscle overactivation is unknown, recent studies of changes in cerebral blood flow during writing have demonstrated a reduction in the activation of the primary motor cortex (MC) and hyperactivity of parts of the frontal non-primary motor areas. Therefore, any measures that decrease the activities of non-primary motor areas such as the premotor cortex (PMC) and the supplementary motor area (SMA) might improve dystonic symptoms. To explore this possibility, we studied nine patients with writer's cramp and seven age-matched control subjects, using subthreshold low-frequency (0.2 Hz) repetitive transcranial magnetic stimulation (rTMS), which exerts an inhibitory action on the cortex. Previous studies have demonstrated shortened cortical silent periods in dystonia, suggesting deficient cortical inhibition in the MC. We compared the silent periods and computer-assisted ratings of handwriting before and after rTMS applied to the MC, SMA or PMC. We also used the sham coil for control runs. Stimulation of the PMC but not the MC significantly improved the rating of handwriting (mean tracking error from the target, P = 0.004; pen pressure, P = 0.01) and prolonged the silent period (P = 0.02) in the patient group. rTMS over the other sites or using a sham coil in the patient group or trials in the control group revealed no physiological or clinical changes. This increased susceptibility of the PMC in dystonia suggests that the lack of inhibition in the MC is secondary to the hyperactivity of PMC neurons. Inhibition of the PMC using rTMS could provide a therapeutic measure of writer's cramp.

Adult↗
PubMed2004

Influence of interhemispheric interactions on motor function in chronic stroke.

In patients with chronic stroke, the primary motor cortex of the intact hemisphere (M1(intact hemisphere)) may influence functional recovery, possibly through transcallosal effects exerted over M1 in the lesioned hemisphere (M1(lesioned hemisphere)). Here, we studied interhemispheric inhibition (IHI) between M1(intact hemisphere) and M1(lesioned hemisphere) in the process of generation of a voluntary movement by the paretic hand in patients with chronic subcortical stroke and in healthy volunteers. IHI was evaluated in both hands preceding the onset of unilateral voluntary index finger movements (paretic hand in patients, right hand in controls) in a simple reaction time paradigm. IHI at rest and shortly after the Go signal were comparable in patients and controls. Closer to movement onset, IHI targeting the moving index finger turned into facilitation in controls but remained deep in patients, a finding that correlated with poor motor performance. These results document an abnormally high interhemispheric inhibitory drive from M1(intact hemisphere) to M1(lesioned hemisphere) in the process of generation of a voluntary movement by the paretic hand. It is conceivable that this abnormality could adversely influence motor recovery in some patients with subcortical stroke, an interpretation consistent with models of interhemispheric competition in motor and sensory systems.

Adult↗
PubMed2004

Dynamic MR imaging in Tolosa-Hunt syndrome.

OBJECTIVE: To evaluate the cavernous sinuses with dynamic magnetic resonance (MR) imaging in patients with Tolosa-Hunt syndrome (THS). METHODS: The sellar and parasellar regions of five patients with THS and 12 control subjects were examined with dynamic MR (1.5 T) imaging in the coronal plane. Dynamic images were obtained with spin-echo (SE) sequences in three patients, and with fast spin-echo (FSE) sequences in two patients and control subjects. Conventional MR images of the cranium including sellar and parasellar regions were also obtained on T1-weighted pre- and post-contrast SE, and T2-weighted FSE sequences in the coronal plane. RESULTS: MR images revealed affected cavernous sinus with bulged convex lateral wall in three patients and concave lateral wall in two patients. In all control subjects, cavernous sinuses were observed with concave lateral wall. The signal intensity on T1- and T2-weighted images and contrast enhancement on post-contrast images of the affected cavernous sinuses in patients were similar to those of the unaffected cavernous sinuses in patients and control subjects. The dynamic images in all patients disclosed small areas adjacent to the cranial nerve filling-defects within the enhanced venous spaces of the affected cavernous sinus, which showed slow and gradual enhancement from the early to the late dynamic images. No such gradually enhancing area was observed in control subjects except one. The follow-up dynamic MR images after corticosteroid therapy revealed complete resolution of the gradually enhancing areas in the previously affected cavernous sinus. CONCLUSION: Dynamic MR imaging may facilitate the diagnosis of THS.

Adult↗
PubMed2003

Movement-related cortical potentials before jaw excursions in oromandibular dystonia.

Oromandibular dystonia is a neurological disorder characterized by involuntary contraction of masticatory and/or tongue muscles. Cortical negative shifts preceding voluntary movements called "movement-related cortical potentials" (MRCPs) reflect a central motor control process. Reduced amplitude of MRCPs has been reported in other types of dystonia. To elucidate whether the abnormality is observed also in oromandibular dystonia, we compared MRCPs associated with mandibular movements in 6 patients with this condition and in 8 normal subjects. Electroencephalograms (EEGs) were recorded from 11 electrodes, and electromyograms (EMGs) were recorded from the masseter muscle and the suprahyoid muscles. The subjects were asked to repeat mouth opening, closing, and left and right lateral mandibular excursions. MRCPs were obtained by averaging the EEG using the EMG onset as the trigger signal. In the patient group, MRCP amplitudes over central and parietal areas for mouth opening and lateral movements were significantly reduced compared to normal subjects. In normal controls, the MRCPs at mouth opening and closing were symmetrically distributed, whereas those at lateral movements showed predominance over the hemisphere ipsilateral to the direction of the movement. This laterality was lost in the patient group. These results suggest impaired cortical preparatory process for jaw movements in oromandibular dystonia.

Adult↗