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I Shimoyama

Publications and source records attributed to I Shimoyama.

At least 19 recordsLinked to original sources
PubMed1992

Verbal versus non-verbal visual evoked potentials: Kanji versus line drawings.

Cortical areas related to perception of verbal and non-verbal stimuli were studied using VEPs. Kanji characters, line drawings (LD), or a blank were displayed. Verbal VEPs were obtained by subtracting the blank-VEPs from the Kanji-VEPs, and non-verbal VEPs by subtracting the blank-VEPs from the LD-VEPs. Both the verbal and non-verbal VEPs showed a negative peak (100-300 msec) focally over bilateral occipital, posterior temporal and parietal areas, and a positive peak diffusely over frontal halves. Differences between the non-verbal from the verbal VEPs showed an initial peak (100-200 msec) focally over bilateral occipital and posterior temporal areas, followed by a peak (200-300 msec) focally over bilateral posterior temporal areas. The frontal areas diffusely showed peaks at 100-200, 200-300 and 300-400 msec. Left-right asymmetries of both the verbal and non-verbal VEPs showed peaks between 100 and 300 msec over posterior temporal, parietal, and occipital areas. Left-right asymmetries of the subtraction to the non-verbal from the verbal VEPs showed a peak (100 msec) over occipital and parietal areas, and a broader peak over posterior temporal area (100-200 msec). Bilateral occipital, posterior temporal, and parietal areas are focally activated by the two perceptions (100-300 msec), while frontal areas are activated diffusely. Further, different processes may be focally involved between the hemispheres over occipital (100-200 msec) and posterior temporal (100-200 and 200-300 msec) regions. Initial left-right asymmetries of the subtracted VEP between the two perception would occur over occipital and parietal areas (100 msec) and last for 200 msec over posterior temporal area.

Acoustic Stimulation↗
PubMed1992

Relation between protein kinase C and calmodulin systems in cerebrovascular contraction: investigation of the pathogenesis of vasospasm after subarachnoid hemorrhage.

The protein kinase C (PKC) and calmodulin systems each play a role in vascular contraction. However, the correlation of these two systems in producing contraction has been unclear. To clarify the pathophysiology of vasospasm after subarachnoid hemorrhage, the authors demonstrated tonic contraction of the cerebral artery in a study of isometric tension, and investigated the correlation of the PKC and calmodulin systems in producing the contraction. To develop better management for vasospasm, they also examined the effect of calmodulin antagonists on tonic contraction. The development of isometric tension in canine basilar arteries was measured, with the following results: 1) tonic contraction was dependent on the PKC system, but initiation of the contraction by the calmodulin system was necessary for the subsequent PKC-dependent tonic contraction; 2) specific calmodulin antagonists like chlorpromazine and pimozide partially inhibited the tonic contraction associated with PKC activation; 3) another calmodulin antagonist, trifluoperazine, inhibited the PKC system as well. On the basis of these results, the authors conclude that the PKC system plays a role in the development of vasospasm. In the early phase of contraction, the calmodulin system contributes to the subsequent fully-activated, PKC-induced tonic contraction. To manage vasospasm, a specific calmodulin antagonist would therefore not be sufficient. Suppression of both the calmodulin and PKC systems with trifluoperazine in the earliest stage of vasospasm is recommended.

Animals↗
PubMed1991

Post-irradiation vasculopathy of intracranial major arteries in children--report of two cases.

We report two rare cases of post-irradiation vasculopathy of intracranial major arteries in children. A 13-year-old girl suffered from transient right hemiparesis 1 year after irradiation for suprasellar germinoma. Left carotid angiograms revealed marked stenoses of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries, which were previously normal, and moyamoya vessels. A 2.5-year-old girl underwent internal irradiation with 198Au colloid for cystic craniopharyngioma. At the age of 10 years, she suddenly became unconscious after vomiting. Computed tomographic scans showed a right frontal intracerebral hematoma. Right carotid angiograms disclosed complete obstruction of the intracranial internal carotid, middle cerebral, and anterior cerebral arteries and moyamoya vessels, previously not present. The danger of radiation therapy causing occlusive vasculopathy in small and major cerebral arteries in children is emphasized. To prevent permanent ischemic neurological deficits, vasculopathy should be treated either medically or surgically as early as possible.

Adolescent↗
PubMed1991

Cerebellar ganglioglioma--case report.

A 14-year-old boy presented with cerebellar ganglioglioma manifesting as severe headache and confusion. Computed tomographic scans showed a huge, partly enhanced cystic cerebellar tumor. The tumor was totally removed. Histological examination disclosed glial cells and mature ganglion cells. The latter were identified by Nissl's staining and immunostaining for neurofilaments. Ganglion cells were present in the cerebellum and the surrounding subarachnoid space. This heterotopic growth of ganglion cells enabled a firm diagnosis of cerebellar ganglioglioma.

Adolescent↗
PubMed1990

The finger-tapping test. A quantitative analysis.

A quantitative analysis of the so-called finger-tapping test was performed on 111 normal subjects. Quantitative analysis was also performed on 17 patients with cerebellar diseases, 14 with parkinsonism, and 14 with hemiparesis. All analyses were performed in a simple fashion using an 8-bit microcomputer fed through an electrocardiographic apparatus. The results in normal subjects were as follows: (1) tapping frequency lowered with advancing age; (2) men tapped faster than women; and (3) tapping with the dominant finger was faster than tapping with the nondominant finger in normal subjects. Tapping frequency can distinguish patients with motor dysfunctions of cerebellar, basal ganglia, and cerebral origins from normal subjects. Only the time-sequential histograms of tapping intervals could distinguish the motor dysfunctions studied.

Adult↗
PubMed1990

Effect of pinealectomy on cortically kindled rats.

Cortical kindling in pinealectomized rats was studied to observe the effect of pinealectomy on local afterdischarge thresholds and seizure development. Although the local afterdischarge thresholds were not affected by pinealectomy, the kindling process itself was hastened. These results suggest that the anticonvulsive function of the pineal body is due not to a decrease in local afterdischarge thresholds, but to retardation of secondary generalization.

Animals↗
PubMed1990

Lipoma in the cerebellopontine angle--case report.

The authors report a case of a cerebellopontine (CP) angle lipoma with a very unusual histological appearance. The 38-year-old male patient suffered vertigo, left tinnitus, and left hearing disturbance. Computed tomography and magnetic resonance imaging showed a nonenhanced low-density area and a high-intensity region in the left CP angle, respectively. The tumor, which was only partially removed because of its tight adhesion to the VIIIth nerve and brainstem, consisted of mature lipocytes and contained a piece of cartilage, which is highly unusual.

Adult↗
PubMed1990

[Angiographic findings of vertebral dissecting aneurysm. Report of two cases and review of literature].

The authors report two cases of vertebral dissecting aneurysm. The first case, a 49-year-old female, developed severe headache and computed tomography scan showed subarachnoid hemorrhage (SAH), but 4-vessel cerebral angiography failed to show an aneurysm. The second angiograms obtained 2 weeks later showed possible aneurysmal dilatation on the right vertebral artery. The third angiograms, 2.5 months after SAH, disclosed a right vertebral fusiform aneurysm on the arterial phase and it was diagnosed as a dissecting aneurysm since the contrast medium remained until the very late venous phase. The previous angiograms were reviewed using the subtraction technique, which revealed retention of the contrast medium. The second case, a 42-year-old female, suffered from SAH. Left vertebral angiography revealed a fusiform aneurysmal tapered narrowing just distal to the aneurysm, which was a typical "pearl and string sign." The subtraction film of the venous phase also showed retention of the contrast medium in the aneurysmal portion. These findings accurately diagnosed dissecting aneurysm of the vertebral artery. Since the classical true diagnostic "double lumen sign" was rarely observed in the angiograms, it was not easy to diagnose dissecting aneurysm of the vertebral artery. The authors emphasize the angiographic findings of retention of the contrast medium in the venous phase as a "true diagnostic sign" for correct diagnosis of dissecting aneurysm.

Aortic Dissection↗
PubMed1990

Line-drawing test across ages.

A line-drawing test was standardized for normal subjects to examine effects of normal aging. For this purpose, the results of the test for 168 normal volunteers were quantified using a digitizer and a microcomputer across ages from 9 to 78 yr. Three sets of parallel vertical lines were presented to every subject, the distances between the parallel vertical lines (5, 10, and 15 cm) differed in the three sets. A subject drew an horizontal line starting exactly on the left vertical line and stopped exactly on the right one, and the computer could detect minute inaccuracy at the start and at the stop, which inaccuracy was expressed in mm. In this study, effects of four parameters were evaluated, i.e., ages, sex, distances from the paired vertical lines, and order of trials; all were nonsignificant. The normal range of the deviations was within 2.1 mm (average + 2 SD).

Adolescent↗
PubMed1989

[Unilateral nerve deafness due to rupture of a right vertebral artery aneurysm. Case report].

A 49-year-old female with no history of hearing disturbance developed sudden onset of headache and was admitted with no neurological deficits other than mild nuchal rigidity. Computed tomography (CT) showed subarachnoid hemorrhage. Four-vessel cerebral angiography disclosed no aneurysm. A second angiogram obtained on the 14th day showed vasospasm of the bilateral posterior cerebral arteries and right anterior inferior cerebellar artery, but still failed to demonstrate an aneurysm. Following the second angiography, she developed mild disturbance of consciousness and cerebellar ataxia of the right limbs, and repeat CT showed an infarct in the right cerebellar hemisphere. When she regained consciousness a few days later, she was completely deaf on the right side. The third angiography revealed a right vertebral artery dissecting aneurysm. Following clipping of the proximal portion of the right vertebral artery, she did well and was discharged, although right cerebellar ataxia and deafness persisted. Neuro-otological evaluation, including pure-tone audiography, auditory brainstem responses, electrocochleography, and caloric testing, indicated that her deafness resulted from ischemia in the territory of the right internal auditory artery due to vasospasm.

Deafness↗
PubMed1989

[Intra-operative monitoring with ABR during neurovascular decompression for VIIth and VIIIth cranial nerves: a warning sign for surgeons].

Auditory brain stem responses (ABR) were monitored during 18 cases of neurovascular decompression (12 with hemifacial spasm, and 6 with tinnitus, vertigo and/or hearing disturbance). As criteria for warning the surgeon, we adopted such changes as disappearance or marked decrease in amplitude of wave V. ABR changes were classified into 3 types as follows. Type 1 (7 cases): prolongation of latencies without wave form changes, Type 2 (5 cases): temporary disappearance of the waves after wave II, Type 3 (6 cases): temporary loss of all waves. In all cases except in one of the 2, with technical failure, all the waves reappeared within 5 minutes after releasing the retraction and irrigating the cerebellopontine cistern with warm normal saline solution. No patient had severe post-operative hearing deficit, but type 3 patients showed hearing disturbance of statistically significant magnitude (-8.33 +/- 3.16 dB). In type 1 patients, the mean prolongation of wave V latency during operation reached 1.27 +/- 0.44 msec, but the mean hearing loss after operation was only 3.57 +/- 4.4 dB. We believe that as soon as the waves disappear, one should immediately release the retraction and irrigate cisterns with warm normal saline solution, and wait until the waves reappear. Prolongation of latencies alone does not indicate postoperative hearing disturbances, and even if the waves disappear their prompt recovery suggests that hearing will be preserved after operation.

Adult↗
PubMed1989

[Significance of "on-off phonation test" to detect oral diadochokinesia in dysarthric patients].

Oral diadochokinetic abilities in 6 patients with ataxic dysarthria (ATAXICs), 6 with spastic dysarthria (SPASTICs), 3 with parkinsonism (PARKINs), and 6 normal subjects (NORMALs) were investigated using repetition of monosyllable /pa/ and "on-off phonation test" in which they had been requested to repeat interrupted vowel /a/ as fast as possible. Oscillographic as well as photographic records of the speech acoustic signal were obtained to analyse interval for a syllable, which consisted of voiced and unvoiced intervals, and peak-value of voiced interval. The results were as follows: 1) ATAXICs and SPASTICs showed prolonged interval for a syllable, yet that of PARKINs was within normal range, when tested either in /a/ or in /pa/. 2) Standard deviation and coefficient of variation for intervals of syllable and those of peak-values in voiced interval could not distinguish their characteristics among ATAXICs, SPASTICs, and PARKINs. 3) In "on-off phonation test", ATAXICs showed prolonged unvoiced intervals, while SPASTICs did prolonged voiced intervals. Results suggested that hypotonic laryngeal muscles in ATAXICs might result in prolongation of unvoiced interval, but that prolonged voiced interval related to biased hypertonus of laryngeal adductor. It is concluded that "on-off phonation test" could, with reasonable sensitivity, reflect the phonatory dynamics of laryngeal muscles in dysarthric patients.

Aged↗
PubMed1988

Thalamic, brainstem, and cerebellar glucose metabolism in the hemiplegic monkey.

Unilateral ablation of cerebral cortical areas 4 and 6 of Brodmann in the macaque monkey results in a contralateral hemiplegia that resolves partially with time. During the phase of dense hemiplegia, local cerebral metabolic rate for glucose (1CMRG1c) is decreased significantly in most of the thalamic nuclei ipsilateral to the ablation, and there are slight contralateral decreases. The lCMRGlc is reduced bilaterally in most of the brainstem nuclei and bilaterally in the deep cerebellar nuclei, but only in the contralateral cerebellar cortex. During the phase of partial motor recovery, lCMRGlc is incompletely restored in many of the thalamic nuclei ipsilateral to the ablation and completely restored in the contralateral nuclei. In the brainstem and deep cerebellar nuclei, poor to moderate recovery occurs bilaterally. Moderate recovery occurs in the contralateral cerebellar cortex. The findings demonstrate that a unilateral cerebral cortical lesion strongly affects lCMRGlc in the thalamus ipsilaterally and in the cerebellar cortex contralaterally, but in the brainstem bilaterally. Partial recovery of lCMRGlc accompanies the progressive motor recovery. The structures affected include those with direct, and also those with indirect, connections to the areas ablated.

Animals↗
PubMed1988

[Cerebral lateralization in two cases of crossed dextral aphasia with right-hemisphere arteriovenous malformation].

This paper reports two cases of crossed dextral aphasia. The first patient was a 60-year-old right-handed male with no family history of sinistrality. He experienced sudden onset of left hemiplegia and loss of consciousness. A CT scan showed high-density area in the right fronto-parietal region. An angiography revealed an arteriovenous malformation (AVM) in the right parietal lobe. It was fed by a branch of the middle cerebral artery and drained through a cortical vein. Neuropsychological examination one week after the surgery showed severe defects of all language moderalities. He was alert and cooperative, but completely mute. He recognized common words by auditory and visual stimuli, but could not perform simple command. He wrote some meaningless letters when asked to write his own name. Auditory and reading comprehension gradually improved thereafter, but Broca's type of aphasia with non-fluent hesitant and effortful output was still present four months after the surgery. The second patient was a 38-year-old right-handed male. All members of this family are right-handed except for one sister who is left-handed. He suddenly suffered left hemiparesis and loss of consciousness. A CT scan disclosed a right parietal intracerebral hematoma. And an AVM which was fed by the angular artery and drained through a cortical vein was angiographically demonstrated in the same area. Postoperatively the left hemiparesis rapidly disappeared, but left homonymous hemianopsia and anomic type of aphasia still persisted. His speech was fluent and daily communication was possible in spite of circumlocutory paraphasic output.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Clinical study of traumatic cerebellar contusion].

Numerous authors have reported cases of traumatic cerebellar contusion. A few authors have emphasized delayed deteriorations in patients with cerebellar contusion. Since CT scan was introduced into daily clinical practice, it has become obvious that cerebellar contusion were not necessarily associated with severe head injuries. Of 1176 head-injured cases admitted to our department in the past five years, eight (0.7%) were diagnosed by CT scans to have cerebellar contusion. Among eight cases, two of them were deeply comatose on admission because they had concomitant diffuse cerebral contusions and died soon after admission. Remaining six cases had predominantly cerebellar contusion on CT scans and showed minimal neurological deficits on admission. Most of them recovered without any significant disabilities. But two of them deteriorated several hours after injury, showing brain-stem compression for which emergency posterior fossa decompression were carried out without recovery. One of them underwent external decompression which resulted in intracerebellar massive hemorrhage and the other missed the timing of surgery. In conclusion, it is important to prepare for unexpectedly rapid deterioration, for which wide craniectomy and sufficient internal decompression would be required.

Adult↗