Biomedical subjects
Publications and source records attributed to H Tohgi.
The mode of cerebral representation for each half of the body is various according to the functions that are represented; contralateral, ipsilateral and bilateral. We reviewed, and discussed the meaning of, such different patterns of cerebral representation for somatic and autonomic functions.
Vascular dementia is almost always associated with organic brain lesions due to ischemia, not with arteriosclerosis alone. In Japan, more than 50% of dementia in population older than 65 years are of vascular origin. Vascular dementia occurs with diffuse vascular lesions in the cerebral white matter or circumscribed lesions in particular areas such as the thalamus, anterior limb of the internal capsule, and cingulate gyrus, all of which constitute the ascending activating system or the limbic system. Vascular dementia is clinically characterized by stepwise progression, fluctuating course and predominant deterioration of intelligence with relative preservation of personality. Reversibility, disproportionate impairment of intelligence and personality, and dementia caused by a focal lesion observed in vascular dementia pose problems with regard to the classical concept of dementia. The similarity and difference between remitting dementia and disturbance of consciousness remain to be scrutinized.
The cerebral white matter is highly susceptible to ischemic damage because of its location in the end-fields of penetrating arteries. Our studies have shown that hypertension, short-term variability of blood pressure, decreased oxygen dissociation of hemoglobin, and increased resistance of cerebral arterioles play important roles in the pathogenesis of Binswanger type dementia. While hypoperfusion was most remarkable in the frontal area and dopamine metabolism in the cerebrospinal fluid was impaired in Binswanger type dementia, cerebral blood flow decreased most conspicuously in the parietal area and there was an impairment of noradrenaline metabolism in the cerebrospinal fluid in senile dementia of Alzheimer type. Previous anatomical studies have indicated that the ascending dopaminergic system predominantly innervates the frontal cortex, while the noradrenergic system projects all cortical areas, including the parietal cortex. Our findings suggest frontally-dominant dysfunctions in Binswanger type dementia.
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Oxygen affinity of hemoglobin, erythrocyte 2,3-diphosphoglycerate (DPG) and adenosine triphosphate (ATP) concentrations were compared before and after oral administration of vinpocetine (TCV-3B) (15 mg/d), a primarily vasodilating agent, for three weeks in eight patients with vascular dementia of the Biswanger type which is characterized by diffuse myelin pallor and multiple lacunes in the cerebral white matter. After vinpocetine administration, oxygen affinity of hemoglobin (P50) was significantly increased (26.5 +/- 0.55 to 27.6 +/- 0.62 mmHg; mean and standard deviation, p less than 0.05), red blood cell (RBC) ATP concentrations were significantly increased (846 +/- 168 to 1,158 +/- 130 mumol/l RBC, p less than 0.05), while DPG concentrations were unaltered (4.46 +/- 0.48 to 4.59 +/- 0.57 mmol/l RBC). There was a significant positive correlation between the increase of P50 and the increase of erythrocyte ATP concentrations (r = 0.67, p less than 0.05). The effect of vinpocetine of enhancing oxygen release of hemoglobin may offer an additional benefit to its primary vasodilating action in the treatment of vascular dementia of the Binswanger type due to chronic ischemia.
A 46-year-old woman presented acute sensorimotor neuropathy of the Guillain-Barré type, followed by a protracted course of profound autonomic and sensory dysfunction. Tests of autonomic functions showed denervation hypersensitivity. Neuropathologically, the trigeminal sensory nuclei, solitary nucleus, the dorsal columns of the spinal cord and dorsal spinal roots showed severe degeneration. Degeneration was found both in the preganglionic (intermediolateral cell columns of the spinal cord) and postganglionic (sympathetic ganglion and celiac ganglion) neurons of the sympathetic nervous system, and the preganglionic (dorsal motor nucleus of the vagus) and postganglionic (Auerbach's plexus) neurons of the parasympathetic nervous system.
Bilateral anterior opercular syndrome is clinically characterized by facio-pharyngo-glossomasticatory diplegia due to bilateral opercular lesions. Reported cases of the syndrome have been relatively rare probably because of difficulty in determining opercular damage on clinical symptoms alone. We report a case of this syndrome in whom bilateral opercular damage could be detected not by CT, but suggested by SPECT, and confirmed by MR imaging.
The effects of low daily oral doses of aspirin (40 mg/day) on platelet aggregability and serum thromboxane B2 concentrations were studied in 19 poststroke patients. Although platelet aggregation was reduced significantly after 1 week, there was wide individual variation in the inhibition of platelet function in spite of marked decreases of serum thromboxane B2 concentrations by greater than 90% (from 224 +/- 58 to 8 +/- 8 ng/ml). There was no correlation between collagen-induced platelet aggregability and serum thromboxane B2 concentration before aspirin administration in the range 100-350 ng/ml, but after 1 week of repeated administration of aspirin, there was a correlation between platelet aggregability and serum thromboxane B2 concentrations of less than 25 ng/ml (r = 0.68, p less than 0.01). However, platelet inhibition was insufficient even in some patients with markedly decreased thromboxane B2 concentrations (less than 5 ng/ml). Our results suggest that individual variation of platelet aggregability in response to low-dose aspirin may be due to variation not only in the degree of inhibition of thromboxane A2 production but also in the relative dependence of platelet aggregation on extra-arachidonic pathways.
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To determine the individual contribution of the right and left cerebral hemispheres to micturition control, a clinical analysis was performed concerning frequency and urgency of micturition in 134 chronic hemiplegic patients. A mean frequency of urination, 9 times or more in 24h, was found more frequently in left than right hemiplegics. Left hemiplegics also complained more often of urgency than did right hemiplegics. A mean frequency of urination of 9 times or more in 24h and urgency co-existed more frequently in left hemiplegics than in right hemiplegics. In the present study, dealing with the chronic sequelae of stroke, frequency and urgency of micturition were found more commonly in patients with right hemisphere than left hemisphere lesions.
Blood pressure and R-R interval variation were studied during postural changes using a tilting table. The subjects were 64 normal controls and 52 patients with various disorders. None of the normal controls showed postural falls of more than 15 mm Hg in mean blood pressure. The mean loge coefficient of variation of 100 R-R intervals was significantly reduced in groups with Parkinson's disease, spinocerebellar degeneration, Shy-Drager syndrome and diabetes mellitus, compared with a normal control group. Reduced heart-rate variation was frequently associated with sphincter disturbance and orthostatic hypotension.
The amplitude of visual evoked potentials (VEPs) to pattern hemifield stimulation was measured in 14 normal right-handed subjects. The paired t test was used to determine if the values differed between right and left hemifield stimulation. The amplitude of transient VEPs from a midoccipital electrode and a lateral occipital electrode ipsilateral to the hemifield stimulated was significantly greater with right hemifield stimulation. This result is compatible with neuroanatomic asymmetries of human striate cortex. Amplitude distribution over the scalp was markedly different between transient and steady-state VEPs that probably reflect activities of different populations of cortical neurons.
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The present experiment was performed to investigate the effect of stimulating the parasympathetic superior laryngeal nerve (SLN) on thyroid blood flow and its mediator substances in urethane-chloralose anesthetized rats. Thyroid blood flow was measured by counting number of blood drops from a thin catheter inserted into the thyroid vein. SLNs were cut bilaterally and their peripheral portions were electrically stimulated. Electrical stimulations (intensity, 10 V; pulse duration, 0.5 ms) of SLNs increased thyroid blood flow in a frequency-dependent manner as stimulus frequencies increased from 2 to 40 Hz. The intravenous administration of atropine (0.5 mg/kg) reduced these responses, but did not abolish them. The basal secretion rate of vasoactive intestinal peptide (VIP) from thyroid glands in the resting state was nearly zero (0.25 +/- 0.14 pg/(kg.min)). SLN stimulation increased markedly the VIP secretion rate to 3.40 +/- 0.64 pg/(kg.min). The VIP secretion responses evoked by SLN stimulation remained in atropinized rats. Furthermore, exogenously applied VIP increased the thyroid blood flow dose-dependently. These results suggest that SLN stimulation increases the thyroid blood flow by dilating thyroid blood vessels via activation of cholinergic and non-cholinergic (probably VIP-containing) nerve fibers. Thus, these parasympathetic vasodilation systems may play a supplementary role in regulating the secretion of thyroid hormone by changing the thyroid blood flow in addition to the role of hormonal regulation by the thyroid stimulating hormone (TSH).
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We report a patient suffering from persistent myoclonic jerks in the right forearm without any definite EEG abnormality under routine recording conditions. By computer summation, using the jerk-locked averaging technique, a sharp spike was recognized as a precisely time-locked event in relation to myoclonic twitches. A cranial CT scan revealed a small cortical lesion, which was found very close to the sensorimotor cortex of the right arm. Cerebral blood flow study using the xenon inhalation method revealed a discrete focus of high flow, which corresponded well with the CT lesion. On electrical stimulation of the right median nerve, a large somatosensory evoked potential and an enhanced transcortical long loop reflex were observed. Electrocorticogram showed active focal spike discharges localized at the left precentral gyrus. We postulate that an epileptogenic focus in the motor cortex and an enhanced transcortical long loop reflex appear to be important for the occurrence of epilepsia partialis continua in this patient.