Biomedical subjects

C Kadoya

Publications and source records attributed to C Kadoya.

27 records · Page 2Linked to original sources

PubMed1988

Clinico-experimental studies on auditory evoked middle latency response (AEMLR) with specific reference to generation and auditory dominancy.

The present study was carried out on animals and humans in order to clarify auditory dominancy or lateralization and the contribution site of auditory evoked middle latency responses (AEMLRs). Normal AEMLRs on guinea pigs and humans were quite similar and consisted of two negative and two positive peaks between 8 and 50 msec following the start of an auditory stimulus. In normal human subjects, the component Pa (peak to baseline measurement) or Na-Pa (trough to peak measurement) was significantly greater in the temporal area contralateral to the stimulated ear than in the ipsilateral temporal area. In guinea pigs, however, AEMLRs were attenuated only by stimulation contralateral to the side, on which a lesion was made by unilateral aspiration of the lemniscus or the inferior colliculus. This auditory lateralization and contralateral dominancy were also verified by the direct cortical recording of AEMLRs in humans and also by analysis of auditory evoked brain mapping. In clinical studies, AEMLRs have been obtained even in a premature infant born after a 44-week pregnancy. In patients with well localized lesions of the brain stem, all components of the AEMLR to stimulation contralateral to the lesion side were affected. However, component Pa of the response to stimulation contralateral to the lesion was mainly abolished in patients with unilateral thalamic or temporal lesions. The following results were obtained: 1) component Pa (or Na-Pa) of AEMLR has significant lateralization, 2) the generation site of Pa may be in the subcortical thalamic projection of the contralateral lobe, 3) component Po (or No-Po) is a true neurogenic response but is frequently enhanced by the post-auricular reflex, 4) the contralateral inferior colliculus is very important for the generation of Po, 5) the auditory system (hearing) may have contralateral AEMLR dominancy.

Adolescent↗

PubMed1987

[Barbiturate therapy in 16 cases with intracranial lesion with special reference to the indication and limitation].

The effects and indications of barbiturate therapy for brain protection, and prevention and reduction of the intracranial hypertension were investigated using an ultrashort acting barbiturate, thiamylal, in sixteen cases with intracranial lesions. Final outcome of the treatment revealed 8 good recoveries which were actively administered thiamylal during operation or immediately after. On the other hand, four cases, whose intracranial pressures (ICPS) of over 40 mmHg could not be controlled suffered brain death. Barbiturate therapy was not effective for brain protection of primary damaged lesions. It is concluded that barbiturate therapy may provide a satisfactory reduction of the intracranial hypertension in cases during the early postoperative stage or of under 40 mmHg initial ICP.

Adolescent↗

PubMed1987

[Clinical significances of auditory brainstem responses (ABRS) in cases with intracranial lesion].

In 47 cases with intracranial lesions, auditory brainstem responses (ABRS) were studied. From a detailed analysis of these data, the following results were concluded: In some cases, the intramedullary and extramedullary pontine tumor could be differentiated by ABR, A very small cerebello-pontine angle tumor was detected by ABR, ABR monitering was useful to evaluate brainstem function during the surgical operation, and ABRS were clinically very useful methods for predicting the outcome of a severe head injury and diagnosis of brain death. These results indicate that ABRS contribute to functional diagnosis of various diseases of the central nervous system.

Adolescent↗

PubMed1986

[A case of inferior vena cava thrombosis associated with cholelithiasis demonstrated by ultrasonic examination].

A case of a 44 year old female with inferior vena cava thrombosis associated with cholelithiasis was reported. The patient had chest and back pain due to pulmonary embolism. Ultrasonic examination showed stone echoes in the gallbladder and thrombus echoes in the inferior vena cava (IVC) at the height from renal veins to bifurcation of iliac veins, but iliofemoral thrombosis was not found by RI angiography and venography. Anticoagulant and urokinase were administered, then pulmonary embolus disappeared and IVC thrombus reduced. IVC thrombus was removed by incision of IVC. Thrombus was white thrombus. Etiology of thrombus was not clear. IVC ligation or plication for prevention of pulmonary emboli was not carried out. Etiology, diagnosis and treatment of IVC thrombosis were also discussed.

Adult↗

PubMedDate not supplied

Topography of somatosensory evoked potentials to median nerve stimulation in patients with cerebral lesions.

Scalp distributions and topographies of early cortical somatosensory evoked potentials (SEPs) to median nerve stimulation were studied in 22 patients with 5 different types of cerebral lesion due to cerebrovascular disease or tumor (thalamic, postcentral subcortical, precentral subcortical, diffuse subcortical and parieto-occipital lesions) in order to investigate the origins of frontal (P20, N24) and central-parietal SEPs (N20, P22, P23). In 2 patients with thalamic syndrome, N16 was delayed in latency and N20/P20 were not recorded. No early SEP except for N16 was recorded in 2 patients with pure hemisensory loss due to postcentral subcortical lesion. In all 11 patients with pure hemiparesis or hemiplegia due to precentral subcortical lesion N20/P20 and P22, P23/N24 components were of normal peak latencies. The amplitude of N24 was significantly decreased in all 3 patients with complete hemiplegia. These findings support the hypothesis that N20/P20 are generated as a horizontal dipole in the central sulcus (3b), whereas P23/N24 are a reflection of multiple generators in pre- and post-rolandic fissures. P22 was very localized in the central area contralateral to the stimulation.

Adolescent↗

PubMedDate not supplied

Absence of spinal N13-P13 and normal scalp far-field P14 in a patient with syringomyelia.

Short latency somatosensory evoked potentials to median or ulnar nerve stimulation were recorded in a patient with syringomyelia. Scalp-recorded far-field P14 was clearly preserved, but spinal N13-P13 components disappeared. Our findings support the hypothesis that spinal N13-P13 is generated by structures intrinsic to the cervical cord, most likely in the ventral central gray matter.

Adult↗

PubMedDate not supplied

Origin of scalp far-field N18 of SSEPs in response to median nerve stimulation.

To identify the origin of scalp-recorded far-field negativity of short-latency somatosensory evoked potentials to median nerve stimulation (designated N18), direct records were made from the thalamus and ventricular system during 4 stereotaxic and 3 posterior fossa operations. In the thalamus a negative potential with almost the same latency as the scalp N18 was restricted to the Vim nucleus, but there was a large positive potential in the VC nucleus and medial lemniscus. Vim negativity increased in amplitude when high frequency stimulation was given to the median nerve, indicative of a facilitation effect. In contrast, the amplitude of scalp N18 decreased at high frequency stimulus. Direct recordings made through the medulla oblongata to the mid-brain showed a negative potential with gradually increasing latency. Above the upper pons, there was stationary negativity with no latency shift. The similarity between this negative potential and N18 is shown by their having the same latency and same response to the amplitude reduction and latency prolongation produced by high frequency stimulus. Our data suggest that scalp N18 comes from brain-stem activity between the upper pons and the mid-brain rather than from the thalamus.

Adult↗

PubMedDate not supplied

Spinal intramedullary recording of human somatosensory evoked potentials.

We here report the first description of the intramedullary spatial distribution of evoked dorsal horn potentials in a human spinal cord. Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded within the cervical spinal cord of a patient with syringomyelia. Spinal intramedullary recording demonstrated a negative slow wave of the same polarity as the dorsal spinal surface response and a complex wave interpreted as the summation of its negativity and phase-reversed positivity. These two wave forms may depend on the locations at which the recording electrodes are attached to the dorsal horn.

Adult↗

PubMedDate not supplied

Amplitude abnormalities in the scalp far-field N18 of SSEPs to median nerve stimulation in patients with midbrain-pontine lesion.

Various amplitude ratios were measured in 20 normal controls and 36 patients with midbrain-pontine, thalamic or putaminal lesions in order to evaluate the amplitude abnormalities in scalp far-field N18 following median nerve stimulation. A study of normal controls showed that the distributions of P9/N18, P14/N18 and N18/P14 + N18 resembled a gaussian distribution and could be used as criteria for determining the decrease in N18 amplitude in each patient. There was a decrease in N18 amplitude, or the absence of N18, in patients with midbrain-pontine lesions, but not in those with thalamic or putaminal lesions. Nine amplitude ratios (P11/P9, P14/P9, N18/P9, P9/P11, P9/P14, P9/N18, N18/P14, P14/N18 and N18/P14 + N18) were compared statistically for normal controls and 3 groups of patients based on non-parametric, Wilcoxon's non-pairs and signed-rank tests. A decrease in N18 amplitude in midbrain-pontine lesion was shown by significant changes in N18/P9, P9/N18, N18/P14, P14/N18 and N18/P14 + N18, no amplitude decreases in P11 and P14 being found from the amplitude ratios of P11/P9, P9/P11, P14/P9 and P9/P14. No significant changes were seen in any of the 9 amplitude ratios when the normal controls and patients with thalamic and putaminal lesions were compared. The amplitude ratios of N18 can be used to detect a decrease in N18 amplitude in patients with midbrain-pontine lesions. The data obtained support the hypothesis that N18 originates in the midbrain-pontine region and that neither the thalamus nor thalamocortical radiation make major contributions to the formation of the N18 peak.

Adult↗