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Biomedical subjects

Y Kakisu

Publications and source records attributed to Y Kakisu.

15 recordsLinked to original sources
PubMed1991

Pattern visually evoked cortical potential and magnetic resonance imaging in optic neuritis.

We studied the extent of optic nerve lesion with magnetic resonance imaging (MRI) in 24 patients with optic neuritis and compared it with visually evoked cortical potentials (VECP). Patients were divided into acute and chronic stage groups according to the duration of the disease from its onset. The short TI inversion recovery (STIR) mode of the MRI was selected for study. In the acute stage group, abnormally high signals of optic nerve on MRI were demonstrated in 11 of 12 eyes, and the amplitude and peak latency of pattern VECP were unrelated to the extent of the optic nerve lesion visualized by MRI. Conversely, in the chronic stage group, the abnormal MRI findings were exhibited in 19 of 23 eyes, and the relationship between the measurements was statistically significant. This difference in the optic nerve lesion observed by MRI between the acute stage and the chronic stage of optic neuritis may indicate pathophysiologic differences in their origins.

Acute Disease↗
PubMed1990

[Magnetic resonance imaging in optic nerve lesions with multiple sclerosis].

Magnetic resonance imaging (MRI) of the optic nerves was performed in 10 patients with multiple sclerosis (MS) using short inversion time inversion recovery (STIR) pulse sequences, and the results were compared with the visual evoked potentials (VEP). The 10 patients had optic neuritis in the chronic or remitting phase together with additional symptoms or signs allowing a diagnosis of clinically definite or probable MS. Sixteen optic nerves were clinically affected and 4 were unaffected. MRI was performed using a 0.5 tesla superconducting unit, and multiple continuous 5 mm coronal and axial STIR images were obtained. A lesion was judged to be present if a focal or diffuse area of increased signal intensity was detected in the optic nerve. In VEP, a delay in peak latency or no P 100 component was judged to be abnormal. With regard to the clinically affected optic nerves, MRI revealed a region of increased signal intensity in 14/16 (88%) and the VEP was abnormal in 16/16 (100%). In the clinically unaffected optic nerves, MRI revealed an increased signal intensity in 2/4 (50%). One of these nerves had an abnormal VEP and the other had a VEP latency at the upper limit of normal. The VEP was abnormal in 1/4 (25%). In the clinically affected optic nerves, the degree of loss of visual acuity was not associated with the longitudinal extent of the lesions shown by MRI. The mean length was 17.5 mm in optic nerves with a slight disturbance of visual acuity and 15.0 mm in nerves with severe visual loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Flash electroretinograms and pattern visually evoked cortical potentials in Behçet's disease.

Behçet's disease with posterior uveitis was studied in 12 cases by flash electroretinography (FERG) and pattern visually evoked cortical potential (PVECP). Disappearance of oscillatory potentials was the initial change noted in FERG. Subnormal FERG and a delay in peak latency of the P100 component of PVECP were observed in patients with poor visual acuity and long-standing Behçet's disease. Amplitudes of PVECP were significantly decreased in these patients. It was suggested that FERG together with PVECP were good indicators for monitoring posterior segment changes and visual prognosis in Behçet's disease.

Adult↗
PubMed1990

[MRI lesions of the optic nerves in optic neuritis].

Magnetic resonance imaging (MRI) was performed in 14 patients with optic neuritis. Three patients suffered from multiple sclerosis but the etiologies of the remaining 11 cases could not be identified. They were bilateral in 6, and unilateral in 8. The MR images were compared with the symptomatic lesions of optic neuritis and pattern reversal VECP. The STIR mode (short time inversion recovery), was employed for the MRI in the orbit and T2-weighted mode in the brain. In 11 eyes with hyperemia of the optic disc, 7 eyes showed a high signal in the optic nerve with the MRI, and 9 eyes showed an abnormal pattern VECP. Seven eyes with normal disc and two eyes with a pale disc showed a high signal in the optic nerve with MRI, those 9 eyes had abnormal pattern VECP. The high signal in the optic nerve was not related to visual acuity or visual field abnormalities of patients. However, the degree of the high signal of the optic nerve lesion in MRI was associated with the clinical course and prognosis of the optic neuritis. The degree of the high signal of the optic nerve lesion decreased with the recovery of visual acuity in optic neuritis.

Adolescent↗
PubMed1989

[Evaluation of color pattern VECP in deutan].

Using an Equi-Energy-Color Pattern Generator, color vision experiments were performed on nine normal subjects, six cases of deuteranomalies, and six cases of deuteranopias with the use of Visually-evoked cortical potentials (VECPs). Checkerboard patterns, consisting of the pairing of any chosen one of three colors with its complementary color in terms of equal energy, were used. The pairing of a neutral color with its complementary color of protan, deutan and tritan were displayed on a color TV monitor. We measured the amplitude and latency of P100 component of VECPs. Cases of deuteranopia showed significantly smaller amplitude and longer latency of P100 component in protan and deutan responses than did normal subjects. Cases of deuteramomaly showed significantly smaller amplitude and longer latency of P100 component in only protan response compared to those of normal subjects. It was possible to objectively detect the deutan in color pattern VECPs.

Adolescent↗
PubMed1989

[Magnetic resonance imaging (MRI) in the diagnosis of optic neuritis and neuropathy].

Magnetic resonance imaging (MRI) was performed in thirty patients who had been suffering from optic neuritis (ON). Twenty-one cases were caused by multiple sclerosis (MS) and in 9 cases the causes been defined. In MRI, abnormalities were found in 17 out of 21 MS cases in several places such as near the ventricles, mid-brain, spinal cord etc. Increased signals from the optic chiasm to optic radiation were found in 5 cases. However, abnormal MRI findings did not always correspond to Goldmann visual field defects. In 3 out of 9 cases of ON with unknown causes, high signals in the white matter of the brain were found, and it was suggested that those may develop to MS. MRI was, thus, proved to be very useful for the diagnosis of MS.

Adolescent↗
PubMed1987

Pattern electroretinogram and visual evoked cortical potential in ethambutol optic neuropathy.

Forty-one eyes in 21 cases of ethambutol optic neuropathy were investigated for the pattern visual evoked cortical potential (VECP) and the pattern electroretinogram (ERG). In 21 of the eyes the disappearance VECP responses were not detectable. In the other 20 eyes the peak latency and amplitude of the disappearance VECP were delayed and decreased significantly compared with normal eyes. The recovery of the peak latency of the disappearance VECP in ethambutol optic neuropathy was faster than that of the amplitude. Twelve eyes in six patients were studied by pattern reversal ERG. Though the mean peak latency of the pattern ERG was within normal limits, the mean amplitude was decreased significantly. Our investigations indicated that ethambutol optic neuropathy disturbed not only the optic nerve but also the retina.

Adult↗
PubMed1987

Check size and defocusing effects on equipotential maps of pattern-evoked electroretinograms.

The spatial distribution of the pattern-evoked potentials on the face was studied with a simultaneous 16-channel recording system. The potentials had the first positive component at a peak latency of approximately 55 msec, which was much earlier than the latency of the response picked up from the scalp. The maximal potential value in the maps was found at the region around the stimulated eye. This configuration of the equipotential map was not influenced by defocusing and check size of the pattern, but was altered by changing the contrast. Our results of equipotential maps constructed at around 55 msec after pattern reversal proved that the responses recorded in the facial region originated in the retina and were not a reflection of the scalp potentials.

Electrodes↗
PubMed1986

Clinical application of the pattern electroretinogram with lid skin electrode.

Pattern evoked potentials were recorded simultaneously with an electrode placed on the skin of the lower eyelid, gold foil electrodes hooked on the right and left eyelids, and a skin electrode at Oz in normal subjects and in patients with optic nerve and macular diseases. Peak latencies and amplitudes of the pattern electroretinogram (PERG) were compared between the two electrodes. In both records, the peak latency showed no difference at 56.7 +/- 2.9 ms (mean +/- S.D.), while the amplitude of the PERG with the lid skin electrode was at 1.2 +/- 0.3 microV, approximately one-third of that obtained with the gold foil electrode. Although the skin electrode did not always record responses as well as the gold foil, its advantages recommend its use in clinical cases.

Adolescent↗
PubMed1986

Pattern disappearance visually evoked cortical potential in the diseases of visual pathway.

Visually evoked cortical potentials in response to pattern-appearance, -disappearance, and -reversal stimuli were studied in normal subjects and in patients suffering from optic neuritis. It was found in normal subjects that pattern disappearance VECPs were as reliable as the pattern reversal ones. On the other hand, the appearance response showed interindividual differences which made its evaluation rather difficult. The same was true in the records of the patients. Both the mean peak latencies of the disappearance responses and those of the pattern reversal ones were prolonged significantly in optic neuritis, compared with those obtained from normal subjects. We concluded that the peak latencies of the disappearance response could be more confidently used than those of the appearance response for diagnosing optic neuritis.

Adult↗
PubMed1985

Pattern-evoked cortical potentials and nuclear magnetic resonance imaging in total and partial agenesis of the corpus callosum.

We have examined two cases of agenesis of the corpus callosum without any associated abnormalities. They were accidentally detected in X-ray-computed tomography. Total agenesis of the corpus callosum could be differentiated by nuclear magnetic resonance imaging from partial agenesis. They had moderately depressed stereopsis. Visually evoked cortical potentials to pattern stimuli showed abnormal findings in binocular viewing, and VECP equi-potential maps were similar to those of normal controls.

Adult↗
PubMed1985

Horizontal scalp distribution of steady-state pattern visual evoked cortical potentials in response to quadrant field stimulation.

Scalp profiles of steady-state pattern visual evoked cortical potentials (VECPs) along the horizontal line at Pz (for upper field stimuli) and Oz (for lower field stimuli) were studied in 12 normal subjects by simultaneous five channel recordings from electrode positions 3 cm and 6 cm laterally on either side of, and at, Oz or Pz. Each electrode was referred to Fz or to the right earlobe. The amplitude and phase of the averaged VECPs (n = 20) were calculated by means of Fast Fourier Transform. With smaller check size the amplitude data verified that the scalp profile of the lower visual field peaked at the hemisphere contralateral to the quadrant stimulated. With larger check size the peak shifted to the ipsilateral hemisphere. With upper field quadrant stimulation, position of the reference electrode at Fz was found to be unsuitable since the VECP amplitude at the level of Pz was greatly reduced. Phase and apparent latency also varied with the field stimulated as well as with the position of electrodes.

Cerebral Cortex↗