Biomedical subjects

H Mikawa

Publications and source records attributed to H Mikawa.

At least 289 records · Page 16Linked to original sources

PubMedDate not supplied

Improvement in auditory brainstem response of hyperbilirubinemic infants after exchange transfusions.

Auditory brainstem response tests were performed before and after exchange transfusions in 6 infants with hyperbilirubinemia. The latencies of Waves I, II, and V decreased significantly after the exchange transfusions (p less than .05, p less than .02, p less than .005, respectively) and I-V interpeak latencies also were decreased (p less than .01). However, the latencies of Wave I both before and after exchange transfusions were within normal limits. The central conduction times were prolonged by hyperbilirubinemia, but the peripheral auditory pathways were not impaired. These auditory brainstem response abnormalities became normal with decreased serum bilirubin concentration. Neonatal hyperbilirubinemia is associated with transient brainstem lesions which are reversible in the early stages. Auditory brainstem response testing is an effective and readily available technique for detecting bilirubin neurotoxicity.

Brain Stem↗

PubMedDate not supplied

Maturation of somatosensory evoked potentials upon posterior tibial nerve stimulation.

Somatosensory evoked potentials produced in response to posterior tibial nerve stimulation were studied in 42 normal infants and children, ages 4 months to 16 years. The maturation of afferent conduction from the lower limb was evaluated for the peripheral nerve, spinal cord, and central nervous system. Although the maturation of conduction in the peripheral nerve (from the ankle to the popliteal fossa and from the popliteal fossa to L3) was complete by 6 years of age, afferent conduction in the spinal cord (from L3 to C7) was not complete until 12 years of age or older. Spinal evoked potentials investigated in the thoracolumbar area revealed a phase-reversed potential located between the lower thoracic spine and upper lumbar spine in over 80% of patients. Reciprocal velocities for the major cortical positive potential P1 (corresponding to P37 in adults) and its onset, N1, steadily decreased with age and leveled off at greater than 12 years of age and by 12 years of age, respectively. The propagation velocity from L3 to the cerebral cortex also increased steadily with age, leveling off at greater than 12 years of age. Accordingly, the maturation of afferent conduction in the central nervous system was not complete until after 12 years of age.

Adolescent↗

PubMedDate not supplied

Nontraumatic spinal intramedullary hemorrhage in an infant.

After an uncomplicated pregnancy and delivery, this female child suddenly became quadriplegic on the fifth day of life. She gradually regained movement in her upper extremities. At 2 months of age, she exhibited paraplegia with exaggerated deep tendon reflexes in the lower extremities. Babinski reflex was present bilaterally and sensory disturbances below the trunk were suspected. Somatosensory evoked potentials after median and ulnar nerve stimulation revealed preserved conduction from the upper extremities through the cervical spinal cord to the cortex. Somatosensory evoked potentials after posterior tibial nerve stimulation suggested disturbed conduction in the upper thoracic spinal cord. Magnetic resonance imaging disclosed a hypodense area in the thoracic cord between T1 and T4 on both the T1-weighted and gradient echo images consonant with an old hematoma cavity. Digital subtraction angiography failed to demonstrate any vascular malformation.

Evoked Potentials, Somatosensory↗

PubMedDate not supplied

Sequential 123I-IMP-SPECT in acute infantile hemiplegia.

Sequential 123I-N-isopropyl-p-iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) was performed in 2 patients with acute infantile hemiplegia. In both patients, low uptake of IMP was detected in the targeted abnormal hemisphere. The 123I-IMP-SPECT findings indicative of a pathologic condition persisted even when the clinical findings and electroencephalographic abnormalities improved. Because of its sensitivity, noninvasiveness, and accurate reflection of the cerebral blood flow distribution, 123I-IMP-SPECT is useful in the examination of acute infantile hemiplegia and in the evaluation of prognosis.

Acute Disease↗

PubMedDate not supplied

MRI in infantile neuroaxonal dystrophy.

A 6-year-old boy with the typical clinical features of infantile neuroaxonal dystrophy was examined with magnetic resonance imaging. The findings suggested increased metal deposition in the globus pallidus. Magnetic resonance imaging findings of Hallervorden-Spatz syndrome and infantile neuroaxonal dystrophy are similar, suggesting that these two disease entities overlap. Magnetic resonance imaging findings, as well as relevant clinical features, may be useful in the diagnosis and classification of infantile neuroaxonal dystrophy.

Basal Ganglia Diseases↗

PubMedDate not supplied

ACTH therapy in infantile spasms: relationship between dose of ACTH and initial effect or long-term prognosis.

The relationship between the dose of ACTH and the initial effect was investigated in 41 children with infantile spasms. More than 0.015 mg (0.6 IU)/kg/day of ACTH was needed for a good initial response of seizures and electroencephalographic abnormalities. The relationship between the dose of ACTH and long-term prognosis was investigated in 29 patients. There was no relationship between the daily or total ACTH dosage, provided the dose was greater than 0.015 mg (0.6 IU)/kg/day, and the outcome of seizures and electroencephalographic abnormalities; however, ACTH 0.04-0.06 mg (1.6-2.4 IU)/kg/day and a total ACTH dose of 1.1-1.5 mg (44-60 IU)/kg resulted in better mental development than smaller doses of ACTH. Side effects of ACTH increased with dosage. Too small or too large a dose of ACTH does not lead to better mental development. The proper dose of ACTH should be used with careful attention to potential side effects.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

CT, MRI, and autopsy findings in brain of a patient with MELAS.

Brain autopsy findings in a 14-year-old patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes were compared with those of computed tomography (CT) and magnetic resonance imaging (MRI). Pathologic examinations revealed extensive laminar necrosis bordered by gliotic tissues throughout the cerebral cortices. Moderate losses of myelin and fibrous gliosis were also observed in the subcortical and deep white matter. These lesions were demonstrated as low-density areas on CT and as high-signal areas on T2-weighted MRI. MRI revealed the lesions more distinctively and precisely than CT. Neither CT nor MRI could reveal abnormalities in the basal ganglia, including vascular proliferation and calcium deposits in the blood vessels.

Acidosis, Lactic↗

PubMedDate not supplied

Vitamin B6 and valproic acid in treatment of infantile spasms.

Twenty patients with infantile spasms were treated with high doses of vitamin b6, valproic acid, or both. Three of 13 patients (23%) treated initially with high doses of vitamin B6 demonstrated a definite reduction in seizures; 2 patients had no improvement on electroencephalography. Vitamin B6 therapy alone was continued in a single patient (8%) who remained seizure-free during the 15-month follow-up period. Initial treatment with vitamin B6 and valproic acid improved the electroencephalogram significantly more (P less than 0.05) than initial vitamin B6 treatment alone. The group which had valproic acid added to vitamin B6 therapy had significantly fewer seizures (P less than 0.05) and better electroencephalograms (P less than 0.01) than did the group treated initially with vitamin B6 alone. There were no significant differences among the group treated initially with vitamin B6, the group treated initially with valproic acid, and the group in which valproic acid was substituted for vitamin B6. ACTH was more effective in abolishing seizures than was valproic acid or vitamin B6 and valproic acid. ACTH had an excellent effect on seizures in 86% of patients who did not respond well to vitamin B6, valproic acid, or both; however, many of these patients had later recurrence of infantile spasms. The combination of vitamin B6 and valproic acid is effective and safe in the treatment of infantile spasms.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

Ictal 99mTc-HMPAO SPECT in alternating hemiplegia.

99mTc-hexamethylpropylenamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) was performed in a patient with alternating hemiplegia during 2 episodes of the disease. The regional cerebral blood flow patterns correlated with the clinical manifestations during both episodes. Hyperperfusion of the contralateral hemisphere was suggested by asymmetric 99mTc-HMPAO uptake, whereas symmetric 123I-N-isopropyl-p-iodoamphetamine uptake was detected during the interictal period. The results suggested that alternating hemiplegia in infants represents an atypical manifestation of epilepsy, despite the lack of paroxysmal electroencephalographic abnormalities during the episodes. 99mTc-HMPAO SPECT appears to be a useful method for detecting transient regional cerebral blood flow alterations during paroxysmal events because the tracer is rapidly available for emergencies and retains a fixed distribution for 5-8 hours, sufficient time to allow for SPECT acquisition.

Cerebrovascular Circulation↗

PubMedDate not supplied

Early diagnosis of leukoencephalopathy of acute lymphocytic leukemia by MRI.

Using repeated computed tomographic and magnetic resonance imaging scans, we examined 8 patients with acute lymphocytic leukemia during remission induction therapy between 1988 and 1989. In 3 patients, leukoencephalopathy was diagnosed by T2-weighted magnetic resonance imaging. In 1 patient, leukoencephalopathy was progressive and irreversible brain damage and mental retardation persisted. In the other 2 patients, hyperintense lesions in the periventricular white matter were transient and no neurologic sequelae ensued. Magnetic resonance imaging was more useful than computed tomography in the early diagnosis and management of these acute lymphocytic leukemia patients with leukoencephalopathy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

Chronic mumps virus encephalitis.

A previously well 4-year-old girl developed frequent seizures and mental deterioration after mumps parotitis. Direct IgG antibody capture enzyme-linked immunosorbent assay revealed a high titer of anti-mumps viral antibodies in the cerebrospinal fluid. Chronic mumps encephalitis was diagnosed. Her mental state and seizures improved markedly with inosine pranobex therapy.

Antibodies, Viral↗

PubMedDate not supplied

Somatosensory evoked potentials after posterior tibial nerve stimulation in focal spinal cord diseases.

We investigated the somatosensory evoked potentials (SEPs) produced by posterior tibial nerve (PTN) stimulation in 8 infants and children with focal spinal cord disorders. The spinal responses of the PTN-SEPs were considered to assist in the localization of spinal lesions because their abnormalities were consistent with the neurologic and/or radiologic findings in all 6 examinations that revealed abnormal spinal SEPs. The cortical responses correlated significantly with proprioception in the lower limbs because proprioception was only disturbed when the cortical SEPs were absent (3 examinations). When both the spinal and cortical responses were abnormal, the spinal lesion probably involved the dorsal column so extensively that it completely interrupted the afferent impulses. In contrast, when SEP studies demonstrated abnormal spinal and normal cortical SEPs (3 examinations), the dorsal column involvement was probably less severe; therefore, both the spinal and cortical responses provided useful information regarding afferent conduction in the dorsal column. PTN-SEPs appear to have the potential to be of value in the diagnosis of focal spinal disease, especially in infants and young children who cannot cooperate with detailed neurologic examinations.

Child↗

PubMedDate not supplied

Ipsilateral atrophy in children with hemispheric cerebral tumors: CT findings.

The CT findings of 19 children under 16 years of age with primary brain tumors in the cerebral hemisphere were investigated with special reference to the existence of cerebral hemiatrophy ipsilateral to the side of the tumor. "Ipsilateral cerebral hemiatrophy" was observed in four of 19 cases (21%). These included two cases with germinoma in the basal ganglia and two with low-grade astrocytoma in the frontal and occipital cortex. This peculiar CT finding was not specific to the location or histology of the tumor. The four cases were characterized by slow progression, which contrasted with the rapid progression of tumors shown in seven cases with a mass effect on CT.

Adolescent↗

PubMedDate not supplied

MR imaging of a group I case of Hallervorden-Spatz disease.

Magnetic resonance (MR) imaging of a case of Hallervorden-Spatz disease (HSD) using a 1.5 T system is described. The patient showed progressive spastic diplegia with equinovarus deformity of the feet, dystonic postural movements, dysarthria, dysphagia, mental deterioration, optic nerve atrophy, and peripheral neuropathy. These clinical features were compatible with HSD. Symmetrical, decreased signal intensity was seen on both proton density weighted and T2-weighted spin echo images in the globus pallidus as well as in the substantia nigra (Group I). This MR finding suggests an increased iron deposition in these subcortical nuclei, which is characteristic of HSD. The characteristic MR imaging, together with the relevant clinical features, was considered to be useful for establishing the diagnosis of HSD.

Adult↗

PubMedDate not supplied

Neurotoxicity of vincristine after the osmotic opening of the blood-brain barrier.

The direct effect of intravascularly injected vincristine on the rat brain was investigated after the osmotic opening of the blood-brain barrier. This was opened unilaterally by injecting 2.5 ml of 1.4 molal mannitol solution into the right carotid artery through a cannula inserted in the external carotid artery in retrograde fashion. Vincristine (0.75 mg/kg) was then injected into either the carotid artery or into a vein. Animals, thus treated, developed left hemiparesis and choreo-athetoid head motion within several days. Microscopical analysis revealed 1 intracytoplasmic eosinophilic inclusions at an early period, 2 neuronal argyrophilic change and axonal thickening with spheroid formation at later times, and 3 glial mitotic arrest, a finding not reported in the previous studies with intrathecal injection of vincristine. Neuronal changes were usually confined to the selected area in the midbrain, whereas glial mitotic figures were seen in the hippocampus, midbrain and cerebellum. These changes are thought to be direct effects of the vincristine binding with cellular microtubules, including mitotic spindle tubules and neurotubules. The transient opening of the blood-brain barrier seems to be a useful technique for studying the experimental neurotoxicology of drugs to which the blood-brain barrier is impermeable.

Animals↗

PubMedDate not supplied

De novo reciprocal translocation t(6;14)(q27;q13.3) in a child with infantile spasms.

A boy with infantile spasms was found to have a balanced de novo translocation, 6q;14q. The karyotype was 46,XY,t(6;14)(q27;q13.3). He had mental retardation and microcephaly but no dysmorphic features. Whether or not there is a relationship between the translocation in our patient and his infantile spasms is unknown. If there is a connection, a gene or genes on chromosome 14 may be implicated in the seizure disorders that are common in patients with ring chromosome 14 syndrome or proximal partial trisomy 14 syndrome.

Chromosomes, Human, 13-15↗

PubMedDate not supplied

Immunoreactive leucine-enkephalin content in brains of epileptic E1 mice.

The immunoreactive leucine-enkephalin (IR Leu-E) content in the brains of epileptic E1 mice was determined. E1 mice are mutants from the dd strain of mice and are susceptible to convulsions. Seizures were elicited in E1 mice by repeated postural stimulations. As controls, ddY strain (nonconvulsive) mice and nonstimulated E1 mice (which had not developed convulsions) were used. IR Leu-E content was measured by radioimmuno-assay. Before the convulsion, the IR Leu-E content in the striatum of E1 mice was 60% of the content in the controls. In the hypothalamus, IR Leu-E levels were increased by 85% 45 min after a convulsion. IR Leu-E was also increased in the striatum (176% of preconvulsive state), cortex (121%), medulla oblongata + pons (132%), hypothalamus (180%), and midbrain (159%) 48 h after a convulsion.

Animals↗

PubMedDate not supplied

Carbamazepine therapy and long-term prognosis in epilepsy of childhood.

Sixty-seven of 90 patients (74% who had been treated with carbamazepine (CBZ) alone were seizure-free for greater than 3 years. The EEG of the patients given CBZ monotherapy was more often normal in those without neurologic abnormalities other than mental retardation or a genetic predisposition. The prognosis of patients with partial seizures secondarily generalized was poorer than that of the other patients. Patients without mental retardation more often had monotherapy CBZ. The lowest blood level of CBZ for maintenance was considered to be 4 micrograms/ml, although the therapeutic blood level was between 6 and 12 micrograms/ml. Most of the side effects were mild.

Adolescent↗