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Biomedical subjects

Y Maegaki

Publications and source records attributed to Y Maegaki.

At least 19 recordsLinked to original sources
PubMed2006

Diffusion MRI abnormalities after prolonged febrile seizures with encephalopathy.

BACKGROUND: Patients with encephalopathy heralded by a prolonged seizure as the initial symptom often have abnormal subcortical white matter on diffusion-weighted MRI (DWI). OBJECTIVE: To determine if these patients share other common features. METHODS: Patients with encephalopathy heralded by a prolonged seizure and followed by the identification of abnormal subcortical white matter on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed. RESULTS: Seventeen patients were identified, ages 10 months to 4 years. All had a prolonged febrile seizure (longer than 1 hour in 12 patients) as their initial symptom. Subsequent seizures, most often in clusters of complex partial seizures, were seen 4 to 6 days after the initial seizure in 16 patients. Outcome ranged from almost normal to severe mental retardation. MRI performed within 2 days of presentation showed no abnormality. Subcortical white matter lesions were observed on DWI between 3 and 9 days in all 17 patients. T2-weighted images showed linear high intensity of subcortical U fibers in 13 patients. The lesions were predominantly frontal or frontoparietal in location with sparing of the perirolandic region. The diffusion abnormality disappeared between days 9 and 25, and cerebral atrophy was detected later than 2 weeks. Three patients having only frontal lesions had relatively good clinical outcome. CONCLUSIONS: Although the pathophysiologic mechanism remains unknown, these patients seem to have a distinctive encephalopathy syndrome. MRI is helpful in establishing the diagnosis of this encephalopathy.

Atrophy↗
PubMed2006

Biphasic clinical course and early white matter abnormalities may be indicators of neurological sequelae after status epilepticus in children.

Clinical course and serial neuroimaging findings are not fully described in children who have had neurological sequelae following status epilepticus. We found four patients who had neurological sequelae out of 42 children with status epilepticus in 2004. MRI studies were reviewed with specific attention to diffusion-weighted images (DWI) and the apparent diffusion coefficient (ADC). Proinflammatory cytokines, including tumor necrosis factor-alpha and interleukin-6, were measured in the cerebrospinal fluid (CSF) (3 patients). The clinical course showed biphasic; initial status epilepticus and neurological exacerbation along with seizure recurrence four to five days after onset. Within three days after initial status epilepticus, CT (all patients) and MRI (2 patients) did not show any abnormalities. From four to ten days after onset, MRI demonstrated diffuse hyperintensity in the cerebral white matter on DWI and hypointensity on ADC maps in all patients. Diffuse brain atrophy progressed thereafter. Tumor necrosis factor-alpha or interleukin-6 was elevated in all patients. A biphasic clinical course may be a specific feature for neurological sequelae. The preferential white matter involvement on MRI and elevated CSF cytokines indicate that glial dysfunction may play an important role in the pathophysiology of status epilepticus-associated cerebral damage.

Brain Mapping↗
PubMed2005

Risk factors for fatality and neurological sequelae after status epilepticus in children.

Using multivariate regression analysis, we examined risk factors for fatality and neurological sequelae after status epilepticus (SE) in children. Possible risk factors included sex, age at onset, the cause of SE, pyrexia, asthmatic attack during SE, past history of seizure, predisposing neurological abnormality, seizure duration, type of seizure, and medication with theophylline. Consecutive patients with SE, aged 1 month to 18 years, who were referred to Tottori University Hospital from 1984 to 2002 were reviewed. Of the 234 patients enrolled, 45 patients (19.2 %) showed poor outcomes, namely early death in 9 and neurological sequela in 36. Acute neurological insult and progressive neurological disease as the cause of SE were very significantly related to poor outcome (OR = 33.68, p = 0.000). We excluded 21 patients with the etiology of acute neurological insult and progressive neurological disease and then reanalyzed risk factors in the remaining 213 patients. Twenty-nine patients (13.6 %) showed poor outcome, namely early death in 6 and neurological sequela in 23. Seizure duration of more than 2 hours (OR = 12.73, p = 0.000) and moderate to severe asthmatic attack (OR = 31.61, p = 0.010) were associated with poor outcome. These results indicate that long-lasting seizure activity and asthmatic attack can exacerbate SE-associated brain injury.

Adolescent↗
PubMed2003

Frontal N30 of median nerve SSEPs for evaluation of movement disorders with destructive basal ganglia deficits.

This study was performed to show the usefulness of N30 and N20 of median nerve SSEPs for evaluating the pathogenesis of central nervous system movement disorders. The subjects were 14 patients, consisting of 7 patients with an extrapyramidal lesion, 3 patients with suspicion of hypoxic-ischemic cerebral injury before birth period (H-I group), 3 patients with kernicterus during the neonatal period (kernicterus group), and 1 patient having Wilson's disease. Seven patients had spastic hemiplegia. Patients with athetotic CP had the ability to handle an electric wheelchair alone, and those with spastic hemiplegia could walk alone. Thirty control subjects were included in this study for clinical investigation. The characteristic finding of a predominant absence or amplitude reduction of frontal N30 compared with that of parietal N20 (4 and 1, respectively, out of 6 examinations) was obtained in athetotic CP patients of the H-I group. The predominant absence of N30 compared with N20 did not appear in the kernicterus group, hemiplegic patients or a patient with Wilson's disease. Therefore, frontal N30 might sensitively reflect destructive damage in the frontal basal ganglia in children.

Adolescent↗
PubMed2003

Vertebral artery dissection in an infant: ultrastructural aberrations in connective tissue components.

We report on a 14-month-old boy who had acute multiple infarcts in the posterior circulation due to an extremely early onset of spontaneous vertebral artery dissection. Despite the absence of clinical signs of connective tissue disorders, an ultrastructural change of collagen fibrils and elastic fibers indicated connective tissue abnormalities. Arterial dissection should be considered as a cause of stroke during infancy.

Elastic Tissue↗
PubMed2001

[Mitochondrial DNA T to G mutation 8993 in Leigh encephalopathy and organic aciduria].

We report a 10-month-old female infant with Leigh encephalopathy caused by a T to G mutation at nucleotide 8993 of mitochondrial DNA. Initial manifestations were diarrhea and pyrexia, followed by disturbance of consciousness. Blood chemistry showed lactic acidosis, and cranial T2 weighted magnetic resonance imaging demonstrated symmetric high-intensity areas in the basal ganglia, consistent with Leigh encephalopathy. Analysis of urinary organic acids revealed a increase of alpha-ketoglutamate. Derivatives of branched chain amino acids, which accumulate in maple syrup disease, were also increased. Lipoamide dehydrogenase (E3) deficiency was initially suspected; however, normal activity of pyruvate dehydrogenase complex excluded the diagnosis. The organic aciduria disappeared after two weeks. The CNS lesions in our case were observed more prominently in the floor of the bilateral frontal lobes than in the globus pallidus and putamen. In this case, mitochondrial DNA mutation may have caused organic aciduria and the atypical imaging findings.

DNA, Mitochondrial↗
PubMed2000

Somatosensory evoked high-frequency oscillations recorded directly from the human cerebral cortex.

OBJECTIVE: To elucidate the generator sources of high-frequency oscillations of somatosensory evoked potentials (SEPs), we recorded somatosensory evoked high-frequency oscillations directly from the human cerebral cortex. SUBJECTS AND METHODS: Seven patients, 6 with intractable partial epilepsy and one with a brain tumor, were studied. With chronically implanted subdural electrodes, we recorded SEPs to median nerve stimulation in all patients, and also recorded SEPs to lip and posterior tibial nerve stimulation in one. High-frequency oscillations were recorded using a restricted bandpass filter (500-2000 Hz). RESULTS: For the median nerve oscillations, all oscillation potentials were maximum at the electrodes closest to the primary hand sensorimotor area. Most oscillations were distributed similar to or more diffusely than P20/N20. Some later oscillations after the peak of P20 or N20 were present in a very restricted cortical area similar to P25. We investigated the phase change of each oscillation potential around the central sulcus. One-third of the oscillations showed phase reversal around the central sulcus, while later oscillations elicited in a restricted cortical area did not. High-frequency oscillations to posterior tibial nerve and lip stimulation were also maximum in the sensorimotor areas. Most of the lip oscillations showed phase reversal around the central sulcus, but most of the posterior tibial nerve oscillations did not. CONCLUSION: High-frequency oscillations are generated near the primary sensorimotor area. There are at least two different generator mechanisms for the median nerve high-frequency oscillations. We suspect that most oscillations are derived from the terminal segments of thalamocortical radiations or from the primary sensorimotor cortex close to the generator of P20/N20, and some later oscillations from the superficial cortex close to the generator of P25.

Brain Neoplasms↗
PubMed2000

Unilateral involuntary movement associated with streptococcal infection: neurophysiological investigation.

Two boys developed rhythmic involuntary movements in the extremities on one side of the body after febrile illness. They also showed behavioral disturbances. In both patients, serum antistreptolysin-O and antistreptokinase titers were elevated in acute illness and decreased a few months later. One patient showed tremorous movement, and the other choreiform movement. In the former, a surface EMG showed short-duration (30 to 60 ms), highly frequent (6 to 8 Hz) and synchronous discharges of multiple muscles, including the antagonists, suggesting myoclonic jerk. In the latter, a surface EMG showed long-duration (0.5 to 1 s), repetitive (about 0.5 Hz) and synchronous or asynchronous discharges of the antagonists, suggesting choreoathetosis. In both patients, giant somatosensory evoked potentials and high-voltage slow EEG activities were observed predominantly in the hemisphere contralateral to the involuntary movement. In the myoclonic patient, long-latency EMG responses were enhanced and cortical potentials preceding the myoclonus were present by jerk-locked back averaging technique. The present data suggest that unilateral rhythmic involuntary movements occur secondary to streptococcal infection. The pathophysiology of the involuntary movements may be associated with sensorimotor cortex hyperexcitability.

Child↗
PubMed1999

Normalization of creatine kinase level during arthritis in a patient with Becker muscular dystrophy.

A patient with Becker muscular dystrophy had transient arthritis. During the active illness his serum creatine kinase (CK) level normalized and serum levels of soluble interleukin 2 (IL-2) receptor, IL-6, IL-1 receptor antagonist, and soluble tumor necrosis factor receptor 2 were elevated. CK increased to his usual levels after arthritis remission whereas the levels of inflammatory cytokines and their inhibitors decreased.

Arthritis↗
PubMed1999

Epileptic negative myoclonus induced by carbamazepine in a child with BECTS. Benign childhood epilepsy with centrotemporal spikes.

A 7-year-old female with benign childhood epilepsy with centrotemporal spikes developed epileptic negative myoclonus (ENM) seizures during carbamazepine (CBZ) treatment. She had experienced nocturnal partial seizures since 5 years of age. Interictal electroencephalography demonstrated typical rolandic discharges. Valproate was first initiated at 6 years of age, but the seizures were uncontrollable. Carbamazepine was added and valproate withdrawn. The frequency of partial seizures did not decrease. Moreover, she had brief episodes of tone loss in each or both arms and eye blinking several weeks after CBZ introduction. Unilateral loss of arm tone corresponded to spike-and-wave discharges in the contralateral centrotemporal region, and a loss of tone in arms was associated with bilateral synchronous discharges. Eye blinking was also related to bilateral synchronous discharges and classified as a myoclonic seizure. The ENM and myoclonic seizures disappeared soon after CBZ withdrawal. Therefore the authors concluded that CBZ induced the ENM and myoclonic seizures in this patient. CBZ sometimes induces generalized seizures in the treatment of partial epilepsy and generalized epilepsy. CBZ-induced ENM seizures should be considered when a brief lapse of tone appears during CBZ treatment.

Anticonvulsants↗
PubMed1999

Central motor reorganization in cerebral palsy patients with bilateral cerebral lesions.

Transcranial magnetic stimulation (TMS) has been used to describe cortical plasticity after unilateral cerebral lesions. The objective of this study was to find out whether cortical plasticity occurs after bilateral cerebral lesions. We investigated central motor reorganization for the arm and leg muscles in cerebral palsy (CP) patients with bilateral cerebral lesions using TMS. Seventeen patients (12 with spastic diplegia, 1 with spastic hemiplegia, and 4 with athetoid CP) and 10 normal subjects, were studied. On CT/MRI, bilateral periventricular leukomalacia was observed in all spastic patients with preterm birth. In two normal subjects, motor responses were induced in the ipsilateral tibialis anterior, but no responses were induced in any normal subject in the ipsilateral abductor pollicis brevis (APB) or biceps brachii (BB). Ipsilateral responses were more common among CP patients, especially in TMS of the less damaged hemisphere in patients with marked asymmetries in brain damage: in 3 abductor pollicis brevis, in 6 BBs, and in 15 tibialis anteriors. The cortical mapping of the sites of highest excitability demonstrated that the abductor pollicis brevis and BB sites in CP patients were nearly identical to those of the normal subjects. In patients with spastic CP born prematurely, a significant lateral shift was found for the excitability sites for the tibialis anterior. No similar lateral shift was observed in the other CP patients. These findings suggest that ipsilateral motor pathways are reinforced in both spastic and athetoid CP patients, and that a lateral shift of the motor cortical area for the leg muscle may occur in spastic CP patients with preterm birth.

Adolescent↗
PubMed1999

Excitability recovery curves of blink reflexes in patients with athetotic cerebral palsy.

We evaluated the brainstem function or its excitability by the blink reflex evoked with the electrical stimulation to the supraorbital nerve in 10 patients with athetotic cerebral palsy compared with 10 normal subjects and 7 spastic type patients. There were no differences in stimulus intensity, latency of R1 and R2 components, and duration and area of EMG activity of the R2 component of the blink reflex elicited by single stimulation among the two patients' groups and normal subjects. R1 recovery cycle to paired stimuli in the athetotic group showed a facilitation of the test responses by the conditioning stimuli at 100 and 200 ms intervals, but were not significantly different from those in the normals. On the other hand, the R2 recovery curve in the athetotic group showed a significant hyperexcitability at all intervals from 100 to 600 ms compared to the normals. Our results from the R2 hyperexcitable recovery to paired stimuli are indicative of increased brainstem interneuronal excitability in athetotic patients and similar to the results reported in the disorders of the basal ganglia, i.e. Parkinson's disease, dystonia and blepharospasm. We suggest that this hyperexcitability might be caused by abnormal input possibly from the basal ganglia upon these brainstem interneurons.

Adolescent↗
PubMed1998

Successful treatment of progressive myoclonus epilepsy with TRH.

Thyrotropin-releasing hormone (TRH) is sometimes used for the treatment of neurologic disorders such as intractable epilepsy and spinocerebellar degeneration. A 14-year-old girl with progressive myoclonus epilepsy was treated with intravenous TRH for 12 months. Clinical symptoms, such as cortical myoclonus and cerebellar signs, were improved, and P25-N33 amplitudes of somatosensory-evoked potentials decreased after TRH therapy. P100 amplitudes on flash visual-evoked potentials and photosensitivity on electroencephalograms also decreased but only temporarily. Changes in neurophysiologic findings after TRH therapy indicate that TRH inhibits hyperexcitability in the sensorimotor cortex and the visual cortex. Therefore, intravenous TRH therapy is recommended as an alternative therapy in the treatment of progressive myoclonus epilepsy.

Adolescent↗
PubMed1998

Neuroleptic malignant syndrome and methylphenidate.

A 1-year-old female presented with neuroleptic malignant syndrome probably caused by methylphenidate. She had defects in the supratentorial brain including the basal ganglia and the striatum (multicystic encephalomalacia) due to severe perinatal hypoxic-ischemic encephalopathy, which was considered to be a possible predisposing factor causing neuroleptic malignant syndrome. A dopaminergic blockade mechanism generally is accepted as the pathogenesis of this syndrome. However, methylphenidate is a dopamine agonist via the inhibition of uptake of dopamine, and therefore dopaminergic systems in the brainstem (mainly the midbrain) and the spinal cord were unlikely to participate in the onset of this syndrome. A relative gamma-aminobutyric acid-ergic deficiency might occur because diazepam, a gamma-aminobutyric acid-mimetic agent, was strikingly effective. This is the first reported patient with neuroleptic malignant syndrome probably caused by methylphenidate.

Brain↗