• Toxicological Research
• /
• v.17
• /
• pp.11-16
• /
• 2001

The development of the central nervous system is a continuous process during the embryonic and fetal periods. For a better understanding of congenital anomalies of central nervous system, three major events of normal development, i.e., neurulation (3 to 4 weeks), brain vesicle formation (4 to 7 weeks) and mantle formation (over 8 weeks) should be kept in mind. The first category of anomalies is neural tube defect. Neural tube defects encompass all the anomalies arise in completion of neurulation. The second category of central nervous system anomalies is disorders of brain vesicle formation. This is anomaly that applies for "the face predicts the brain". Holoprosencephaly covers a spectrum of anomalies of intracranial and midfacial development which result from incomplete development and septation of midline structures within the forebrain or prosencephalon. The last category of central nervous system malformation is disorders involving the process of mantle formation. In the human, neurons are generated in two bursts, the first from 8 to 10 weeks and next from 12 to 14 weeks. By 16 weeks, most of the neurons have been generated and have started their migration into the cortex. Mechanism of migration disorders are multifactorial. Abnormal migration into the cortex, abnormal neurons, faulty neural growth within the cortex, unstable pial-glial border, degeneration of neurons, neural death by exogenous factors are some of the proposed mechanism. Agyria-pachygyria are characterized by a four-layerd cortex. Polymicrogyria is gyri that are too numerous and too small, and is morphologically heterogeneous. Cortical dysplasia is characterized by the presence Q[ abnormal neurons and glia arranged abnormally in focal areas of the cerebral cortex. Neuroglial malformative lesions associated with medically intractable epilepsy are hamartia or hamartoma, focal cortical dysplasia and microdysgenesis.ysgenesis.

• Annals of Clinical Neurophysiology
• /
• v.13 no.1
• /
• pp.1-12
• /
• 2011

Transcranial magnetic stimulation (TMS) is a non-invasive tool used to study aspects of human brain physiology, including motor function and the pathophysiology of various brain disorders. A brief electric current passed through a magnetic coil produces a high-intensity magnetic field, which can excite or inhibit the cerebral cortex. Although various brain regions can be evaluated by TMS, most studies have focused on the motor cortex where motor evoked potentials (MEPs) are produced. Single-pulse and paired-pulse TMS can be used to measure the excitability of the motor cortex via various parameters, while repetitive TMS induces cortical plasticity via long-term potentiation or long-term depression-like mechanisms. Therefore, TMS is useful in the evaluation of physiological mechanisms of various neurological diseases, including movement disorders and epilepsy. In addition, it has diagnostic utility in spinal cord diseases, amyotrophic lateral sclerosis and demyelinating diseases. The therapeutic effects of repetitive TMS on stroke, Parkinson disease and focal hand dystonia are limited since the duration and clinical benefits seem to be temporary. New TMS techniques, which may improve clinical utility, are being developed to enhance clinical utilities in various neurological diseases.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.7
• /
• pp.861-867
• /
• 2000

Purpose : Neuronal migration disorder(NMD) is a major underlying pathology of patients with intractable epilepsy. The role of NMD on seizure susceptibility or epileptogenecity, however, has not been documented. Methods : External irradiation of total amount of 250 cGY was performed to the fetal rats on days 16(E16) and 17(E17) of gestation. After delivery, the rats of 230-260g were decapitated for the histopathologic study. Epileptog-enecity of the NMD was studied by observing electroclinical events after intraperitoneal kainic acid(KA) injection in the control rats and NMD rats. Results : Histopathologic findings revealed focal and/or diffuse cortical dysplasia consisting of dyslamination of the cerebral cortex and appearance of the cytomegalic neurons, neuronal heterotopia in the periventricular white matter, dispersion of the pyramidal layer and the dentate gyrus of the hippocampus, and agenesis of the corpus callosum. Abnormal expression of neurofilaments protein(NF-M/H) was characteristically observed in the dysplastic neurons of the neocortex and hippocampus. Early ictal onset and prolonged ictal activity on EEG and clinical seizures were observed from the NMD rats unlike with the control rats. Conclusions : Exteranl irradiation on the fetal rats produced NMD. And the rats with NMD were highly susceptible to kainic acid provoked seizures. This animal model would be useful to study the pathophysiology of clinically relevant NMDs.

• Journal of Korean Medical Science
• /
• v.33 no.44
• /
• pp.279.1-279.16
• /
• 2018

Magnetic resonance-guided focused ultrasound (MRgFUS) is a new emerging neurosurgical procedure applied in a wide range of clinical fields. It can generate high-intensity energy at the focal zone in deep body areas without requiring incision of soft tissues. Although the effectiveness of the focused ultrasound technique had not been recognized because of the skull being a main barrier in the transmission of acoustic energy, the development of hemispheric distribution of ultrasound transducer phased arrays has solved this issue and enabled the performance of true transcranial procedures. Advanced imaging technologies such as magnetic resonance thermometry could enhance the safety of MRgFUS. The current clinical applications of MRgFUS in neurosurgery involve stereotactic ablative treatments for patients with essential tremor, Parkinson's disease, obsessive-compulsive disorder, major depressive disorder, or neuropathic pain. Other potential treatment candidates being examined in ongoing clinical trials include brain tumors, Alzheimer's disease, and epilepsy, based on MRgFUS abilities of thermal ablation and opening the blood-brain barrier. With the development of ultrasound technology to overcome the limitations, MRgFUS is gradually expanding the therapeutic field for intractable neurological disorders and serving as a trail for a promising future in noninvasive and safe neurosurgical care.

• Journal of Yeungnam Medical Science
• /
• v.12 no.2
• /
• pp.306-318
• /
• 1995

To evaluate the intractability of partial epileptic patients by variables, the author studied 113 patients (uncontrolled: 45, controlled: 68) who were admitted to the Department of Neurology, College of Medicine, Yeungnam University from January, 1991 to August, 1993. The results were as follows. The items related to complex partial seizures, multiple seizure types and a histories of status epilepticus or clusters of seizures were significantly associated with drug-refractoriness (p<0.01). A high frequency of seizures before evaluation was associated with a poor outcome(p<0.01). The presences of known etiology of seizures, neurologic abnormalities and psychiatric disturbance were associated with limited treatment responses(p<0.01, p<0.05, p<0.01). An abnormal EEG findings such as background slowing, focal slowing, epileptiform discharges or secondarily bilateral synchrony were statistically significant (p<0.01). Age at onset, sex, distribution of epileptic foci, duration of seizure before evaluation, family history and abnormal neuroradiologic findings were not statistically significant. By these results, it was suggested that having at least four factors of the above variables were associated with limited treatment response.

• Annals of Clinical Neurophysiology
• /
• v.11 no.1
• /
• pp.16-23
• /
• 2009

Background: The intermittent delta activity in electroencephalographies (EEGs) of patients with focal brain lesions has been reported to be a marker of an epileptogenic focus. This study investigated the concordance between the current source distribution (CSD) of the interictal epileptiform discharges (IEDs) and that of the background delta frequency bands (DFBs) of the scalp EEG. Methods: We collected scalp EEGs of 13 patients with focal epilepsy that contained uniregional IEDs and unilateral delta to theta slow waves. We applied a distributed source model using LORETA$^{(R)}$ to determine the CSD of the peak points of the IEDs and the DFBs of the background activity. Results: The CSDs of the DFBs were ipsilateral to the CSDs of the peak point of the averaged IEDs in ten patients, and bilateral with ipsilateral predominance in three patients. In the cases with an ipsilateral CSD of the DFB, 8 of 10 patients had concordance of the CSD localization between the averaged IED and the DFB. In the cases with bilateral CSD of the DFB, 2 of 3 patients had concordance of the CSD localization between the averaged IED and the DFB. Conclusions: The CSD localization and lateralization appear to be concordant between the IEDs and the DFB of background activity in epileptic patients. Therefore, the CSD of the DFB in EEGs with visually observable slow activities may predict those of IEDs.

• Clinical and Experimental Pediatrics
• /
• v.48 no.11
• /
• pp.1225-1231
• /
• 2005

Purpose : This study compares the first epileptic seizures between preterm and term-born children with periventricular leukomalacia and epilepsy. Methods : From 108 cases having lesions of high signal intensity around the ventricles in T2 weighted imaging of a brain magnetic resonance study, we selected 37 cases that showed epileptic seizures two times or more and divided them into the group of preterm-born(27 cases) and term-born children(10 cases). A retrospective study was made by comparing the two groups with regard to age, type of the first epileptic seizures, EEG findings and responsiveness to anticonvulsants. Results : The age of the first epileptic seizure was $22.2{\pm}18.3$ months in the preterm-born group and $26.9{\pm}21.1$ months in the term-born group(P=0.505). As for the first epileptic seizure, 11 out of the 27 cases in the preterm-born group had infantile spasms. Out of the 10 cases in the term-born group, 7 had complex partial seizures. In the preterm group, hypsarrhythmias were found in 11 cases, focal epileptiform discharges in 6 cases. In term-born group, focal epileptiform discharges were found in 5 cases but no epileptiform discharge was found in 3 cases. Intractable epilepsies were diagnosed in 6 cases and all of them belonged to the preterm-born group. Conclusion : More severe epilepsies such as infantile spasm and intractable epilepsies seem to be more common in preterm-born epileptic children with PVL as well as more severely abnormal EEG finding compared to term-born epileptic children.

• Clinical and Experimental Pediatrics
• /
• v.51 no.3
• /
• pp.286-292
• /
• 2008

Purpose : We performed EEG and PET on children with epilepsy concomitantly in order to evaluate the effects of epileptiform and non-epileptiform discharge of EEG on glucose metabolism. Methods : Seventy three children with epilepsy who had PET and EEG simultaneously were included in our study. The subjects were classified in two ways: (1) based on the frequency of epileptiform discharge and (2) the severity of non-epileptiform discharge. We evaluated the clinical aspects of their seizures, the severity of focal slow waves during the interictal period with the frequency of spikes or sharp waves in order to compare with the PET results. Results : The subjects were divided by the frequency of epileptiform discharge, with 13 in the no/rare group, 7 in the occasional group, and 53 children in the frequent group. The concordant rates with PET in each group were 0%, 42.9%, and 67.9%, respectively, showing high correlations with the frequency of epileptiform discharge (P<0.05, r=0.491). The subjects as divided by the severity of non-epileptiform discharge were 15 in the no group, 25 in the infrequent group, 17 in the intermediate group, and 16 in the continuous group. The concurrence rates with PET for each group were 13.3%, 52.0%, 64.7%, and 68.8%, respectively, also showing a high correlation with the severity of non-epileptiform discharge (P<0.05, r= 0.365). Conclusion : Epileptiform discharge and non-epileptiform discharge in EEG showed a certain association with hypometabolism in PET. We recommend EEG to reduce false lateralization and to localize lesions in cases of high frequency and severity.

• Clinical and Experimental Pediatrics
• /
• v.55 no.2
• /
• pp.63-67
• /
• 2012

A 4-year-old girl with Panayiotopoulos syndrome presented with a history of 4 prolonged autonomic seizures. The clinical features of her seizures included, in order of occurrence, blank staring, pallor, vomiting, hemi-clonic movement on the right side, and unresponsiveness. A brain magnetic resonance imaging (MRI) showed a slightly high $T_2$ signal in the left hippocampus. Interictal electoencephalogram revealed spikes in the occipital area of the left hemisphere. We analyzed the current-source distribution of the spikes to examine the relationship between the current source and the high $T_2$ signal. The current source of the occipital spikes was not only distributed in the occipital area of both cerebral hemispheres, but also extended to the posterior temporal area of the left hemisphere. These findings suggest that the left temporal lobe may be one of the hyperexcitable areas and form part of the epileptogenic area in this patient. We hypothesized that the high $T_2$ signal in the left hippocampus of our patient may not have been an incidental lesion, but instead may be related to the underlying electroclinical diagnosis of Panayiotopoulos syndrome, and particularly seizure. This notion is important because an abnormal $T_2$ signal in the hippocampus may represent an acute stage of hippocampal injury, although there is no previous report of hippocampal pathology in Panayiotopoulos syndrome. Therefore, long-term observation and serial follow-up MRIs may be needed to confirm the clinical significance of the $T_2$ signal change in the hippocampus of this patient.

• Clinical and Experimental Pediatrics
• /
• v.52 no.1
• /
• pp.81-86
• /
• 2009

Purpose : Febrile convulsions are classified into simple or complex types, the latter being characterized by increased risk of recurrence and progression to epilepsy. This study aimed to delineate the clinical characteristics of complex febrile convulsions. Methods : Between January 2003 and December 2006, 550 children were diagnosed with febrile convulsions at the Department of Pediatrics, Ilsan Paik Hospital. Their medical records were retrospectively reviewed for comparison between simple and complex febrile convulsions, and clinical findings of complex febrile convulsions were clarified. Results : Our subjects comprised a male-to-female ratio of 1.64:1; the age range was from 8 months to 8 years. Simple febrile convulsions comprised 432 cases, i.e., 4 times as many as complex febrile convulsions (118 cases). The causes of febrile illness included acute pharyngotonsillitis (357 cases, 64.9%), pneumonia (55 cases, 10.0%), acute gastroenteritis (37 cases, 6.7%), and otitis media (20 cases, 3.6%). We did not find any significant difference between simple and complex febrile convulsions in most clinical parameters such as gender, age, family history of febrile convulsions, and cause of febrile illness. Regarding subtypes of complex febrile convulsions, repeated convulsions were the most frequent (72.0%), followed by prolonged convulsions (16.9%) and focal convulsions (5.1%). Conclusion : We have reported here the clinical features of complex febrile convulsions. Although the results did not show any significant difference between simple and complex febrile convulsions in most clinical parameters such as gender, age, family history of febrile convulsion, and cause of febrile illness, further studies are essential to delineate complex febrile convulsions.