Chih-Chuan Chen

Chang Gung University, Taoyuan, Taiwan, Taiwan

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Publications (16)49.82 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: The aim of this study was to identify the neuropsychological features in patients with temporal lobe epilepsy (TLE) and their correlation with seizure-related variables. For this purpose, we carried out a retrospective analysis of data from 65 patients with TLE who had undergone a comprehensive neuropsychological assessment. The results suggest that the majority of patients with TLE were impaired in more than one cognitive domain, and among these patients, the mean proportions with defective semantic memory, language, motor/psychomotor speed, verbal episodic memory, and executive function were >50% each. Moreover, age at seizure onset was the strongest predictor of general intellectual impairment, and number of antiepileptic drugs and seizure frequency could significantly predict deficits in verbal memory, language, and psychomotor speed. However, epilepsy duration was a less potent predictor of cognitive deficit than has been reported in cross-sectional studies.
    Epilepsy & Behavior 12/2011; 22(4):728-34. · 1.84 Impact Factor
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    ABSTRACT: We studied geographic variation in age- and gender-specific prevalence and incidence of epilepsy in four different areas of Taiwan. By using large-scale, National Health Insurance (NHI)-based data from 2000-2003 in Taiwan, we identified 131,287 patients diagnosed with epilepsy (ICD code 345) receiving at least of one of 11 antiepileptic drugs (AEDs). Information on age, gender, and location were also collected. The multivariable Poisson regression analysis was used to assess the heterogeneity of the morbidity of epilepsy in different regions. External data validation was also performed to assess the accuracy of capturing epilepsy cases through our NHI data set. The age-adjusted prevalence and incidence of epilepsy were 5.85 (per 1,000) between 2000 and 2003 and 97 (per 100,000 person-years) during the follow-up time from 2001 to 2003 in Taiwan. The sensitivity and specificity of ICD-9 coding for epilepsy in the NHI data set were 83.91% and 99.83%, respectively, resulting in a slight overestimation. Male patients had a higher probability of having epilepsy than did females. East Taiwan had significantly higher prevalence and incidence than did other areas. The age-specific incidence pattern in east Taiwan was atypical in that it revealed clustering in young and middle-aged groups. Our study demonstrated geographic variation in epidemiologic patterns of epilepsy within Taiwan. The findings are informative and provide insight into the clinical management of epilepsy based on consideration of different target groups in different areas.
    Epilepsia 11/2011; 53(2):283-90. · 3.96 Impact Factor
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    ABSTRACT: A 53-year-old male patient developed insidious onset of length-dependent painful neuropathy on a background of encephalopathy during prolonged treatment with metronidazole for a cumulative dose of 146 g in 88 days. The reversible encephalopathy was documented with gradual resolution of hyperintense lesions in bilateral cerebellum and brainstem on brain MRI together with the improvement in symptoms of ataxia and dysarthria. The concomitant impairment of small-diameter sensory nerves posed a diagnostic challenge. The authors took advantage of serial skin biopsies to demonstrate reversible metronidazole-induced small-fibre sensory neuropathy, that is, skin denervation after metronidazole and corresponding skin reinnervation with the disappearance of sensory symptoms.
    Journal of neurology, neurosurgery, and psychiatry 04/2011; 82(4):462-5. · 4.87 Impact Factor
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    ABSTRACT: Temporal lobe epilepsy (TLE) is the most common focal epilepsy and frequently causes memory problems. It is often associated with hippocampal sclerosis (HS) and is useful in exploring memory functions. We aimed to examine the effect of restricted hippocampal lesions on gist memory function in patients with TLE. Forty-five patients with TLE and HS (16 left, 15 right, and 14 bilateral lesions) and 22 control subjects were recruited. Patients with magnetic resonance imaging (MRI) or electroencephalography (EEG) evidence of extratemporal lesions were excluded. All participants performed a gist-based recognition task following the Deese-Roediger-McDermott paradigm and were tested for verbal IQ and memory functions. We conducted hippocampal volumetry on MRI of all the participants. Patients showed multidomain memory impairments. Gist memory was impaired in patients with bilateral HS and probably in patients with right HS. Hippocampal volumetry supported such findings that total volume of hippocampi and volume of right hippocampus correlated positively with gist memory function. HS has a dose effect and a probable right dominance effect on gist memory; good item memory supports gist memory performance; and a disproportionate deficit was noted in tasks with high relational demand but not in tasks with simple association. We should develop memory skills for patients with TLE by enhancing performance of gist memory related to simple association task.
    Epilepsia 06/2010; 51(6):1036-42. · 3.96 Impact Factor
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    Chun-Yao Lee, Chih-Chuan Chen, Horng-Huei Liou
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    ABSTRACT: Levetiracetam is an effective anti-epileptic drug in the treatment of partial and generalized seizure. The purpose of the present study was to investigate whether levetiracetam regulates AMPA and NMDA receptor-mediated excitatory synaptic transmission and to determine its site of action in the dentate gyrus (DG), the area of the hippocampus that regulates seizure activities. Whole-cell patch-clamp method was used to record the AMPA and NMDA receptor-mediated excitatory postsynaptic currents (EPSC(AMPA) and EPSC(NMDA)) in the presence of specific antagonists, from the granule cells in the DG in brain slice preparations from young Wistar rats (60-120 g). Levetiracetam (100 microM) inhibited both evoked EPSC(AMPA) and EPSC(NMDA) to an equal extent (80%), altered the paired-pulse ratio (from 1.39 to 1.25), decreased the frequency of asynchronous EPSC and prolonged the inter-event interval of miniature EPSC(AMPA) (from 2.7 to 4.6 s) without changing the amplitude, suggesting a presynaptic action of levetiracetam. The inhibitory effect of levetiracetam on evoked EPSC(AMPA) was blocked by omega-agatoxin TK (100 nM), a selective P/Q-type voltage-dependent calcium channel blocker, but not by nimodipine (10 microM) or omega-conotoxin (400 nM). These results suggest that levetiracetam modulated the presynaptic P/Q-type voltage-dependent calcium channel to reduce glutamate release and inhibited the amplitude of EPSC in DG. This effect is most likely to contribute to the anti-epileptic action of levetiracetam in patients.
    British Journal of Pharmacology 11/2009; 158(7):1753-62. · 5.07 Impact Factor
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    ABSTRACT: The aim of this prospective, multicenter, open-label study was to investigate the efficacy of levetiracetam (LEV) and determine its effects on cognitive and neuropsychological function. Sixty-nine patients were evaluated for effects of LEV on seizure control, cognitive (Mini-Mental State Examination [MMSE]) and neuropsychological (Symptom Checklist-90 Revised [SCL-90-R]) functions, and quality of life (Quality of Life in Epilepsy--10 [QOLIE-10]) assessments at 3 and 12 months of follow-up. Thirty-nine percent of patients achieved seizure freedom, and 68% had a > or =50% seizure frequency reduction after 1 year of LEV (1235.5+/-392.7 mg/day). There were also significant improvements in mean MMSE score and in the recall and language items of MMSE. There were modest improvements in interpersonal sensitivity and paranoid ideation scales of the SCL-90-R, and improvements in cognition and medication effect items of the QOLIE-10. The results demonstrate that LEV not only effectively reduces seizure frequency, but also possibly contributes to improvements in neuropsychological functions such as recall, language, interpersonal sensitivity, and paranoid ideation.
    Epilepsy & Behavior 09/2009; 16(3):468-74. · 1.84 Impact Factor
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    ABSTRACT: We aimed to quantify the mortality reduction by which the early detection of Parkinson's disease (PD) within a community-based study could reduce the number of advanced cases. Data used in this study were derived from two community-based surveys and from a clinical series of PD cases identified from a medical centre. The cumulative survival by Hoehn-Yahr (H-Y) scale was estimated and the mortality reduction derived from a community-based survey was predicted. A total of 117 PD patients were detected through two community-based approaches. By comparing the H-Y stage distribution of screen-detected cases with those from the clinical series, a 22.5% excess in the number of early PD (H-Y stage I and stage II) were identified with screening. The risk ratios of being H-Y stage III or severe for community-based detected cases versus clinical series were 0.49 (95% confidence interval: 0.30-0.78). The total death rate adjusted by H-Y stage distribution was 21% and 28% for cases from community and clinical series, respectively. The present study revealed that early detection of PD through a community-based survey may reduce 51% incidence of stage III or more severe PD at diagnosis, leading to a 25% reduction in mortality.
    Journal of Evaluation in Clinical Practice 09/2009; 15(4):587-91. · 1.51 Impact Factor
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    ABSTRACT: Mossy fiber sprouting (MFS) is the main characteristic of temporal lobe epilepsy (TLE), which is highly correlated with the frequencies of recurrent seizures as well as degrees of severity of TLE. A recent MRI technique, referred to as diffusion spectrum imaging (DSI), can resolve crossing fibers and investigate the intravoxel heterogeneity of water molecular diffusion. Being able to achieve higher accuracy in depicting the complex fiber architecture, DSI may help improve localization of the seizure-induced epileptic foci. In this study, two indices of DSI, which represented the mean diffusivity (MSL) and diffusion anisotropy (DA), were proposed. A correlative study between diffusion characteristics and the severity of MFS was investigated in the pilocarpine-induced status epilepticus (SE) rat model. Nine SE rats and five control rats were studied with MRI and histological Timm's staining. For MSL, no significant correlation was found in the dentate gyrus (DG), r=-0.36; p=0.2017, and positive correlation was found in cornu ammonis (CA3), r=0.62; p=0.0174. The correlation between DA and Timm's score showed positive correlation in DG, r=0.71; p=0.0047, and negative correlation in CA3, r=-0.63; p=0.0151. Our results were compatible with the previous reports on fiber architecture alterations in DG and CA3 subregions. In conclusion, the histological correspondence of DSI indices was demonstrated. With DSI indices, longitudinal follow-up of hippocampal fiber architecture can be achieved to elucidate the pathophysiology of TLE, which might be helpful in disease localization.
    NeuroImage 08/2008; 41(3):789-800. · 6.25 Impact Factor
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    ABSTRACT: The ABCB1 haplotype combinations have been demonstrated to be associated with epilepsy treatment outcomes. The aim of this study is to investigate whether ABCB1 haplotype combinations would affect P-glycoprotein (Pgp) function and impact the clinical responses of antiepileptic drugs (AEDs). Transport of substrate rhodamine 123 and calcein-AM by human Pgp carrying 12 haplotype combinations of 1236C>T, 2677G>T/A and 3435C>T were assayed in the absence and presence of known inhibitors and AEDs. The inhibitory potency of the tested drugs from the dose-response relationships was cyclosporin A>verapamil> phenytoin> carbamazepine> lamotrigine>phenobarbital>valproic acid, levetiracetam, gabapentin. The silent polymorphisms combination (1236T-3435T) and triple haplotypes (1236T-2677A/T-3435T) resulted in profoundly less effective inhibition against substrates with significantly lower intracellular substrate concentration. These results confirmed that ABCB1 polymorphisms were associated with clinical responses of AEDs. Our findings demonstrated that human ABCB1 polymorphisms may alter the interactions between Pgp and substrates, and provided functional evidence for ABCB1 haplotypes-associated epilepsy treatment responses.
    Pharmacogenetics and Genomics 06/2008; 18(5):390-402. · 3.61 Impact Factor
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    ABSTRACT: The natural course of Parkinson's disease (PD), as measured on the Hoehn-Yahr (H-Y) scale, and the impact that early detection would have on prognosis for those with the disease, has barely been addressed since the introduction of L-dopa. This study aimed to elucidate the natural history of PD and effectiveness of early detection in reducing advanced disability and mortality. A total of 21 362 participants aged 40 years or older were invited to two community-based programmes for the early detection of PD. The step-by-step annual progression rates from H-Y stage I to stage IV or V, and cumulative survival rates, by the H-Y scale, were estimated and applied to simulated data to assess the impact of different screening intervals upon stage at diagnosis and subsequent survival. The average duration in stages I, II and III was estimated as 2.83, 6.62 and 1.41 years, respectively. The average delay time before deteriorating into H-Y stage III was 9.45 year. Application of these parameters to simulated model predicted a 36% (95% CI: 28-39%), 26% (95% CI: 20-32%) and 19% (95% CI: 13-24%) reduction in death for annual, 5-yearly and 10-yearly screening programmes, respectively. The present study recommended a 5-yearly screening programme, with 74% of PD cases prevented from progressing to H-Y stage III or worse within 10 years of diagnosis, and leading to a corresponding 26% reduction in mortality.
    Journal of Evaluation in Clinical Practice 05/2008; 14(2):198-202. · 1.51 Impact Factor
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    ABSTRACT: The dentate gyrus (DG) is a gateway that regulates seizure activity in the hippocampus. We investigated the site of action of lamotrigine (LTG), an effective anticonvulsant, in the regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartic acid (NMDA) receptor-mediated excitatory synaptic transmission on DG. Evoked AMPA and NMDA receptor-mediated excitatory postsynaptic currents (eEPSCampa and eEPSCnmda) were recorded by whole-cell patch-clamp recording from the granule cells of DG in brain slice preparation of young Wistar rats (60-120 g). Exogenously applied AMPA and NMDA-induced currents and AMPA receptor-mediated miniature EPSC (mEPSCampa) were recorded in the presence of specific antagonists. LTG inhibited both eEPSCampa and eEPSCnmda, and had no effect on exogenously applied NMDA-induced current indicating LTG inhibited glutamate release. Previous studies demonstrated that alteration in glutamate concentration in synaptic cleft causes parallel changes of eEPSCampa and eEPSCnmda. Our results showed that LTG inhibited eEPSCampa significantly more than eEPSCnmda (p < 0.05), suggesting that LTG may also have blocked the postsynaptic AMPA receptor. The hypothesis is further supported by the facts that; (1) LTG (30-100 microM) inhibited direct exogenously applied AMPA-induced currents (to 90%), (2) LTG significantly reduced the amplitude, but not the frequency of mEPSCampa and asynchronous (EPSC), and (3) LTG-induced reduction of eEPSCampa was not associated with a modification of the paired-pulse ratio. To sum up, LTG exerts a postsynaptic inhibitory mechanism on the AMPA receptor. Our results demonstrate that LTG suppresses postsynaptic AMPA receptors and reduces glutamate release in granule cells of DG. The postsynaptic effect can be one of the underlying mechanisms of LTG's anticonvulsant action.
    Epilepsia 05/2008; 49(5):888-97. · 3.91 Impact Factor
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    ABSTRACT: To determine the prevalence rate and patterns of adult patients with epilepsy in Taiwan, we conducted a community-based neuroepidemiological survey. Epilepsy was detected by neurologists using one-stage method. It was integrated into a community health screening service and performed from 1 January 2001 to 31 December 2001 in Keelung, a northern city in Taiwan. A total of 13,663 subjects aged 30 years or older participated in this survey. There were 52 patients with epilepsy in this study. Among them, 37 were patients with active epilepsy. The age-adjusted prevalence rate of active epilepsy above 30 years old was 2.77/1000 (to the 1980 US population) with the highest rate in subjects aged 40-49 years (4.0/1000). There was a trend of higher prevalence rate in male than in female. The most common seizure type was complex partial seizure (46.0%). Using one-stage detection method, we found nine (24.3%) patients with active epilepsy who had never been diagnosed before. Among the patients with active epilepsy, 35.1% were symptomatic cases. Head injury (13.5%) is the leading cause, followed by CNS infection (8.1%), stroke (5.4%) and perinatal insult (5.4%). The lifetime prevalence rate of epilepsy (including active epilepsy and epilepsy in remission) was 3.14/1000 for age above 30 years. Comparing to previous epilepsy survey in 1993, our results showed that the prevalence rate of epilepsy was rather stable over the past decade in northern Taiwan. Head injury is the leading cause responsible for active epilepsy. Improving public safety is an important public health issue which may help to reduce occurrence of epilepsy.
    Epilepsy Research 12/2006; 72(1):67-74. · 2.24 Impact Factor
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    ABSTRACT: Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the development of multiple hamartomas in many internal organs. Mutations in either one of 2 genes, TSC1 and TSC2, have been attributed to the development of TSC. More than two-thirds of TSC patients are sporadic cases, and a wide variety of mutations in the coding region of the TSC1 and TSC2 genes have been reported. Mutational analysis of TSC1 and TSC2 genes was performed in 84 Taiwanese TSC families using denaturing high-performance liquid chromatography (DHPLC) and direct sequencing. Mutations were identified in a total of 64 (76 %) cases, including 9 TSC1 mutations (7 sporadic and 2 familial cases) and 55 TSC2 mutations (47 sporadic and 8 familial cases). Thirty-one of the 64 mutations found have not been described previously. The phenotype association is consistent with findings from other large studies, showing that disease resulting from mutations to TSC1 is less severe than disease due to TSC2 mutation. This study provides a representative picture of the distribution of mutations of the TSC1 and TSC2 genes in clinically ascertained TSC cases in the Taiwanese population. Although nearly half of the mutations identified were novel, the kinds and distribution of mutation were not different in this population compared to that seen in larger European and American studies.
    BMC Medical Genetics 02/2006; 7:72. · 2.54 Impact Factor
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    ABSTRACT: To compare the health-related quality of life (HRQL) for patients with epilepsy and health subjects, we collected the clinical and demographic data and information on health states by using the Taiwan version of World Health Organization quality of life (WHOQOL)-BREF questionnaire in 296 patients (aged 19-73 years) with confirmed active epilepsy visiting the clinic of National Taiwan University Hospital, and 296 age-, gender-, municipal- and education-matched Taiwanese healthy subjects sampled from a national health interview survey. Multiple regression analyses with stepwise selection strategy were conducted to study risk factors for impairment of HRQL. Patients with epilepsy have poorer HRQL than the healthy population in physical, psychological and social domains but not in environment domain (p<0.005). Patients with less than 4 attacks during the previous 1 month had a better score in the availability and quality of health and social care in environment domain than healthy subjects (p<0.05). After controlling other determinants, seizure frequency, and comobid with other diseases are the important factors in predicting HRQL for epilepsy patients. Patients with employment and married had a significantly better HRQL. Effective control of seizure frequency and thoughtful promotion of positive attitudes in community are essential to improve the HRQL of epilepsy patients.
    Epilepsy Research 06/2005; 64(3):151-9. · 2.24 Impact Factor
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    ABSTRACT: To search for the optimal dosage of phenytoin in patients with epilepsy based on the metabolic activities of CYP2C9 and CYP2C19 polymorphisms, a total of 169 patients receiving phenytoin treatment for more than 1 month were recruited. Phenytoin concentration, serum albumin, liver function tests, and renal function tests were measured. CYP2C9 and CYP2C19 polymorphisms were genotyped by PCR-RFLP analysis, and NONMEM models were built to evaluate factors that would affect phenytoin metabolism. Patients were divided into 5 groups according to genotyping results (G1 to G5). Compared with extensive metabolizers in both CYP2C9 and CYP2C19 (G1), the Vmax (mg/kg/d) was 8.29% and 36.96% lower in CYP2C19 poor metabolizers (G3) and CYP2C9 poor metabolizers (G4), respectively. For the patient who was identified as a poor metabolizer in both CYP2C19 and CYP2C9 (G5), the Vmax was 45.75% lower than that of G1. In respect to Km (mg/L), it was 15.09% higher in G3 and 27.36% higher in G4 compared with that in G1. The Km of G5 was 91.71% higher than that of G1. The results revealed that the CYP2C9 and CYP2C19 polymorphisms have dramatic effects on the population pharmacokinetic parameters of phenytoin, especially for CYP2C9. Based on the Vm and Km values obtained in this study, the recommended dose ranges for G1, G2, G3, G4, and G5 patients would be 5.5-7, 5-7, 5-6, 3-4, and 2-3 mg/kg/d, respectively.
    Therapeutic Drug Monitoring 11/2004; 26(5):534-40. · 2.23 Impact Factor
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    ABSTRACT: To estimate the prevalence, incidence, and case-fatality of infantile spasms (IS) in Taiwan. A retrospective cohort of patients with IS was obtained from one medical center to identify 69 IS cases from 1985 to 1997. This cohort, in conjunction with the claimed data from the National Health Insurance, was used to estimate the prevalence and incidence of IS by capture-recapture design, taking the case-fatality of IS into account. The prevalence rate of IS for aged 0-9 years was 0.046 per thousand. The incidence rate was estimated as 6 over 100,000 per year in Taiwan. Of the 69 IS cases, 8 deaths were ascertained. The case-fatality rate was 11.6%. The leading cause of death was status epilepticus. We have demonstrated an efficient method to estimate the incidence and prevalence rates of IS in Taiwan. Our results help to make a clear understanding of the disease burden of IS in this society.
    Epilepsy Research 02/2004; 58(1):37-42. · 2.24 Impact Factor

Publication Stats

202 Citations
49.82 Total Impact Points


  • 2009
    • Chang Gung University
      • Department of Neurology
      Taoyuan, Taiwan, Taiwan
  • 2004–2009
    • National Taiwan University
      • College of Medicine
      Taipei, Taipei, Taiwan
    • National Taiwan University Hospital
      T’ai-pei, Taipei, Taiwan