Biomedical subjects

Chun-Hing Yiu

Publications and source records attributed to Chun-Hing Yiu.

10 recordsLinked to original sources

PubMed2007

Plastic phase-locking and magnetic mismatch response to auditory deviants in temporal lobe epilepsy.

The magnetic equivalent (MMNm) of mismatch negativity may reflect auditory discrimination and sensory memory. To study whether temporal lobe epilepsy (TLE) affects automatic central auditory-change processing, we recorded magnetoencephalographic (MEG) responses to standard and duration-deviant sounds in 12 TLE patients and 12 age-matched controls, and repeated MEG measurement in 8 patients 6-30 months following epilepsy surgery and in 6 controls 3-8 months after their first measurement. We compared the MMNm between patients and controls, and also evaluated intertrial phase coherences as indexed by phase-locking factors (PLF) using wavelet-based analyses. We observed longer MMNm latencies for patients than for controls. Dipole modeling and minimum-current estimates together showed bi-frontotemporal sources for MMNm. The phase locking across trials was dominant at the 4- to 14-Hz band, and the main difference in PLF between deviant- and standard-evoked responses occurred in the time frame of 150-250 ms after stimulus onset. Notably, in the 5 patients who became seizure free after removal of right temporal epileptic focus, the phase-locking phenomena resulting from deviant stimuli were enhanced, and even more distributed in the frontotemporal regions. We conclude that mesial TLE might affect auditory-change detection, and a successful surgery causes a possible plastic change in phase locking of deviant-evoked signals.

Acoustic Stimulation↗

PubMed2006

A comparison of seizure outcome after callosotomy in patients with Lennox-Gastaut syndrome and a positive or negative history for West syndrome.

PURPOSE: This retrospective study was designed to clarify the role of West syndrome in post-callosotomy seizure outcome in patients with Lennox-Gastaut syndrome. METHODS: From September 1989 to May 1999, 74 patients diagnosed with Lennox-Gastaut syndrome received anterior corpus callosotomy at Taipei Veterans General Hospital, Taiwan. All patients were followed for more than 4 years after surgery. Among them, 21 (28.4%) patients had a history of West syndrome (Group A) whereas 53 (71.6%) patients did not have a history of West syndrome (Group B). Postoperative seizure outcome was compared for these two patient groups. RESULTS: A total of 16 (76.2%) patients in Group A (positive history) and 29 (54.7%) patients in group B (negative history) achieved significant improvement in seizures after surgery (e.g., seizure reduction of more than 50%). There was no statistical significance (p=0.088) in the difference in outcome between the two groups. CONCLUSIONS: A history of West syndrome does not appear to influence post-callosotomy seizure outcome in patients with Lennox-Gastaut syndrome.

Adolescent↗

PubMed2006

Selective posterior cerebral artery amobarbital test in patients with temporal lobe epilepsy for surgical treatment.

PURPOSE: To evaluate whether the selective posterior cerebral artery amobarbital test (PCAAT) can predict postoperative memory function in patients with temporal lobe epilepsy (TLE) for surgical treatment and its clinical safety. METHODS: The database included adult patients with intractable TLE undergoing presurgical evaluation at Taipei Veterans General Hospital between 1995 and 2002. The PCAAT was carried out on patients who had failed conventional intracarotid amobarbital test (IAT) or had IAT results that evoked a concern of postoperative memory function decline. A battery of learning and memory testing was performed immediately before and after injection of amobarbital into the peduncular segment of the posterior cerebral artery (PCA) on the presumed hemisphere of epileptogenicity. Neuropsychological assessments were followed in surgically treated patients. RESULTS: A total of 16 patients completed PCAAT successfully and underwent anterior temporal lobectomy (ATL). Four patients failed PCAAT angiographic procedures due to technical difficulty in one patient, transient signs of vasospasm in two patients, and subarachnoid hemorrhage in one patient. Of the 12 patients who performed well in PCAAT learning and memory testing items by free recall or recognition, only 1 patient demonstrated postoperative memory decline in follow-up neuropsychological assessments. In contrast, two of the four patients with a deficit in PCAAT memory testing showed postoperative memory decline. Regarding subjective memory function (not necessarily associated with objective memory decline), patients not seizure-free after ATL were more likely to have memory complaints (in 3 out of 6 patients) than patients with seizure-free outcomes (in 1 out of 10 patients). CONCLUSIONS: The PCAAT memory test reliably predicts postoperative memory function in patients with TLE for surgical treatment. However, the inherent risks of PCAAT must be considered and it should be used judiciously.

Adult↗

PubMed2006

Isolated acute hearing loss as the presenting symptom of leptomeningeal carcinomatosis.

Leptomeningeal carcinomatosis is characterized by diffuse infiltration of the meninges by metastatic cancer. We report a rare case of leptomeningeal carcinomatosis with an initial presentation of isolated acute hearing loss. Progressive unsteady gait and multiple cranial nerve palsies ensued. Computed tomography of the chest with contrast revealed a 2 cm nodule over the right upper lung. Cytology of cerebrospinal fluid confirmed the diagnosis of adenocarcinoma. The patient was discharged after diagnosis. Isolated acute hearing loss is a rare initial presentation in leptomeningeal carcinomatosis, not necessarily with a known history of malignancy. A high index of suspicion is mandatory for accurate diagnosis.

Acute Disease↗

PubMed2005

Prognostic value of electrocorticography findings during callosotomy in children with Lennox-Gastaut syndrome.

OBJECTIVE: To analyze findings and acute changes in electrocorticograms (ECoGs) obtained during corpus callosotomy in order to identify any relationships with the postoperative outcome of seizure activity. METHODS: We retrospectively analyzed ECoGs obtained during anterior callosotomy (4-6 cm) in 48 patients with Lennox-Gastaut syndrome (32 boys and 16 girls, age 1-20 years, mean age 7.6 years) who underwent surgery between July 1993 and November 1996 to correlate recording findings with postoperative seizure activity. At the time of analysis, all patients had been followed postoperatively for more than 4 years. RESULTS: Of 48 patients, 31 (64.6%) had significant improvement in seizure control after surgery. In pre-excisional ECoGs, 38 (79.2%) of 48 patients had bisynchronous epileptiform discharges. Patients (23 of 33 patients, 69.7%) with significant blockage of bisynchronous discharges recorded during callosotomy achieved the best postoperative seizure outcomes, but the difference did not reach statistical significance (P>0.05). CONCLUSIONS: Based on our experience, changes in ECoG during callosotomy do not predict postoperative seizure outcome. Insignificant blockage of bisynchronous epileptiform discharges in ECoGs during callosotomy does not predict a worse prognosis than that associated with significant intraoperative blockage.

Adolescent↗

PubMed2004

[Another seizure classification--Semiological Seizure Classification].

The International League Against Epilepsy (ILAE) introduced in 1981 a seizure classification based on clinical semiology, interictal EEG findings, and ictal EEG patterns. Such classification depends heavily on detailed electroclinical correlation. After 20 years' progress in epileptology, many clinicians have found it difficult to make a "definite" seizure diagnosis clinically without a series of electrophysiological examinations, particularly in the infants, and further advancement in epileptology has findings have made the previous classification inefficient. Lüders and colleagues have proposed a classification, Semiological Seizure Classification (SSC), based exclusively on ictal semiology, which was published in the official journal of ILAE-EPILEPSIA in 1998. The EEG, neuroimaging and other laboratory results should be analyzed separately and then integrated to define the epileptic syndromes. The seizure diagnosis is thus made through a "what-you-see-is-what-you-get" way. It has also provoked an extensive discussion about the necessity of this new classification. In this review, we present the original guideline, which has been used at The Cleveland Clinic Foundation for years, to introduce another method of epileptic seizure classification.

Adult↗

PubMed2003

Magnetoencephalographic analysis of bilaterally synchronous discharges in benign rolandic epilepsy of childhood.

The purpose of this study was to examine the spatial and temporal relationship between bilateral foci of bilaterally synchronous discharges in benign rolandic epilepsy of childhood (BREC) using a whole-scalp neuromagnetometer. We simultaneously recorded interictal magnetoencephalographic (MEG) and electroencephalographic (EEG) signals in six children with BREC. Interictal spikes were classified into three groups: bilaterally synchronous discharges (BSDs), unilateral discharges on right side (UD-R), and unilateral discharges on left side (UD-L). We used equivalent current dipole (ECD) modelling to analyse the cortical sources of interictal spikes. Both BSDs and UDs were found in Patients 1-4, whereas only UDs were identified in Patients 5 and 6. The ECDs of interictal spikes were located in rolandic regions, 10-20mm anterior and lateral to hand somatosensory cortices. Multi-dipole analysis of BSDs showed two ECDs in homotopic motor areas of the hemispheres. During BSDs, the right-sided activation preceded the left-sided activation by 15-21 milliseconds in Patients 1 and 2. In Patients 3 and 4, the activation occurred 17-20 milliseconds earlier in the left than the right hemisphere. Within the same hemisphere, the sources of BSDs and UDs were located in similar areas. In conclusion, our results imply the cortical epileptogenicity in bilateral perirolandic areas in BREC. The sequential activation during BSDs in both hemispheres suggest the existence of synaptic connections, possibly via the corpus callosum, between bilateral irritative foci.

Brain Mapping↗

PubMed2003

Medication education for patients with epilepsy in Taiwan.

The aim of this study is to evaluate the medication knowledge achieved by conventional verbal education and the influence of drug information leaflets in patients with epilepsy. Drug compliance and sources of information of the patients were also examined. Fifty-one adults in an epilepsy outpatient clinic participated this survey. These patients were asked to complete a questionnaire and to specify sources of drug information. Serum drug levels were checked and compared with the self-reported compliance. Then, drug information leaflets were given to patients. In the next follow-up visit, patients were asked to fill out the same questionnaire again. In the baseline assessment, 36 patients (70.6%) could accurately list their medications. However, half of patients were not knowledgeable about side effects and did not keep a seizure diary. After provision of drug leaflets, the epilepsy medication assessment score increased from 3.9 +/- 1.9 to 5.1 +/- 1.7 (P<0.001). In addition, patients reported being compliant most of the time and this matched drug levels. On average, each patient had 2.8 sources of information and 5 patients used Internet as a tool. Despite achieving good compliance, conventional verbal education did not sufficiently cover drug-related issues. Providing patients with written information apparently increase their medication knowledge and probably enhance seizure control.

Adolescent↗

PubMed2003

Olfactory auras in patients with temporal lobe epilepsy.

PURPOSE: To investigate olfactory auras in patients with temporal lobe epilepsy (TLE). METHODS: We reviewed medical records of 217 Chinese patients who underwent temporal lobectomy for medically intractable TLE between 1987 and 1998 in Taiwan. Patients with olfactory auras asked for detailed characteristics of their auras. RESULTS: In all, 12 (5.5%) patients had olfactory auras, seven men and five women. All patients except one described and characterized the unpleasant olfactory auras. Olfactory auras were usually combined with other auras, most frequently sensations of epigastric rising, nausea, and fear. Association with gustatory hallucination was uncommon, in only one patient. On neuroimaging study, 11 patients had structural lesions involving the mesial temporal structures, two exclusively involving the amygdala. Histologic diagnosis included gliosis of the mesial temporal regions in seven (58.3%) patients, neoplasm in four (33.3%) patients, and arteriovenous malformation in one patient. Postoperatively, eight patients were seizure free. Three patients had rare seizures; however, none reported residual olfactory auras. CONCLUSIONS: Olfactory auras are infrequent in TLE. In this study, mesial temporal sclerosis is the most common etiology rather than tumors. Mesial temporal structures, especially the amygdala, may play important roles in the genesis of olfactory auras.

Adolescent↗

PubMed2003

Surgery of intractable temporal lobe epilepsy presented with structural lesions.

BACKGROUND: Structural lesions are found in about 30% of surgical specimens resected for intractable temporal lobe epilepsy (TLE). Detailed presurgical evaluations can identify the epileptogenic foci, the structural lesions and their correlation. Different surgical approaches have variable seizure control outcomes. METHODS: The preoperative investigations for the intractable TLE consisted of serial electroencephalogram (EEG) recordings, long-term EEG/video monitoring with sphenoidal electrodes, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), positron emission tomography with fluorodeoxyglucose (FDG-PET) and neuropsychological assessment. Among the 217 patients who underwent anterior temporal lobectomy (ATL) for TLE at Taipei Veterans General Hospital between 1987 and 1998, 47 (21.7%) had structural lesions in the resected specimen. The patients were divided into neoplastic (n = 35) and vascular (n = 12) groups, based on the pathological findings. RESULTS: In the neoplastic group, the interictal scalp-sphenoidal EEG recordings were abnormal in all 35 cases and lateralizing in 30 (85.7%). MRI revealed tumor growth within the temporal lobe in 26 patients (74.3%). FDG-PET was performed on 17 patients. Fifteen (88.2%) of them revealed unilateral mesial temporal lobe hypometabolism. In the vascular group, the interictal EEG tracings revealed unilateral mesial temporal lobe spikes in 11 patients (91.6%). MRI revealed abnormal enhanced lesions within the temporal lobes in all 12 patients. FDG-PET was available for 7 patients, 6 (86%) of whom had unilateral mesial temporal lobe hypometabolism. At the last follow-up (range 2-10 years, with a mean period of 4.2 years), 25 patients (73%) in the neoplastic group became and remained seizure-free postoperatively, 3 (9%) had fewer than 3 attacks per year. Among the vascular group, all 12 patients became and remained seizure-free after surgery. CONCLUSIONS: For intractable TLE with structural lesions, detailed presurgical evaluations are mandatory to identify the concordance of the lesions and the epileptogenic foci. Standard ATL with removal of the lesion may offer good seizure control postoperatively.

Brain Neoplasms↗