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Biomedical subjects

L M Li

Publications and source records attributed to L M Li.

At least 19 recordsLinked to original sources
PubMed2006

Asymmetrical extra-hippocampal grey matter loss related to hippocampal atrophy in patients with medial temporal lobe epilepsy.

BACKGROUND: Structural neuroimaging studies have consistently shown a pattern of extra-hippocampal atrophy in patients with left and right drug-refractory medial temporal lobe epilepsy (MTLE). However, it is not yet completely understood how extra-hippocampal atrophy is related to hippocampal atrophy. Moreover, patients with left MTLE often exhibit more intense cognitive impairment, and subtle brain asymmetries have been reported in patients with left MTLE versus right MTLE but have not been explored in a controlled study. OBJECTIVES: To investigate the association between extra-hippocampal and hippocampal atrophy in patients with MTLE, and the effect of side of hippocampal atrophy on extra-hippocampal atrophy. METHODS: Voxel-based morphometry analyses of magnetic resonance images of the brain were performed to determine the correlation between regional extra-hippocampal grey matter volume and hippocampal grey matter volume. The results from 36 patients with right and left MTLE were compared, and results from the two groups were compared with those from 49 healthy controls. RESULTS: Compared with controls, patients with MTLE showed a more intense correlation between hippocampal grey matter volume and regional grey matter volume in locations such as the contralateral hippocampus, bilateral parahippocampal gyri and frontal and parietal areas. Compared with right MTLE, patients with left MTLE exhibited a wider area of atrophy related to hippocampal grey matter loss, encompassing both the contralateral and ipsilateral hemispheres, particularly affecting the contralateral hippocampus. CONCLUSIONS: Our results suggest that left hippocampal atrophy is associated with a larger degree of extra-hippocampal atrophy. This may help to explain the more intense cognitive impairment usually observed in these patients.

Adolescent↗
PubMed2006

MRI reveals structural abnormalities in patients with idiopathic generalized epilepsy.

OBJECTIVE: To evaluate MRI findings in a large group of patients with idiopathic generalized epilepsies. METHODS: Idiopathic generalized epilepsies were diagnosed according to clinical and EEG criteria following International League Against Epilepsy recommendations. MRI was performed in a 2.0 T scanner using a previously established epilepsy protocol. Images were reviewed, and any abnormality was reported. Patients were divided in those with and without MRI abnormalities. Comparisons were made between these groups concerning age, age at seizure onset, subsyndrome, EEG findings, and seizure control. RESULTS: Of the 134 MRIs evaluated, 33 (24%) showed abnormalities, most of which (88%) were nonspecific. There were eight main abnormalities: arachnoid cyst, diffuse cortical atrophy, basal ganglia abnormalities (signal alterations and prominent perivascular spaces), ventricular abnormalities (uni- or bilateral increased volume of the lateral ventricles), white matter abnormalities (increased T2 signal in the frontal lobes), reduced hippocampal volume, focal gyral abnormality, and area of gliosis in the frontal lobe. Comparisons between the groups showed a higher proportion of EEG focalities in patients with abnormal MRI, which were in most part concordant with the location of the MRI abnormalities. CONCLUSIONS: Twenty-four percent of patients with idiopathic generalized epilepsies had MRI abnormalities. However, the majority of these abnormalities were nonspecific.

Adolescent↗
PubMed2006

Hippocampal abnormalities and seizure recurrence after antiepileptic drug withdrawal.

The authors performed hippocampal volumetry and T2 relaxometry in 84 consecutive patients with partial epilepsy from a protocol for antiepileptic drug (AED) withdrawal after at least 2 years of seizure control. Seizure recurrence after AED withdrawal was more frequent among patients with hippocampal atrophy and abnormal hippocampal T2 signal.

Adolescent↗
PubMed2006

Hippocampal atrophy in systemic lupus erythematosus.

OBJECTIVES: To determine the frequency and progression of hippocampal atrophy in systemic lupus erythematosus (SLE) and the clinical, laboratory and treatment features associated with its occurrence. METHODS: 150 patients with SLE and 40 healthy volunteers were enrolled in our study. A complete clinical, laboratory and neurological evaluation was performed. Magnetic resonance imaging was carried out using a 2T scanner (Elscint Prestige) and coronal T1-weighted images were used for manual volumetric measurements. Atrophy was defined as values <2 standard deviations from the means of controls. RESULTS: At entry into the study, the mean right and left hippocampal volumes of patients were significantly smaller than the hippocampal volumes of controls (p<0.001). After the follow-up magnetic resonance imaging, a significant progression of reduction in right and left hippocampal volumes in patients was observed (p<0.001). At entry, atrophy was identified in 43.9% and at follow-up in 66.7% of patients with SLE. Hippocampal atrophy was related to disease duration (p<0.001) total corticosteroid dose (p = 0.01) and history of central nervous system (CNS) manifestations (p = 0.01). Progression of atrophy was associated with cumulative corticosteroid dose (p = 0.01) and number of CNS events (p = 0.01). Patients with cognitive impairment had more severe hippocampal atrophy than those without. CONCLUSION: Disease duration, total corticosteroid dose and greater number of CNS manifestations were associated with hippocampal atrophy in patients with SLE. A significant progression of hippocampal atrophy related to total corticosteroid dose and number of CNS events was observed. Further studies are necessary to confirm these findings.

Adolescent↗
PubMed2006

Patterns of hippocampal abnormalities in malformations of cortical development.

OBJECTIVE: To assess whether different types of malformation of cortical development (MCD) are associated with specific patterns of hippocampal abnormalities. METHODS: A total of 122 consecutive patients with MRI diagnosis of MCD (53 males, age range 1-58 years) were included in the study. Hippocampal measurements were made on 1-3 mm coronal T1-weighted MRIs and compared with MRIs of normal controls. RESULTS: A total of 39 patients had focal cortical dysplasia, 5 had hemimegalencephaly, 5 had lissencephaly-agyria-pachygyria, 11 had SLH, 11 had PNH, 12 had bilateral contiguous PNH, 5 had schizencephaly, and 34 had polymicrogyria. The frequency of hippocampal abnormalities in these patients with MCD was 29.5%. A small hippocampus was present in all types of MCD. Only patients with lissencephaly and SLH had an enlarged hippocampus. Abnormalities in hippocampal rotation and shape were present in all types of MCD; however, these predominated in PNH. None of the patients with lissencephaly-agyria-pachygyria or SLH had hyperintense signal on T2 or FLAIR images or abnormal hippocampal internal architecture. CONCLUSION: A small hippocampus was present in all types of MCD; however, the classic MRI characteristics of hippocampal sclerosis were often lacking. Abnormal enlargement of the hippocampus was associated with only diffuse MCD due to abnormal neuronal migration (lissencephaly-agyria-pachygyria and SLH).

Adolescent↗
PubMed2006

Striatal and extrastriatal atrophy in Huntington's disease and its relationship with length of the CAG repeat.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that affects the striatum most severely. However, except for juvenile forms, relative preservation of the cerebellum has been reported. The objective of the present study was to perform MRI measurements of caudate, putamen, cerebral, and cerebellar volumes and correlate these findings with the length of the CAG repeat and clinical parameters. We evaluated 50 consecutive patients with HD using MRI volumetric measurements and compared them to normal controls. Age at onset of the disease ranged from 4 to 73 years (mean: 43.1 years). The length of the CAG repeat ranged from 40 to 69 (mean: 47.2 CAG). HD patients presented marked atrophy of the caudate and putamen, as well as reduced cerebellar and cerebral volumes. There was a significant correlation between age at onset of HD and length of the CAG repeat, as well as clinical disability and age at onset. The degree of basal ganglia atrophy correlated with the length of the CAG repeat. There was no correlation between cerebellar or cerebral volume and length of the CAG repeat. However, there was a tendency to a positive correlation between duration of disease and cerebellar atrophy. While there was a negative correlation of length of the CAG repeat with age at disease onset and with striatal degeneration, its influence on extrastriatal atrophy, including the cerebellum, was not clear. Extrastriatal atrophy occurs later in HD and may be related to disease duration.

Adolescent↗
PubMed2005

The importance of accurate anatomic assessment for the volumetric analysis of the amygdala.

There is a wide range of values reported in volumetric studies of the amygdala. The use of single plane thick magnetic resonance imaging (MRI) may prevent the correct visualization of anatomic landmarks and yield imprecise results. To assess whether there is a difference between volumetric analysis of the amygdala performed with single plane MRI 3-mm slices and with multiplanar analysis of MRI 1-mm slices, we studied healthy subjects and patients with temporal lobe epilepsy. We performed manual delineation of the amygdala on T1-weighted inversion recovery, 3-mm coronal slices and manual delineation of the amygdala on three-dimensional volumetric T1-weighted images with 1-mm slice thickness. The data were compared using a dependent t-test. There was a significant difference between the volumes obtained by the coronal plane-based measurements and the volumes obtained by three-dimensional analysis (P < 0.001). An incorrect estimate of the amygdala volume may preclude a correct analysis of the biological effects of alterations in amygdala volume. Three-dimensional analysis is preferred because it is based on more extensive anatomical assessment and the results are similar to those obtained in post-mortem studies.

Amygdala↗
PubMed2004

Abnormalities of hippocampal signal intensity in patients with familial mesial temporal lobe epilepsy.

Mesial temporal lobe epilepsy (MTLE) is associated with hippocampal atrophy and hippocampal signal abnormalities. In our series of familial MTLE (FMTLE), we found a high proportion of hippocampal abnormalities. To quantify signal abnormalities in patients with FMTLE we studied 152 individuals (46 of them asymptomatic) with FMTLE. We used NIH-Image for volumetry and signal quantification in coronal T1 inversion recovery and T2 for all cross-sections of the hippocampus. Values diverging by 2 or more SD from the control mean were considered abnormal. T2 hippocampal signal abnormalities were found in 52% of all individuals: 54% of affected subjects and 48% of asymptomatic subjects. T1 hippocampal signal changes were found in 34% of all individuals: 42.5% of affected subjects and 15% of asymptomatic subjects. Analysis of the hippocampal head (first three slices) revealed T2 abnormalities in 73% of all individuals (74% of affected subjects and 72% of asymptomatic subjects) and T1 abnormalities in 59% (67% of affected subjects and 41% of asymptomatic subjects). Affected individuals had smaller volumes than controls (P < 0.0001). There was no difference in hippocampal volumes between asymptomatic subjects and controls, although 39% of asymptomatic patients had hippocampal atrophy. Patients with an abnormal hippocampal signal (133 individuals) had smaller ipsilateral volume, but no linear correlation could be determined. Hippocampal signal abnormalities in FMTLE were more frequently found in the hippocampal head in both affected and asymptomatic family members, including those with normal volumes. These results indicate that subtle abnormalities leading to an abnormal hippocampal signal in FMTLE are not necessarily related to seizures and may be determined by genetic factors.

Analysis of Variance↗
PubMed2004

Texture analysis of medical images.

The analysis of texture parameters is a useful way of increasing the information obtainable from medical images. It is an ongoing field of research, with applications ranging from the segmentation of specific anatomical structures and the detection of lesions, to differentiation between pathological and healthy tissue in different organs. Texture analysis uses radiological images obtained in routine diagnostic practice, but involves an ensemble of mathematical computations performed with the data contained within the images. In this article we clarify the principles of texture analysis and give examples of its applications, reviewing studies of the technique.

Algorithms↗
PubMed2003

Medial temporal lobe atrophy in patients with refractory temporal lobe epilepsy.

OBJECTIVE: The objective of this study was to assess the volumes of medial temporal lobe structures using high resolution magnetic resonance images from patients with chronic refractory medial temporal lobe epilepsy (MTLE). METHODS: We studied 30 healthy subjects, and 25 patients with drug refractory MTLE and unilateral hippocampal atrophy (HA). We used T1 magnetic resonance images with 1 mm isotropic voxels, and applied a field non-homogeneity correction and a linear stereotaxic transformation into a standard space. The structures of interest are the entorhinal cortex, perirhinal cortex, parahippocampal cortex, temporopolar cortex, hippocampus, and amygdala. Structures were identified by visual examination of the coronal, sagittal, and axial planes. The threshold of statistical significance was set to p<0.05. RESULTS: Patients with right and left MTLE showed a reduction in volume of the entorhinal (p<0.001) and perirhinal (p<0.01) cortices ipsilateral to the HA, compared with normal controls. Patients with right MTLE exhibited a significant asymmetry of all studied structures; the right hemisphere structures had smaller volume than their left side counterparts. We did not observe linear correlations between the volumes of different structures of the medial temporal lobe in patients with MTLE. CONCLUSION: Patients with refractory MTLE have damage in the temporal lobe that extends beyond the hippocampus, and affects the regions with close anatomical and functional connections to the hippocampus.

Adult↗
PubMed2002

Predicting surgical outcome in temporal lobe epilepsy patients using MRI and MRSI.

OBJECTIVE: To develop a classifier that uses MR data to predict surgical outcome in patients with temporal lobe epilepsy (TLE). METHODS: Eighty-one patients with medically refractory TLE who underwent surgical treatment were studied. Patients underwent comprehensive presurgical investigation, including ictal video-EEG recording, 1H MRS imaging, and volumetric MRI. Outcome was measured using Engel's classification system, condensed into two outcome groups. Two approaches were taken. First, outcome was defined as experiencing worthwhile improvement with >90% reduction of seizure frequency (Classes I, II, and III) or not (Class IV). A second approach was to define outcome as experiencing freedom from seizures following surgery (Class I) or not (Classes II, III, and IV). For each approach, a Bayesian classifier was constructed to predict outcome by calculating the probability of a patient's pattern of results from spectroscopic analysis of the temporal lobes and volumetric analysis of the amygdala and hippocampus being associated with the various outcome groups. RESULTS: The worthwhile improvement classifier correctly predicted the surgical outcomes of 60 of 65 (92%) of patients who experienced worthwhile improvement and 10 of 16 (63%) of patients who did not. The seizure-free classifier correctly predicted the surgical outcomes of 39 of 52 (75%) of patients who became seizure free and 21 of 29 (72%) of patients who did not. CONCLUSION: MR features are important markers of surgical outcome in patients with TLE and can provide assistance in identifying surgical candidates.

Adult↗
PubMed2002

Proton magnetic resonance spectroscopic imaging suggests progressive neuronal damage in human temporal lobe epilepsy.

Whether temporal lobe epilepsy (TLE) is the result of an isolated, early injury or whether there is ongoing neuronal damage due to seizures is often debated. We attempted to examine the long-term effect of seizures using proton magnetic resonance spectroscopic imaging (1H-MRSI), which can quantify neuronal loss or dysfunction based on reduced signals from the neuronal marker N-acetylaspartate (NAA). We performed 1H-MRSI in 82 consecutive patients with medically intractable, non-foreign-tissue TLE to determine whether there was a correlation between seizure frequency, type or duration of epilepsy and NAA to creatine ratios (NAA/Cr). Spectroscopic resonance intensities were categorized as to whether they were measured from the temporal lobe ipsilateral or contralateral to the predominant EEG focus. Ipsilateral and contralateral NAA/Cr was negatively correlated with duration of epilepsy. Furthermore, patients with frequent generalized tonic-clonic seizures had lower NAA/Cr than patients with no or rare generalized tonic-clonic seizures. The results suggest that although an early injury may cause asymmetric temporal lobe damage that is present at the onset of epilepsy, generalized seizures may induce additional neuronal damage that progresses over the course of the disease.

Cross-Sectional Studies↗
PubMed2001

Time course of postoperative recovery of N-acetyl-aspartate in temporal lobe epilepsy.

PURPOSE: To assess the time course of increases in N-acetyl-aspartate/creatine (NAA/Cr), which can be measured using proton MR spectroscopic imaging (1H-MRSI), in patients with intractable nonlesional temporal lobe epilepsy (TLE) after successful epilepsy surgery. METHODS: We performed pre- and postoperative 1H-MRSI in 16 seizure-free (SF) patients and 16 not seizure-free (NSF) TLE patients. We calculated a mixed-design analysis of variance (ANOVA) between SF and NSF groups, ipsi- and contralateral to the side of operation, and pre- and postoperative NAA/Cr measurements. We applied nonlinear regression between pre- and postoperative NAA/Cr differences and the time interval between 1H-MRSI scans to fit a negative exponential model to NAA recovery. RESULTS: Mixed-design ANOVA revealed that (a) postoperative NAA/Cr was significantly higher in SF than in NSF patients (p = 0.02) and that (b) in the SF group, postoperative NAA/Cr values were significantly higher than preoperative values (p < 0.05) and returned to the normal range in most patients. According to our nonlinear regression model, in SF patients, there was a 50% increase relative to preoperative NAA/Cr values after 5.8 months, whereas an improvement of 95% was reached after 25 months. CONCLUSIONS: Our results extend preliminary observations of postoperative NAA recovery of SF patients by characterizing the time course of recovery as an exponential function with a half-time of approximately 6 months. The reversal of neuronal metabolic dysfunction remote from the epileptic focus may underlie the clinical observation of improvement of cognitive dysfunction after successful epilepsy surgery.

Adolescent↗
PubMed2001

Childhood epilepsy due to neurocysticercosis: a comparative study.

PURPOSE: To assess the clinical profile of pediatric patients with epilepsy and neurocysticercosis (NC), and compare them with a group of pediatric patients with benign partial epilepsy to determine clinical differences, response to treatment, and prognosis. METHODS: We studied 28 patients (16 girls) with probable or definitive diagnosis of NC and epilepsy and 32 patients (16 girls) with partial benign epilepsy (BE). All patients had normal neurologic examination. We compared NC and BE patients looking for differences in demographics (age at first seizure, gender, family history); clinical presentation (type, frequency, duration, and total number of seizures, duration of epilepsy, status epilepticus, cluster, and postictal deficit); treatment [duration, number of antiepileptic drugs (AEDs), maximal dose, drug association, number of seizure-free patients, time to obtain control and recurrence after medication discontinuation]; complementary examinations (the first and the last EEG). RESULTS: The mean follow-up was 5.4 years for the 28 NC patients and 4.6 years for the 32 BE patients (p=0.98). We did not find statistical differences between NC and BE in gender, family history, types of seizures, frequency and length of seizures, previous status epilepticus, seizure clustering, and presence of postictal deficits. However, we found that NC compared with BE patients had significant longer AED treatment, more seizures after AED introduction, tried more AEDs and at maximal dose, and in 20%, required polytherapy. The recurrence rate in NC was 54.4% and this was not significantly associated with number of lesions and disease activity seen on CT scans or the presence of EEG abnormalities. CONCLUSIONS: NC presents with a mild form of epilepsy in terms of seizure severity; however, it is more challenging in regard to drug management and has a less favorable long-term prognosis in terms of seizure remission. The number of lesions or disease activity seen on computed tomography (CT) as well as EEG abnormalities have no prognostic value in childhood epilepsy due to NC.

Adolescent↗
PubMed2001

[Synthesis of substituted 4-styrylcoumarin and their antitumor activities].

AIM: A series of 4-styrylcoumarin derivatives had been designed and synthesized in order to find compounds of antitumor activities by screening. METHODS: Title compounds (1-20) were synthesized by Phase-Transfer Wittig-Horner reaction, and screened by several antitumor models in vitro. Their structures were determined by 1HNMR, MS and elemental analysis. RESULTS: Twenty compounds (1-20) are new compounds. Compound 18 had effects on KB cell lines in vitro. CONCLUSION: It was seen that compound 18 had certain antitumor activities, and it was worth further studying.

Antineoplastic Agents↗
PubMed2000

Reconstruction of damaged corneas by transplantation of autologous limbal epithelial cells.

BACKGROUND: Stevens-Johnson syndrome, ocular pemphigoid, and thermal or chemical burns can cause scarring and opacification of the cornea and loss of vision. Transplantation of epithelial cells from the limbus of the contralateral cornea can restore useful vision. However, this procedure requires a large limbal graft from the healthy eye and is not possible in patients who have bilateral lesions. METHODS: We took specimens of limbal epithelial cells from the healthy contralateral eyes of six patients with severe unilateral corneal disease. The epithelial cells were cultured and expanded on amniotic membrane. The amniotic membrane, together with the sheet of limbal epithelial cells, was transplanted to the denuded corneal surface of the damaged eye after superficial keratectomy to remove fibrovascular ingrowth. The mean (+/-SD) follow-up period was 15+/-2 months. RESULTS: Complete reepithelialization of the corneal surface occurred within two to four days of transplantation in all six eyes receiving transplants. By one month, the ocular surface was covered with corneal epithelium, and the clarity of the cornea was improved. In five of the six eyes receiving transplants (83 percent), the mean visual acuity improved from 20/112 to 20/45. In one patient with a chemical burn who had total opacification of the cornea, the acuity improved from the ability to count fingers at 40 cm to 20/200. No patient had recurrent neovascularization or inflammation in the transplanted area during the follow-up period. CONCLUSIONS: Transplantation of autologous limbal epithelial cells cultured on amniotic membrane is a simple and effective method of reconstructing the corneal surface and restoring useful vision in patients with unilateral deficiency of limbal epithelial cells.

Adult↗
PubMed2000

Successful epilepsy surgery in catastrophic postencephalitic epilepsy.

The authors studied prognostic factors for surgical treatment in 22 patients with intractable postencephalitic epilepsy. A small subgroup of patients (9/22) had a positive outcome after resective surgery. They had a higher functional level after encephalitis as measured by Glasgow Outcome Score, a longer time interval between encephalitis and onset of seizures, and localization of ictal EEG to one temporal lobe. The other patients had devastating seizures with poor outcome after surgery.

Adolescent↗