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Biomedical subjects

Yi-Chung Lee

Publications and source records attributed to Yi-Chung Lee.

13 recordsLinked to original sources
PubMed2005

Cognitive reserve: a SPECT study of 132 Alzheimer's disease patients with an education range of 0-19 years.

This study examines the associations between education, cerebral perfusion, and cognitive test performance among 132 patients with Alzheimer's disease. The participants had had between 0 and 19 years of formal schooling, and had either mild or moderate dementia according to the Clinical Dementia Rating Scale. Cerebral perfusion was evaluated by the (99m)Tc-hexamethylpropylene amine oxime single photon emission computed tomography. The Mini-Mental State Examination and the Cognitive Abilities Screening Instrument were used to assess cognitive performance. For patients at each clinical dementia severity level, statistical parametric mapping was used to examine voxel by voxel the association between education and cerebral perfusion, and Pearson's correlation coefficients were calculated between education and cognitive test scores. Years of formal schooling had negative associations with cerebral perfusion and positive associations with cognitive test scores. The brain regions showing a significant education effect on perfusion involved bilateral posterior association areas in mild dementia, and bilateral parieto-temporo-frontal areas in moderate dementia. The present findings indicate that the cognitive reserve effect starts at the low end of the education range. They also suggest that the main effect of more education is a more facile use of alternative brain circuits instead of locally increased synaptic connections.

Aged↗
PubMed2005

Median nerve motor conduction velocity is concordant with myelin protein zero gene mutation.

BACKGROUND: Myelin protein zero gene (MPZ) mutations may account for a small proportion of cases of Charcot-Marie-Tooth disease (CMT). Different MPZ mutations may be associated with different clinical and electrophysiological phenotypes. OBJECTIVES: To expand our understanding of the characteristics of nerve conduction velocity (NCV) in patients with different MPZ mutations, the authors collected and analysed the NCV values from patients with MPZ mutations. MATERIALS AND METHODS: The NCVs of fourteen patients from six families carrying MPZ mutations of Val58Asp, Ser63Phe, Thr65Ile,Arg98Cys, Arg98His, and Ser233fs were collected retrospectively. Five of them had received nerve conduction studies (NCS) twice. The mutations were verified by polymerase chain reaction (PCR) amplifications and nucleotide sequencing. Scatterplot analyses of median motor NCV (MNCV) versus specific MPZ mutation were performed. RESULTS: The median MNCV varied widely, with a mean of 16.3 m/s (SD = 7.7 m/s) and a range of 5.1-32.9 m/s. Median MNCVs of patients with particular MPZ mutations were similar. Moreover, Median MNCV did not change significantly over time. CONCLUSIONS: There was concordance between median MNCV and specific MPZ mutations. However, median MNCV is not an ideal measure with which to distinguish CMT1B patients with MPZ mutations from CMT1A patients with PMP22 mutations.

Adolescent↗
PubMed2004

Longitudinal cerebral perfusion decrease in mild alzheimer's disease revealed by SPECT with statistical parametric mapping method.

Fifteen patients with mild Alzheimer's disease received baseline and follow-up technetium-99m hexamethylpropylene amine oxime SPECT examinations paired with neuropsychological assessments, including the Cognitive Ability Screening Instruments (CASI). The differences between baseline and follow-up SPECT images were analyzed by the voxel-based paired t test of the statistical parametric mapping technique. A simple regression analysis was also conducted to analyze the correlation between CASI sub-scores and both sets of SPECT images. In comparison with baseline images, cerebral perfusion at follow-up was significantly reduced in the left superior and middle temporal gyri, right middle and inferior temporal gyri, and right fusiform gyrus. A significant correlation was demonstrated between the list-generating fluency CASI sub-score and perfusion of the left fusiform gyrus. The visual construction sub-score was significantly correlated with perfusion of the right superior and medial frontal gyri.

Aged↗
PubMed2004

Myelin protein zero gene mutations in Taiwanese patients with Charcot-Marie-Tooth disease type 1.

BACKGROUND: Charcot-Marie-Tooth disease type 1 (CMT1) is the most common inherited peripheral neuropathy and represents a genetically heterogeneous condition. In addition to the peripheral myelin protein 22 gene (PMP22) duplication (CMT1A), myelin protein zero gene (MPZ) mutations may account for a certain portion of CMT1 patients (CMT1B). OBJECTIVES: The authors analyzed the MPZ mutations in Taiwanese patients who do not have PMP22 duplication. Specifically, their clinical and molecular features were characterized. MATERIALS AND METHODS: Twenty-four of 57 unrelated Taiwanese patients with CMT1 were selected after excluding the CMT1A duplication. Subsequent analysis of the coding regions of the MPZ gene was performed with single-strand-conformation polymorphism (SSCP), which was then followed by nucleotide sequencing. RESULTS: Four missense mutations and one 4-base pair (bp) deletion, respectively, were identified in five patients, of which one mutation, c.173 T>A, has never been previously reported. Three missense mutations were located in exon 2, the other one in exon 3, and the deletion in exon 6. CONCLUSIONS: This study expands the number of CMT1 associated MPZ mutation and suggests that analysis of the coding sequence of MPZ should be performed in all CMT patients without CMT1A duplication to clarify their disease nature.

Adult↗
PubMed2004

Prolonged central motor conduction time of lower limb muscle in spinocerebellar ataxia 6.

We investigated the function of corticospinal tract in spinocerebellar ataxia 6 (SCA6) by measuring the central motor conduction time (CMCT). Motor evoked potentials (MEP) of tibialis anterior (TA) muscle were elicited by magnetic stimulation to motor cortex and spinal cord in 9 SCA6 patients and 10 normal height- and age-matched subjects. CMCT in lower limb of SCA6 patients (18.1+/-1.9 ms) was significantly prolonged than that of the normal subjects (15.0+/-1.0 ms) ((p < 0.001). The prolonged CMCT was well correlated with the duration of disease (p = 0.005), but MEP amplitudes and stimulation intensities were not significantly different. These results indicate that the corticospinal tract function is also impaired and correlate with the disease duration in SCA6.

Adult↗
PubMed2004

Isolated oculomotor nerve palsy due to head injury.

Traumatic isolated oculomotor nerve palsy with negative imaging studies is extremely rare. We reported such a case who after head injury had normal brain computerized tomography (CT), magnetic resonance imaging (MRI), and angiography. The absence of other neurological signs and normal brain MRI indicated the lesion was most likely within the subarachnoid space, as the other important structures near the third nerve, such as the brainstem, cavernous sinus and orbit, were undamaged. The prognosis of traumatic oculomotor palsy is usually poor. Generally speaking, patients experience more rapid and complete recovery of ptosis than of extraocular movements, while pupillary size and light reflex show the least degree of recovery. Further case collections with modern imaging studies are needed to clarify the mechanisms and clinical characteristics associated with this phenomenon.

Brain↗
PubMed2003

Prolonged cortical relay time of long latency reflex and central motor conduction in patients with spinocerebellar ataxia type 6.

OBJECTIVE: Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disorder characterized by a slowly progressive ataxia and dysarthria. Anatomically. SCA6 was said to affect only the cerebellum. However, ithasbeen argued that SCA6 may involve widespread regions of the brain. This study was designed to investigate the electrophysiological functions of the central nervous system in patients affected with SCA6. METHODS: Nine patients with SCA6 and 10 normal, age-matched control subjects were included in the study. The motor evoked potentials, somatosensory evoked potentials, and long latency reflex (LLR) of the hand muscle were measured to evaluate the functions of the central nervous system. RESULTS: Significantly delayed LLR, as well as prolonged cortical relay time (CRT) and central motor conduction time (CMCT) of the hand muscle, were noted in the patients with SCA6. CONCLUSIONS: The prolongation of CMCT andCRT suggested that SCA6 disturbed the functions of the corticospinal tract and the transcortical polysynaptic pathways from the sensory to motorcortices. It seems likely that the CNS dysfunction caused by SCA6 is not limited to the structures that are anatomically abnormal. Furthermore, the prolongation of CMCT alone does not seem to suffice to differentiate between various types of autosomal dominant cerebellar ataxias. Molecular analysis is indispensable for the diagnosis of different genetic types of SCA.

Adult↗
PubMed2003

Statistical parametric mapping of brain SPECT perfusion abnormalities in patients with Alzheimer's disease.

Brain perfusion in 20 patients with mild Alzheimer's disease (AD), 20 patients with moderate AD and 20 control subjects (matched for age, gender and education) were assessed by single photon emission computed tomography (SPECT) using technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO). SPECT images were transformed to a standard size and shape for group comparisons by the voxel-based t test of the statistical parametric mapping techniques. Cerebral hypoperfusion in the left lower parietal area was found in mild AD patients. In moderate AD patients, significant cerebral hypoperfusion was located in bilateral posterior parietotemporal cortices, contiguous anterior occipital lobes, posterior cingulate gyri and, to a lesser extent, in frontal areas.

Aged↗
PubMed2003

Selective hypoperfusion of anterior cingulate gyrus in depressed AD patients: a brain SPECT finding by statistical parametric mapping.

This study tests the hypothesis that depression in patients with Alzheimer's disease (AD) is due to a specific pathogenesis rather than a reactive phenomenon. Forty-three AD patients received a psychiatrist's interview, neuropsychological assessments, and a 99mTc-hexamethyl propyleneamine oxime single photon emission computed tomography (HMPAO-SPECT). Analysis by statistical parametric mapping (SPM) showed that the depressed group had selective hypoperfusion in the bilateral anterior and posterior cingulate gyri and precuneus. Using the Hamilton Depression Rating Scale as a parameter, an inverse correlation was found between cerebral perfusion and the severity of depression. The right anterior cingulate gyrus demonstrated a most significant reduction in perfusion. These locations are akin to the imaging findings in patients with primary depression, indicating a specific pathogenesis for depression in AD.

Aged↗
PubMed2003

Using electrodiagnostic machine to study movement rhythm variation.

BACKGROUND: Hand movement constitutes the most common daily activities in our life. Hand dexterity is often impaired in patients with neurological disease. We developed an adjunct method, based upon the electrodiagnostic software, for study of motor control and hand dexterity. METHODS: Thirty-two normal subjects, 2 stroke patients and 2 Parkinson patients were included in the study. All of them were right-handed, and were asked to pace rhythmic finger tapping at a comfortable rate without cue or any external stimuli. A trigger kit was designed to transform the finger tapping. After using the triggering mode and adjusting the sweep speed, 2 tapping signals were simultaneously displayed on the screen. The first signal was the triggering potential, and the variation in timing of the second signal represented the variation in timing of the inter-response interval. Twenty sweeps were recorded, superimposed and measured on the screen. Movement rhythm variation (MRV) was defined as b/a x 100 (b = [maximal interval of finger tapping - minimal interval of finger tapping]; a = [maximal interval of finger tapping + minimal interval of finger tapping]/2). Each subject started with right hand and then left hand. RESULTS: MRV measurement showed excellent intrarater (r = 0.97) and interrater (r = 0.97) reliability. In normal right-handed subjects, the MRV was better in right hand than in left hand (right 16.5 +/- 4.1% and left 21.0 +/- 7.6%; p < 0.05). The MRV improved in stroke patients along with the recovery and improved in Parkinson patients after levodopa treatment. CONCLUSIONS: MRV was a good method to provide quantitative data for assessment of hand dexterity. Our study also showed the potential role of MRV in motor control study.

Adult↗
PubMed2002

Cutoff scores of the cognitive abilities screening instrument, Chinese version in screening of dementia.

The purpose of this study of dementia screening was to obtain different cutoff scores of the Cognitive Abilities Screening Instrument, Chinese versions (CASI C-2.0) for subjects with different educational backgrounds. The diagnosis of dementia was based on the Diagnostic and Statistical Manual of Mental Disorders, ed 3 revised or ed 4 criteria. To diagnose Alzheimer's disease, the guidelines of the National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer's Disease and Related Disorders Association was followed. The severity of dementia was determined on the Clinical Dementia Rating scale. Altogether 2,096 subjects, aged 65 years and more, were included. Of them, 1,178 were normal and 918 were demented. Their performance on CASI C-2.0 was influenced by their education and age. Gender difference on CASI C-2.0 scores was only significant in the illiterate, but not in the literate group. We recommend that the population be divided into three levels, namely those who (1) had no formal education (Edu = 0); (2) received 1-5 years of schooling (Edu = 1-5), and (3) received 6 or more years of education (Edu >/=6). The cutoff scores of CASI C-2.0 in the diagnosis of dementia in these three educational groups were as follows: Edu = 0: 49/50 (sensitivity = 0.83; specificity = 0.85); Edu = 1-5: 67/68 (sensitivity = 0.83; specificity = 0.91), and Edu >/=6: 79/80 (sensitivity = 0.89; specificity = 0.90).

Aged↗