Chung-Fen Tsai

Transcranial imaging of substantia nigra hyperechogenicity in a Taiwanese cohort of Parkinson's disease

Transcranial Doppler imaging (TCDI) has been used as a noninvasive diagnostic tool to differentiate Parkinsons disease (PD) from atypical parkinsonism by detecting hyperechogenicity in the substantia nigra (SN). To our knowledge, no TCDI data are available for Asian populations, and TCDI sensitivity is uncertain across populations. Early‐onset PD (EOPD) represents a specific PD subtype based on clinical features and pathogenic mechanisms. It is not known if EOPD patients have abnormal echogenicity in SN comparable to late‐onset PD (LOPD) patients. We assessed the area of SN hyperechogenicity (hyper‐SN) and a ratio of hyper‐SN over ipsilateral midbrain (S/M ratio) with TCDI in 164 healthy Taiwanese, 40 EOPD patients, and 40 LOPD patients. The upper 95th percentile values for hyper‐SN and S/M ratio were 0.20 cm2 and 0.07. Our results indicate that S/M ratio is a more sensitive measure than hyper‐SN in diagnosing PD. Approximately 92.5% of the LOPD patients and 57.5% of the EOPD patients had S/M ratios ≥ 0.07. Enlarged hyperechogenicity of SN is a common finding in LOPD, but not in EOPD. Iron‐independent mechanisms of SN cell degeneration in EOPD distinct from that in LOPD might contribute to the sonographic findings.

Transcranial color-coded sonography helps differentiation between idiopathic Parkinson's disease and vascular parkinsonism

BackgroundRecently, transcranial color-coded sonography (TCCS) has been found to have a diagnostic value in patients with idiopathic Parkinsons disease (IPD), which displays increased hyperechogenicity at the substantia nigra (SN).ObjectiveTo use TCCS, to assess the difference in SN hyperechogenicity and intracranial hemodynamics among subjects with IPD, vascular parkinsonism (VP) and controls.MethodsEighty IPD and 30 VP patients, and 60 controls were recruited into this study. The hyperechogenicity area at the SN and midbrain were calculated by encircling the outer circumference from the ipsilateral temporal window, using TCCS in each subject. The hemodynamics of intracranial large arteries, including flow velocity and pulsatility index (PI), were also measured.ResultsThe presence of SN hyperechogenicity was significantly higher in the IPD patients than in the VP patients and controls (84% vs. 20% & 5%, respectively, p < 0.001). In IPD patients, the SN hyperechogenicity was correlated with the neurological severity and disease duration. Twenty-five (66.7%) VP patients had obvious vascular abnormality, as seen in TCCS study. The mean PI was significantly more elevated in the VP patients than those in the IPD patients and controls (all p < 0.05), but there was no significant difference of flow velocities among the VP, IPD patients and controls.ConclusionTCCS, combining B-mode imaging for SN echogenicity and trancranial Doppler for intracranial hemodynamics, is a useful diagnostic tool in the differentiation between IPD and VP. These findings also suggest that multiple subcortical vascular lesions may damage the basal ganglia and thalamocortical circuit and result in parkinsonism features in VP patients.

Clinical and ultrasonographic manifestations in major causes of common carotid artery occlusion.

Background and Purpose. Atherosclerosis is the main cause of common carotid artery occlusion in most reports. This study aimed to identify the major causes of common carotid artery occlusion and compare the clinical features and carotid duplex ultrasonography findings of patients with common carotid artery occlusion attributable to each cause. Methods. Patients with common carotid artery occlusion documented by carotid duplex ultrasonography at the Neurovascular Laboratory (National Taiwan University Hospital) from 1988 to 2003 were included. Medical records and ultrasonographic findings were reviewed in detail to clarify the possible etiology of common carotid artery occlusion. Results. A total of 44 patients (male, 27 [61%]; female, 17 [39%]; mean age, 58 years) had common carotid artery occlusion attributable to a carotid duplex ultrasonography–identifiable cause. The causes of common carotid artery occlusion included atherosclerosis (17 [39%]), Takayasus arteritis (11 [25%]), postirradiation arteriopathy (7 [16%]), cardiac embolism (6 [14%]), syphilis (1), blunt trauma (1), and homocystinuria (1). Among the patients with common carotid artery occlusion due to the 4 major causes, 27 (66%) had ischemic stroke and 14 (34%) had no symptoms or nonlocalizing symptoms. The frequency of symptomatic com mon carotid artery occlusion was 83% in those with cardioembolism, 76% in those with atherosclerosis, 71% in those with postirradiation arteriopathy, and 36% in those with Takayasus arteritis. Common carotid artery occlusion usually involved the carotid bulb and distal common carotid artery in atherosclerosis (88%) and postirradiation arteriopathy (100%), but not in Takayasus arteritis (27%). Echogenicity of occluded material was heterogeneous in atherosclerosis and post‐irradiation arteriopathy patients but homogeneous in all Takayasus arteritis patients. The authors postulate that the thrombotic mechanism might differ according to etiology. Con clusions. The causes of common carotid artery occlusion are diverse. Atherosclerosis, Takayasus arteritis, and post‐irradiation arteriopathy are the most common causes of com mon carotid artery occlusion in Taiwan. The clinical features, pathophysiology, and carotid duplex ultrasonography findings vary according to the cause of common carotid artery occlusion.

Vibrational dephasing dynamics at hydrogenated and deuterated semiconductor surfaces: Symmetry analysis

Raman scattering has been performed on single crystal hydrogenated silicon and germanium surfaces to investigate the temperature dependence of their vibrational spectral profiles. Based on a single-mode dephasing model for pure vibrational dephasing, the frequency shift and line broadening were analyzed to extract the following dephasing parameters: exchange mode frequency, coupling strength, and friction parameter. The exchange modes for the XH stretches on hydrogenated X(100) surfaces (X=Ge, Si, and C) are found to match their respective bending frequencies. The corresponding ones for hydrogenated X(111) surfaces, on the other hand, are located within the bulk phonon. This surface dependence of the exchange mode in surface vibrational dephasing dynamics is correlated with the structural relaxation and its associated symmetry variation at surfaces. It is further confirmed by the experiments performed on deuterated semiconductor surfaces. A site-symmetry induced representation method is exploited to analy...

Interaction of atomic hydrogen with a Ge(111) surface: low-energy electron diffraction and surface Raman studies

Abstract We report the preparation and characterization of a sufficiently ordered Ge(111)-1×1:H surface by prolonged hydrogenation of Ge(111)-c(2×8) at elevated temperatures. For both annealed and sputtered/annealed c(2×8) surfaces, a (1×1) pattern with distinct primary-order spots was observed by low-energy electron diffraction (LEED) after extensive hydrogenation treatment. We demonstrated that a surface Raman spectroscopic method based on polarization effects can be used successfully to characterize such a prepared Ge(111)-1×1:H surface, which is flat enough to yield a single prominent peak of the monohydride GeH stretch. The possible mechanism for surface smoothing by atomic hydrogen is also discussed. The smoothness of this surface makes various spectroscopic characterization methods feasible.

The impacts of acute carbon monoxide poisoning on the brain: Longitudinal clinical and 99mTc ethyl cysteinate brain SPECT characterization of patients with persistent and delayed neurological sequelae.

OBJECTIVE Acute carbon monoxide (CO) poisoning poses a significant threat to the central nervous system. It can cause brain injury and diverse neurological deficits including persistent neurological sequelae (PNS) and delayed neurological sequelae (DNS). The study aimed to investigate the long-term impacts of acute CO poisoning on brain perfusion and neurological function, and to explore potential differences between PNS and DNS patients. METHODS We evaluated brain perfusion using (99m)Tc ethyl cysteinate (ECD) brain single photon emission computed tomography (SPECT) and assessed clinical neurological symptoms and signs one month following acute poisoning. For DNS patients, ECD SPECT and clinical evaluation were performed when their delayed symptoms appeared. All patients had follow-up SPECT imaging, along with clinical assessments six months following poisoning. RESULTS 12 PNS and 12 DNS patients were recruited between 2007 and 2010. Clinically, the main characteristic presentations were cognitive decline, emotional instability, and gait disturbance. SPECT imaging demonstrated consistent frontal hypoperfusion of varying severities in all patients, which decreased in severity at follow-up imaging. DNS patients usually had more severe symptoms and perfusion defects, along with worse clinical outcomes than the PNS group. CONCLUSION These results suggest that acute CO poisoning might lead to long term brain injuries and neurological sequelae, particularly in DNS patients.

Reversible Vasospasm in Migrainous Infarction: A Transcranial Doppler Follow-up Study

Migraine is a common disorder in young women, but it is rarely associated with ischemic stroke. According to previous stroke registries, migrainous infarcts account for 0.5% to 1.5% of all ischemic strokes and about 10% to 14% of young ischemic strokes. 1,2 The pathophysiologic mechanism of migrainous infarction is still unclear. Here we report a patient with a migraine history in whom acute cerebral infarction developed during a migraine attack due to an arterial vasospasm, which was illustrated by serial transcranial Doppler sonography (TCD).

Neurosarcoidosis Affecting the Spinal Cord

Sarcoidosis is a chronic inflammatory disease that involves multiple systems. Complications in the nervous system are rare, especially in Asia. This report describes an unusual case of neurosarcoidosis affecting the spinal cord and other systems in a 53-year-old Taiwanese women patient. The patient presented with subacute onset of right arm radicular pain followed by quadriparesis. Magnetic resonance imaging revealed a hyperintense lesion on T2WI in the cervical spinal cord. The patient also had a history of facial neuropathy, bilateral parotid enlargement, intrathoracic lymphadenopathy, hypercalcemia, nephrocalcinosis, and renal function impairment. Parotid gland biopsy showed granulomatous lesion with multinucleated giant cells. Sarcoidosis was diagnosed after other possibilities were excluded. Oral steroid treatment resulted in initial significant clinical improvement. Awareness of the systemic and neurological presentations of sarcoidosis can prompt the correct diagnosis and treatment.

Neuropsychological performance in patients with carbon monoxide poisoning

This study investigated changes in cognitive function in acute and delayed carbon monoxide (CO) poisoning groups with comprehensive neuropsychological tests at 1 month and 6 months after therapy. For this study, 11 patients with acute and 14 with delayed CO poisoning were recruited. The neuropsychological tests included psychomotor speed, visual-spatial ability, language, logical memory, working memory, and executive function. The results showed that patients with delayed neuropsychiatric syndrome (DNS) had poorer performance on neuropsychological tasks than did those with acute CO poisoning at the 1st month and reached almost the same level as the acute group on the neuropsychological tasks at the 6-month follow-up assessment. The DNS group had more significant progress on general cognitive function, psychomotor speed, and visual-spatial ability than did the acute group after continuous hyperbaric-oxygen therapy.