Zin-An Wu

Prevalence and subtypes of dementia in a rural Chinese population.

We conducted a single-stage community-based study of dementia on all registered residents ≥65 years in age in a rural Chinese community. Neurologists conducted semistructured interviews and examined all participants; they also interviewed family members in cases where dementia was suspected. The diagnosis was made by consensus according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders. 3rd ed, revised (DSM-III-R). Among the 2,055 contacted individuals, 1,736 (84.5%) participated in the study and 44 (13 men and 31 women) were diagnosed as having dementia, including 35 (80%) with probable Alzheimer disease (AD) and 3 (7%) with vascular dementia (VsD). The rates of dementia were 0.5% for ages 65–74 years, 2.9% for ages 75–84 years, and 12.0% for ages 85–101 years. The overall rate was 2.5% for age 65 years. After controlling for age, neither a lack of formal education nor being a woman was a risk factor for dementia. At 2-year follow-up, 30 of the 44 demented participants had died, yielding a 2-year survival rate of 32%. The present results corroborated our previous findings of lower prevalence rates of dementia among the Chinese than among Western populations, and both genetic and sociocultural factors may have contributed to the low rates. The lack of neuroradiological imaging studies in the present study may have contributed to the finding of an unusually low rate of VsD.

Magnetoencephalographic yield of interictal spikes in temporal lobe epilepsy: Comparison with scalp EEG recordings

To compare magnetoencephalography (MEG) with scalp electroencephalography (EEG) in the detection of interictal spikes in temporal lobe epilepsy (TLE), we simultaneously recorded MEG and scalp EEG with a whole-scalp neuromagnetometer in 46 TLE patients. We visually searched interictal spikes on MEG and EEG channels and classified them into three types according to their presentation on MEG alone (M-spikes), EEG alone (E-spikes), or concomitantly on both modalities (M/E-spikes). The M-spikes and M/E-spikes were localized with MEG equivalent current dipole modeling. We analyzed the relative contribution of MEG and EEG in the overall yield of spike detection and also compared M-spikes with M/E-spikes in terms of dipole locations and strengths. During the 30- to 40-min MEG recordings, interictal spikes were obtained in 36 (78.3%) of the 46 patients. Among the 36 patients, most spikes were M/E-spikes (68.3%), some were M-spikes (22.1%), and some were E-spikes (9.7%). In comparison with EEG, MEG gave better spike yield in patients with lateral TLE. Sources of M/E- and M-spikes were situated in the same anatomical regions, whereas the average dipole strength was larger for M/E- than M-spikes. In conclusion, some interictal spikes appeared selectively on either MEG or EEG channels in TLE patients although more spikes were simultaneously identified on both modalities. Thus, simultaneous MEG and EEG recordings help to enhance spike detection. Identification of M-spikes would offer important localization of irritative foci, especially in patients with lateral TLE.

Theta oscillation during auditory change detection: An MEG study

To study the phase and power characteristics of brain oscillations during the preattentive detection of auditory deviance, we recorded magnetoencephalographic responses in 10 healthy subjects with an oddball paradigm. As the subject was watching a silent movie, standard tones (1000-Hz frequency, 100-ms duration) and their duration deviants (50-ms duration, probability of 15%) were randomly delivered binaurally. In addition to localizing the magnetic counterpart of mismatch negativity (MMNm) with equivalent current dipole modeling, we also measured the phase-locking value (PLV) and power change of the oscillatory responses to standard and deviant stimuli by employing the Morlet wavelet-based analysis. The MMNm signals peaking at 150-200ms after the onset of deviant were localized in bilateral temporal regions with larger amplitudes in the right hemisphere. Then 50ms after the onset of either standard or deviant stimuli, we observed an increase of PLV and power of theta and alpha oscillations in bilateral temporal regions. PLVs of theta and alpha activities to deviant stimuli were significantly larger in the right than left hemisphere (P<0.001). Compared with standard stimuli, deviants elicited a larger theta PLV (P<0.001) at 150-300ms and a larger theta power change (P<0.05) at 50-300ms for the responses in the right temporal region. In addition, a prominent theta phase-locking of deviant-elicited responses was found in the right frontal area at 110-250ms (P<0.01). Our current data suggest that a pronounced phase and power modulation on sound-elicited theta oscillations might characterize the change detection processing in the temporo-frontal network as reflected by the mismatch negativity.

Bathing headache: a variant of idiopathic thunderclap headache.

Bathing headache is rarely described in literature. We report four middle-aged Taiwanese women who developed severe throbbing headache with maximum intensity of onset during bathing. Diffuse cerebral vasospasm was demonstrated in one of them. All their headaches resolved spontaneously (n = 1) or after nimodipine treatment (n = 3). Except for one patient with vasospasm in whom reversible posterior leukoencephalopathy and an asymptomatic cerebellar infarction developed, the others recovered without any complications. The clinical profile of bathing headache points to idiopathic thunderclap headache. It may not be as benign as previously reported. Nimodipine might be effective in treatment of this special headache syndrome.

Bath‐related thunderclap headache: a study of 21 consecutive patients

We consecutively recruited 21 patients (all women, mean 54 ± 8 years) with bath-related thunderclap headache (BRTH). Thirteen of them were in menopause, two had just ceased hormonal therapy, and one was at 3 months postpartum. Bathing was the initial trigger for thunderclap headaches in nine patients (43%). Many patients (n = 15, 71%) had other non-bath-related attacks. Most patients (n = 18, 86%) reported that the headache occurred immediately when water was sprayed over their body, with warm water (52%) as the most common. During the disease course [mean 14 days (6-34)], the mean number of BRTH was 5.1 ± 3.6 attacks. Nineteen patients (90%) changed bathing habits to prevent attacks. Thirteen patients (62%) had magnetic resonance angiography vasoconstrictions, and two of them (15%) developed reversible posterior encephalopathy. None of the patients without vasoconstrictions had this complication. Nimodipine was effective in stopping further attacks in 84% (16/19) treated patients. No relapse was reported at a mean follow-up of 30 months. BRTH occurred exclusively in women and predominantly in middle age. Deficiency or fluctuation of female sex hormones may play a role. About 60% patients showed cerebral vasospasms, fulfilling the diagnosis of reversible cerebral vasoconstriction syndrome and indicating a risk of posterior encephalopathy.

Collapsed superior ophthalmic veins in patients with spontaneous intracranial hypotension.

The authors measured the average diameter of bilateral superior ophthalmic veins (SOV) in 13 patients with spontaneous intracranial hypotension (SIH) on contrast-enhanced, coronal, T1-weighted MRI. Compared with sex- and age-matched neurology inpatients with normal CSF pressure, the SIH group had a smaller SOV diameter (0.90 vs 1.85 mm, p < 0.001), which partly reversed after treatment (1.09 vs 0.90 mm, p = 0.045, n = 7). Collapsed SOV might provide an additional MRI finding for SIH.

MEG localization of rolandic spikes with respect to SI and SII cortices in benign rolandic epilepsy.

The purpose of this study was to study the relationship between interictal spike sources and somatosensory cortices in benign rolandic epilepsy of childhood (BREC) using a whole-scalp neuromagnetometer. We recorded spontaneous magnetoencephalography (MEG) and EEG signals and cortical somatosensory-evoked magnetic fields (SEFs) to electric stimulation of the median nerve in 9 children with BREC. Interictal rolandic discharges (RDs) and SEFs were analyzed by equivalent current dipole (ECD) modeling. Based on the orientation and locations of corresponding ECDs, we compared generators of RDs with primary (SI) and second somatosensory cortices (SII). Our results showed that RDs and SII responses had similar ECD orientation on the magnetic field maps. The ECDs of RDs were localized 15.3 +/- 1.9 and 12.2 +/- 2.8 mm anterior to SI and SII, respectively. The spatial distance on average from the location of RDs to SII (21.9 +/- 1.6 mm) cortex was significantly shorter than to SI cortex (29.7 +/- 1.7 mm) (P<0.01, Wilcoxon signed-rank test). In conclusion, the cortical generators for RDs in patients with BREC are localized in the precentral motor cortex, closer to hand SII than to SI cortex.

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.

Generalized Neuropathy in Taiwan: An Etiologic Survey

From July 1988 to June 1989, the etiology was registered of 520 patients with generalized neuropathy in 5 neurological centers in Taiwan. The neuropathy was diabetic in 256 cases (49.23%), alcoholic in 45 (8.65%), inflammatory in 34 (6.53%; including 21 with acute inflammatory demyelinating polyneuropathy, 12 with chronic inflammatory demyelinating polyneuropathy, and 1 with chronic relapsing polyneuropathy), 12 with associated malignancy (2.31%), 9 with dysproteinemia (1.73%), uremic in 22 (4.23%), hereditary motor and sensory in 22 (4.23%), toxic in 14 (2.69%), ischemic in 12 (2.31%), hypothyroidism in 10 (1.92%), nutritional deficiency and malabsorption in 6 (1.15%), chronic liver disease in 4 (0.77%), other diseases in 11 (2.12%) and unclassified in 63 (12.12%). This survey provided a crude etiological picture of generalized neuropathy on this island.

Guillain–Barré syndrome coexisting with pericarditis or nephrotic syndrome after influenza vaccination

A 68-year-old woman and a 72-year-old man presented with distal weakness of the limbs and numbness following an influenza vaccination within 2 weeks. Moreover, Guillain-Barré syndrome (GBS) was diagnosed in two patients. Pericarditis was diagnosed in the first patient who also had precordial chest pain with referral to trapezius ridge, and nephrotic syndrome, was observed in the second patient who had leg edema and proteinuria. The relationship among GBS, pericarditis and nephrotic syndrome after an influenza vaccination is discussed.