PubMed Health⌕ Search

Biomedical subjects

Z A Wu

Publications and source records attributed to Z A Wu.

At least 19 recordsLinked to original sources
PubMed2003

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.

Child↗
PubMed2003

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.

Adolescent↗
PubMed2001

Brain dysfunction explored by long latency reflex: a study of adrenomyeloneuropathy.

OBJECTIVES: We can assess brain function by measuring the cortical relay time (CRT) of long latency reflex (LLR) of hand muscle. We would study if measurement of CRT of LLR can explore the brain involvement of adrenomyeloneuropathy (AMN). METHODS: Two AMN patients were included in the study. Both of them had spastic gait and mild sensory deficits but normal mental function. The LLRs were provoked at the first dorsal interosseous muscle by electrical stimulation of the middle finger. We measured the latency of LLR and its CRT. RESULTS: Delayed LLR and prolonged CRT were noted in AMN patients, even though the magnetic resonance imaging of brain did not show any significant abnormalities. CONCLUSIONS: Measuring CRT of LLR reveals brain involvement of AMN patients, and it is an adjunct in the assessment of brain function though without specific anatomic diagnosis.

Adrenoleukodystrophy↗
PubMed2000

Modulation of symptomatic palatal tremor by magnetic stimulation of the motor cortex.

OBJECTIVES: Magnetic stimulation of the motor cortex can be used to determine the involvement of the cortex in rhythmic movement disorders. Symptomatic palatal tremor (SPT) is thought to come from a pacemaker that is relatively resistant to internal and external stimulation. In this study, we investigated the effect of magnetic stimulation of motor cortex on SPT. METHODS: Five male patients, aged 67-79 years, with SPT after brain stem infarction or hemorrhage, all had a synchronous mouth angle twitch with the palatal movement. Electromyographic activity was recorded with a monopolar needle electrode from orbicularis oris. In experiment 1, transcranial magnetic stimulation (TMS) was delivered at 200% motor threshold (MT) to reset SPT. In experiment 2, the effect of TMS intensities was studied at 80-240% MT in two SPT patients. To determine the influence of the TMS, we used the resetting index (RI). RESULTS: TMS reset the tremor in all 5 SPT patients at 200% MT with RIs of 0.86-0.96. The latency of the tremor reappearance after TMS was longer than the pre-stimulus tremor interval, and the intervals between the subsequent tremor bursts were also prolonged. The degree of tremor resetting was closely correlated with the magnetic stimulus intensity and the latency of the tremor reappearance after TMS. CONCLUSIONS: Stimulation of the motor cortex may modulate the generator of SPT.

Aged↗
PubMed2000

Problem-based, small-group tutorial learning in clinical neurology for second-year medical students.

BACKGROUND: Problem-based learning (PBL) in small-group tutorials has been a trend in medical education. Chinese students are known to be reserved and passive; thus, they may not be adaptable to PBL. Neuroanatomy, important to clinical neurology, is difficult to learn. We incorporated clinical neurology with PBL, complementary to the traditional neuroanatomy curriculum, to evaluate the feasibility of PBL for Chinese students in Taiwan. METHODS: Forty-two second-year medical students and seven tutors participated in the clinical neurology PBL small-group tutorials. Twelve case reports were discussed weekly beginning in February, 1999. Each case was designed to meet the progressive curriculum of the neuroanatomy course. The tutors evaluated the students by the degree of their preparation, participation, key-point comprehension and interaction. All tutors and students filled out questionnaires at the end of each session. RESULTS: The majority of the students and tutors agreed that the case materials were clearly written. Ninety percent of the students agreed that the case materials matched the traditional content of neuroanatomy. Eighty-five percent of students and 71% of tutors were satisfied and found the class rewarding. Ninety-one percent of students and 74% of tutors were in favor of PBL being continued. CONCLUSIONS: This preliminary PBL, small-group tutorial learning in clinical neurology showed satisfactory results and was, indeed, complementary to a traditional neuroanatomy course. The students, as early as during the second year of their medical school education, were able to learn through the PBL. More integration of basic and clinical sciences by PBL may be considered in future curricula designs.

Education, Medical↗
PubMed1999

Transient elevation in plasma prolactin level in rats with temporal lobe status epilepticus.

Microinjection of kainic acid into the CA3 subfield of hippocampus in anesthetized rats elicited seizure-like hippocampal EEG activity that persisted for more than 180 minutes. There was a concomitant rise in plasma prolactin level that peaked at 15 to 20 minutes but endured less than 60 minutes. We conclude that plasma prolactin exhibited only transient elevations during experimental temporal lobe status epilepticus in rats.

Animals↗
PubMed1999

Effect of stimulation of an upper limb on motor evoked potentials in lower limb muscles to transcranial magnetic stimulation in normal subjects and patients with thalamic infarction.

The effects of conditioning stimulation of an upper limb on motor evoked potentials (MEPs) of relaxed muscles in both lower limbs were studied in 7 normal subjects and two patients with left thalamic infarction. A possible mechanism for the Jendrassik maneuver (JM) is that induced proprioceptive input ascends supraspinally to facilitate the descending volleys. In order to mimic the JM with a more controlled influence, we used an electrical conditioning (C) stimulation (4 times sensory threshold) delivered to the left index finger preceding the transcranial (T) magnetic stimulation at C-T intervals of 0-200 ms. The MEP facilitation of bilateral tibialis anterior (TA) and gastrocnemius medialis (GC) was within C-T 70-110 ms. The peak facilitation was at C-T 80 ms for ipsilateral TA (309%) and GC (405%) and at C-T 90 ms for contralateral TA (207%) and GC (283%). In the two thalamic infarction patients with right-sided sensory loss, the facilitation did not occur when the conditioning stimulation was delivered to the affected index finger. Therefore, it is likely that the peripheral volley must be transmitted supraspinally to facilitate MEPs of the lower limbs. This method for studying sensory facilitation is more quantitative and reproducible than the JM and technically better than other previously described methods for somatosensory conditioning.

Adult↗
PubMed1999

Botulism: heart rate variation, sympathetic skin responses, and plasma norepinephrine.

BACKGROUND: Botulism may involve the autonomic nervous system. METHODS: We assessed the autonomic function of 6 botulism patients with heart rate variations, sympathetic skin responses, and plasma norepinephrine. RESULTS: Two weeks after onset, all the patients had absent sympathetic skin response in the palm and sole. Compared with controls, the heart rate variation of botulism patients was significantly decreased at rest (3.1 +/- 1.2% vs. 20.9 +/- 2.0%, p = 0.0018) and during deep breathing (4.3 +/- 2.3% vs. 29.7 +/- 2.6%, p = 0.0018). The botulism patients had significantly lower plasma norepinephrine levels (supine 29.2 +/- 10.1 pg/ml vs. 257.5 +/- 65.8 pg/ml, p = 0.0018; standing 40.3 +/- 13.1 pg/ml vs. 498.5 +/- 85.6 pg/ml, p = 0.0018). The heart rate variation and sympathetic skin response was greatly improved 6 months after onset. CONCLUSIONS: Heart rate variation, absence of sympathetic skin response, and low plasma norepinephrine are all manifestations of autonomic dysfunction in botulism patients.

Adult↗
PubMed1998

Cutaneous reflexes in patients with acute lacunar infarctions.

Cutaneous reflex (CR) was measured in 15 patients with acute lacunar stroke and in 15 age- and sex-matched normal subjects. EMG activities were recorded from the first dorsal interosseous muscle with surface electrodes, rectified and averaged. Intensity of the stimulation on the index finger was four times the sensory threshold. Aided by audio- and visual-feedback monitoring, the subjects abducted the index finger. Side-to-side comparison was made on all the subjects. CR abnormalities were found in all of our patients. The early inhibitory (I1) and second excitatory (E2) components were attenuated in 11 of 15 patients. The I1-E2 interpeak amplitude (A2) was significantly reduced in all the patients. Prolonged latency of I1-E2 components was found to be pronounced in six of eight patients with sensory symptoms. Eight patients were followed up 1 month later. By that time, the abnormal CR had reversed to some degree in all of them. CR alternation was still present in two fully recovered patients. Our results implied a thalamic relay in the afferent limb of the CR. CR could be a valuable adjunct for assessing long tract dysfunction and monitoring functional recovery.

Aged↗
PubMed1998

Prevalence and subtypes of dementia in a rural Chinese population.

We conducted a single-stage community-based study of dementia on all registered residents > or =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 > or =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.

Aged↗
PubMed1998

Conditioning effect on the long latency potentials in the lower limb to transcranial magnetic stimulation.

OBJECTIVES: We used an electrical conditioning stimulation followed by transcranial magnetic stimulation (TMS) to facilitate the occurrence of long latency potentials (LLPs) in order to study the relationship between primary motor evoked potentials (MEPs) and LLPs in the lower limbs. MATERIALS AND METHODS: The study group included 6 healthy subjects, 1 patient with right thalamic infarction, and 3 patients with spinal cord injuries. The subjects were subjected to electrical conditioning (C) stimulation delivered to the left big toe at 250 Hz in a train of pulses of 20 ms duration prior to TMS (T) from 0 to 150 ms at an increment of 10 ms. The surface electromyographic signals were recorded at the tibialis anterior and gastrocnemius medialis for 400 ms. RESULTS: The C-T test facilitated both primary MEPs and LLPs with a pattern similar to the primary MEPs of its antagonist. There was no facilitation of the primary MEPs or LLPs in the affected limb of patients with thalamic or spinal cord lesions. CONCLUSION: At appropriate C-T interval, LLPs could be consistently provoked by TMS. The LLPs were absent in the patients with thalamic infarction and spinal cord injuries. It suggests that LLPs might be provoked through a supraspinal control.

Adult↗
PubMed1998

Long latency responses in pure sensory stroke due to thalamic infarction.

OBJECTIVES: Our study was designed to clarify the role of the thalamus in the generation of the electrically elicited long-latency reflexes (LLR) in voluntarily activated hand muscles. MATERIALS AND METHODS: EMG responses of the thenar muscles were evoked by electrical stimulation of the median nerve at the wrist at motor threshold intensity in 10 patients with acute pure sensory stroke due to thalamic infarction. Concomitant recording of somatosensory evoked potentials (SEPs) was performed. The subjects were asked to steadily abduct the thumb at 20-30% of maximal force against a force transducer. Rectified and averaged EMG activities were recorded. RESULTS: The LLR II was missing completely or significantly attenuated in the majority of the patients (9 of 10), of whom 3 also had delayed latency. Abnormal SEPs were documented in 7 patients (7 of 10). In the follow-up, 5 patients had partial reversal of LLR II. LLR II was still pathological in 1 fully recovered patient. CONCLUSION: Our results further confirm the transcortical generation of LLR II and imply that a thalamic relay is present in the afferent limb of the LLR.

Adult↗
PubMed1997

Functional connectivity of the transected brachial plexus after intercostal neurotization in monkeys.

Microsurgical reconstructions of brachial plexuses were performed on twelve monkeys by using ipsilateral intercostal nerves (T3-9). Reinnervation in individual nerves was evaluated monthly by observations of neuromuscular and electromyographic improvements. The electromyographic studies revealed reappearance of motor unit potentials. According to a motor scale ranging from 0 to 4, the mean muscle power 6 months after operation improved to 2.75 in the deltoid muscles, 2 in the biceps muscles, 1.22 in the triceps muscles, 1.13 in the flexor carpi radialis muscles, and 1.6 in the intrinsic muscles of the hands. Retrograde transport of horseradish peroxidase (HRP) from the neuromuscular junctions of the reconstructed musculocutaneous nerves 6 months after complete brachial plexus lesion in four animals demonstrated HRP-labeled neurons in the anterior horns, spinal ganglia and sympathetic ganglia of the thoracic spinal cords. It suggested that the regenerated afferent and efferent circuits in the thoracic cords innervating the transected brachial plexuses were able to generate the movements in the paralyzed upper limbs. However, as evidenced by the behavior patterns and the fact that retrograde-labeled neurons were all found in the thoracic cords, the novel movements observed in the reconstructed brachial plexuses were in synchrony with respiration. These results suggested that the plasticity of central neural networks is limited between two widely separated areas, such as between the midcervical and midthoracic motor cortical areas in the present studies, and therefore, the efforts to reconstruct neural networks, both centrally and peripherally, should aim at rebuilding situations as nearly to the original status as possible.

Animals↗
PubMed1997

Genetic screening for Huntington's disease in Chinese patients with involuntary movements.

The diagnosis of Huntington's disease (HD) can be confirmed by detecting the expanded CAG repeat in the IT15 gene. Besides chorea, patients with HD may present with a variety of bizarre involuntary movements, resulting in confusion in making the diagnosis. Under such conditions, genetic analysis is the final confirmatory test. To determine if any patient with involuntary movements of undetermined etiology might be related to HD, we did genetic analysis on 22 patients and identified three with expanded CAG repeat. We could not obtain family history of HD in these patients due to adoption, early death of parents, or a vague history. All three patients were among the group with generalized chorea, but one had additional marked dystonic posturing. Together with four clinically recognizable HD patients, the relative frequency of HD among the 103 patients with choreiform movements in this hospital is 6.8%.

Adult↗
PubMed1997

Relationship between mesial temporal seizure focus and elevated serum prolactin in temporal lobe epilepsy.

We evaluated the relationship between mesial temporal seizure focus and serum prolactin (PRL) in patients before and after they underwent anterior temporal lobectomy (ATL) for medically intractable temporal lobe epilepsy (TLE). These patients had a confirmed unilateral epileptogenic focus in mesial temporal structures, a postictal rise in serum PRL 15 to 20 minutes after onset of complex partial seizures, and were refractory for more than 2 years to antiepileptic drugs. Presurgical interictal serum PRL levels were significantly elevated (16.47 +/- 0.85 ng/mL, n = 62) and declined after ATL to normal values (patients, 9.63 +/- 0.55 ng/mL, n = 54; normal subjects, 8.99 +/- 0.57 ng/mL, n = 52). Serial evaluations indicated that normalization was seen 3 months after surgery (9.42 +/- 1.22 ng/mL, n = 9). The postsurgical reduction in serum PRL was similar in men and women, in patients with epileptogenic focus on either side of mesial temporal structures, and was unaffected by antiepileptic medication. We conclude that PRL is elevated following seizures and that a seizure focus in mesial temporal structures may exert a sustained excitatory influence on PRL release in patients with medically intractable TLE.

Adolescent↗
PubMed1996

Myasthenia gravis complicated with hyperthyroidism, thymoma and serological evidence of systemic lupus erythematosus: a case report.

A 55-year-old woman with a several-decade history of thyroid goiter is presented here as a case of myasthenia gravis complicated with hyperthyroidism and thymoma with serological evidence of systemic lupus erythematous (SLE). She had had right eyelid ptosis since July 1992, with a positive tensilon test. The acetylcholine receptor antibody titer was 4.01 nmol/L. A thyroid function test revealed T3: 162 ngidl, T4: 14.98 micrograms/dl, TSH:0.09 microIU/ml and positive anti-microsomal antibody (1:400). An MRI of the chest showed a thymoma in the left thymus. Other autoantibody screenings include ANA (1:320, speckled pattern) and anti-ds DNA (+) suggesting a serological association with SLE. After three courses of plasmapheresis, she received an extended maximal thymomectomy and a subtotal thyroidectomy. She was then treated with prednisolone, Mestinon, Eltroxin and discharged without complications. The coexistence of myasthenia gravis, hyperthyroidism, thymoma and a serological evidence of SLE have not previously been documented in the literature.

Female↗
PubMed1994

Sympathetic skin response and R-R interval variation in chronic uremic patients.

Sympathetic skin response (SSR) and R-R interval variation (RRIV) were studied in 36 chronic, nondiabetic uremics to compare with their nerve conduction studies (NCS) and clinical dysautonomia. Abnormal SSR was noted in 5 (13.9%) patients, abnormal RRIV in 14 (38.9%), and abnormal NCS in 26 (72.2%). The patients were classified into three groups: group (GP) 1: "normal," n = 21 (58.3%), normal RRIV and SSR; GP 2: "isolated parasympathetic dysfunction," n = 10 (27.8%), abnormal RRIV and normal SSR; and GP 3: "sympathetic sudomotor dysfunction," n = 5 (13.9%), abnormal SSR. A significant difference in age was found among the three groups (GP 3 > GP 2 > GP 1; P < 0.0001, ANOVA). After controlling the age factor, we still noted a tendency toward increasing NCS disturbances (distal latency and nerve conduction velocity of peroneal nerve; P < 0.05, multiple regression analysis) and frequencies of clinical autonomic symptoms (postural dizziness and impotence; P < 0.05, Mantel-Hanszel test) from GP 1 to GP 3. Patients with abnormal SSR (GP 3) displayed significantly higher frequencies of postural dizziness and impotence, indicating the relationship between an absence of SSR and clinical dysautonomia.

Aged↗