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Biomedical subjects

Zin-An Wu

Publications and source records attributed to Zin-An Wu.

27 records · Page 2Linked to original sources
PubMed2004

Transcranial magnetic stimulation in patients with transient ischemic attacks.

BACKGROUND: By definition, transient ischemic attacks (TIAs) do not leave a neurological deficit beyond 24 hours after onset. However, a subgroup of TIA patients is characterized by persistent perfusion defect on single photon emission computed tomogram or infarction on brain computerized tomogram and magnetic resonance imaging. Here, we applied transcranial magnetic stimulation (TMS) to study whether TIA could produce persistent subclinical dysfunction for more than 24 hours. METHODS: The study included 23 TIA patients who had the criteria of hand weakness as one of their clinical manifestations. TMS was done twice in each TIA patient. The first time was during the period of 24-48 hours after onset and the second 7 days after onset. We studied the cortical motor threshold, the latencies and the amplitudes of the motor evoked potentials, the central motor conduction time, and the cortical silent period at the intensity of 1.5 times motor threshold with maximal voluntary isometric contraction. The recording was at the first dorsal interosseous muscle. RESULTS: There was no significant difference between the whole group of TIA patients and normal control. However, in the subgroup of TIA patients who had hand weakness more than 1 hour, they had increased motor threshold and prolonged cortical silent period during the first test. Both improved 1 week after onset. On the contrary, in TIA patients who had hand weakness less than 1 hour, their data were all within normal limits during the first and the second studies. CONCLUSIONS: Our results indicate that the motor function of TMS study will recover to full if the motor symptoms subside within 1 hour in TIA patients. Subclinical motor deficits may persist in TIA patients who have motor symptoms more than 1 hour.

Aged↗
PubMed2003

Use of CT angiography in patient selection for thrombolytic therapy.

It has been shown that thrombolytic therapy can improve clinical outcome in some patients with acute cerebral ischemia. These patients have been reported to be characterized by certain clinical and imaging findings, mainly with non-contrast enhanced computed tomography (CT). Our purpose in this study was to find out whether CT angiography (CTA) information about the status of the cerebral vessels is helpful in the selection of patients who may benefit the most from thrombolytic therapy for acvte cerebral ischemia. CTA was prospectively performed in 15 consecutive patients (6 women and 9 men; age range 44-83 years) with moderate or severe symptoms of hyperacute cerebral ischemia. The clinical manifestations of the patient's condition and the findings on CTA were analyzed. Three-dimensionally reconstructed CTA images of diagnostic quality could be obtained for all 15 patients. Of the 15 patients 14 had a vessel occlusion identified on CTA, which was consistent with and/or helpful for making the clinical diagnosis in all 14 cases; one patient had an aneurysm of the anterior communicating artery without detectable hemorrhage on CTA. Although a thrombolytic agent was not given because of CTA evidence of intracranial aneurysm, the patient nevertheless developed a massive subarachnoid hemorrhage during hospitalization. Ischemic symptoms reversed after CTA and before the initiation of thrombolytic therapy in 2 patients whose CTAs showed occlusion of secondary branch of the middle cerebral artery (MCA). CTA can provide important information before the initiation of thrombolytic therapy. Identification both of the occluded vessel and of an intracranial aneurysm is feasible with the use of CTA, which is particularly important if the intracranial aneurysm is a potential contraindication to thrombolytic therapy. Occlusion of a secondary branch of the MCA and internal carotid artery occlusion are valuable prognostic predictors.

Adult↗
PubMed2003

Differential effects of stimulus intensity on peripheral and neuromagnetic cortical responses to median nerve stimulation.

To study the differential effects of tactile stimulus intensity on cortical and peripheral responses, we measured neuromagnetic cortical responses, compound muscle action potentials (CMAP), sensory nerve action potentials (SNAP), and the subjective estimation of tactile magnitude to electric median nerve stimulation at the wrist in 13 male healthy adults. The sensory perception threshold (ST) for electric pulses at wrist skin was determined and then various levels of stimulus intensity (1 approximately 6 ST) were given to each subject. At 1 ST, only the P50m components of the primary somatosensory (SI) cortical responses were recorded. The second somatosensory (SII) cortical responses were saturated at 2 ST, while the SI responses reached maximum at 3 ST equivalent to the subjective threshold intensity for "strong" tactility. The CMAP and SNAP were maximum at 4-5 ST. At 2 ST, >70% of maximum SI responses were produced, whereas only <40% of maximum CMAP or SNAP responses were obtained. We concluded that the stimulus intensities for activating or saturating somatosensory cortical responses were lower than those for CMAP and SNAP. The differential intensity effects on cortical and peripheral responses suggest a polysynaptic organization underlying the central amplification for somatosensory cortical activation. The optimal intensity levels for producing maximum SI and SII responses were 3 and 2 ST, respectively. Compared with the SII, the SI plays a crucial role in the coding of the tactile stimulus intensity.

Action Potentials↗
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

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.

Adult↗
PubMed2003

Diameter of the superior ophthalmic vein in relation to intracranial pressure.

BACKGROUND AND PURPOSE: Bilateral engorged superior ophthalmic veins (SOV) have been reported in patients with diffuse brain swelling. We investigated the relationship between the diameter of the SOV on brain MR images and the intracranial pressure (ICP). METHODS: We reviewed the medical records of neurologic inpatients who had undergone both MR imaging of the brain and lumbar puncture. MR imaging had to have been performed before lumbar puncture, and the two studies had to have occurred within 2 days. The diameters of the SOV were measured on coronal contrast-enhanced fat-saturated T1-weighted MR images. For this, the image nearest the rear of the globe of the eye was chosen. RESULTS: Sixty-nine patients (32 male, 37 female; mean age, 46 years +/- 19) were included. The average diameters of the SOV and the ICP were positively correlated (r = 0.58, P <.001), if an SOV diameter of <1 mm was treated as 0.5 mm for calculations. In patients with increased ICP (CSF pressure >200 mm H(2)O), SOV diameters were larger than those of patients with a normal CSF pressure (3.0 vs 1.6 mm, P <.001). Frequencies of increased ICP were 3% among patients with an average SOV diameter of 0.5-1 mm, 15% for 1.5-2 mm, and 58% for 2.5-5 mm (P <.001). CONCLUSION: This study showed that the SOV diameter, determined on the basis on MR imaging, was positively correlated with ICP. Dilatation of the SOV should alert physicians to the possibility of increased ICP.

Adult↗
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↗
PubMedDate not supplied

Transcranial magnetic stimulation after conditioning stimulation in two adrenomyeloneuropathy patients: delayed but facilitated motor-evoked potentials.

Two male patients were diagnosed with adrenomyeloneuropathy. Their chief problems were progressive spastic paraparesis, sensory impairment, hyperpigmentation and testis atrophy. Transcranial magnetic stimulation (TMS) does not easily elicit motor-evoked potentials (MEPs) in patients with a central nervous system dysfunction, even though a few methods, such as contraction of the target muscles and the Jendrassik maneuver (JM), are used in the attempt to facilitate them. In these two patients, we used a conditioning method (prior electrical stimulation over the cutaneous nerve of the left index finger) in order to facilitate MEPs, elicited by TMS, in the left tibialis anterior muscle. In patient 1, facilitation of MEPs was present at conditioning-test (C-T) intervals in the range 60-220 ms, with the maximal MEP recorded at C-T 160 ms; in patient 2, it occurred in the C-T interval range 110-140 ms, with the maximal MEP recorded at C-T 130 ms. By means of conditioning electrical stimulation, we can facilitate MEPs elicited by TMS in those subjects in whom MEPs are minimal or difficult to elicit even using the conventional JM or muscle contraction. The facilitation of MEPs by conditioning stimuli allowed us not only to assess central motor conduction time, but also to demonstrate the preserved continuity of the corticospinal tract in these two patients.

Adrenoleukodystrophy↗