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Biomedical subjects

P H Tchen

Publications and source records attributed to P H Tchen.

9 recordsLinked to original sources
PubMed1992

Motor-evoked potentials in diabetes mellitus.

By using magnetic stimulation of the motor cortex and in the cervical region, conduction time in the central motor pathway was measured in 35 patients with diabetes mellitus (DM) and in 41 control subjects. Motor-evoked potentials (MEPs) were recorded from the contralateral thenar muscles. Central conduction time (CCT) was obtained by subtracting the latency of the spinal MEP from that of the scalp MEP. To compare central and peripheral nerve functions, the motor nerve conduction velocity (MCV) of the median nerve was also tested in patients with DM. In the 35 cases of DM, the mean latency of the cortical MEPs showed a significant increase, compared with normal controls; the mean CCT was also significantly prolonged in the patient group. There was a good correlation between central motor abnormalities and the duration of DM, as well as with impairment of the peripheral nervous system. Latencies of greater than two standard deviations were defined as abnormal. The abnormal rate in patients with DM was 29% for latency of the cortical MEP, 20% for latency of the cervical MEP and 37% for the CCT. In addition, there was a 35% abnormal rate for distal latency of the median MCV and a 40% abnormal rate for the median MCV. These findings support the theory that the metabolic disturbance in DM affects both the central and peripheral nervous systems in man. MEP studies provide objective measurements of central motor pathways.

Adult↗
PubMed1992

The relation between motor evoked potential and clinical motor status in stroke patients.

Forty-one stroke patients and 41 normal controls of matched age, sex and body height were studied by magnetic stimulation of the motor cortex and lower cervical area. The cortical and cervical motor evoked potentials (MEPs) were detected from the abductor pollicis brevis muscle. The amplitudes and latencies of cortical MEPs, central conduction time (CCT), and interside difference of bilateral CCT (DCCT) in stroke patients showed significant difference in comparison with normal controls. The degree of motor weakness was statistically correlated with the severity of cortical MEP findings, but not with the deep tendon reflex and Babinski sign. The abnormal rate of cortical MEP was higher in patients with hemorrhage than in those with infarction. Six out of 17 patients with hemorrhage had prolonged CCT or DCCT, but only 3 out of 24 patients with infarction had the same findings. The cortical MEP findings in putaminal hemorrhage were more severe than in thalamic hemorrhage. In instances of infarction involving total middle cerebral artery territory (cortical and subcortical areas), the cortical MEP was absent in all cases (4/4). It was concluded that cortical MEP findings in stroke patients examined by magnetic stimulation showed good correlation both with the lesion radiologically and the motor deficit clinically. This is an acceptable method for quantitative evaluation of motor system function in stroke.

Adult↗
PubMed1991

n-Hexane polyneuropathy in a ball-manufacturing factory.

Five overt and two occult cases of n-hexane polyneuropathy occurred in a ball-manufacturing factory in Taiwan. The severity of polyneuropathy was directly related to the index of n-hexane exposure that occurred during the processes of cement coating and nylon fiber winding in a poorly ventilated room. The n-hexane concentrations over eight hours of personal sampling of the air of the cement coating and nylon fiber winding areas were 109 ppm and 86 ppm, respectively. After installation of a new factory ventilation system, these seven patients recovered completely, and there were no new cases in the two-year follow-up.

Adult↗
PubMed1990

Vibratory perception threshold in diabetic neuropathy.

A total of 263 diabetic patients and 129 normal controls were enrolled in a study of vibratory perception threshold (VPT) using an electromagnetic vibrometer at two sites, the dorsum of the metacarpal bone of the index finger (IF) and the dorsomedial aspect of the metatarsal bone of the great toe (GT). The results showed that the mean values of VPT for both IF and GT were significantly higher in diabetics than in normal subjects. In both control and diabetic groups, the VPT values at GT only were elevated with increasing age. Furthermore, the mean VPTs at both IF and GT were related to the duration of illness and the severity of diabetes mellitus in the patient group. Eighty cases of diabetes mellitus received nerve stimulation tests including motor and sensory nerve conduction velocities of the upper and lower limbs. The results from these cases demonstrated good correlation between VPT and motor conduction velocity (MCV), but not between VPT and sensory conduction velocity (SCV). There was a negative correlation between VPT at IF and median MCV (p less than 0.0005) in the upper limbs, as well as VPT at GT and tibial MCV (p less than 0.0005) in the lower limbs. For clinical applications, VPT values seemed to be more sensitive than MCV in detecting neuropathic change in diabetic patients. Hence, impairment of vibratory perception can be taken as a subtle clinical sign of diabetic neuropathy, and measurement of VPT can be used as an index of a patient's current subclinical state.

Adolescent↗
PubMed1990

Secondary prevention of ischemic stroke with low dose acetylsalicylic acid.

In order to evaluate the efficacy of low dose acetylsalicylic acid (ASA) for the secondary prevention of ischemic stroke, this cooperative multicenter clinical trial was conducted on a non-blind basis. Patients having a first transient ischemic attack (TIA), reversible ischemic neurological deficit (RIND) or completed ischemic stroke were eligible for this trial. A total of 590 patients including 47 cases of TIA, 23 cases of RIND and 520 cases of completed stroke entered this study. These patients were allocated by the time of admission to one of the following 5 trial regimens: (1) vasodilators having no known inhibitory effect on platelet function (control group), (2) dipyridamole (DP) 50 mg 3 times a day (DP group), (3) ASA 300 mg once a day (ASA 300 mg group), (4) ASA 300 mg once in combination with DP 50 mg 3 times a day (ASADP group), and (5) ASA 100 mg once a day (ASA1 group). No difference in effect between the control and DP groups was observed, nor between the ASA 300 mg and ASADP groups. Therefore, we combined the control and DP groups to make a non-ASA group, and joined the ASA 300 mg and ASADP groups to make an ASA3 group. The differences in the cumulative event-free rate appeared to be significant between the non-ASA group and the ASA3 group and also between the non-ASA group and the ASA1 group. But the frequency distribution of age, territory of stroke, diabetes mellitus, cardiac disease, hematological disease and hyperuricemia were significantly different among these 3 study groups. We thus included these covariates in the Cox's proportional hazard model to control their possible confounding effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Cutaneous thermal thresholds in normal subjects and diabetic patients without symptoms of peripheral neuropathy.

An automated system operating on the Peltier principle and using a two-alternative forced-choice testing technique was applied to measure the heat and cold thermal thresholds (HT and CT) in 63 normal subjects and 68 diabetic patients who had no clinical symptoms of peripheral neuropathy. To compare large and small nerve fiber functions, 34 of the diabetic group were also tested for vibration perception threshold (VPT) and nerve conduction velocity (NCV). The testing algorithm of the devices selected for used, including reference temperature and number of turns, was investigated for assessment of variability and reliability. The age effect on thermal thresholds was found in the normal group (p less than 0.001). There was a significant difference between HT and CT in an individual (p less than 0.01). CT was greater than HT in 68% of the subjects. The diabetic group had significantly higher thermal thresholds than the normal group (HT, 0.30 +/- 0.32 degree C vs 0.10 +/- 0.05 degree C, p less than 0.005; CT, 0.39 +/- 0.43 degree C vs 0.15 +/- 0.09 degree C, p less than 0.005). Thermal thresholds greater than the linear regression estimate for age plus three standard errors of estimate were defined as abnormal. The abnormality rate in diabetics was 33.8% for HT and 22.1% for CT. Of the 34 patients, 91.1% had abnormal results in at least one of the three tests: 47.1% abnormal for HT or CT, 67.6% for VPT, and 26.4% for NCV. No correlation existed between the thermal threshold and VPT (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗