PubMed Health⌕ Search

Biomedical subjects

J M Teijeira

Publications and source records attributed to J M Teijeira.

7 recordsLinked to original sources
PubMed1998

[Visual evoked potentials (VEP). Current perspectives].

INTRODUCTION: The objective of this study is to describe current tendencies in the recording and interpretation of visual evoked potentials (VEP). In the introduction we describe the history of the three main classical schools and the modern methodology which combines them, so as to study the photopic and scotopic systems together and thus be better able to determine the origin of the underlying pathology. MATERIAL AND METHODS: We describe recording techniques using flash and chequer-board and a strategy for study of the visual pathway. RESULTS: The application of this technique is described for pathologies in which its findings are of particular interest: Silent multiple sclerosis, Parkinson, hepatic encephalopathy, dementia and psychiatric disorders in which certain neurotransmitters play a part; visual acuity; coma and brain death; cortical blindness. A separate section deals with paediatrics, in view of its special characteristics. We call for a return to the use of this technique with great future diagnostic potential.

Brain Death↗
PubMed1981

[Conduction and origin of evoked potentials in the somesthetic pathway (author's transl)].

In 24 normal subjects, sensory conduction velocity increased progressively from the distal to the proximal segments of the peripheral nervous system. In the central somatosensory pathway, sensory impulses slowed down at a rate much greater than what could be expected from just the three known synaptic delays (1 ms each) in medulla, thalamus and somatosensory cortex. The present data point to the special characteristic of conduction in the thalamo-cortical axons as the main cause for the deceleration observed in the central somatosensory pathway. A conduction velocity of 14 m/s has been calculated for this last segment. However it is also possible that sensory conduction in the medial lemniscus might be reduced in relation to the conduction values in the peripheral segments.

Adult↗
PubMed1980

Neurophysiological assessment of alpha pattern coma.

Somatosensory evoked potentials, blink reflexes, and H wave reflexes, were recorded on several days from three patients with alpha pattern coma. Coma was secondary to cardiac arrest in two cases and to brainstem infarction in one. Results are compatible with damage to the brainstem reticular formation with sparing of thalamo-cortical circuits as the main physiopathological characteristic of alpha pattern coma. This condition should not be regarded as a discrete entity when establishing the prognosis of patients in coma, since they only differ from other patients in coma from the point view of the EEG record.

Aged↗
PubMed1979

Conduction velocity through the somesthetic pathway in chronic renal failure.

The latencies of evoked potentials recorded at different levels of the peripheral and central nervous system by median nerve stimulation were measured before and after dialysis, and compared with similar recordings in normal volunteers. Abnormally slow conduction velocity was more often found in proximal rather than in distal segments of the peripheral pathway in patients with chronic renal failure. This abnormality was not correlated with the presence of clinical signs of neuropathy or low values of motor conduction velocity, neither was it affected by dialysis. These findings support the hypothesis of peripheral nerve dysfunction secondary to metabolic derangement in uraemic patients.

Adult↗
PubMedDate not supplied

[The most significative parameters for the diagnosis of focal neuropathy of the cubital nerve in the elbow].

OBJECTIVE: Determine the diagnostic validity of the most usual neurophysiological procedures in the examination of compressive neuropathies and/or ulnar nerve entrapment at the elbow. PATIENTS AND METHODS: A prospective observational study was carried out over a period of one year which included 19 patients with clinical features compatible with entrapment/compression of the ulnar nerve at the elbow, their neurophysiological diagnosis and surgical confirmation. We also studied 49 patients who were attended in our clinic for other reasons not related to disorders of the ulnar nerve. The variables studied were: maximum rate of motor conduction above the elbow; the amplitudes between spikes and the area between the first negative deflection and the last positive spike of the responses at the wrist and above the elbow. RESULTS: In the group of persons without disorders of the ulnar nerve the average rate of motor conduction was 58.07 m/s, with a confidence interval of 53-65. In the group of patients with specific clinical features the average rate of motor conduction was 47.26 m/s, with a confidence interval of 43.74-50.77. No relation was found between age and pathology, although rate of motor conduction was related to the presence of pathology. CONCLUSIONS: It was seen on logistical regression that the main variables for prediction of the presence or absence of pathology in a person were firstly motor conduction and secondly the amplitude index.

Adolescent↗