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Biomedical subjects

M Treviso

Publications and source records attributed to M Treviso.

10 recordsLinked to original sources
PubMed1993

Physiological basis of voluntary activity inhibition induced by transcranial cortical stimulation.

Apart from exciting corticospinal cells and evoking a motor response, electrical or magnetic transcranial cortical stimulation (TCCS) delivered during voluntary activity produces a prolonged inhibition of activity, a silent period (SP), that can last up to 280 msec. The SP duration after TCCS is directly proportional to stimulus intensity. To determine the anatomic substrate and underlying physiological properties of the SP from TCCS, we (1) compared the SP from TCCS with the SP from cutaneous and mixed nerve stimulation, (2) studied the excitability cycle of spinal motor neurons in 3 double stimulus conditions: (a) after paired peripheral nerve stimulation, (b) after TCCS and peripheral nerve stimulation, and (c) after paired electrical TCCS, (3) investigated the timing of the excitability of the sensorimotor cortex measuring long latency responses from median nerve stimulation delivered inside the SP from TCCS. We found that after TCCS, spinal motor neuron segmental excitability is reduced for a period up to 100 msec. Inhibition at a suprasegmental, possibly cortical, level was even more prolonged for a period up to 160 msec, suggesting that at least the late part of the SP after TCCS is due to supraspinal inhibition. Determining the nature of the supraspinal inhibition such as the possible role of cortical inhibitory mechanisms may be useful in further understanding central mechanisms of voluntary motor control and sensorimotor processing.

Adult↗
PubMed1988

Associated central and peripheral demyelination: an electrophysiological study.

A case is reported in which retrobulbar neuritis preceded Guillain-Barré syndrome by 4 weeks. The visual evoked potential latencies were prolonged. After peripheral nervous system signs had cleared, median and peroneal somatosensory evoked potentials showed prolonged cervical N13, scalp N20 and L3-scalp conduction times.

Adult↗
PubMed1988

Diagnosis of diabetic polyneuropathy. Correlation between clinical and instrumental findings and assessment of simple diagnostic criteria.

In the present study minimal clinical and electrophysiological criteria for the diagnosis of diabetic polyneuropathy (DP) have been tested in 48 unselected subjects attending an outpatient service for diabetics at the University Hospital of Chieti. A standard electrophysiological examination was performed in all patients on the median nerve (sensory and motor), peroneal nerve and sural nerve. Depending on the importance of the laboratory values for each nerve, nerve conduction velocity, distal latency and potential amplitude were given separate scores ranging from 0.5 to 2. A diagnosis of probable DP was made when abnormal findings were present in more than one nerve with a total score of 2.5 or more. As a whole, 28 cases (58%) had abnormal laboratory findings supporting the diagnosis of probable DP. There was a relatively high correlation between probable DP and a positive clinical examination although the validity coefficients of the neurological exam were not high enough to allow its use as a screening test for DP.

Adolescent↗
PubMed1988

Polyneuropathy in an adult hospital population. Assessment of the prevalence through a simple screening procedure.

An epidemiological survey has been conducted during a 3-month period in the Regional Hospital of S. Giovanni Rotondo, a small city in Southern Italy. A total of 1,878 patients aged 12 years and over admitted to the hospital were randomized during the study period. Each patient was asked 7 specific questions focusing on symptoms most likely due to polyneuropathy. The sensitivity and specificity of the screening procedure were tested separately and found to be high. All cases who gave affirmative answers to at least 2 questions were carefully investigated in search of a polyneuropathy. Of the 20 cases which gave an affirmative answer to 2 or more questions, 19 (1% or 10 cases per 1,000 hospital population) had a neurological examination fitting with the diagnosis of polyneuropathy. There were 3 males and 16 females with a median age of 61 years. Diabetes was the commonest associated disorder. The disease ran a mild course in 12 cases and was severe in only 1. The screening model used in the current study seems a valuable and simple approach for case ascertainment in epidemiological investigations of polyneuropathy.

Adolescent↗
PubMed1987

Strümpell's familial spastic paraplegia: an electrophysiological demonstration of selective central distal axonopathy.

Three patients with autosomal dominant Strümpell's familial spastic paraplegia (SFSP) were evaluated by means of somatosensory evoked potentials (SEPs) from upper and lower limb and determination of sural nerve conduction velocity. Findings of normal sural nerve conduction but reduced amplitude and poor definition of SEPs with normal latencies on peroneal nerve stimulation support a pattern of central nervous system degeneration characterized by a selective involvement of centrally directed axons within the gracile fasciculi.

Adult↗
PubMed1983

Nervous impulse propagation along peripheral and central fibres in patients with chronic renal failure.

In thirty-one patients with chronic renal failure we measured the conduction velocities in the proximal regions of median and peroneal nerves and concurrently evaluated the propagation properties of an afferent input along the related central (spinal and supraspinal) sensory pathways. In 26 of these patients the sensorimotor velocities of median, peroneal and sural nerves were also calculated. Lower limb peripheral conduction was more frequently abnormal than that of upper limb, the distal segment being involved to a greater degree. Since central propagation was more impaired during lower (11 out of 27 cases) than during upper limb (1 out of 27 patients) stimulation and the intracranial propagation time was rarely prolonged, a predominantly spinal defective impulse conduction was hypothesized. Neurophysiological data seem to confirm that early stages of defective neural conduction in CRF are in agreement with the model of central-peripheral distal axonopathy. However, an abnormal impulse propagation was also rarely found in proximal districts of peripheral fibres as well as along the intracranial sensory pathways. Correlations were found between some of the impulse propagation properties and the duration of CRF or dialysis. Serum parathyroid hormone, creatinine and BUN levels were correlated with some peripheral and central conduction indexes.

Adolescent↗
PubMed1983

Central conduction velocity (lumbar-vertex) in man calculated by means of a new method. Studies on variability, the effects of sex, age and different equipments.

Lumbar-to-scalp conduction velocity has been measured in 40 volunteers of both sexes, subdivided in two age groups, during uni- and bilateral peroneal nerve stimulation. It was calculated from the lumbar response to the main positive component of the simultaneously recorded, short latency scalp potentials (P3a). The mean value was 39.7 +/- 2.4 m/s (mean +/- SD). The mean side difference during unilateral stimulation was 2.08 +/- 1.6 m/s. It was extremely steady in a group of subjects repeatedly tested during a 14-month follow-up, even when different equipment was used.

Adolescent↗
PubMed1981

Checkerboard reversal pattern and flash VEPs in dialysed and non-dialysed subjects.

In forty-three patients suffering from chronic renal failure (CRF; 32 non-dialysed, 11 dialysed) the flash VEP and the pattern VEP to different spatial (7.5', 15', 30', 60' checks) and temporal (2, 10, 20, 40 Hz) frequencies were investigated. Abnormally delayed flash VEPs were obtained in 53.6% of the cases; transient pattern VEPs had a delayed major positive deflection in 46% of the tested eyes and altered steady-state response in 58% with a total of 65% abnormal responses. Chronically dialysed subjects showed higher levels of altered VEPs for both the techniques. The shorter latencies normally observed with coarser checks in healthy people were maintained in CRF patients, resulting in an abnormal prolongation of the shift between high and low spatial frequencies. Higher statistical correlations linked the pattern VEP with blood urea nitrogen (P less than 0.001) and other renal chemistry than the flash VEP. These and other features could be ascribed to a specific involvement of a maculo-calcarine channel devoted to 'detailed' vision and suggest the usefulness of this method to provide a tool for the early detection of an encephalopathic uraemia.

Adult↗