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Biomedical subjects

A Lozza

Publications and source records attributed to A Lozza.

9 recordsLinked to original sources
PubMed1998

Central motor conduction after magnetic stimulation in diabetes.

Central motor conduction times (CMCTs), obtained by means of magnetic stimulation of the motor cortex and spinal roots, were studied in 138 patients affected by diabetes mellitus but with no signs or symptoms of central nervous system (CNS) involvement. CMCTs were significantly increased in diabetic patients (p < 0.001, t-test) with respect to normal controls, with values exceeding upper confidence limits (mean +/- 2.5 SD of controls) in about 30% of patients. There was no correlation between CMCT delay and type of diabetes (insulin-dependent or non-insulin-dependent), patient age, disease duration, degree of metabolic control compensation, presence or absence of retinopathy or nephropathy, and presence or absence of peripheral or autonomic neuropathy. CNS involvement in diabetes mellitus is discussed. Particular emphasis is given to the sensitivity and reliability of CMCTs obtained by means of magnetic stimulation as a tool in the early diagnosis of CNS functional alterations in diabetes mellitus.

Adult↗
PubMed1998

Neurophysiological approach to primary headache pathophysiology.

Electroencephalography (EEG), evoked potentials (EP), and electromyography (EMG) techniques are useful tools in the clinical assessment of headache and in understanding the pathophysiological mechanisms of these pathologies. EEG and EP studies in migraine revealed functional abnormalities in cortical electrical activity and in sensory processing. EMG studies resulted in pain syndromes involving nerves or myofascial structures such as tension-type headache and cluster headache. Moreover, it was possible to test the effect of old and new drugs with the help of these neurophysiological techniques. An updated review is reported of the literature.

Electrocardiography↗
PubMed1997

Functional changes of brainstem reflexes in Parkinson's disease. Conditioning of the blink reflex R2 component by paired and index finger stimulation.

Recovery curves of the R2 component of the blink reflex have been studied in 10 control subjects and 13 parkinsonian patients both after ipsilateral paired stimulation of the supraorbital nerve and after index finger stimulation. In control subjects, both types of conditioning induced a comparable marked inhibition lasting more than 600 ms. In parkinsonian patients, inhibition was reduced after both conditionings. However, differences appeared in the magnitude of the changes: after paired stimulation, it was less significant (ANOVA and post-hoc Duncan's test: p = 0.04) than after index finger stimulation (p = 0.002). In that latter situation, the more marked reduction in inhibition is interpreted, in the light of current physiologic knowledge, by hypoactivity of the Nucleus Reticularis Giganto Cellularis (NRGC) which would make less efficient inhibitory interneurones in the trigemino-facial pathway. The results are thus compatible with the suggestion that NRGC is made indirectly less active in Parkinson's disease.

Analysis of Variance↗
PubMed1997

Inhibition of the blink reflex R2 component after supraorbital and index finger stimulations is reduced in cluster headache: an indication for both segmental and suprasegmental dysfunction?

Peripheral as well as central mechanisms are thought to play a role in cluster headache pathogenesis. We have studied recovery curves of the R2 component of the blink reflex after conditioning by supraorbital or index finger stimuli in 10 episodic cluster headache (CH) patients during a cluster period and in 10 healthy controls. There was no significant change of R2 threshold, latency or area in CH patients. After paired supraorbital stimuli, R2 recovered more rapidly in patients on the symptomatic side. After index stimulations, R2 recovery was more rapid on both symptomatic and non-symptomatic sides in patients compared to controls. Naloxone (0.4 mg) i.v. in two subjects partially reversed the R2 suppression induced by index finger stimuli. The unilateral decrease of R2 inhibition after a segmental supraorbital stimulus most likely reflects sensitisation in the spinal trigeminal nucleus. Whether the latter is due to irritation of the ophthalmic nerve within the cavernous sinus region, which is thought to be pivotal in CH pathogenesis, remains to be proven. In addition, we propose that the bilateral deficit of R2 inhibition after an extrasegmental exteroceptive stimulus might reflect hypoactivity of reticular nuclei, possibly because of reduced central opioid activity.

Adult↗
PubMed1997

Neurophysiological and neuropsychological monitoring of fatigue during extreme environmental and driving conditions.

Aim of the present study was to evaluate the modifications of neurophysiological and neuropsychological variables during extreme environmental and driving conditions. Eight subjects (four drivers and four passengers) were evaluated while driving a four wheels drive across the Big West Algerian Erg. The following procedures were carried out in basal conditions and at the end of the 1st, 3rd, and 5th day of driving: surface EMG of masseter and cervical para-spinal muscles during maximum isometric contraction lasting 12 sec; test of simple visual and acoustic reaction times, Cancellation test, Trial Making test. As from the second day, the drivers used appropriate dental plates. In the drivers, EMG spectrum analysis revealed a significant decrease in mean frequency values at the end of the 1st day. This finding was more relevant in masseter muscles. No significant fatigue phenomena were detected on the subsequent controls. On the contrary, the passengers showed a decrease in mean EMG frequency values. No significant modifications in the cognitive variables were detected at the end of the 1st day (initial response to stress), whereas a progressive worsening was observed in the subsequent evaluations. EMG fatigue of masseter muscles seems to be more related to psychic stress. The beneficial effects of the dental plates were also confirmed.

Adolescent↗
PubMed1995

Twitch response of striated muscle in patients with progressive external ophthalmoplegia, mitochondrial myopathy and focal cytochrome c-oxidase deficiency.

Some aspects of the contractile properties of skeletal muscle in patients with progressive external ophthalmoplegia (PEO), mitochondrial myopathy and focal cytochrome c-oxidase deficiency were investigated by studying the twitch response (TR) of the tibialis anterior muscle both at rest and after maximum isometric contraction. The results of needle electromyography were normal in four of the six examined patients, and myopathic in the remaining two. A slowing in muscle relaxation was the most frequently observed abnormality; significantly prolonged muscle contraction times and reduced twitch torque potentiation values after isometric contraction were also detected. TR abnormalities in PEO patients may be due either to a dysfunction of the contractile machinery depending upon impaired muscle energy supply or to altered muscle fiber characterized by the predominance of type I slow fiber. In addition to conventional electromyographic investigations, TR study may be a useful diagnostic tool in PEO patients.

Adult↗
PubMedDate not supplied

Electrophysiological study on jaw-opening reflex recorded from digastric muscle in Parkinson's disease and primary cranial dystonias.

We investigated digastric reflex excitability in normals and in patients with extrapyramidal disorders such as primary cranial dystonias and Parkinson's disease. Relationships between exteroceptive suppression of masseter muscle and digastric reflex were also investigated in some cases. Digastric reflex hyperexcitability was observed in dystonic patients when compared to normals and parkinsonian patients. Furthermore, some patients with cranial dystonia presented absence of exteroceptive suppression reflex in masseter muscle with enlarged digastric response. These results indicate hyperexcitability of the digastric reflex and abnormal agonist-antagonist muscle co-contraction in chewing reflexes of patients with cranial dystonias. This shows that digastric reflex is an important electrophysiological investigation to explore the physiopathological mechanisms of primary cranial dystonias.

Aged↗
PubMedDate not supplied

Local venous lactate changes and spectral analysis of surface EMG during fatiguing isometric efforts in intrinsic hand muscles.

In this study relationships between local venous lactate concentrations and power spectrum changes in surface EMG due to fatiguing isometric contractions were investigated. Two different isometric efforts of the opponents pollicis muscle, 25% and 50% of maximum voluntary contraction, were examined. In 25% of maximum voluntary contraction no changes in local venous lactate were observed, whereas mean power frequency values of surface EMG shifted significantly towards lower frequencies. On the contrary, in 50% of maximum voluntary contraction lactate significantly increased and was related to the mean power frequency shifts of the surface EMG. These data suggest that lactate plays a role in muscle fatigue only in a limited intensity range of isometric muscle contractions.

Adult↗