Biomedical subjects

V Cosi

Publications and source records attributed to V Cosi.

At least 19 recordsLinked to original sources

PubMed1992

Efficacy of intranasal administration of neostigmine in myasthenic patients.

The efficacy of intranasally administered neostigmine was tested in 22 patients with generalized myasthenia gravis (MG). Topical therapy to the highly vascularized oropharynx proved to be quickly effective in 5-15 min both clinically and electrophysiologically. Twenty-eight MG patients were then recruited from different centres and their morning doses of oral pyridostigmine were substituted with intranasal neostigmine over a period of 2 or 3 weeks. Intranasal neostigmine proved to be equally efficacious in this regimen. No side-effect was noted even in 4 patients treated in this way for 1 year. Intranasal administration of anti-acetylcholinesterase may be very beneficial: (1) for patients with irregular absorption of oral doses; (2) early in the morning and every time a fast and temporary effect is needed; (3) in bulbar impairment and emergencies, in which a handy atomizer may be life-saving.

Administration, Intranasal↗

PubMed1992

Multimodal evoked potentials in myotonic dystrophy (MyD).

By means of multimodal evoked potentials (EPs), we evaluated the central nervous system (CNS) involvement in 25 subjects suffering from myotonic dystrophy: brainstem auditory evoked potentials (BAEPs), middle-latency auditory evoked potentials (MLAEPs) and somatosensory evoked potentials (SEPs) from the upper limb were performed on all subjects, whereas only the 19 patients, whose clinical ocular abnormalities were slight, underwent pattern-electretinograms (PERGs) and pattern visual-evoked potentials (VEPs) in order to identify the site of lesion among visual pathways (retinal and/or retroretinal). PERGs were abnormal in 8/19 subjects, VEPs in 8/19 subjects (the two techniques were simultaneously abnormal in 8 eyes), BAEPs in 7/25 subjects, MLAEPs in 4/25 subjects (in one subject both BAEps and MLAEPs were abnormal) and SEPs were abnormal in 1/25 subjects. 13/25 of our subjects showed at least one EP that revealed a CNS involvement. The electrophysiological alterations were not correlated either with subject age or with disease duration. Multimodal EPs enabled us to demonstrate that CNS involvement in myotonic dystrophy is important and mainly affects the visual and auditory system.

Adult↗

PubMed1992

Spinal and cortical potentials evoked by tibial nerve stimulation in humans: effects of sex, age and height.

Somatosensory evoked potentials by posterior tibial nerve stimulation at the ankle were performed in 74 healthy volunteers (36 females and 38 males) aged 14-76 years. Cortical potentials were obtained in all subjects and spinal potentials (N22) in 71 subjects. All parameters were related to subject's age, height and sex. Sex influenced only P40-N50 amplitude, which was greater in females. All latencies of spinal and cortical components increased in a similar manner with subject's height (about 0.16-0.18 ms per cm), whereas the N22-P40 interpeak latency was independent from height, but related to T12-Cz distance. Absolute latencies of the spinal and of most cortical components, but not interpeak latencies, increased with subject's age (about 0.06-0.09 ms per year). The parameters to compute normative data (according to univariate or bivariate regression models) are furnished. Limits of right-left differences are reported.

Adolescent↗

PubMed1992

A one-week test-retest reliability study of Brainstem Auditory Evoked Potentials.

Brainstem Auditory Evoked Potentials (BAEPs) are increasingly used in longitudinal evaluation of brainstem function. The reliability of the neurophysiological parameters and definition of the normal test-retest variability are required for such investigations. In the present study we submitted 20 healthy volunteers (10 males and 10 females; mean age 35.1 years, range 24-49) to BAEPs in two sessions separated by seven days. The reliability of the parameters was estimated by means of intraclass correlation coefficient (R). All BAEP parameters showed excellent R values (above 0.75). In addition, the confidence interval lower limits of all R coefficients had good to excellent values. Finally we computed the upper normal limits of the test-retest variability of each parameter, with alpha = 0.01, using the within-subjects mean square. The confirmed good reliability of the analyzed parameters enables us to employ BAEPs as useful monitoring instruments in longitudinal studies.

Adult↗

PubMed1992

The reliability of eye movement quantitative evaluation. I. Saccadic eye movements.

We adopted the estimate of the intraclass coefficient of reliability, R, to evaluate the reliability of saccadic eye movements quantitative analysis. At a one-week interval we recorded refixative saccadic eye movements twice from fifteen healthy subjects by means of the binocular electrooculographic technique. R was computed for the constants and the slopes of the amplitude/duration and the amplitude/peak velocity relationships, for the mean precision values and for the mean latency values adjusted for subject's age. Our data demonstrated that the reliability of saccade parameters is fairly good for the amplitude/peak velocity relationship, good for the precision and very good for the amplitude/duration relationship. Finally, we believe that the normal variability values we obtained can be usefully employed in neurophysiological longitudinal studies not only in normal subjects, but also in pathological condition provided the more reliable parameters and the more adequate strategies to compute normal variability values are chosen.

Adult↗

PubMed1992

The reliability of eye movement quantitative evaluation. II. Smooth pursuit eye movements.

We adopted the estimate of the intraclass coefficient of reliability, R, to evaluate the reliability of smooth pursuit eye movement quantitative analysis. At a one-week interval, we recorded twice smooth pursuit eye movements from fifteen healthy subjects by means of the binocular electrooculographic technique. R was computed for the constant and the slope of the target velocity/gain relationships. R values were rated good for the slope and excellent for the constant. Finally, we computed for each parameter the maximum variability value according to two differing methods; on the basis of the within-subjects mean square values, we defined the normal range of biological test-retest variability for the two parameters.

Adult↗

PubMed1991

Prognosis of myasthenia gravis: a multicenter follow-up study of 844 patients.

The prognosis of myasthenia gravis (MG) was assessed retrospectively using life-table analysis in 844 patients followed up for a mean period of 5 years in 3 major Italian centers. The chance of achieving at least a 1-year remission after treatment withdrawal (complete remission) was assessed as a specific end-point in the whole population and in selected subgroups with reference to the principal prognostic variables. The cumulative probability of complete remission was 1% by 1 year, 8% by 3 years, 13% by 5 years, and 21% by 10 years. The only variables correlated to the chance of complete remission were younger age at onset of MG, lower severity of symptoms at onset and nadir, and shorter disease duration at diagnosis. In addition, thymectomy and early surgery seemed to influence the chance of remission. Other factors (including the presence of thymoma) did not significantly influence the outcome of the disease.

Adult↗

PubMed1991

Effectiveness of steroid treatment in myasthenia gravis: a retrospective study.

The records of 142 patients with generalized autoimmune myasthenia gravis who had been treated with steroids as the single immunosuppressive agent, collected at regular intervals, were employed for a retrospective evaluation. The effectiveness of treatment was assessed after 24 months; the data from the 6th and 12th months were also considered. After 24 months, 63.4% of the whole sample had improved (33.8% were in clinical or pharmacological remission); 13.4% were unchanged or had worsened and 22.3% had moved to a different immunosuppressive treatment. The rate of positive outcome was higher in patients over the age of 40 at disease onset.

Adolescent↗

PubMed1991

Treatment of myasthenia gravis with high-dose intravenous immunoglobulin.

We treated 37 patients affected by autoimmune generalized myasthenia gravis (MG) with high-dose intravenous gammaglobulin (HDIVIg), 400 mg/kg per day on 5 consecutive days. A one-degree improvement of Oosterhuis global clinical classification of myasthenic severity (OGCCMS), the disappearance of bulbar involvement or both were recorded 12 days after the beginning of the treatment in 70.3% of the patients and persisted up to 60 days in 58.7%. A two-degree improvement of OGCCMS was recorded in 54.1% of the patients and it was maintained up to 60 days in 37.8%. The percentage of improvement did not significantly differ between patients entering the treatment in a long-standing, drug-refractory stationary phase of the illness (n = 26) and patients who received HDIVIg in an acute phase of MG (n = 11). None of the patients experienced side effects. Our data indicates that HDIVIg is an interesting, virtually riskless therapeutic choice for MG patients, and allows the planning of a controlled trial versus plasma-exchange.

Adolescent↗

PubMed1991

Multimodal evoked potentials in progressive external ophthalmoplegia with mitochondrial myopathy.

Multimodal evoked potentials were studied in 13 patients affected by progressive external ophthalmoplegia with histologically proven mitochondrial myopathy. Progressive external ophthalmoplegia occurred with craniosomatic spreading in all the patients and with a varying degree of nervous and/or other system involvement in most of them. In all but one of the subjects, at least one evoked potential modality was abnormal; 11 of them demonstrated an abnormal visual evoked potential, but this finding might have been influenced by concurrent retinal dysfunction. Abnormalities in brainstem auditory evoked potentials and/or somatosensory evoked potentials, revealing an impairment of central sensory pathways, were detected in 7 subjects, 5 of whom lacked clinical evidence of central nervous system involvement. Thus, evoked potentials represent an useful tool for the detection of subclinical central nervous system involvement in patients affected by progressive external ophthalmoplegia with mitochondrial myopathy.

Adult↗

PubMed1991

Evoked potentials monitoring of a cerebral focal ischemia model.

A model of cerebral ischemia by microsphere embolization in the rabbit was monitored with somatosensory evoked potentials by median nerve stimulation (SEPs) and by flash visual evoked potential (VEPs). The degree of SEP alterations paralleled the type of lesions (focal or multifocal ischemia or diffuse oedema). Alterations present at the first hour after ischemia were generally unchanged during the follow-up, which ended at the 24th hour. The prevalence of VEP alterations was low (only 16% in focal ischemia). These results are compared to EEG modifications performed in the same animals.

Animals↗

PubMed1991

Somatosensory evoked potentials by electrical stimulation of the third trigeminal branch in humans.

Somatosensory Evoked Potentials by stimulation of the trigeminal nerve (TSEPs) were recorded from 30 healthy subjects (15 males, 15 females; mean age: 45.2 years; range: 21-66 years) in order to assess normative data for clinical purposes. To elicit the TSEPs, electrical square pulses (duration: 0.1 msec; frequency: 3.3 Hz; intensity: 4-6 mA) were delivered by bipolar skin electrodes (cathode over the foramen mentale and anode on the middle of the chin, stimulating the trigeminal third branch). TSEPs were obtained from C3-Fpz and C4-Fpz by twice averaging 1000 responses. Time base was 100 msec; bandpass filter setting was 5-1500 Hz. In our normal subjects the TSEPs were composed of several components (N1, P1, N2, P2 and N3); the components, with the exception of N3, were always bilaterally detectable. Statistical analysis (repeated measures analysis of variance) demonstrated a dependence of TSEP latencies on sex; it did not demonstrate an analogous dependence on either side of stimulation or age. Finally, we propose some guidelines for the evaluation of TSEPs: consider N1, P1, N2 and P2 waves, base the judgement of normality on latencies rather on amplitudes, use differing normative data according to sex.

Adult↗

PubMed1991

Visual evoked potentials in the white New Zealand rabbit: source localization and normative aspects.

Normative data of visual evoked potentials were obtained from occipital screw electrodes referenced to a nasal electrode in 10 white New Zealand rabbits. Two time-bases were used (200 and 400 ms) in order to reliably identify both early components (of retinal and cortical origin), as well as late components. The putative origin of the single components was established by simultaneous recording of ERG and by stereotaxic recordings from the lateral geniculate body. Test-retest variability was measured repeating the recordings after 24 hours.

Animals↗

PubMed1991

Brainstem auditory evoked potentials in the rabbit.

Eight white New Zealand rabbits were submitted to auditory stimulation in order to obtain normative BAEP parameters. A monaural alternating 0.1 ms click stimulation at 20 Hz, 90 dB was used. Two series of 1000 responses were averaged (10 ms time-base, 160-3000 Hz band-pass) and highly reproducible peaks were obtained. Peaks P1, P2, P3, P4 were obtained in all ipsilateral recordings, whereas peak P5 was detectable in only 6 animals. In contralateral recordings P1 was absent and the following peaks were similar to those of ipsilateral recordings. Normative values of absolute and interpeak latencies, peak amplitudes and amplitude ratios were obtained. The procedure was repeated 24 hours after basal recordings and measures of test-retest variability were obtained.

Animals↗

PubMed1991

EEG changes and platelet aggregation in experimental cerebral focal ischemia in rabbits.

Nine white New Zealand rabbits were submitted to internal carotid embolization with microspheres which caused a histologically verified focal cerebral ischemia. Six animals were sham-operated. EEG, QEEG, ECG, blood pressure, rectal temperature and platelet aggregation were monitored in basal conditions and one hour after ischemia. Embolized animals showed an increase in power density spectrum (PDS) and delta activity (0.15-3.70 Hz) and the appearance of platelet aggregation. The QEEG changes were correlated to the degree of platelet aggregation after ischemia.

Animals↗

PubMed1991

Prestimulus EEG influence on late ERP components.

Ten healthy volunteers were submitted to an auditory oddball event related potentials (ERP) paradigm. Single trial 500 ms poststimulus ERPs (Pz, Cz, Fz--linked earlobes) along with the correspondent 1000 ms prestimulus EEG (O1-Cz) were stored. EEG epochs were submitted to spectral analysis and a slow wave index (SWI = delta + theta/total) was computed. Three selective ERP averages corresponding to low, medium and high SWI were computed. N2 latency was longer and P3a amplitude was lower in high SWI averages as compared to low SWI averages.

Analysis of Variance↗

PubMed1991

Effect of repetition rate on middle latency auditory evoked potentials in humans.

Middle Latency Auditory Evoked Potentials (MLAEPs) were recorded from 15 healthy subjects in order to evaluate the influence of different repetition rates on the latency and the amplitude of their main components Na, Pa and Nb. MLAEPs were obtained from Cz-ipsilateral ear lobe by averaging responses to 2000 monaural clicks delivered to both ears, at 65 dB SL of intensity, for each of 3 different repetition rates (1.1, 4.1, 8.1 Hz). Time base was 100 ms, analogical band-pass filter 5-1000 Hz (off-line digital bandpass: 20-100 Hz). The statistical analysis (repeated measures analysis of variance), demonstrated that, the latency and the amplitude of the Nb component were slightly influenced by repetition rate while Pa and Na were not. Moreover Nb showed the greatest interindividual variability (as already pointed out by other authors too); thus, we suggest that a stimulus rate of 8.1 Hz and the analysis of Na and Pa component only, can be regarded as the best assessment for MLAEPs evaluation when they are used for clinical purposes.

Adult↗

PubMed1991

Effect of stimulus mode on middle latency auditory evoked potentials in humans.

Middle Latency Auditory Evoked Potentials (MLAEPs) were recorded in 35 healthy subjects; all underwent monaural stimulation and 18 of them additionally underwent binaural stimulation. The aim of the study was to determine the effect of stimulus mode on MLAEP Na, Pa and Nb components and to assess normative data for clinical purposes. MLAEPs were respectively obtained from Cz-ipsilateral ear lobe (monaural mode) and from Cz-A1 and Cz-A2 (binaural mode) by twice averaging 1000 responses to 65 dBHL alternating clicks delivered at a repetition rate of 8.1 Hz. Time base was 100 msec; analogical band-pass filter setting was 5-1000 Hz (off-line digital badpass: 20-100 Hz). The statistical analyses (paired t-test, repeated measures analysis of variance) were not able to demonstrate any differences that derived from differing sides of stimulation (monaural mode) or from differing recording derivations (binaural mode); on the contrary, we demonstrated a slight increase in waveform amplitudes when the binaural mode was employed. In particular, we observed an increase in Na-Pa peak-to-peak amplitude, whereas Pa-Nb amplitude was unmodified. This finding is explicable in terms of a binaural interaction effect. Finally, we propose some guidelines for the correct performance and evaluation of MLAEPs in clinical practice.

Acoustic Stimulation↗