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Biomedical subjects

F Pierelli

Publications and source records attributed to F Pierelli.

At least 19 recordsLinked to original sources
PubMed1995

Increasing doses of l-sulpiride reveal dose- and spatial frequency-dependent effects of D2 selective blockade in the human electroretinogram.

The amplitude and phase of the second harmonic (15 Hz) of the electroretinographic responses to three different spatial frequency grating stimuli (0.25, 1 and 4 c/deg), reversed at 7.5 Hz, were studied i normal human subjects, before and 30 min after the systemic administration of three doses (0.071, 0.357 or 1.428 mg/kg) of a selective D2 blocker, l-sulpiride, to three populations of 18, 19, or 20 subjects. The effect of the drug on the pattern electroretinogram (PERG) was clearly dose-dependent, being greatest on the responses to 4 c/deg. The mean decrease in second harmonic amplitude was -13.8% after 0.071 mg/kg of l-sulpiride, -23.5% after 0.357 mg/kg and -28.5% after 1.428 mg/kg. The last two variations were significant at P < 0.01 and P < 0.01 respectively. These data suggest that a dose-dependent effect on the human retinal response to 4 c/deg stimuli exists, probably mediated by a coupling between l-sulpiride and D2 receptors. Lastly, our data suggest that D2 receptors may play an important role in the pathophysiology of visual dysfunction in Parkinson's disease, that has been described to be more significant at medium spatial frequency (2-5 c/deg).

Adult↗
PubMed1995

Infantile autosomal dominant distal myopathy.

INTRODUCTION: Distal myopathies are currently regarded as a non-homogeneous group of disorders including different autosomal dominant, recessive and sporadic forms. MATERIAL AND METHODS: The cases of a mother and her son and daughter are described and compared to previously reported cases from 4 families. Despite minor differences, the clinical picture is remarkably homogeneous, both within the same family and among different families. CONCLUSION: A distinct clinical form can be identified including: a) autosomal dominant inheritance; b) onset in infancy or childhood with peroneal muscles weakness; c) not disabling evolution in spite of possible late involvement of muscles others than tibio-peroneal; d) usually normal serum CK and other muscle enzymes; e) EMG evidence of primary myogenic damage; f) morphological findings of non-specific myopathy. Because of the benign evolution and the absence of true dystrophic changes in most biopsies we suggest the term infantile autosomal dominant distal myopathy should be preferred to infantile autosomal dominant distal muscular dystrophy.

Adolescent↗
PubMed1995

Cerebrovascular CO2 reactivity in migraine with aura and without aura. A transcranial Doppler study.

INTRODUCTION: We studied by means of Transcranial Doppler (TCD) recordings the CO2 cerebrovascular reactivity in migraine patients during the headache-free period. MATERIAL & METHODS: In three groups of subjects (15 controls, 15 suffering from migraine with aura and 15 from migraine without aura) the middle cerebral artery (MCA) mean flow velocity (MFV) was recorded under basal condition and hypocapnia induced by hyperventilation. Relative MFV, PI (Pulsatility Index) changes and Reactivity Index (RI) were calculated. RESULTS: Reactivity Index values were: 0.019 +/- 0.007 (mean +/- SD) in control subjects: 0.029 +/- 0.008 in migraine with aura; 0.022 +/- 0.008 in migraine without aura. Statistical analysis showed a significantly (P < 0.05) increased RI in migraine with aura group. CONCLUSION: Cerebrosvascular CO2 reactivity is increased during the interictal period in migraine with aura patients.

Adult↗
PubMed1995

Visual alterations in de novo Parkinson's disease: pattern electroretinogram latencies are more delayed and more reversible by levodopa than are visual evoked potentials.

There are increased latencies of pattern-reversal visual evoked potentials (VEPs) and electroretinograms (PERGs) in Parkinson's disease (PD) patients who have not received therapy. This study aimed to evaluate whether these delays are present in the early stage of PD and whether they are dopamine-sensitive. The results show that both PERG P50 and VEP P100 latencies are increased (p < 0.0001) in a group of patients with de novo PD (13 subjects; 13.3 +/- 5.6 months' mean disease duration) before therapy in comparison with an age-matched control group (eight subjects). A larger latency increase (9.9% at the 47% contrast level and 7.8% at the 96% contrast level) was present in PERG recordings than in VEPs (6.2% at the 47% contrast level and 3.9% at the 96% contrast level). Levodopa therapy produced recovery of both PERG and VEP latency increases at both contrast levels, but only the PERG recovery at 47% of contrast was statistically significant. Before therapy, five eyes from PD patients showed no reproducible PERG at the 47% contrast level although the simultaneously recorded VEP was present. Both potentials were recordable in the same eyes at the 96% contrast level. During therapy, four of those five eyes showed a clear PERG even at the 47% contrast level. We conclude that, using an adequate midspatial frequency, both VEPs and PERGs are delayed even in the early stage of PD, and that PERGs are more sensitive if low contrast (47%) is used. The larger alterations, as well as the larger recovery during levodopa therapy, seem to correlate the PERG response more than the VEP response to dopaminergic transmission.

Aged↗
PubMed1995

Crural amyotrophy associated with a parietal lesion: a case report.

The authors have observed a 33-year-old woman with a 3-year history of a clinical syndrome characterised by atrophy of the musculature of the left foot and leg with impaired motor function, associated with a paracentral cortical oligodendroglioma located in the right parietal region. Clinical, neuroradiological (MRI), electrophysiological (electromyography: EMG; motor evoked potential: MEP; median and tibial somatosensory evoked potential: m-SEP and t-SEP), and neuropsychological studies were performed every year for three years. Neurological examination showed an abnormal gait along with foot drop, pes cavus and pyramidal involvement. MEP and t-SEP recordings were abnormal on the left side, while EMG and neuropsychological tests gave normal results, which were unmodified over time. Our observations suggest that the crural amyotrophy observed in this case may be defined as of "parietal" or "central" origin, a clinical feature which more frequently affects the hand. A review of the literature is presented.

Adult↗
PubMed1993

Electrophysiological study (VEP, BAEP) in HIV-1 seropositive patients with and without AIDS.

One hundred-twenty nine HIV-1 seropositive patients (39 females, 90 males) were studied by means of pattern visual evoked potential (VEP) and brainstem auditory evoked potential (BAEP) recording. Utilizing the criteria of the Centers for Disease Control the patients were clinically defined and then subdivided into four groups: group A included patients of category II (n:11); group B patients of category III (n:29); group C patients of category IVa and IVc2 (n:55) and group D patients belonging to the other subgroups of category IV (n:34). EP were altered in 26.35% of the entire group with a marked prevalence of BAEP alterations (21.7%) rather than of VEP (4.65%). A considerable amount of BAEP abnormalities (24.13%) were found in patients with persistent generalized lymphadenopathy (group B). A significant increase of BAEP mean interpeak latencies were observed in group B, C, D patients when compared with those of the control group. On the whole, EP were altered in 20.65% of the neurologically asymptomatic patients. EP alterations may precede any clinical manifestation and can be found during the earlier phases of HIV-1 infection.

AIDS-Related Complex↗
PubMed1992

Low contrast stimuli enhance PERG sensitivity to the visual dysfunction in Parkinson's disease.

The pattern electroretinogram (PERG) was recorded at different contrast levels (96%, 71%, 47%) in 10 Parkinson's disease patients before and during dopaminergic monotherapy. The data were compared to a control group of 8 normal subjects recorded with the same procedure. PERG P50 latency progressively increased as contrast was decreased both in normal subjects and patients; however, this trend was much more pronounced in PD patients without therapy; consequently in this group the difference between P50 latency obtained with 96% and 47% contrast was statistically significant (P = 0.01, analysis of variance corrected by post-hoc Tukey test). By contrast this was not seen in the control group. Statistical analysis (Bonferroni's t test) showed at the 47% contrast level a significant P50 latency increase (P less than 0.01) in PD patients without therapy if compared with the control group. Dopaminergic monotherapy induced a P50 latency recovery in PD patients. We conclude that low contrast stimuli enhance PERG sensitivity to the visual dysfunction of PD patients. Moreover, the effects observed after therapy confirm that abnormal contrast response functions in PD patients are linked to dopaminergic deficiency.

Aged↗
PubMed1992

Long-term EEG-video-audio monitoring: computer detection of focal EEG seizure patterns.

Twelve individuals with medically refractory partial seizures had undergone EEG-video-audio (EVA) monitoring over 1-15 (mean 10.5) days. We selectively reexamined available 15-channel EEGs (video-cassettes) totaling 461 h and containing 253 EEG focal seizures. Computer analysis (CA) of these bipolar records was performed using a mimetic method of seizure detection at 6 successive computer settings. We determined the computer parameters at which this method correctly detected a reasonably large percentage of seizures (81.42%) while generating an acceptable rate of false positive results (5.38/h). These parameters were adopted as the default setting for identifying focal EEG seizure patterns in all subsequent long-term bipolar scalp and sphenoidal recordings. Factors hindering or facilitating automatic seizure identification are discussed. It is concluded that on-line computer detection of focal EEG seizure patterns by this method offers a satisfactory alternative to and represents a distinct improvement over the extremely time consuming and fatiguing off-line fast visual review (FVR). Combining CA with seizure signaling (SS) by the patients and other observers increased the correct detections to 85.38% CA is best used in conjunction with SS.

Adolescent↗
PubMed1991

Transcranial Doppler sonography in familial hemiplegic migraine.

A patient affected by familial hemiplegic migraine underwent Transcranial Doppler Sonography twice: the first during a spontaneous attack with right hemiparesis and aphasia, the second during a headache-free period. During the attack the following haemodynamic changes were seen: (a) bilateral increase in the middle cerebral artery and anterior cerebral artery blood flow velocities (this increase was more pronounced on the left side), (b) decreased systo-diastolic ratio and pulsatility index on the right side, (c) increased systo-diastolic ratio and pulsatility index on the left side. Our results indicate that during the attack in this familial hemiplegic migraine patient a diffuse vasoconstriction of the basal cerebral arteries developed. Moreover, Transcranial Doppler Sonography data suggest that a prolonged vasoconstriction of the peripheral arterioles could play a role in determining the neurological symptoms in this syndrome.

Adult↗
PubMed1991

Simultaneous recording of pattern electroretinogram (PERG) and visual evoked potential (VEP) in multiple sclerosis.

We studied 18 multiple sclerosis (MS) patients affected by retrobulbar neuritis (RBN). The patients were subdivided into two groups. Group 1: 14 patients with RBN. Group 2: 4 patients with optic atrophy. An ophthalmological examination (visual acuity, fundus oculi, visual field) was carried out in all the patients. A simultaneous visual evoked potential (VEP) and pattern electroretinogram (PERG) recording at two spatial frequencies (45' and 15') was performed. All the data obtained in Group 1 were compared (Student T-Test) with those of a control group of normal subjects matched for age and sex. Group 1. VEP: a comparison of the data in MS patients affected by RBN with the control group revealed a statistically significant P100 latency delay with both spatial frequencies (P less than 0.001). PERG: no "b" wave latency change at 45' and 15' spatial frequencies were seen. A "b" wave amplitude reduction was observed; this reduction reached significant values at 45' (P less than 0.001). Group 2. In optic atrophies the PERG was absent in 4 eyes at 45' and in 5 eyes at 15'.

Adult↗
PubMed1989

Short-latency sinusoidal wavelets to bright flashed stimuli: studies with corneal lens, nasopharyngeal, retrobulbar and scalp recordings.

Short-latency flash visual evoked potentials (VEPs) and electroretinograms (ERGs) were recorded in 30 healthy volunteers and 14 patients (7 with retrobulbar neuritis and 7 with retinitis pigmentosa). Simultaneous recordings were performed by corneal, scalp, nasopharyngeal and retrobulbar (5 patients) electrodes. In 18 out of 30 healthy controls a brief sequence of oscillating wavelets was recorded between 15 and 40 ms on the scalp sites behind the vertex. In retrobulbar neuritis (RBN) patients normal responses were recorded by lens, retrobulbar, nasopharyngeal and frontal scalp electrodes. On the contrary none of these patients displayed short-latency activity behind the Cz scalp position. In 5 out of the 7 patients with retinitis pigmentosa, corneal, nasopharyngeal and scalp electrodes failed to detect any reliable waveform time-locked to the flash onset. In the remaining 2, a small lens ERG was recorded, while all other electrodes recorded a sequence of low-volted wavelets initiating 30 ms after the stimulus onset. In these patients an occipital VEP reduced in amplitude and with prolonged latency was also recorded. It is concluded that in presence of a normal corneal ERG because of the presence of volume spread oscillating retinal activity, it is hard to define while part of the scalp recorded, short latency, oscillating potentials is generated in subcortical visual structures.

Adolescent↗
PubMed1986

Early auditory evoked potential changes during hypoxic hypoxia in the rabbit.

Early auditory evoked potentials and electroencephalograms were recorded in 10 rabbits during hypoxic hypoxia (5% O2 in N2 gas mixture) and after reoxygenation. In all experiments EEG flattening preceded the disappearance of the early evoked potential, whose recovery after reoxygenation was more rapid than that of the EEG. Significant increases in P3-P4 and P1-P3 interpeak latencies were observed during hypoxic conditions before the complete flattening of the early auditory evoked potential. In addition, negative relationships were found between the P3-P4 interpeak latency increase and mean arterial pressure reduction, and between the former and metabolic acidosis.

Animals↗
PubMed1985

Pain, anxiety, and contingent negative variation: a clinical and pharmacological study.

Contingent negative variation (CNV) behavior was studied in 16 volunteers who were suffering from spontaneous recurrent pain syndromes (idiopathic trigeminal neuralgia, classic migraine). The subjects were divided into two groups, "more anxious" and "less anxious," based on psychometric tests (MMPI and STAI X2). The CNV recordings were carried out, respectively, in basal resting state, during an episode of pain, while under anxiolytic treatment, and lastly, during an episode of pain while under anxiolytic therapy. CNV voltage decrease and frequent appearance of postimperative negative variation (PINV) were observed when pain was present during the recording session. These phenomena were more marked when the pain was accompanied by a greater degree of anxiety. Finally, our results suggest that this slow evoked potential is sensitive to various degrees of anxiety and to pain perception in man, making it useful in the investigation of pain as a complex sensation.

Adult↗
PubMed1985

Pattern visual evoked potentials and flash electroretinogram in clinically definite multiple sclerosis.

The authors have studied, by means of pattern visual evoked potential (VEP) and flash electroretinogram (ERG) recordings, a group of 15 patients affected by definite multiple sclerosis. All of the subjects examined presented a clinical history indicating involvement of the visual pathways; VEPs were altered in a high percentage of eyes examined (93.3%), while a lower percentage of abnormal ERGs was seen (20% of eyes examined). The only type of ERG alteration found consisted of a pathologic b wave voltage increase, observed mainly with red flash stimuli. This finding could be attributed to an involvement of centrifugal optic nerve fibers having inhibitory functions on retinal cells.

Adult↗
PubMed1983

Subjective posttraumatic syndrome. A comparison of visual and brain stem auditory evoked responses.

Evoked responses testing including pattern visual evoked potentials (VEPs) and brain stem auditory evoked potentials (BAEPs) were performed in 57 subjects suffering from subjective posttraumatic syndrome (SPTS). 36 of them had loss of consciousness after head injury. Abnormalities were found in 12 subjects out of 57 (21%). In addition, the pathological findings by percentage were: 25% in subjects who had loss of consciousness after head injury (9 cases out of 36) and 14% in subjects without loss of consciousness (3 cases out of 21). Evoked response alterations were more frequent in subjects with frontal and/or occipital trauma; BAEP abnormalities were found to be more frequent than VEPs. Our findings suggest that evoked responses testing could be a useful noninvasive technique to evidence an organic dysfunction of CNS in some subjects with SPTS.

Adult↗
PubMed1982

Electrophysiological measures (CNV--EEG) and nitrous oxide at low doses in man.

Nitrous oxide (N2O) is a widely used inhalational anesthetic gas, but its exact mode of action and its distribution in the CNS are not yet well known. The aim of this research was to study the effects of N2O at low doses (10 percent) in the CNS of humans. Five healthy volunteers were tested. Contingent Negative Variation (CNV), Reaction time (RT) and quantified EEG recordings were taken while subjects were breathing air and then N2O. A significant reduction of the post-imperative positive CNV components during N2O inhalation was observed; no changes in EEG power spectrum and RT values were seen. These results could be consistent with an early N2O interference with processes underlying CNV resolution, while vigilance and attention were still maintained.

Adult↗