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Biomedical subjects

A Ragazzoni

Publications and source records attributed to A Ragazzoni.

27 records · Page 2Linked to original sources
PubMed1978

[Autism, inhibition, electrophysiology and biochemistry].

The term "inhibition" is not usually employed in the psychopathology of schizophrenia. However, in defining some neuroleptics' action, the work "desinhibition" is currently used and Pavlov explained the main features of the schizofrenic syndrome through a transmarginal inhibition mechanism. The purpose of this study is to investigate if an inhibition process underlies some phenomena shown up by the evoked potentials (EPs) method. Usually, a lower EPs' amplitude is seen in schizophrenic patients than in normals. This phenomenon is displayed by: -- simple stimuli EPs: they show weak amplitude and high variability; -- double-shock EPs: they have a long recovery-cycle; -- conditioned EPs: their amplitude is minimally augmented by coupling the conditioned and the unconditioned stimulus; -- EPs in experiments with increasing-intensity stimuli: their amplitude decreases as stimulation intensity increases. Some of these concurrent data could indicate a transmarginal inhibition, particularly the lengthening of the recovery cycle and the amplitude-reduction phenomenon. Although these are preliminary results, nevertheless some relationships emerge between clemical, electrophysiological and biochemical data.

Brain Chemistry↗
PubMedDate not supplied

Electric and CO2 laser SEPs in a patient with asymptomatic syringomyelia.

We recorded electrically stimulated somatosensory evoked potentials (electric SEPs) and pain-related SEPs following CO2 laser stimulation (CO2 laser SEPs) from a 17-year-old patient affected by myotonic dystrophy whose MRI disclosed a large syrinx extending from spinal level C2 to S3. Careful clinical and electromyographic examinations revealed no motor or sensory disturbances, apart from myotonia. The only abnormality noted in median and ulnar nerve short-latency electric SEPs (recorded with a non-cephalic reference electrode) was the absence of cervical component N13, the other SEP responses (N9, N10, N11, P14, N20) being normal. The cutaneous pain threshold and CO2 laser SEPs (both obtained by a CO2 laser beam applied to the back of the hand) were normal. Thus cervical component N13 appears to be highly sensitive to the effects of central cord lesions, even when these are asymptomatic.

Adolescent↗
PubMedDate not supplied

Abnormal visual event-related potentials in obsessive-compulsive disorder without panic disorder or depression comorbidity.

Visual event-related potentials and spline map topography during a discriminative response task (DRT) were studied in 8 obsessive-compulsive disorder (OCD) patients without comorbidity for panic disorder or depression and in 12 age-matched controls. In the DRT task (like in a go/no-go task) the subject had to press a button when the target stimuli appeared and had to retain the response when the non-target stimulus appeared (vertical bars were intermixed with an equal probability of horizontals). OC patients had greater N1 latency than controls and their N1 and P3 amplitude was larger for the target stimuli, but not for non-target stimuli. In the normals, non-target stimuli (no-go task) produced a larger activation than target stimuli (go task). In the OCD patients the target stimuli produced the same large activation as the non-target. These findings are consistent with theories that consider OCD to be an attentional disorder deriving from a misallocating of cognitive resources. Moreover, spline map topography confirmed that P3 hyperactivation is localised principally on the frontal lobes.

Adult↗
PubMedDate not supplied

[CNV and SEP in shoe-industry workers affected by neuropathy due to toxic effects of adhesive solvents (author's transl)].

The sensitivity of the CNV and somatosensory evoked potentials (SEP) was assessed in shoe industry workers suffering from neurotoxic effects of adhesive solvents. We have examined 21 patients with clear electroneuromiographic and clinical signs of polyneuropathy as well as EEG signs of diffuse brain damage. 10 normal volunteers served as a control group. The maximal motor conduction velocity (MMCV) was considerably reduced in all patients. The maximal sensory conduction velocity (MSCV) was in the lower normal range (or borderline) in 12 patients, whereas in 9 or more severe decrement was detected. In comparison with normal subjects, none of the patients showed clear differences in latency or amplitude of SEP components (p always greater than .2). It was very easy to elicit CNVs over all areas explored and all the 10 patients showed normal characteristics. These results, therefore, suggest that CNV and SEP are not helpful for an early diagnosis of toxic effects of the solvents on the function of the central and peripheral nervous system.

Adolescent↗
PubMedDate not supplied

[Brain-stem auditory evoked potentials (BAEPs) and computerized tomography (CT scans) in patients with reversible ischemic attacks (RIAs) in the vertebro-basilar system (author's transl)].

BAEPs recordings and brain CT Scans have been conducted in 11 patients with RIAs of the vertebral-basilar system. Five patients presented recurrent transient ischemic attacks (TIAs) completely clearing in 24 h, while in the other patients a full recovery took place over a longer period, within 3 week (RINDs). Each patient underwent BAEPs recording, as well CT Scans, EEG and oto-neurological examination, 7-20 days after the last RIA, when all signs and symptoms had disappeared. Both ears were subsequently stimulated and bipolar EEG activity was recorded from Cz and the mastoid electrode ipsilateral to stimulation. At least two sets of 1500 averaged responses from each ear were added. The I-III, III-V, I-V interpeak latencies (IPLs) as well as the IV-V/I amplitude ratio were measured and compared with the values obtained in a control group. Increased IPLs were detected in 4 cases of the TIA group and in 2 of the RIND group. Amplitude ratio was always normal. Any positive information provided by CT Scan showed cerebral atrophy in 4 patients with TIAs and in 1 patient with RIND. BAEPs recording is a relatively simple, non-invasive neurophysiologic test, which can give objective evidence for brainstem dysfunction in vertebro-basilar RIAs.

Adult↗