Biomedical subjects

S Rinalduzzi

Publications and source records attributed to S Rinalduzzi.

11 recordsLinked to original sources

PubMed2006

Brainstem dysfunction in alternating hemiplegia of childhood: a neurophysiological study.

Six patients with alternating hemiplegia of childhood (AHC) underwent motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs) and blink reflex recording. No SEP abnormality was found. As for MEP recording, central conduction time did not differ between patients studied during either interictal or ictal phase, and normal subjects, suggesting that the pyramidal system function is spared. In blink reflex recording, the latencies of both the ipsilateral (iR2) and contralateral (cR2) R2 components were significantly longer (P<0.01) in patients during the interictal phase than in normal subjects. Moreover, the iR2 and cR2 areas were significantly reduced (P<0.01) in patients during the interictal phase, compared with normal subjects. During the ictal phase, the ipsilateral R2 latency was significantly decreased after stimulation of the hemiplegic side, compared with the interictal phase (P<0.05). The blink reflex abnormalities suggest a brainstem dysfunction, which may be linked to the pathophysiological mechanisms of the disease.

Adolescent↗

PubMed2001

Video color perimetry: impairment in glaucoma suspects.

PURPOSE: To detect mild visual field impairment in asymptomatic glaucoma suspect patients. METHODS: Color perception within the visual field was tested with customized color video perimetry. The key features of the system were stimuli color desaturation, low-level luminance and equiluminant gray background. Twenty patients with asymptomatic glaucoma were tested and compared with a group of age-matched control subjects. RESULTS: Automated perimetry test findings differed significantly in the two groups, particularly for short-wavelength sensitivity (blue). The severity of color impairment correlated directly with intraocular pressure. CONCLUSION: Desaturated low-luminance video perimetry will reliably detect and quantify asymptomatic visual field defects. A previous work on multiple sclerosis has detected a mild long-wavelength (red) impairment in asymptomatic patients after an episode of optic neuritis, even in clinically unaffected fellow eyes. Our findings in glaucoma suspect patients indicate that a mild blue impairment could be the initial sign of this disease.

Adult↗

PubMed2001

Variation of visual evoked potential delay to stimulation of central, nasal, and temporal regions of the macula in optic neuritis.

OBJECTIVES: To compare the degree of visual evoked potential (VEP) delay to stimulation of central, nasal, and temporal regions of the macula in optic neuritis, to determine whether the differential involvement of parvocellular and magnocellular fibre types suggested by other studies is governed by retinotopic factors. METHODS: VEPs were recorded to reversal of 40' checks in the central (4 degrees radius) and the left and right surrounding regions of the visual field (as far as 10 degrees vertical and 14 degrees horizontal) in 30 patients recently recovered from the acute stage of optic neuritis, and in 17 age matched controls. RESULTS: In the control group, VEP latencies were similar to stimulation of the central and temporal regions of the macula, marginally shorter from the nasal region. In the patients with optic neuritis, VEPs were significantly more delayed from the central region, on average by about twice as much as from the nasal and temporal regions. Delays seen in some of the VEPs from the patients' fellow eyes tended to be more uniformly distributed. CONCLUSIONS: Although the central region of the macula is where the density of parvocellular innervation is greatest, there is no reason to suppose that the VEPs to stimulation of the nasal and temporal regions (almost all P100 activity arising from within the central 10 degrees ) are mediated by fibres of another type. Consequently it is suggested that the central fibres were most affected by demyelination, not on account of their belonging to the parvocellular type but because of their particular situation in the optic nerve. Centrally located fibres may experience greater exposure to factors causing demyelination, or fibres located closer to the edge of the plaque may undergo more effective remyelination in the first few weeks after the acute episode.

Adult↗

PubMed1999

Migraine and ocular pain in "glaucoma suspect".

A relationship between glaucoma and migraine has been hypothesized by some authors, but not confirmed by others. We studied the prevalence and features of migraine and ocular pain in 460 "glaucoma suspect" patients (with ocular hypertension, but without optic disc and visual field abnormalities) and 460 controls. A higher prevalence of migraine was found in patients (13%), particularly in women (17%), than in controls (7%). At the time of the interview, migraine was still active in 68% of the patients and had decreased in the remaining 32% (prevalently those not being treated for ocular hypertension), whereas it had ceased in 52% of controls. Attacks of "ocular pain" of mild and moderate intensity were found to occur in 51% of the patients with both "glaucoma suspect" and migraine, in almost all who were not taking treatment for ocular hypertension. "Ocular pain" was time-related to the history of glaucoma. Changes in intraocular pressure may play a role in the interaction between "glaucoma suspect", migraine, and ocular pain.

Female↗

PubMed1998

Subclinical visual impairment in phenylketonuria. A neurophysiological study (VEP-P) with clinical, biochemical, and neuroradiological (MRI) correlations.

During detailed visual function testing, pattern-reversal visual evoked potentials (VEP), generated by different spatial frequencies (3 c/d, 1 c/d and 0.6 c/d) and visual contrasts (100% and 10%) were recorded in 21 adolescent and young adult phenylketonuric (PKU) patients (11 females and 10 males; mean age 14.8 years, range 9-22.8) on and off diet. In 14 of the 21 patients, disease had been detected at neonatal screening and in 7 later. Ten age-matched healthy subjects acted as controls. Recordings in more than 40% of eyes in the whole group and 30% of eyes in the screening subgroup showed a prolonged P100 latency. All visual pattern stimuli elicited a significantly longer P100 latency in PKU patients than in controls. VEP latencies to 3 c/d, 1 c/d and 1 c/d with 10% contrast--but not to 0.6 c/d--were longer in patients off diet than in patients on diet. No differences were found between VEP latencies in early- and later-detected subjects. To study the link between biochemical variables and VEP latencies, we envisaged either a linear relationship between recent exposure to phenylalanine (Phe) and VEP abnormalities or a threshold model considering phenylalanine (Phe) concentrations among the factors influencing VEP latencies. The correlation analysis detected an association between plasma Phe concentrations and abnormal VEP latencies, predicting that plasma Phe concentrations > 901 mumol/L would prolong VEP latencies to 1 c/d; concentrations > 879 mumol/L would prolong latencies to 3 c/d; and concentrations > 898 mumol/L would prolong latencies to 1 c/d with 10% contrast.

Adolescent↗

PubMed1998

Computerized color perimetry in multiple sclerosis.

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 1 degree angle vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.

Adolescent↗

PubMed1997

Clinical multisegmental posturography: age-related changes in stance control.

Unlike conventional platform posturography, which analyses the sway in the projection of the body baricentre on a supporting plane, multisegmental posturography provides information about body segmental movements during stance, including those that keep the baricentre still. This paper presents a new technical approach to multisegmental posturography using Virtual Reality electromagnetic tracking devices. This device was used to study age-related differences in normal subjects in the control of upright posture. Body sway was studied by recording the oscillations of two trackers placed on the head and the hip during the Romberg test. The tracking device allowed us to detect age-related differences in postural stance strategies. Although the amplitude and velocity of the oscillations measured at the head did not differ in the two groups, the flexibility of the ankle-hip head axis differed significantly: elderly subjects exhibited a more rigid stance. Closing the eyes increased rigidity in both age groups and this change appear more pronounced in the young.

Adolescent↗

PubMed1997

Color perimetry with personal computer.

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in M. S., yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. 264 colored patches subtending 1 degree angle of vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative informations. Comparison between normals and a selected population of Patients with Multiple Sclerosis and with Glaucoma without luminance visual field defects, showed high statistical difference.

Adult↗

PubMed1994

Color VEPs in Parkinson's disease.

Evoked potential studies have confirmed visual pathway impairment in Parkinson's disease. Dopamine is also known to be involved in retinal color vision mechanisms. In this study, pattern evoked potentials were recorded in 20 parkinsonian patients in "on" and "off" conditions to compare the sensitivity of black-and-white and color pattern stimuli. Evoked responses to colored patterns proved more sensitive to L-DOPA therapy. This finding supports the proposed dopamine modulation of the retinal color system and suggests that color pattern evoked potential studies might be used in monitoring dopamine therapy in parkinsonian patients.

Adult↗

PubMedDate not supplied

Changes in color vision after a single dose of vigabatrin or carbamazepine in healthy volunteers.

In patients with epilepsy the older antiepileptic drugs induce distinct electroencephalographic changes and may also alter visual function. Although the effects of the newer antiepileptic drugs on the electroencephalogram remain less clear, long-term treatment with vigabatrin (VGB) has been reported to induce severe and permanent visual impairment. Our aim in this study was to investigate the effects of a single oral dose of VGB and carbamazepine (CBZ) on visual function in normal healthy volunteers randomly assigned to three groups according to a single-blind, placebo-controlled design. All subjects underwent color visual evoked potential tests and color perimetry at baseline and after receiving placebo, VGB (2,000 mg) or CBZ (400 mg). Whereas CBZ induced a mild overall impairment of the chromatic and achromatic systems, VGB induced a selective blue impairment. The differential changes the two antiepileptic drugs induced in visual tests presumably depend on their different mechanisms of action. The selective blue impairment in color visual tests in VGB-treated healthy subjects is consistent with gamma-aminobutyric acid (GABA)-ergic inhibition also at retinal level. Hence, color visual tests may be suitable to detect initial visual abnormalities in VGB-treated patients with epilepsy.

Adult↗

PubMedDate not supplied

Clinical and electroencephalographic effects of topiramate in patients with epilepsy and healthy volunteers.

Although topiramate, one of the newer drugs used in treating epilepsy, is effective in reducing seizure frequency and has a wide spectrum of action, it often induces intolerable adverse effects, predominantly related to the central nervous system. Information that would help document adverse reactions early, thus allowing topiramate doses to be adjusted during the drug titration and maintenance phases, could be obtained from electroencephalogram (EEG) studies. We studied the clinical effects and EEG changes induced by topiramate in patients with refractory partial epilepsy receiving the drug as add-on therapy. To exclude effects related to the other drugs and to epilepsy itself, we compared data from patients and healthy volunteers. After receiving topiramate, 22.6% of patients became seizure free and 29% had their seizures reduced by 50% or more. Topiramate nevertheless induced noteworthy adverse reactions, the main problems being sedative and cognitive changes. Also, in healthy volunteers, a single 100-mg dose of topiramate induced mild adverse reactions, mainly affecting concentration and attention, with difficulties in speech and writing. In patients with epilepsy, the EEG changes induced by topiramate consisted of increased delta and theta activities and decreased activity in the rapid bands. This recognizable topiramate-induced EEG pattern was again evident in the healthy volunteers, in whom we also detected a significant reduction in the alpha frequency rhythm. Our results confirm that topiramate needs to be introduced gradually while patients undergo close neuropsychologic and neurophysiologic monitoring to detect adverse sedative and cognitive reactions early. The EEG correlate of these events seems to be increased activity in the slower frequency bands.

Adult↗