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Biomedical subjects

P E Bianchi

Publications and source records attributed to P E Bianchi.

18 recordsLinked to original sources
PubMed2004

[Compared progression of visual-evoked potentials in preterm and term newborns].

PURPOSE: To compare the development of the visual pathway in healthy preterm and full-term newborns using flash and patterned (both transient and steady-state) visual-evoked potentials (fVEP, pVEP-t, pVEP-ss). PATIENTS AND METHODS: Twenty-nine preterm newborns (28-35 weeks gestational age) were evaluated at four different times: at 3 months postnatal and corrected age, at 8 months postnatal and corrected age. They were matched with 92 term newborns tested at 3 and 8 months of life. RESULTS: The maximal perceived spatial frequencies in the groups were: 2 C/d at 3 months postnatal age, >2 C/d at 3 months corrected age and at 3 months at term, between 3 and 5C/d, >=5C/d at 8 months corrected age and at 8 months of life, respectively. The latencies of the P1 and P100 waves for the flash and the transient stimulation were, respectively, 192 ms and 207.9 ms at 3 months postnatal age, 144 ms and 137.7 ms at 3 months corrected age, 126.3 ms and 124.1 ms at 8 months postnatal age, 112.7 ms and 112.5 ms at 8 months corrected age, 137.3 and 110.1 ms at 3 months of life; and 122.3 and 100.5 ms at 8 months of life. DISCUSSION: In the preterm infants of 3 gestational months, the latencies of the fVEP are comparable to those of the 3-month-old full-term infants, although the pVEP-t latencies are still delayed at 8 months. In the fVEP; however, we noted a shorter latency in the preterm infants at 8 months corrected age compared to those of the full-term infants. This tendency inversion was also evidenced at the steady-state stimulation. CONCLUSIONS: As evidenced by our results, at 8 months of corrected age the preterm infants recovered the fVEP and pVEP-ss, but not the pVEP-t. Different results obtained with different visual-evoked stimulations suggest that similar neural pools are developed in not completely equal amounts of time.

Age Factors↗
PubMed2000

Octyl 2-cyanoacrylate in sutureless surgery of extraocular muscles: an experimental study in the rabbit model.

BACKGROUND: Sutureless surgery for strabismus eliminates the risk of perforating the ocular bulb in patients with extremely thin sclerae. Thus far, however, the results obtained with tissue adhesives such as the cyanoacrylates instead of sutures have been less than satisfactory. METHODS: A new adhesive, octyl 2-cyanoacrylate, was tested in 36 rabbit eyes in which the superior rectus was recessed 5 mm. In 36 other eyes the same operation was performed using 5/0 Vicryl sutures. Animals were killed 1, 3, 5, 15, 30 and 45 days after surgery. One eye from each animal was used for histopathological examination of the reinserted muscle and sclera, while the other was used in a tensiometric test to measure how many grams of weight were needed to detach the muscle from its new insertion site. RESULTS: The tensile strength of the bond achieved with the cyanoacrylate adhesive was 94+/-12 g 1 day after surgery (vs 238+/-19 g in the suture group) and 520+/-24 g after 45 days (vs 576+/-27 g with sutures). No cases of slippage, muscle detachment, or local tissue reactions were observed in either group. There were no differences in histological findings between the eyes of the two groups. CONCLUSIONS: Although further study will be necessary before this technique can be used in humans, our findings indicate that octyl 2-cyanoacrylate is superior to the cyanoacrylate adhesives used in the past in terms of adhesion and holding power; given its favorable toxicity profile, this product may offer interesting applications in the future.

Animals↗
PubMed1998

Cerebral visual impairment in periventricular leukomalacia.

Infants with cerebral palsy (CP) frequently present cerebral visual impairment (CVI) often caused by damage to retrochiasmatic pathways. This is particularly true of subjects with damage to the periventricular white matter. Thirty-eight preterm infants with periventricular leukomalacia (PVL) diagnosed by MRI were examined to correlate binocular visual acuity with neuroradiological findings. Binocular visual acuity was evaluated using Teller Acuity Cards and a complete ophthalmological examination was also performed. Three infants with ROP III were excluded from the sample. The age of observation ranged from 20 months to 5 and a half years (mean 42 months). The possible involvement of the optic radiations and/or of the calcarine cortex was detected by brain MRI. Twenty-three infants (66%) presented visual impairment. Of these, 9 (26%) were totally or nearly totally blind and 14 (40%) were low vision children. The other 12 (34%) had normal (2) or near normal (9) vision. MRI findings correlated with visual acuity; a relationship was detected between the degree of visual acuity and the reduction of the peritrigonal white matter, and also between the degree of visual acuity and the extent of calcarine atrophy. This report clearly establishes a relationship between visual impairment and specific MRI findings in children with PVL. Teller Acuity Cards and MRI are useful for detecting potential visual impairment and for improving both the clinical diagnosis of these disorders and the therapeutic approach to these subjects.

Atrophy↗
PubMed1998

Transient nystagmus in delayed visual maturation.

Two infants who presented with wide-amplitude and high-frequency nystagmus and lack of visual awareness in the first 3 months of life were studied. No ocular abnormalities were found. Neurodevelopmental examination, visual evoked potentials and electroretinograms were normal. One infant underwent MRI which resulted in normal findings. Two months later both patients showed increased visual responsiveness and a gradual reduction of the nystagmus amplitude. By 5 months of age nystagmus was no longer detectable and both infants appeared to be visually, developmentally, and neurologically normal. Follow-up at 3 years of age for subject 1 and at 11 months for subject 2 showed that both the infants maintained the normal ophthalmological and neurological assessments. We diagnosed delayed visual maturation with oculomotor involvement.

Brain↗
PubMed1997

Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA.

Recent reports have described families in whom a combination of elevated serum ferritin not related to iron overload and congenital nuclear cataract is transmitted as an autosomal dominant trait. We have studied the molecular pathogenesis of hyperferritinemia in two families showing different phenotypic expression of this new genetic disorder. Serum ferritin levels ranged from 950 to 1,890 microg/L in affected individuals from family 1, and from 366 to 635 microg/L in those from family 2. Cataract was clinically manifested in family 1 and asymptomatic in family 2. By using monoclonal antibodies specific for the H and L ferritin subunits, serum ferritin was found to be essentially L type in both normal and affected individuals. The latter also showed normal amounts of H-type ferritin in circulating mononuclear cells; on the contrary, L-type ferritin contents were 13 times normal in family 1 and five times normal in family 2 on average. Serum ferritin was glycosylated in both normal and affected individuals. There was a close relationship between mononuclear cell L-type ferritin content and serum ferritin concentration (r = 0.95, P < .00001), suggesting that the excess production of ferritin in cells was directly responsible for the hyperferritinemia. The dysregulated L-subunit synthesis was found to result from different point mutations in a noncoding sequence of genomic L-subunit DNA, which behaves as an mRNA cis-acting element known as iron regulatory element (IRE). Affected individuals from family 1 were heterozygous for a point mutation (a single G to A change) in the highly conserved, three-nucleotide motif forming the IRE bulge. Affected members from family 2 were heterozygous for a double point mutation in the IRE lower stem. Using a gel retardation assay, the observed molecular lesions were shown to variably reduce the IRE affinity for an iron regulatory protein (IRP), which inhibits ferritin mRNA translation. The direct relationship between the degree of hyperferritinemia and severity of cataract suggests that this latter is the consequence of excessive ferritin production within the lens fibers. These findings provide strong evidence that serum ferritin is a byproduct of intracellular ferritin synthesis and that the L-subunit gene on chromosome 19 is the source of glycosylated serum ferritin. From a practical standpoint, this new genetic disorder should be taken into account by clinicians when facing a high serum ferritin in an apparently healthy person.

Adult↗
PubMed1997

A pigmented free-floating vitreous cyst in a six-year-old child.

We observed a unilateral free-floating vitreous cyst in a 6-year-old boy. The ophthalmologic examination was otherwise normal. The cyst, which was pigmented, had a diameter of approximately 2.5 mm and was localized in the anterior vitreous of the left eye. In its movements it occasionally affected the visual axis, causing only transient and sporadic blurring of vision. Visual acuity in the affected eye was equal to that in the other eye (20/20). Follow-up is by periodic examinations.

Child↗
PubMed1997

Transsynaptic degeneration of lateral geniculate bodies in blind children: in vivo MR demonstration.

PURPOSE: To investigate signal alterations in the thalamic lateral geniculate bodies of blind patients compatible with transsynaptic degeneration of these nuclei caused by pregeniculate or postgeniculate interruption of the visual pathway. METHODS: Six patients were selected from a group of blind children in our care. Four had cerebral palsy caused by periventricular leukomalacia, one had infantile neuroaxonal dystrophy, and one had Chiari I malformation and hydrocephalus, which was worsened by bilateral ischemic lesions of the occipital lobes. MR examinations (obtained at 0.5 T) were reviewed retrospectively by two neuroradiologists, with particular attention to the visual pathway. RESULTS: Symmetric, focal areas of T2 prolongation were found at the precise site of the lateral geniculate bodies. CONCLUSION: Anterograde (pregeniculate) and retrograde (postgeniculate) transsynaptic degeneration of the second neurons of the visual pathway produce alterations in MR signal.

Arnold-Chiari Malformation↗
PubMed1996

[Unilateral congenital cataract and visual function].

The authors report the case of a young patient presented with cytomegalovirus infection involving the nervous, respiratory and ocular systems. A congenital monocular cataract associated with a chorioretinal macular scar in the controlateral eye imposed surgical treatment of the cataract. No retinal damages were found in the cataractous eye after surgery. Three years later the visual function is supported by the phakic eye in spite of the relative precocity of surgery (4th month), and of the correct antiambliopic treatment. This case would suggest that the period in which a monocular cataract can be treated with good functional results, should be restricted within the first few weeks of life.

Age Factors↗
PubMed1996

Cerebral visual impairment in periventricular leukomalacia: MR correlation.

PURPOSE: To evaluate the involvement of central visual pathways in cases of periventricular leukomalacia, and to correlate the neuroradiologic findings with the degree of visual acuity. METHODS: The MR brain examinations of 27 preterm children affected by cerebral palsy resulting from periventricular leukomalacia and without significant ophthalmologic lesions were reviewed retrospectively to search for possible involvement of the optic radiations and/or of the calcarine cortex. The data were compared with the degree of visual acuity estimated by means of the Teller Acuity Cards test. RESULTS: Seventeen (63%) of the 27 patients had cerebral visual impairment, which correlated strongly with MR lesions. Quantitative reduction and signal hyperintensity of the peritrigonal white matter and atrophy of the calcarine cortex were present in the more severe cases. In two blind patients, an altered MR signal was detected in the lateral geniculate bodies. CONCLUSION: This study clearly establishes a relationship between specific MR findings and visual impairment in children with periventricular leukomalacia. The finding of hyperintensity in the lateral geniculate bodies was interpreted as an axonal reaction. MR imaging is useful for detecting potential visual impairment and for improving clinical diagnosis.

Atrophy↗
PubMed1986

Electroretinographic and visual evoked potential abnormalities in myotonic dystrophy.

Pattern visual evoked potentials (VEPs) and electroretinograms (ERGs) were recorded in 20 patients with myotonic dystrophy. Thirteen out of 20 cases presented both VEP and ERG abnormalities, 3 only ERG alterations, 2 only abnormal VEPs. A significant inverse correlation between P100 latencies and b1 wave amplitude was observed, while N1-P100 and b1 wave amplitude exhibited a parallel change. These data suggest that retinal abnormalities may have a role in inducing subclinical visual pathway alterations in myotonic dystrophy.

Adolescent↗
PubMed1985

[Intravenous and oral encainide: electrophysiological effects in patients with paroxysmal reciprocating supraventricular tachycardia].

The electrophysiologic effects of encainide (E) after acute i.v. (1 mg/kg in 60') and oral administration (75 to 150 mg/die for 48-72 h) were evaluated in 10 pts with PSVT (5 men and 5 women, mean age 48 +/- 15 years). The mechanism of PSVT was related to a reentry through an accessory A-V pathway in 6 cases while in the other 4 the reentry was confined in the A-V node. PA, AH and HV intervals lengthened from 42.8 +/- 5.1, 77.8 +/- 19.7 and 38.3 +/- 6.6 msec to 50 +/- 13.5, 91.7 +/- 22.9 and 49.4 +/- 12.9 and to 48.3 +/- 7.1, 94.4 +/- 33.9 and 44.4 +/- 9.2 msec, after i.v. and oral E respectively. Atrial and ventricular refractory periods showed slight not significant variations. Wenckebach point lengthened from 316 +/- 28 msec to 354 +/- 32 and to 359 +/- 45 msec, after i.v. and oral E respectively. Tachycardia cycle length was 358 +/- 32 msec in basal conditions. After i.v. E tachycardia was inducible only in 6 cases, with a mean cycle length of 403 +/- 48 msec. After oral E tachycardia was reproduced only in 3 patients with a mean cycle length of 433 +/- 85 msec. Nine patients were treated chronically with E, at a mean dose of 89 +/- 36 mg/day. After a follow-up of 18 +/- 8 months, tachycardia recurred but with a marked reduction of the attacks, in 3 patients; only 3 patients complained of side effects (blurred vision). Thus E is highly effective in the prevention of PSVT; the drug seems well tolerated thanks to the low dosage required for the control of PSVT.

Administration, Oral↗
PubMed1981

Diagnostic value of objective campimetry.

The results obtained in ten normal subjects with a new method of pupillocampimetry are described and compared with those obtained with routine campimetry. Once the relationship between the two methods was established, ten subjects suffering from pregeniculate or postgeniculate lesions of the optic pathways were examined by pupillocampimetry. This study shows the value of this new method, particularly for the differential diagnosis of pre- or postgeniculate lesions.

Adaptation, Ocular↗
PubMed1976

[Local adaptation curves evoked by the pupillo-motor reflex].

We have studied local dark-adaptation curves using the pupillary reflex. The results obtained indicate that the dark-adaptation curves produced by central and peripheral stimulation are variable and are in principle similar to the psychophysical curves obtained in matching conditions. This result demonstrates that the pupillary reflex is triggered by two different types of receptors which have the same characteristics as the cones and the rods, and that the system of the pupillary receptors and the optical pathways is identical.

Adult↗
PubMedDate not supplied

Review of experience with retinopathy of prematurity from the Pavia registry (1990-1993).

In this retrospective study we analysed the prevalence of retino-pathy of prematurity (ROP) and its sequelae in a sample of premature infants with birth weight less than 1500 grams. From 1 January 1990 to 31 October 1993, we studied 160 surviving premature infants with very low birth weight (< 1.500 g) referred to the Neonatal Intensive Care Unit of the I.R.C.C.S. Policlinico San Matteo, Pavia, Italy. Thirty percent of these infants suffered from ROP, and 13.7%, with severe ROP, underwent cryotherapy. These latter had very-very low birth weight (< 1.000 g) and low gestational age (< 28 weeks). Follow-up of 69 infants at 12 months for retinal sequelae, refraction defects, bin-ocular vision and ocular motility impairments gave the following results: 1) strabismus 20.3%; 2) > 3D hyperopia 3%; 3) myopia 30.4%; 4) > 5D myopia 3.7%. The incidence of refraction and ocular motility anomalies in patients with acute ROP with spontaneous remission was similar to that of unaffected premature infants. Conversely, in the patients treated with cryotherapy the incidence of strabismus and > 5D myopia was greater than for untreated infants: 30% vs 15.4% (n.s.) and 14.7% vs 0% (p = 0.05), respectively. Cryotherapy was successful in 91.9% of cases and in 37.8% of cases the cicatricial sequelae were limited to peripheral chorioretinal scars.

Cryotherapy↗
PubMedDate not supplied

Esotropia and pseudoexotropia in acute ROP sequelae: clinical features and suggestions for treatment.

We report five cases with a mixture of esotropia and pseudoexotropia due to macular ectopia related cicatricial retinopathy of prematurity (ROP). On inspection, the patients, aged from 9 to 28 years, presented a divergence of the eyes and a nasally decentralised corneal light reflex. The cover test showed esodeviation. All the cases presented some clinical features common to congenital strabismus. Fundus examination showed temporal traction of vascular and retinal tissues and macular ectopia, referrable to cicatricial sequelae of spontaneously regressed severe ROP. Treatment is limited to follow-up, with attention being paid to the control of retinal damage rather than to resolving the esthetic defects. Despite cryotherapy, these conditions are increasing with the increase in severe ROP and are now relatively frequent. We suggest that they be carefully identified in order to avoid incorrect orthoptic or surgical treatment.

Acute Disease↗