Biomedical subjects

G P Fava

Publications and source records attributed to G P Fava.

5 recordsLinked to original sources

PubMed1997

A carbon fiber reinforced polymer cage for vertebral body replacement: technical note.

OBJECTIVE: We analyzed the surgical technique used for the replacement of damaged vertebral bodies of the thoracolumbar spine and the carbon fiber reinforced polymer (CFRP) cages that are used to replace the pathological vertebral bodies. We also evaluated the biomechanical properties of carbon composite materials used in spinal surgery. TECHNIQUE: The surgical technique of CFRP implants may be divided into two distinct steps, i.e., assembling the components that will replace the pathological vertebral bodies and connecting the cage to an osteosynthetic system to immobilize the cage. INSTRUMENTATION: The CFRP cages, made of Ultrapek polymer and AS-4 pyrolytic carbon fiber (AcroMed, Rotterdam, The Netherlands), are of different sizes and may be placed one on top of the other and fixed together with a titanium rod. These components are hollow to allow fragments of bone to be pressed manually into them and present threaded holes at 15, 30, and 90 degrees on the external surface, permitting the insertion of screws to connect the cage to an anterior or posterior osteosynthetic system. RESULTS: To date, we have used CFRP cages in 13 patients undergoing corporectomies and 10 patients undergoing spondylectomies. None of our patients have reported complications. CONCLUSIONS: CFRP implants offer several advantages compared with titanium or surgical grade stainless steel implants, demonstrating high versatility and outstanding biological and mechanical properties. Furthermore, CFRP implants are radiolucent and do not hinder radiographic evaluation of bone fusion, allowing for better follow-up studies.

Adult↗

PubMed1992

Early receptor potentials recorded in humans via dermal electrodes. Normative data and prognostic value in retinal detachment.

Early receptor potentials were recorded by skin electrodes positioned at the inferior orbital margin in 32 patients with recent bullous retinal detachments and in nine patients with old, total retinal detachments. Results were compared to those obtained in a normative study performed on 200 healthy subjects. In patients with recent retinal detachments, no significant variations were found with respect to normal subjects. In patients with old retinal detachments, an early receptor potential of decreased amplitude was recorded in only five subjects, while in the other four the trace could not be separated from the noise.

Adolescent↗

PubMed1991

Retinal early receptor potential in retinitis pigmentosa: correlations with visual field and fluorangiography estimates.

The flash induced electroretinogram (ERG) and early receptor potential (ERP) were recorded in a population of patients with definite diagnosis of retinitis pigmentosa in the context of a study protocol including a complete diagnostic screening. ERPs were evoked by full-field 20-joule stimuli (5 stimuli at 10 min of interval in dark adaptation); recording was by skin electrodes positioned at the inferior orbital margin; amplifiers were set at 10-10,000 Hz. The flash ERG was absent or markedly abnormal in all cases, even at an early stage of development of the retinitis, while ERPs (with a normal morphology, latency of the R1 component increased and a reduced amplitude compared to normal controls) could be identified unambiguously in all cases. The amplitude reduction was highly correlated with the severity of the disease as determined by kinetic perimetry and fluorangiography.

Adult↗

PubMed1991

New surgical method for nystagmus without null point.

We report our results in nystagmus without null point surgery, utilizing a new technique consisting in the placement of a silicone encircling band around the globe over the four recti muscles, in the retroequatorial position. This method was tried only in nystagmus without null point and with both horizontal and vertical movements. We have not observed any ischemic complication of the anterior segment nor any important variation of intraocular pressure probably because the silicone band was not tightened. Other advantages of this method are its reversibility (cutting the silicone band) and the possibility of combining it with recession-resection of recti muscles at the same or at a later date.

Adult↗

PubMedDate not supplied

Evaluation of amblyopic scotoma by electrophysiological examinations and computerized perimetry.

To evaluate amblyopic scotoma and the most affected neural cells in suppressive phenomena, eight patients with deep amblyopia from strabismus (visual acuity of the amblyopic eye between 4/50 and 2/10) underwent a pattern electroretinogram (PERG), pattern visual evoked potential (VEP), and event-related potential (ERP) from visual stimuli, and computerized perimetry. The results of stimulation of the amblyopic eye, the leading eye and the leading eye penalized by Ryser filters were compared statistically. Computerized perimetry was used to quantify the depth and amplitude of the amblyopic scotoma. All electrophysiological potentials were reduced in amplitude and the implicit times of VEP and ERP were longer when stimulating the amblyopic eye compared to the leading eye. Only in PERG the penalization induced major changes. Our data suggest that the important suppressive phenomena present in the squint amblyopic eye involve not only the occipital cortex, but also the cognitive areas.

Adolescent↗