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Biomedical subjects

J Fayad

Publications and source records attributed to J Fayad.

15 recordsLinked to original sources
PubMed1994

Erythromycin strengthens the defective lower esophageal sphincter in patients with gastroesophageal reflux disease.

Motilin induces phase III activity of the gastrointestinal tract. Erythromycin has a motilin-like effect on the stomach and significantly increases the lower esophageal sphincter (LES) pressure in normal volunteers. This investigation was performed to evaluate the effects of erythromycin on esophageal function in patients with gastroesophageal reflux disease (GERD). Esophageal manometry was performed in 10 GERD patients before and after intravenous infusion of 500 mg of erythromycin. Values are expressed as mean +/- SEM. LES pressure increased from 13.9 +/- 2.9 mm Hg at baseline to 28.9 +/- 3.6 mm Hg after infusion of erythromycin (p < 0.01). The duration of contractions in the proximal, middle, and distal esophagus was significantly prolonged from 3.5 +/- 0.4 seconds, 3.8 +/- 0.4 seconds, and 4.1 +/- 0.5 seconds to 4.2 +/- 0.2 seconds, 4.6 +/- 0.5 seconds, and 5.6 +/- 0.6 seconds, respectively, after infusion of erythromycin (p < 0.05 for each comparison). Erythromycin did not effect esophageal body contraction amplitude or velocity, or the upper esophageal sphincter. Serum motilin decreased slightly after the administration of erythromycin. We concluded the following: (1) Erythromycin profoundly stimulates the defective LES in patients with GERD. This appears to be a direct motilin agonist-like effect rather than being mediated by release of endogenous motilin. (2) Erythromycin has less effect on the esophageal body, although it does prolong the duration of esophageal contractions.

Erythromycin↗
PubMed1994

Prefabricated microvascular autograft in tracheal reconstruction.

Tracheal reconstruction continues to be a challenge in head and neck surgery. Numerous techniques, including the use of alloplasts, composite grafts, and staged laryngotracheal troughs, have met with limited success because of implant exposure, infection, persistent granulation tissue, and eventual restenosis. With recently introduced techniques for soft-tissue molding, bone induction with bone morphogenetic protein, and microvascular free tissue transfer, a rodent model was developed to create a well-vascularized tracheal autograft. In this model, a rigid tube having the same dimensions and flexibility as the native trachea was created by wrapping a cylindrical silicone tracheal mold with a layer of vascularized adductor thigh muscle pedicled on the femoral vessels in the groin. Tracheal rings were created by filing transverse troughs in the muscle bed with bone morphogenetic protein-primed demineralized bone matrix before wrapping around the silicone mold. Grafts harvested at 2 weeks demonstrated rigid skeletal support provided by heterotopic bone formation in the form of rings and a smooth inner lining produced by fibroplasia. Bone transformation was controlled and restricted to the muscle troughs, allowing intervening regions of soft tissue and thus producing a flexible neotrachia. With this model, a homologous, vascularized tracheal autograft capable of microvascular free tissue transfer was fabricated based on the femoral vessels. Prefabrication of composite grafts, through the use of soft-tissue molding, bone induction, and subsequent free tissue transfer, has an unlimited potential for use in head and neck reconstruction.

Animals↗
PubMed1994

Advances in otology and neurotology.

During the last few years many advances occurred in the field of Otolaryngology. In this article we will present significant advances in the fields of otology and neurotology. The adaptation of laser energy to surgery is a significant event in the evolution of ear microsurgery. Lasers in otology reduce trauma and increase accuracy. Implantable hearing devices are used to rehabilitate patients with mild to moderately severe hearing loss. Cochlear implants have secured a permanent role in the management of selected profoundly deaf patients. Intraoperative cranial nerve monitoring is a major advance in ear surgery. Facial nerve and auditory nerve monitoring are now widely used and are the basis for facial and hearing conservation.

Cochlear Implants↗
PubMed1993

Auditory brainstem implant: II. Postsurgical issues and performance.

The auditory brainstem implant (ABI) restores some hearing sensations to patients deafened by bilateral acoustic tumors. Electrodes are stable for more than 10 years. In most cases nonauditory side effects can be avoided by judicious selection of the stimulating waveform and electrode configuration. Most perceptual measurements demonstrate that the ABI produces psychophysical and speech performance similar to that of single-channel cochlear implants. ABI patients receive suprasegmental information in speech and significant enhancement of speech understanding when the sound from the ABI is combined with lipreading.

Brain Stem↗
PubMed1991

Electrode insertion trauma in cochlear implantation.

Residual hearing conservation may be important in cochlear implantation of children and of adults with disabling tinnitus responsive to extracochlear stimulation. Damage to the neural elements of the cochlea during electrode insertion may have a negative impact on residual hearing conservation. Histologic analysis of eight temporal bones with cochlear implants reveals trauma at essentially two locations: the round window insertion site and along the basal turn of the cochlea. In four of the bones, insertion at the round window resulted in damage to the osseous spiral lamina and the electrode was inserted through the scala media into the scala vestibuli. Evidence of secondary reactive osseous formation was also noted in these bones. This paper relates the surgical anatomy of the round window to histologic findings and microanatomical dissections. Recommendations for implantation surgery include creation of a cochleostomy by removal of the floor of the round window niche and a superior-to-inferior angle of electrode insertion.

Aged↗
PubMed1991

Cochlear implants: histopathologic findings related to performance in 16 human temporal bones.

This paper presents results of a histologic study of 16 temporal bones with cochlear implants from 13 subjects. Damage caused by electrode insertion in the basal turn of the cochlea was evaluated. Dendrite and spiral ganglion cell populations were compared to clinical performance scores to determine structures necessary for stimulation and the minimum number needed for electrical stimulation. Results show that damage from insertion of long electrodes was located mainly at the most anterior part of the basal turn; that despite total degeneration of dendrites in the area near the electrode, some spiral ganglion cells remained; and that spiral ganglion cells or possibly axons are the stimulated structures and that fewer of them than previously thought are necessary to achieve a hearing sensation from electrical stimulation.

Adult↗
PubMed1991

Cochlear implant histopathology.

Twenty-two temporal bones and one brain stem from 13 cochlear implant patients were examined histologically. Sixteen temporal bones had undergone one or more implant procedure. Results of analysis suggested that the ganglion cells were the responding elements to the implant and that useful auditory sensation could result from as few as 10 percent of the normal number of ganglion cells. All implanted bones exhibited varying amounts of fibrosis (some ossified) in the basal turn of the cochlea and beyond in some cases. Usually there was damage to the surviving elements of the organ of Corti and the dendrites throughout the extent of the electrode insertion. However, the ganglion cell population was not affected. Prolonged electrical stimulation (up to 14 years) did not affect ganglion cell survival in three cases, and had no effect on the cochlear nerves in two cases or on cochlear nuclei in one case.

Adult↗
PubMed1991

Inner ear morphologic changes resulting from cochlear implantation.

Insertion of electrodes into the cochlea can damage the spiral ligament, organ of Corti, osseous spiral lamina, and dendrites. The amount of damage depends on the method of insertion and the amount of surgical trauma. Damage is limited to the area immediately adjacent to the electrode. Damage in the cochlea and prolonged electrical stimulation do not affect ganglion cell population. The ganglion cell population responds directly to the electrical stimulus. Examination of three auditory nerves from three cases and the cochlear nuclei from one case also reveals no effect of prolonged electrical stimulation.

Cochlear Implants↗
PubMed1990

Cochlear nucleus anatomy related to central electroauditory prosthesis implantation.

The central electroauditory prosthesis is now used to stimulate the cochlear nuclei to obtain auditory perception in patients with bilateral cochlear nerve transection who are undergoing bilateral acoustic tumor removal. In this study, we used fixed cadaver specimens to identify visible landmarks for accurate placement of the central electroauditory prosthesis through a combined suboccipital-translabyrinthine opening. Histologic features of the regions of probable implantation of the central electroauditory prosthesis were also investigated. We found that the following landmarks might have surgical significance: (1) the tenia of the inferior velum of the fourth ventricle, which crosses the surface of the ventral cochlear nucleus and the vestibulocochlear nerve; (2) the angle between the vestibulocochlear and glossopharyngeal nerves; and (3) the foramen of Luschka. It is suggested that an incision be made in the tenia for insertion of the prosthesis into the lateral recess and eventual placement on the ventral cochlear nucleus surface. To study regions of potential stimulation, we injected ink into different sites on the exposed surface of the cochlear nuclei. We then histologically examined neuronal populations adjacent to the sites. We found that a portion of the ventral cochlear nucleus localized within the lateral recess might be the most appropriate location for placement of the central electroauditory prosthesis.

Cochlea↗
PubMed1990

A technique for reembedding celloidin sections for electron microscopy.

A new technique for reembedding celloidin sections of human temporal bones for transmission electron microscopy is described. It consists of four steps: 1. loosening of celloidin sections from glass slides with use of xylene and dissection of the area of interest, 2. removal of celloidin with use of clove oil, 3. staining with 1% osmium tetroxide and 1% tannic acid, and 4. embedding in epoxy resin. Autolytic changes were seen due to poor fixation. TEM of reembedded celloidin sections of optimally fixed tissue revealed that the celloidin-embedding procedure affected ultrastructural preservation to some degree. This included less well-preserved cell membranes and some increased electron density of the cytosol decreasing the EM resolution of intracytoplasmic organelles. The technique allows TEM analysis of the intact labyrinth at all regions in the same specimen without dissection of the fragile tissue components of the membranous labyrinth. This might make the technique useful for processing freshly fixed human inner ear tissue and temporal bones for ultrastructural histopathological analysis.

Animals↗
PubMed1990

Transmission electron microscopy of previously embedded celloidin sections.

A technique to re-embed celloidin sections of human temporal bones for transmission electron microscopy (TEM) is presented. The procedure consists of basically four different steps, starting with loosening of the celloidin sections from the glass slides, removing the celloidin using clove oil, to staining and embedding in epoxy resin. The technique allows TEM analysis of the intact labyrinth in various regions in the same specimen, as well as on the same section. This may prove useful, as prior dissection of the fragile tissue components of the membranous labyrinth is not longer necessary. The technique makes possible the retrospective study of temporal bone collections. It may also be of value for the study of the ultrastructural histopathology of the human inner ear in optimally preserved tissue.

Animals↗
PubMed1990

[Cochlear implants: histological data].

We have performed a histological examination of the pars petrosa of 13 implanted patients. Morphological data were confronted with the clinical findings. The results of this study show that the nerve elements stimulated by the electrode are the cells of the spiral ganglion, and that a small number of ganglionic cells, as few as 10% of the normal figure, is compatible with auditory perception by electrical stimulation. Furthermore, all the implanted pars petrosa were the seat of a fibrosis and neo-ossification reaction around and sometimes even beyond the tip of the electrode. The trauma caused by the insertion of the electrode into the cochlea involved the sensorial cells of the organ of Corti and the dendritic populations in the lamina spiralis, but the cells of the spiral ganglion were spared. Prolonged electrical stimulation (14 years in 1 case) does not appear to have any deleterious effect on the survival of the spiral ganglion, of the cochlear nerve or of the cochlear nucleus.

Adult↗
PubMed1990

Cochlear otosclerosis: does bone formation affect cochlear implant surgery?

This study aimed to demonstrate that new bone formation in the scala tympani of patients deaf from otosclerosis does not preclude cochlear implant surgery. In seven temporal bones from patients with otosclerosis, we measured the extent of new bone from the round window to the distal part of the new growth. We compared results to surgical data on the extent of drilling and depth and ease of placement of the electrode in 20 patients deaf from otosclerosis. We also examined clinical performance and voltage requirements for long-term implant use in patients with and patients without ossification of the scala tympani. Findings in our limited sample of patients and bones show that obstruction of the basal turn, which occurs in some otosclerotic patients, does not preclude implant surgery. The dynamic range in the studied sample was relatively stable long-term and clinical performance did not differ between groups with and without an ossified scala tympani.

Adult↗