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Biomedical subjects

F H Linthicum

Publications and source records attributed to F H Linthicum.

At least 55 records · Page 3Linked to original sources
PubMed1993

Histopathology of otosclerosis.

This histopathologic review illustrates that otosclerosis is a very pleomorphic bone dyscrasia. It may fix the stapes by a tiny bridge of abnormal bone or may totally obliterate it. It may spread to the cochlea to produce either a sensorineural loss of varying degree or deafness. Lesions may be sclerotic, spongiotic, or fibrous but usually comprise all these histologic types. This diversity of size and anatomic distribution coincides with the variable types of hearing loss, from a mild conductive deficit to a total loss. In spite of more than a century of investigation of otosclerosis, an etiologic agent other than heredity has not been established.

Ear Ossicles↗
PubMed1993

Apparent apical endolymphatic hydrops: computer-aided three-dimensional reconstruction and histologic study of the apical turn of the cochlear duct.

Computer-aided three-dimensional reconstruction of the apex of a cochlea and microscopic evaluation of 14 clinically and histologically normal temporal bones were used to demonstrate that what appears to be distention of Reissner's membrane is normal anatomy. The apparent distention is the transition area between the circular insertion of the apex of the cochlear duct and the rest of Reissner's membrane, which is straight.

Adult↗
PubMed1992

A technique to obtain and process surgical specimens of the human vestibular aqueduct for histopathological studies of the endolymphatic duct and sac.

The endolymphatic sac (ES) may play a crucial role in the pathophysiology of Ménière's disease. This paper presents a technique to obtain and process fresh human specimens of the endolymphatic duct (ED) and the presumably more active intraosseous portion of the ES obtained at surgery. The specimens are preserved with an intact bony shell around the ED and the intraosseous ES. This allows ultrastructural histopathological evaluation of the intraluminal contents, the epithelium and the subepithelial tissue as well as the mutual relationships of these structures. Various factors influencing ES ultrastructure are discussed. The results obtained from this method may increase our understanding of the possible role of the ES in the etiology of different inner ear disorders.

Endolymphatic Duct↗
PubMed1992

Long-term effects of Silastic sheeting in the middle ear.

Silastic sheeting is used to restore a mucosally lined middle ear space and to prevent mucosal adhesions between the medial surface of the tympanic membrane and the promontory after surgical procedures involving the removal of middle ear mucosa. To determine the long-term (1.2 to 21.2 years) effects of Silastic sheeting in the middle ear, six temporal bones from patients with permanent Silastic sheeting in the middle ear cavity after single-stage tympanoplasty were examined. In all six bones, no histologic evidence of foreign body reaction, rejection, or chronic inflammation in the middle ear surrounding the silicone sheeting was observed. Furthermore, the middle ear space was lined by normal-appearing, continuous middle ear mucosa. In four temporal bones, there was no evidence of significant submucosal fibrosis. In two bones, significant submucosal fibrosis was attributable to concurrent middle ear disease rather than to the presence of the silicone. It is concluded that Silastic sheeting in the middle ear after single-stage procedures may prevent adhesions between mucosal surfaces. Given eustachian tube function, Silastic promotes a mucosally lined, aerated middle ear cavity without apparent foreign body reaction, rejection, or chronic inflammatory response.

Ear, Middle↗
PubMed1992

Periductal vessels of the endolymphatic duct.

Light microscope was used to examine the rich vascular plexus surrounding the human endolymphatic duct, both in the periductal loose connective tissue and in the bony channels surrounding the bony vestibular aqueduct. We also performed computer-aided three-dimensional reconstruction on one serially sectioned region of the endolymphatic duct. We found an anastomotic and looping network of vessels residing in the loose connective tissue close to the epithelium of the endolymphatic duct. This network often received a vascular contribution from the vessels in the periaqueductal bony channels. These findings were verified by light microscopic examination of 50 temporal bone specimens. Concurrent with this finding, histologic examination also showed different characteristic features of the vascular system of the endolymphatic duct-proximal sac areas and of the more distal parts of the endolymphatic sac. These features include the arrangement, quantity, and contents of the periaqueductal bony channels, as well as the organization of the bone containing these periductal bony channels. Findings from this study help the understanding of the anatomy of the human endolymphatic duct. In addition, they support and supplement earlier observations of the structure of the endolymphatic duct. We suggest the possible existence of a periductal vasculature system, similar in pattern to that in the endolymphatic sac, but specialized to work with the duct to aid its function.

Connective Tissue↗
PubMed1992

Retrolabyrinthine vestibular nerve section: evaluation of technical modification in 143 cases.

Selective vestibular nerve section is effective in relieving intractable vertigo while preserving hearing. Histologic study demonstrated overlap of the cochlear and vestibular fibers at the cochleovestibular cleavage plane within the posterior fossa. In the hopes of improving surgical results by sectioning these overlapping vestibular fibers, the technique of sectioning the vestibular division of the eighth nerve was modified to include a small portion of the cochlear division. We have evaluated 143 cases of retrolabyrinthine vestibular nerve section in which this technical modification was employed. A patient questionnaire was used to examine control of vertigo as well as changes in tinnitus, unsteadiness, and disability. Hearing preservation and incidence of complications were also reviewed. Resolution or improvement of vertigo occurred in 93 percent of Menièré's cases and 74 percent of non-Menièré's cases as compared to 97 percent and 68 percent, respectively, in the pre-1986 series.

Adult↗
PubMed1991

The lateral skull base: a vascular perspective with clinical implications.

The growing number of options in the surgical management of skull base disease has renewed interest in the microvascular anatomy of the lateral temporal region. We studied this anatomy by injecting colored solutions of methyl methacrylate into the major blood vessels of six human cadaver heads or selectively into their major branches. We used several techniques to see the vascular anatomy and to study its relationship to the layers of the scalp. Results revealed that every anatomically named blood vessel was accompanied by a finer, deeper blood vessel supplying the periosteum and outer table of the skull. These vessels arborized into a network of capillaries in the periosteum adherent to the outer bony cortex, from which we saw tiny perforators entering bone. This layered blood supply has direct implications for both ablative and reconstructive surgery for skull base disease. We also saw a previously undescribed arterial plexus accompanying the commonly described venous plexus in the infratemporal fossa.

Journal Article↗
PubMed1991

Ultrastructural evidence of a merocrine secretion in the human endolymphatic sac.

The results of a light and transmission electron microscopic analysis of an endolymphatic sac (ES) from a patient suffering from episodic vertigo, tinnitus, and hearing loss are presented. A biopsy of the intraosseous portion of the ES was obtained during a translabyrinthine approach to section the vestibular nerve in the internal acoustic meatus. The material consisted mainly of tubular epithelial structures filled with heavily stained material. Pathologically dilated and degranulated rough endoplasmic reticuli and disaggregation of polyribosomes with accumulation of solitary ribosomes in the cytosol and endoplasmic reticulum suggested a disturbed epithelial cell protein synthesis. Ultrastructural evidence of an increased merocrine secretion of glycoprotein conjugates into the ES was noted. This made it possible to analyze the presumed intracellular secretory pathways. An increased number of intraepithelial lymphocytes and monocytes was observed. Since the inner ear had been subjected to surgical intervention before the vestibular nerve section, no conclusions can be drawn as to whether the patient's symptoms were related to the disturbed protein metabolism and hypersecretion of glycoprotein conjugates into the ES. The findings support earlier experimental results that indicate that the ES has not only a resorptive function but also a secretory one.

Adult↗
PubMed1991

Three-dimensional analysis of 61 human endolymphatic ducts and sacs in ears with and without Menière's disease.

We used light microscopy and computerized graphic reconstruction techniques to examine the endolymphatic duct and sac in 20 pairs of bones from patients with Menière's disease and 21 bones from controls. The diameters of the endolymphatic duct and the proximal portion of the vestibular aqueduct were significantly smaller in Menière's disease ears than in controls. Graphic reconstructions showed the Menière's sacs to be smaller and to have fewer tubular epithelial structures in the intraosseous portion than in the control ears. The median volume of the sac in the Menière's disease side was substantially lower than in the contralateral ear. The width of the external aperture of the vestibular aqueduct was significantly smaller in Menière's disease ears than in controls. These findings indicate that the size not only of the vestibular aqueduct but also of the sac is reduced in Menière's disease. The results may suggest that the endolymphatic sac is pathologically changed in Menière's disease and that a reduced resorptive capacity of a small endolymphatic sac could result in endolymphatic hydrops.

Aged↗
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

Technique for transmission and immunoelectron microscopy of the human endolymphatic sac and vestibular epithelia.

A surgical technique is presented to obtain the entire vestibular aqueduct, containing the endolymphatic duct and sac as well as the vestibular epithelia, from the maculae and cristae during labyrinthectomy. The inner ear tissue was fixed in 3% glutaraldehyde, decalcified in 0.1 mol/L Na-EDTA, and routinely processed for transmission electron microscopy, including post-fixation with osmium tetroxide. Postembedding protein A-colloidal gold immunoelectron microscopy was performed after exposure of cellular antigenic sites by sodium metaperiodate. To validate this technique, thin sections from the crista ampullaris and the endolymphatic sac were incubated with antibodies raised against S-100, a protein present in specific types of neural tissue. Specific immunoreactivity was observed in the crista ampullaris, but not in the endolymphatic sac. The surgical biopsy technique described provides a means for the neuro-otologist to collect inner ear tissue from surgical patients that can be used for pathological studies using immunohistochemistry and electron microscopy.

Biopsy↗
PubMed1991

Sudden hearing loss due to AIDS-related cryptococcal meningitis--a temporal bone study.

We have presented the clinical history and temporal bone findings in a patient who manifested sudden hearing loss, and who subsequently was found to have cryptococcal meningitis associated with AIDS. The histopathologic findings are similar to earlier reports in patients without AIDS. Because cryptococcal infection is so much more common in AIDS patients than in the general population, it must be considered a causative factor when presented with an AIDS patient with progressive or sudden hearing loss. This offers the patient a chance for timely and effective treatment.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Menière's disease: an immune complex-mediated illness?

The cause of Menière's disease is unknown. Recent clinical research suggests that one etiology is immune-mediated damage to the inner ear. The diagnosis of autoimmune Menière's syndrome is largely based on history, response to steroids, or results of nonspecific laboratory tests such as serological studies. Polyethylene glycol (PEG) assay was used to determine levels of circulating immune complexes (CIC) in 30 patients with Menière's disease and 20 control subjects. Patients with Menière's disease had a statistically significant elevation of serum circulating immune complexes when compared to the control group. This suggests that CICs may be involved in the pathogenesis of Menière's disease, either as a direct cause of damage, or as a by-product of an underlying autoimmune abnormality. Therapeutic implications include use of plasmapheresis to remove the complexes or CIC monitoring to serve as a marker for treatment efficacy.

Adult↗
PubMed1991

Cochlear implantation of totally deaf ears. Histologic evaluation of candidacy.

Successful cochlear implantation depends on the presence of stimulatable neural elements, which are believed to be the spiral ganglion, neurons, or their axons. We examined the 1,152 temporal bones in our laboratory to determine how many with a total sensorineural hearing loss would be implantable. We defined implantable as having 3,500 neurons or more, as determined by successful implant stimulation in two ears from our collection with less than 3,500 neurons. Of 46 bones with deafness, 37 had 3,500 neurons or more and would be considered implant candidates. The types of deafness in the potentially implantable ears and in ears with sufficient neural elements will be discussed.

Cochlear Implants↗
PubMed1991

Microfissures of the temporal bone: do they have any clinical significance?

Microfissures extending from the inner ear to the middle ear are a common temporal bone finding. Recently they have been implicated as a possible cause of sudden sensorineural hearing loss. We examined 34 temporal bones and related the presence or absence of microfissures to sudden sensorineural hearing loss. No relationship was found.

Collagen↗
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↗