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Biomedical subjects

F H Linthicum

Publications and source records attributed to F H Linthicum.

At least 91 records · Page 5Linked to original sources
PubMed1988

Why do vestibular destructive procedures sometimes fail?

Vestibular nerve specimens and one temporal bone, from patients with vestibular symptoms after destructive surgery on the vestibular system, were studied by light microscopy. Surviving nerve axons in three specimens that followed retrolabyrinthine vestibular nerve section (RLVNS) were counted and compared to normative data. Results are consistent with persistence of the central processes of primary vestibular neurons in three specimens from patients who had persistent symptoms and ice-water caloric responses after RLVNS. Incomplete neurectomy probably results from anatomic variations in the plane of separation of the vestibular and cochlear portions of the eighth nerve in the posterior fossa. Regeneration neuromas were found in the vestibule after a complete transmastoid labyrinthectomy and a Fick sacculotomy; this indicates that wide degrees of injury to the labyrinth may provoke this response. Disabling unsteadiness after labyrinthectomy may or may not respond to revision surgery (translabyrinthine vestibular nerve section). The indications for revision surgery are discussed. The excision of Scarpa's ganglion by the translabyrinthine route offers the best chance to ensure complete removal of peripheral vestibular tissue, minimize postoperative unsteadiness, and prevent neuroma formation.

Adult↗
PubMed1988

Management of vertigo in patients with syphilis: is endolymphatic shunt surgery appropriate?

Endolymphatic shunt surgery has been suggested as a means to relieve vertigo caused by syphilis in patients unresponsive to conventional medical therapy. We reviewed results of endolymphatic shunt surgery on vertigo and hearing in six patients with syphilis. We found no relief of vertigo in four patients who qualified for this measure and no improvement in hearing. Histologic review of temporal bones from three patients with syphilitic hydrops revealed syphilitic involvement of the endolymphatic duct system. This may explain why endolymphatic shunt surgery may not be beneficial.

Ear Diseases↗
PubMed1988

Cochlear histopathology in the labyrinthectomized ear: implications for cochlear implantation.

Limited damage to the cochlea and preservation of hearing after labyrinthectomy have been the subject of many case reports. One might hypothesize that, even when hearing is lost, there may be less damage to the cochlea than anticipated, and some neural elements that can be electrically stimulated may be preserved. Four labyrinthectomized temporal bones on file at the House Ear Institute were evaluated histopathologically. All had some remaining spiral ganglion cell population, the neural element that we think is stimulated by the intracochlear electrode. We also examined the population of hair cells and dendrites and the presence and extent of cochlear ossification, factors that may influence the performance of a cochlear implant. This is the first study of its type. Results indicate that cochlear implantation in the labyrinthectomized ear may be feasible.

Cochlea↗
PubMed1988

Histopathologic study of the cochlear nuclei after 10 years of electrical stimulation of the human cochlea.

This report provides histologic data on the cochlear nuclei of a patient who used a cochlear implant in the right ear for about 10 years and in the left ear for about 1 year. The most pronounced abnormality in the cochlear nuclei is sites of gliosis. However, since areas of necrosis with similar size, shape, and content of cells were observed outside the nuclei, the gliosis was not specific to the nuclei. There were no other unusual changes in the cochlear nuclei, such as excessive chromatolysis, excessive accumulation of lipofuscin, swollen neurons, or accumulation of glial cells. Comparison showed no statistically significant differences in sizes of cell bodies, size of nuclei, and total density of neurons in cochlear nuclei between the right and left sides. However, the density of normal-looking neurons (with visible nucleoli and without visible pathologic features) was noticeably less on the longer-stimulated side. Some differences between the longer- and shorter-stimulated sides may be due to differences before implantation or other factors, as well as to effects of stimulation.

Cochlea↗
PubMed1987

Computer-aided three-dimensional reconstruction of the cochlear nerve root.

Computer-aided three-dimensional reconstruction techniques have been used for reconstruction of the cochlear nuclei and the cochlear nerve root. The cochlear nuclei, the nerve root, and the other adjacent structures were studied in serial frontal and horizontal sections. Boundaries of these structures were digitized into a computer and eight three-dimensional models were produced. Two solid models (reconstructions) showed the spatial surface topography, while the others revealed the appearance of the nerve root within the nuclei. The reconstructions also showed the position of the tenia of the tela choroidea on the surface of the nuclei and its relation to the root. This knowledge makes it possible to use the tenia as a landmark for determination of the root position within the nuclei. As the nerve enters the nucleus and forms the root, there is an appreciable reduction in its thickness. At the same time, the distance between the nuclei surface and the root, which has a cone shape, increases. The cone is curved along its longitudinal axis toward the inferior cerebellar peduncle. The top of the root borders the dorsal cochlear nucleus. This study stems from work in this institution on placement of the central electroauditory prosthesis on the cochlear nuclei surface. The results obtained further knowledge of the anatomy of the nuclei, specifically the areas used for the prosthesis implantation and the underlying tissue.

Brain Stem↗
PubMed1987

Congenital malformations of the inner ear: histologic findings in five temporal bones.

The histopathologic findings in five temporal bones from three patients with congenital malformation of the inner ear are described. The external contour of the cochlea was deformed in two temporal bones, while the internal architecture was abnormal in all five temporal bones. Intracochlear abnormalities included defects in the interscalar septum, deficiencies in the modiolus, and a paucity of neural elements. Spiral ganglion cell populations varied, but were substantially diminished in all five temporal bones. Enlargement of the vestibule and semicircular canals (lateral and posterior) was seen in two temporal bones. A large vestibular aqueduct and saccular hydrops were found in one temporal bone each. An attempt was made to relate the histologic patterns of deformity to the proposed clinical classification of inner ear malformations. Radiographic abnormality of the cochlea would have been detectable in two bones (incomplete partition pattern), while two other bones would have appeared as vestibule-semicircular canal syndromes. One bone would have been radiographically normal.

Chromosomes, Human, Pair 13↗
PubMed1987

Human endolymphatic sac: possible mechanisms of pressure regulation.

The ultrastructure of the normal human endolymphatic sac (ES) has been observed by transmission electron microscopy (TEM). The role of the epithelium, the various regions of the subepithelial space and the general anatomy of the ES in pressure regulation were morphologically studied to generate testable hypotheses of human ES function. Light microscopic (LM) and TEM evidence of pressure regulatory mechanisms by endolymph resorption, mechanical factors, and secretory activity are presented. These mechanisms may be useful in designing experimental studies of the ES, and in interpretation of retrospective LM and TEM studies of patients with Menière's disease.

Adult↗
PubMed1987

Hydrops due to syphilitic endolymphatic duct obliteration.

Three pairs of temporal bones with otologic syphilis were studied histopathologically to detect obliteration of the endolymphatic duct and the associated hydrops. All cases showed infiltration and obliteration of the endolymphatic duct by round cells, giant cells, and fibrous tissue. These findings may be related to failure of medical treatment and sac surgery to arrest or alleviate symptoms of advanced syphilis.

Ear, Inner↗
PubMed1987

Topography of vestibulocochlear nerve fibers in the posterior cranial fossa.

In the posterior cranial fossa, the separation of the vestibular and cochlear subdivisions of the eighth nerve is clear in about 75% of cases. Although in the remaining cases the vestibulocochlear cleavage plane is not visible macroscopically, the large-fibered vestibular subdivision and the small-fibered cochlear subdivision are well recognized in histological sections. Within the cochlear subdivision, some fibers of large caliber are mixed with fibers of small caliber in a region we named the "overlapping zone." We studied, histologically, cross sections of the intracranial portion of six eighth nerves at about 5 mm proximal to the porus acusticus. A computerized video system was used to measure the diameters of the fibers of the vestibular and cochlear subdivisions localized at different distances from the vestibulocochlear cleavage plane. The overlapping zone is located within the cochlear subdivision adjacent to the vestibulocochlear cleavage plane. It has a pear-like shape, with the larger part occupying the anterosuperior part of the cochlear subdivision. The mean cross-sectional area of this zone in our six samples is about 0.4 mm2, which is approximately 23% of the area of the cochlear subdivision. The thickness of the zone in the superior-inferior direction ranges from 0.23 mm to 0.55 mm. The parameters of the described overlapping zone should be taken into consideration in vestibular neurectomy, in which complete sectioning of the vestibular fibers is important.

Adult↗
PubMed1986

Sensorineural hearing loss associated with systemic lupus erythematosus.

Because our recent clinical experiences suggested a possible association between hearing loss and systemic lupus erythematosus (SLE), we prospectively studied the hearing of 30 patients hospitalized because of exacerbation of SLE. Twenty-nine of the 30 patients were receiving immunosuppressive therapy at the time of testing. We found an 8% incidence of substantial, previously undetected hearing loss without attributable cause. Hearing loss could not be correlated to age, sex, disease activity, organ-system involvement, laboratory test abnormalities, or duration of symptoms of SLE. Otolaryngologists treating patients with unexplainable hearing loss--particularly if it is sudden, fluctuating, or rapidly progressive--are alerted to the possibility of underlying systemic autoimmunity. We advise physicians who frequently treat patients with SLE to include questions on hearing in the review of systems and to refer the patient with hearing complaints for thorough otologic evaluation.

Adrenal Cortex Hormones↗
PubMed1986

Diabetes mellitus and hearing loss: clinical and histopathologic relationships.

We compared audiometric and clinical histories with findings in temporal bones of eight diabetics and ten normal controls matched for age and sex. The group with diabetes mellitus had significantly more hearing loss than the normal control group (p less than .01). Only patients with diabetes had microangiopathy. Patients with microangiopathic involvement of the endolymphatic sac had significantly greater hearing loss than patients without such involvement (p less than .01). Microangiopathy in the stria vascularis was highly significant in the diabetics (p less than .001); however, they did not have a significant hearing loss. Diabetic patients with basilar membrane microangiopathy had significantly lower percentages of histologically normal hair cells (p less than .05) and stria vascularis cells (p less than .05) and significantly greater hearing loss (p less than .01) than diabetic patients without such pathologic changes. Results of this study suggest that diabetic sensorineural hearing loss results from microangiopathic involvement of the endolymphatic sac and/or basilar membrane vessels.

Aged↗
PubMed1986

Calcitonin as treatment for hearing loss in Paget's disease.

Progressive hearing loss is a potential complication of Paget's disease, a metabolic disorder of accelerated bone formation and resorption. Calcitonin (Calcimar) is a recently introduced synthetic hormone used as a systemic treatment. Some studies have shown it to halt the progression of hearing loss. This is the first study of the effects of calcitonin on hearing loss to use a large number of patients with continuous use of the drug and long-term follow-up. It confirms that the drug is effective. We conducted chart reviews to compare the degree of hearing loss over time in 45 patients. Twenty-six patients have been taking salmon calcitonin for five to eight years to date and nineteen have received no treatment. Hearing loss was recorded at the initial examination (trial 1), one to four years later (trial 2), and then one to five years after the second evaluation (trial 3). Statistical analyses show a strong relationship between treatment and rate of hearing loss. The average hearing loss in the control group progressed from 47 dB in the first trial to 59 dB in the second trial to 75 dB in the third trial. Average hearing loss in the treated group remained at 47 dB over time. The difference in hearing loss over time between the two groups was less than 1 dB for the treated group and more than 28 dB for the control group. Results thus clearly show that calcitonin is effective in halting the progression of hearing loss in Paget's disease.

Aged↗
PubMed1986

Filamentous structures morphologically similar to viral nucleocapsids in otosclerotic lesions in two patients.

Two of four patients with active stapedial otospongiosis had abnormal filamentous structures in osteoblast-like cells. These structures were rare in these cells and did not occur in any other cells. The structures were 17 nm wide and clustered in a loose skein in dilated cisternae of the rough endoplasmic reticulum. They resembled the nucleocapsids of subacute sclerosing panenecephalitis, a variant of measles virus.

Capsid↗
PubMed1986

Sodium fluoride: effectiveness of treatment for cochlear otosclerosis.

We examined the effectiveness of sodium fluoride in treatment of cochlear otospongiosis in ninety-four patients with cochlear otosclerosis and ninety-eight patients with stapedial otosclerosis and sensorineural hearing loss. The drug halted or slowed the progression of sensorineural hearing impairment in 63% of the patients with cochlear otosclerosis and 46% of the patients with stapedial otosclerosis. The single factor that best predicted which patients would respond most favorably to treatment was rate of progression before treatment. Sodium fluoride therapy was successful for 79% of the patients losing their hearing at a rate of 5 dB or more per year at one or more of the speech frequencies. The finding that patients with more rapid rates of progression responded most favorably to sodium fluoride therapy suggests that patients with the most active otospongiotic processes will be the most responsive to treatment.

Cochlea↗
PubMed1985

Is the endolymphatic sac always accessible?

All surgical manipulations of the endolymphatic sac have a common requirement: to identify the intradural part. We studied the position of the intradural endolymphatic sac in relation to the posterior semicircular canal, the sigmoid sinus, the retrofacial air cell tract, and the jugular bulb in 50 temporal bones. The intradural sac was identifiable in 48 cases; in two the sac either was absent or would not have been identifiable surgically without jeopardizing other important structures, particularly the posterior semicircular canal.

Ear, Inner↗