Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fenestration, Labyrinth”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1999

Impact of bacillus thuringiensis var. israelensis On larvae of chironomus thummi thummi and psectrocladius psilopterus (Diptera: chironomidae)

Chironomid larvae, especially species of the subfamily Chironominae, are known to be sensitive to the mosquitocidal bacterium Bacillus thuringiensis var. israelensis (B.t.i.). In this study, bioassays and electron microscopic investigations were carried out with third- and fourth-instar larvae of Chironomus thummi thummi Kieffer (subfamily Chironominae) and Psectrocladius psilopterus Kieffer (subfamily Orthocladiinae) in order to study the sensitivity of species belonging to different chironomid subfamilies. Both species showed susceptibility to increased B.t.i. concentrations, with LC50 values (24 h) ranging from about 40- to 60-fold the LC50 for Aedes aegypti (LC50 (24 h) is 0.77 mg/L for C. thummi thummi and 1.17 mg/L for P. psilopterus). C. thummi thummi was shown to be twice as sensitive as P. psilopterus. Ultrastructural investigations of the anterior midgut showed cellular alterations in larvae exposed to a high B.t.i. concentration (2.8 mg/L, about 50-fold the LC50 for A. aegypti), such as swelling of mitochondria, dilatation of intercellular spaces and basal labyrinth, fenestration or disorganization of the Golgi complex, concentric arrangement of rough endoplasmic reticulum, and an increase of lysosomes and myelin figures. Electron-lucent regions within the cell, cell protrusion, and, in some cases, swelling or lysis of cells were further effects observed in treated animals. Most effects were found in both species, though they seemed to be more severe in C. thummi thummi. The alterations coincide with those known from target organisms (Culicidae, Simuliidae). This study shows that there is a difference in sensitivity to B.t.i. between chironomid species from different subfamilies and that the susceptibility of chironomid larvae to the bacterial toxins is due to damage of the midgut epithelium as it is in target organisms. Copyright 1999 Academic Press.

Journal Article↗
PubMedDate not supplied

Evidence for sound perception with the labyrinth.

A report is presented of experiments on guinea pigs and pigeons concerning behavioural and electrophysiological responses of the labyrinth to sound. In the guinea pigs the cochlea was destroyed on both sides by CO2 laser radiation and fenestration of the lateral semicircular canal was done. In the pigeons the cochlea was removed before fenestration. On account of the results obtained, fenestration of the lateral canal in patients with bilateral total cochlear loss can be considered as an alternative to monopolar cochlear implants.

Action Potentials↗
PubMed1991

[Selective resection of the lateral semicircular canal with hearing preservation--an animal experiment study].

The goal of our investigation was to develop a method for removing parts of the vestibular labyrinth by surgery without inducing a loss of auditory function. Three different surgical lesions were created in the lateral semicircular canal of the rabbit: (1) fenestration; (2) fibrin glue perfusion of the canal following fenestration; and (3) destruction of the semicircular canal by drilling after fenestration and fibrin glue perfusion. Brain-stem auditory potentials were recorded repeatedly up to 3 months after operation. They demonstrated preservation of hearing in all rabbits in the first group, in 78% of the second and 67% of the third group. In the last group a 20 dB deterioration of hearing was regularly noticed. Histological study revealed the utmost importance of the fibrin glue perfusion of the perilymph space of the semicircular canal inducing an interruption of the peri- and endolymph flow. A precise microsurgical technique was crucial for hearing preservation.

Animals↗
PubMed1981

Small fenestra stapedectomy. A preliminary report.

The small fenestra stapedectomy is based on a rationale of creating a more effective acoustical mechanical transmission system, while reducing potential labyrinthine disturbance. Surgical technique for the small fenestra stapedectomy is described, including the creation of the fenestra and the use of McGee stainless steel piston prosthesis with loose areolar tissue around the piston. Postoperative results are compared in a series of 100 cases, 50 having the small fenestra technique, SFT, and 50 having partial or total footplate removal procedure. Vestibular results demonstrate a noticeable reduction in postoperative complaints of balance disorders in the SFT patients. Hearing results, when compared between the two groups, show a statistically significant advantage for the SFT patients in postoperative high frequency threshold sensitivity and speech discrimination scores. Technical difficulties in creating the fenestra without fracturing the entire footplate are discussed and suggestions made for their avoidance. The advantages of lowered risk, based on reduced trauma to and contamination of the labyrinth, as well as improved high frequency hearing sensitivity and speech discrimination, support the use of this procedure and call for further investigation and development of its clinical potential.

Audiometry↗
PubMedDate not supplied

Vestibular and cochlear responses to acoustic transients. Some properties of whole-nerve action potentials in pigeons.

In a previous paper attention was drawn to the possibility of introducing the labyrinth as an organ for sound perception. Behavioural responses of the guinea pig as well as electrophysiological results in the pigeon indicated that fenestration of the labyrinth might be an alternative to cochlear implants. In this paper gross electrode electrophysiological responses to transient acoustic stimuli in the pigeon are further analysed and the influence of fenestration of the lateral canal and cochlea extirpation upon these responses was studied. The vestibular AP generated by sound stimuli could, among other things, be distinguished from the cochlear AP by its shorter latency. The dynamic range of this vestibular AP is at least 30 dB. The largest vestibular responses were obtained for stimulus frequencies below about 1.5 kHz. A simple hydromechanical model to explain the observed responses is discussed.

Acoustic Stimulation↗
PubMed1981

Failures in surgery for stapedial otosclerosis.

The causes for failure in surgery for stapedial otosclerosis are many. Most of these occur in the early postoperative period. Failures occurring later are due to either a breakdown of the reconstructed transformer system or to a labyrinthitis due to failure of the vestibular seal. The role of cochlear otospongiosis in producing late failures has not been sufficiently emphasized. This clinical review of 105 surgical failures examined consecutively during the years of 1975 through 1979 will demonstrate the importance of cochlear otospongiosis in this consideration. The fate of the unoperated-on ear in unilateral surgical failures will be demonstrated. Control of the progressive sensorineural hearing loss in these instances can be gained by the use of sodium fluoride therapy.

Adolescent↗
PubMed1992

[Otosclerosis--diagnosis and therapy].

Otosclerosis (synonym: otospongiosis) is a focal or diffuse spongifying disease of the bony labyrinth. So far pathogenesis is unknown, some recent investigations assume a paramyxovirus infection. But there are no doubts about hereditary and genetic factors, females are twice often affected as males with a maximum incidence between 20 and 40 years. If the disease invades the oval window niche it causes fixation of the stapes with conducting hearing loss. In some cases otospongiosis is associated with and presumably causes cochlear degeneration alone with sensoneurale hearing impairment of varying degree. The surgical technique is now well developed and the operative treatment enables in over 90% a closure of the air-bone gap by using stapes pistons. The medical therapy in cases of sensoneural hearing loss with sodium fluoride is still controversially discussed.

Adult↗
PubMed1990

Selective chemical vestibulectomy.

In an attempt to destroy selectively the affected peripheral vestibular labyrinth in patients with intractable vertigo as a result of Meniere's disease, a known quantity of streptomycin was introduced within the bony labyrinth following fenestration of the horizontal semicircular canal. Initial laboratory results in animal models proved that near total ablation of the vestibular end-organs (including the hair cell population of the cristae ampularis, utricle, and to some extent the saccule) could be achieved chemically without involvement of the cochlear hair cell population. The exact dose required to accomplish this in the animal model was 250 micrograms of streptomycin. However, this dose proved excessive in initial human application possibly because the animals had excellent hearing in nondiseased ears while our patients uniformly had long standing inner ear disease with marked decrease in auditory thresholds. The current dose of streptomycin utilized is 125 micrograms, and patients treated thus far have maintained (or improved) their preoperative audiologic pure tone average. The aim of this preliminary report is to detail our developmental animal research and subsequent clinical application of selective chemical vestibulectomy (SCV) in 15 patients with intractable vertigo as a result of Meniere's disease, which have failed conventional medical management.

Adolescent↗