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Biomedical subjects

A G Kerr

Publications and source records attributed to A G Kerr.

At least 73 records · Page 4Linked to original sources
PubMed1978

Ossicular replacement prostheses.

To find a way of improving the results of ossicular reconstruction in ears that were rendered hard of hearing by chronic otitis media, the suitability of two biocompatible materials has been investigated. After three years' experience with Proplast and two years with Plastipore, it is concluded that for ears which lack an incus and stapes arch, these materials provide results at least as good as those previously reported with homologous materials and have the advantage of easy manipulation, timesaving, and ready availability. As with all foreign material in the chronically infected middle ear, the risks of extrusion cannot be ignored. The results so far indicate that this problem can be overcome with the use of cartilage film to separate the prosthesis from the tympanic membrane.

Auditory Threshold↗
PubMed1978

Ganglion cell populations in normal and pathological human cochleae. Implications for cochlear implantation.

A histological study of 100 hearing ears showed that some capability for speech discrimination requires at least 10,000 spiral ganglion cells. The spiral ganglion cell populations were then estimated in another group of 62 ears which were profoundly deaf for a variety of causes and it was found that 45% of these met the criterion of having 10,000 ganglion cells. The ganglion cell populations were largest in ears deafened by sudden deafness, Meniere's Disease, and ototoxic drugs; they were somewhat less for those with vascular occlusion, temporal bone fracture, otosclerosis, and cochlear dysplasias; they were least in those with measles, bacterial labyrinthitis and congenital syphilis. The data is of relevance in the selection of patients for cochlear implantation.

Adolescent↗
PubMed1976

Vestibular nerve section for Ménière's disease.

In summary: (i) the fact that VNS spares auditory function makes it preferable to labyrinthectomy. A comparison of VNS and the "conservative" operations on the inner ear shown that they have much the same effect on hearing. VNS by controlling vertigo may also provide an additional benefit by eliminating one of the stress factors concerned in the perpetuation of hydrops; (2) in the treatment of vertigo, VNS is now the most effective method of treatment. Because of elimination of vertigo is what chiefly concerns most of our patients, we suggest that when medical treatment fails to control vertigo, VNS is the surgical method of choice.

Adult↗
PubMed1976

Destruction of the endolymphatic sac in the cat.

The endolymphatic duct and sac were destroyed by drilling in a cat that was sacrificied after 2 3/4 years. Histological examination of the temporal bones showed marked endolymphatic hydrops; degeneration of the stria vascularis in the upper coil; degeneration of the organ of Corti and spiral ganglion in the upper and middle coils; and degeneration of the macula of the saccule. It is probable that, in some cases at least, the primary pathology of Menière's disease is in the endolymphatic sac.

Animals↗
PubMed1976

Sensorineural hearing after removal of cholesteatoma from labyrinthine fistulae.

An investigation was undertaken to determine what factors improve or worsen bone conduction thresholds following treatment of labyrinthine fistula produced by cholesteatoma. It is suggested that closure of the fistula and reconstruction of normal sound transmitting pathways by ossicular reconstruction produce a favorable mechanical situation to produce this response. In addition there remains the possibility that removal of cholesteatoma matrix may prevent a toxic degeneration of the cochlea at the site of the fistula. Therapy advocated is a two stage combined approach tympanoplasty.

Audiometry↗
PubMed1975

Second ear stapedectomy--a continued controversy.

This paper presents the results of an investigation into the effects of stapedectomy on vestibular function. We detected a disturbingly high incidence of vestibular abnormality in the results of caloric tests at three months postoperatively. Surprisingly, this was not usually accompanied by concurrent vestibular symptoms and there was no evidence of cochlear dysfunction in most cases. Although the caloric response at 12 months postoperatively showed an improvement in most instances, the responses rarely became symmetrical. We believe that a long-term alteration in vestibular response is not uncommon following stapedectomy. Although most patients will compensate quite quickly after unilateral stapedectomy we suspect that this occurs much less readily after bilateral stapedectomy and not at all should bilateral impairment of vestibular function occur. On the basis of this evidence, we submit that bilateral stapedectomy is justified only when vestibular function can be shown to be normal prior to the second ear operation.

Cochlea↗
PubMed1975

Ossiculotympanic transplantation.

Continued investigations into current tympanoplasty problems have been carried out in the Eye and Ear Clinic, Royal Victoria Hospital, Belfast. Retrospective studies have been helpful in identifying some of the main problems responsible for many of our unsatisfactory results, both in the irradication of disease and the restoration of aural function. Prospective studies into the behavior of grafting materials for tympanic reconstruction in the experimental animal have led us to an overwhelming preference for natural materials as opposed to plastics or stainless steel. Both homologous and autologous bone and cartilage appear to offer good prospects in ossicular replacement techniques. The most satisfactory material we have used for repair of tympanic membrane defects continues to be either autologous or homologous temporalis fascia. The long-term success of these materials in functional restoration is utterly dependent on continued aeration of the tubotympanic cleft.

Animals↗