Central nervous system involvement in patients with facial palsy due to borrelial infection

Patients with a peripheral facial palsy due to an underlying Ixodes-borne borreliosis often have cerebrospinal fluid findings indicating meningeal involvement. The aim of the present study was to identify signs of CNS involvement by means of brain-stem evoked response audiometry (BSER) in patients with a facial palsy due to borreliosis, as well as in patients with a facial palsy of unknown aetiology. Bell's palsy. Abnormalities in BSER were found to be significantly more common along the borrelial patients. Furthermore, a reversal of these abnormalities following treatment with benzyl-penicillin was found in the majority of patients with borreliosis. The results of the present study emphasize the importance of diagnosing and treating an underlying borreliosis in patients with a peripheral facial palsy.

Brainstem response audiometry in chronic Lyme borreliosis

Auditory brainstem responses (ABR) were investigated in 26 patients with acrodermatitis chronic atrophicans, which is a late manifestation of Lyme borreliosis. Nine of the patients showed pathological ABR, four of them unilaterally and five bilaterally. The main pathological findings were: 1) Poor reproducibility of waves IV-V or of wave V; 2) Increased latency of wave V. After antibiotic treatment, ABR was improved in eight of the nine patients, and in three of them it was normal. In the five patients who did not completely recover, the improvement consisted in better reproducibility and a tendency towards normal wave V latencies. The results of this study indicate that the central nervous system may become involved in patients with acrodermatitis chronica atrophicans.

Plaster of Paris and hair cell morphology. A scanning electron microscopic study of an alternative implant material for ear surgery

Many techniques have been proposed for reconstruction of the posterior canal wall and/or obliteration of the mastoid bowl after radical mastoidectomy. The variety of materials that have been used, biological as well as foreign materials of different kinds, indicates that the ideal solution has yet to be found. Plaster of Paris, a biocompatible, degradable ceramic material prepared from CaSO4, may have an osteogenic property and become an alternative implant material for ear surgery. However, its possible ototoxicity has not been studied previously. Plaster was implanted in the tympanic cavity of guinea pigs. On investigation in the scanning electron microscope after 4.5 to 8 months, no toxic damage to the hair cell morphology was observed. Thus, from an ototoxic point of view, plaster of Paris would seem suitable for use as an implant material in ear surgery. Studies concerning the possible osteogenic property of plaster of Paris and its clinical application in human ear surgery are in progress.

Hair cell distributions in the normal human cochlea. A report of a European working group

Cochlear hair cell counts from individuals who had clinically normal hearing prior to their death have been plotted for various age bands as a function of the number of hair cells per millimetre against their position in the cochlea. Position has been expressed as the distance of that observation of hair cell density from the base of the cochlea, divided by the total length of the cochlea, thereby giving a proportional representation of the cochlea in the range of 0.0 to 1.0 with 20 subdivisions of 0.05. There is an age-related decrease in the number of hair cells in the normal population, and this is more marked for the outer hair cells.

Ultrastructural evaluation of the microslicing method for the study of temporal bone pathology

Microslices 3 mm thick from undecalcified human temporal bones were prepared with a special cutting machine and then processed for SEM and TEM in order to evaluate advantages and disadvantages of the microslicing technique for the study of the temporal bone pathology. In the examined microslices there was some mechanical distortion of the membranous labyrinth, detachment of soft tissues from bone and a considerable amount of contamination by bone dust and debris which are circulated during sectioning. For SEM the method therefore has limited value. For TEM a relatively contamination free area can be found some distance from the cutting surface of each microslice.

Plaster of Paris: thermal properties and biocompatibility. A study on an alternative implant material for ear surgery

There is no single technique for reconstruction of the canal wall following radical mastoidectomy. Autograft tissues may be unsuitable because of resorption and limited availability. An ideal foreign implant material should be bone-like in quality, non-ototoxic, readily available and malleable. Plaster of Paris, a degradable ceramic powder of CaSO4, may be regarded as a bone mineral. But a certain amount of heat develops during its solidifying process and may present a risk for injury to the facial nerve and the labyrinth. We studied the temperature rise with respect to added solution, to volume, and to surroundings, and investigated its biocompatibility when implanted in soft tissue in guinea pigs. The investigations suggested no risk of thermal injury and the biocompatibility was excellent. Hence plaster of Paris may constitute an alternative implant material for mastoid obliteration and reconstruction of the canal wall in ear surgery.

Ototoxicity of kanamycin in albino and pigmented guinea pigs. I. A morphologic and electrophysiologic study

Ototoxic drugs of the aminoglycoside type have been shown to accumulate to melanin, suggesting a possible mechanism for their ototoxicity. The present study was undertaken by combining electrophysiologic and morphologic methods to investigate whether the ototoxicity of kanamycin is different in pigmented and albino guinea pigs. In pigmented animals a kanamycin dose of 200 mg per kilogram of body weight per day resulted in hearing loss together with loss of both inner and outer hair cells. The albino animals in the same dose group showed significantly less hearing loss and hair cell degeneration. With daily doses of 20 and 60 mg/kg/day, no difference in ototoxicity was found between the pigmented and albino animals. The results support the hypothesis that affinity of kanamycin to inner ear melanin might be responsible for the difference in ototoxicity between albino and pigmented guinea pigs.

Functional histopathology of the human audio-vestibular organ. Euro-Data-Hearing

The present paper describes the setting-up of a new project, sponsored by the Commission of the European Communities, to promote the study of functional histopathology of the human audio-vestibular organ. The project has the purpose of co-ordinating in Europe morphological research on the hearing and equilibrium organ and promoting the comparison of data from clinical, physiological and morphological studies in the field of hearing and equilibrium impairment. A manual (Iurato et al., 1982) has been prepared with the objectives of (1) stimulating clinicians to participate in the project, (2) encouraging the collection of audiological data for comparison with pathology, and (3) supplying clinicians with the necessary information about the technique of fixation and preparation of the specimens. The fixation procedures for the two major techniques of studying ear pathology: (1) microdissection and electron microscopy, and (2) embedding of the whole block for serial sectioning and light microscopy, are described in detail. Special paragraphs deal with the technique of fixation of the brain and with the technique of removal of the temporal bones and brain at autopsy. The instructions for delivery of the specimens and the publication rules are enclosed in the main body of the manual. Appendix 1 contains a list of the participating laboratories. Appendix 2 deals with autopsy legislation in the different European countries. Appendix 3 contains the sender's data sheet which supplies the instructions for collecting the clinical history of the patient and the audiological and vestibular data.

Electrophysiological and morphological changes in the guinea pig cochlea following mechanical trauma to the organ of Corti

Small discrete lesions were produced in the organ of Corti of the guinea pig cochlea using fine probes to produce direct mechanical insult. The electrophysiological state of the cochlea was assessed using N1 electrocochleography and loss of receptor cells determined by scanning electron microscopy. Principal findings were: 1) Excellent agreement between the location of hair cell losses and the frequency of maximum sensitivity change in the N1 audiogram; 2) The spatial extent of the mechanically induced lesion appears to be more important than the total number of hair cells lost, in determining the magnitude of N1 sensitivity loss; 3) Hair cell losses extending over only 72 micrometers could be detected as significant changes in N1 sensitivity. These results further emphasize the accuracy and usefulness of the N1 electrocochleogram for assessing the functional status of the cochlea; 4) Lesions involving only outer hair cell loss also produced marked elevations of N1 threshold.

Response properties of spiral ganglion neurons in cochleas damaged by direct mechanical trauma

Electrical activity of single neurons in the spiral ganglion of the guinea pig cochlea was correlated with receptor hair cell damage produced by local mechanical lesions of the organ of Corti. Damage to or loss of hair cells was assessed using scanning electronmicroscopy. Principal finds were (1) neurons emanating from damaged regions showed changes in their tuning curves such as loss of sensitivity, broadening of tuning curves; (2) in some cases, the loss of sharp tuning tip resulted in an apparent shift of the tuning curve to lower frequencies; and (3) apparently pure outer hair cell lesions, of limited spatial extent, could result in the same effects as mixed inner and outer hair cell lesions.

Scanning electron microscopy of the nerves within the organ of Corti

A method of studying the innervation inside the organ of Corti is presented. Rabbits, guinea pigs and chinchillas were fixed with perfusion of the perilymphatic spaces. The cochleas were dissected according to the surface specimen technique and the specimens critical point dried, coated with gold and studied in the SEM. The final dissection into the planes of the fluid spaces of the organ of Corti was done in the dry state using especially sharpened watch makers forceps and razor blade knives. The course of the afferent and efferent innervation is described and differences between the species illustrated. Small high nerve endings on the outer hair cell degenerate after cutting the efferent nerve supply by dividing the vestibular nerve indicating their efferent nature.

The innervation of the organ of Corti. A scanning electron microscopic study

The innervation within the organ of Corti of guinea pigs, chinchillas and rabbits was studied in the scanning electron microscope. Specimens were fixed, dissected, critical point dried and coated with gold. Final dissection of the specimens was done in the dry state in the planes of the former fluid spaces. The courses of the efferent and afferent nerve fibres are described. The efferent fibres reach the outer hair cells by crossing the tunnel space, run between the outer pillars and divide several times in the space of Nuel. The afferent fibres cross the floor of the tunnel and turn basalwards in the outer spiral bundles where they run for at least 0.5-0.8 mm before connecting with the outer hair cells. Small nerve endings on every fifth to tenth outer hair cell disappear after cutting the efferent nerves, thus indicating their efferent nature.

Inner ear damage and hearing loss after exposure to tones of high intensity

Experimental animals (cats) were exposed to tones of 125, 1000, 2000, and 4000 Hz at sound pressure levels in the range 120 to 157.5 dB, and for durations of one hour (1000, 2000, 4000 Hz) or four hours (125 Hz). Pure tone audiograms were obtained for each animal before and after exposure. Post-exposure tests were continued until complete recovery of hearing had occurred or until a stable permanent threshold shift had been measured. Cochleas of animals were examined by phase-contrast microscopy; condition of all hair cells was recorded. Extent of inner-ear damage and range of frequencies for which hearing loss occurred increased as exposure tone was decreased in frequency. For example, exposure to 4000 Hz produced damage in a restricted region of the cochlea and hearing loss for a relatively narrow range of frequencies; exposure to 125 Hz produced wide-spread inner ear damage and hearing loss throughout the frequency range 125 to 6000 Hz.

Scanning electron microscopy of the organ of Corti

With the scanning electron microscope we have examined normal cochlear sensory epithelium of the guinea pig and cat and that damaged by noise. The studies demonstrate how the regular surface architecture of the organ of Corti is altered after exposure to noise. The changes include loss of sensory hairs, formation of giant hairs, and complete degeneration of circumscribed areas of the organ of Corti. Our method greatly reduces the artifacts.