Biomedical subjects

P Kylén

Publications and source records attributed to P Kylén.

17 recordsLinked to original sources

PubMed1990

[The value of magnetic resonance scanning in the diagnosis of small acoustic neurinomas].

This article describes three cases of acustic neurinoma in which both clinical examination and audiovestibular investigations raised strong suspicions of acustic neurinoma but no tumours could be demonstrated by CT. Magnetic resonance scanning employing gadolinium-DTPA revealed small intrameatal acustic neurinomas in all three cases. Attention is drawn to the fact that magnetic resonance scanning provides a new diagnostic possibility for acustic neurinoma and is a valuable supplement to the established diagnostic procedures in suspected acustic neurinoma even although CT reveals normal anatomical conditions in the internal auditory meatus.

Adult↗

PubMed1982

Calculation of hearing results after tympanoplasty.

At present there is no universally accepted method for calculating hearing results after chronic ear surgery. In this study the methods most frequently used have been applied to a material of 105 tympanoplasties and compared to each other. In addition a comparison between pre- and post-operative bone conductions (BC) thresholds for calculating post-operative air-bone gaps has been performed using multiple regression analysis. The results lend support to the conclusion that BC thresholds will improve with surgery in successful cases and that the post-operative BC threshold is a closer approximation of the cochlear function than the pre-operative one and consequently should be used for gap calculations. However, until the masking procedures in audiometry are standardized, hearing gain may be regarded as the most satisfactory alternative for describing hearing results as it is based on the air conduction thresholds only. This method requires a careful description of pre-operative air and bone conduction thresholds.

Audiometry↗

PubMed1982

Reliability of bone-conducted electrocochleography. A clinical study.

The correlation between pure-tone bone conduction thresholds (BC) and thresholds obtained by electrocochleography with bone conducted stimulation (BC-ECoG) for 1, 2, 4 and 8 kHz was studied in 26 ears due for ear surgery. The correlations proved to be statistically highly significant and the results lend support to the conclusion that BC-ECoG can be considered to be well adapted for clinical use in cases where conventional audiometry has failed to reveal the capacity of the cochlea.

Audiometry↗

PubMed1980

Ossicular manipulation in chronic ear surgery. An electrocochleographic study.

Twelve patients were submitted to ossicular dissections for between 2 1/2 and 35 minutes during ear surgery. A comparison between premanipulatory and portmanipulatory electrocochleographic threshold determinations did not disclose any thrshold shifts. The results lend support to the conclusion that manipulations on ;the ossicular chain, performed with customary care, are less harmful to the inner ear than other generally recognized threats to the cochlea during surgery, eg, perilymph fistulae and acoustic traumas from the drill.

Cochlea↗

PubMed1980

Preoperative bone-conducted electrocochleography in otosclerosis.

Prior to surgery, pure-tone audiometry and bone-conducted (BC) electrocochleography (ECOG) were performed on 17 patients with preoperatively diagnosed otosclerosis. Short tone bursts, approximately 5 ms in duration and presented by means of a bone conductor on the exposed surface of the mastoid, were used as stimuli in BC ECOG. The thresholds thus obtained were compared by regression analysis with conventional psychoacoustic thresholds. Thresholds recorded at BC ECOG showed a close correlation to preoperative pure-tone BC thresholds, and there was no difference in predictability of postoperative hearing thresholds between preoperative BC ECOG and conventional preoperative pure-tone BC thresholds. The results lend support to the conclusion that BC ECOG, offering a monaural, objective estimation of cochlear function, is a valuable complement to conventional audiometry in the preoperative evaluation of hearing in otosclerosis.

Audiometry↗

PubMed1979

Hearing gain calculations after stapedectomy.

A comparison of the postoperative air-bone gaps to pre- and postoperative bone condition (BC) was made in two groups of patients with otosclerosis, 18 cases with poor preoperative BC thresholds and 15 cases with good preop, thresholds. The gaps to the postoperative BC showed less variation than the gaps to the preop. BC threshold, the postop. BC may therefore serve as a more stable and natural reference when calculating a postoperative air--bone gap.

Audiometry↗

PubMed1979

Vestibular symptoms in mumps deafness.

Deafness appears in as many as 4% of adult cases of epidemic parotitis. It is often severe, though reversible and is usually unilateral. Vertigo has been reported in mumps, as have occasional cases with impaired caloric reaction. Twenty cases of unilateral hearing impairment in mumps have been investigaed with audiometry and electronystagmography in order to determine the degree of permanent lesions. Nine of the patients had noted vertigo when falling ill with protitis. Five of these had normal calorics, 3 were impaired and one was without response in the deaf ear. No certain correlation between vertigo and permanent caloric impairment was found. An interesting finding was that 5 cases without vertigo showed an impaired or absent caloric responsiveness, which might confuse future diagnostics. Presumably, most patients with hearing impairment in mumps suffer vesticular damage, but the acute vertigo in early childhood is easily overlooked. No certain correlation between age at the onset of mumps and any permanent caloric disturbance was found. One mumps case is described, in which a severe hearing loss and caloric impairment returned to normal.

Adolescent↗

PubMedDate not supplied

Two families with Alport's syndrome.

Alport's syndrome is a hereditary disease striking cochlea, eye and kidney. The diseased women usually have a nonlethal degree of the kidney disease, but the prognosis for the men is worse. They often die from renal failure before the age of 35. Most cases of hearing loss occurs in men. The hearing loss is progressive after the age of 10. Audiological tests are characteristic for a cochlear lesion. The debut of the disease usually appears in the post natal period giving microscopic haematuria. It can, however, occur later with haematuria and proteinuria. The hearing loss may be the first symptom, which is an observandum to otologists. Two families with Alport's syndrome are described. The patients have been examined concerning kidney disease, audiological and vestibular pathology. The hereditary pattern is described.

Adult↗

PubMedDate not supplied

Nosocomial parotitis.

A total of 22 cases of acute suppurative parotitis are reviewed. The causative factors were severe primary disease with salivary gland hyposecretion related to age (77 years), dehydration, oral inactivity and drugs (19 patients). The oral hygiene was poor and permitted ascending canalicular invasion of resistant staphylococci. The mortality was 27%. The treatment, including preferably cloxacilline and incision, is discussed. To stress the importance of prophylaxis the name "nosocomial parotitis" is suggested.

Acute Disease↗

PubMedDate not supplied

Drill-generated noise levels in ear surgery.

The noise levels in the cochlea when a drill is used in the mastoid process have been calculated from vibration measurements on intact skulls of human cadavers and temporal bones. The results lend support to the conclusion that, in ear surgery the ipsilateral cochlea is exposed to noise levels of about 100 dB and the contralateral cochlea to levels 5-10 dB lower every time the drill is used. This noise trauma may account for some of the high-tone sensorineural hearing losses after tympanoplasty described by other authors.

Ear↗

PubMedDate not supplied

Variables affecting the drill-generated noise levels in ear surgery.

The manner in which the variables rotation speed, type of burr, burr size and site of drilling influence bone-conducted, drill-generated noise levels in ear surgery, has been investigated. From the results obtained, the following conclusions can be drawn. 1. The noise levels were primarily influenced by the size of the burr. The 6 mm cutting burrs gave a noise level of 88-108 dB, the use of a 4 mm one resulted in a reduction of 1-6 dB and the use of a 2 mm one, 5-16 dB. The mean noise levels of the diamond burrs were 5-11 dB lower than the mean noise levels of the cutting ones. 2. Variations in rotation speed had only a slight influence on the noise levels produced (0-5 dB). 3. Three different types of cutting burr were tested. All gave noise levels of about the same order of magnitude. 4. The noise levels around the cochlea were only slightly influenced by the localization of the drilling within the ear (less than 1.8 dB). 5. Drill-induced noise levels in ear surgery cannot be reduced to any great extent. Possible noise traumas to the inner ear can only be avoided by minimizing the duration of drilling and thus, the duration of harmful noise exposure to the cochlea.

Ear↗

PubMedDate not supplied

Bone-conducted stimulation in electrocochleography.

The mechanical vibration patterns close to the cochlea in intact skulls of human cadavers have been studied by means of a miniature accelerometer. A Radioear B70A vibrator and a Brüel & Kjaer Mini Shaker have been used, fed with filtered clicks and with short tone bursts. The tone bursts were found to be superior to the clicks with regard to the vibration spectrum. At 500 Hz a considerable distortion was observed in the accelerometer signal, also when using tone bursts. This distortion was presumably due to resonant vibrations in the skull itself, and may be a source of error not only when using stimuli of short duration as in bone-conduction ECoG but also in conventional bone-conduction audiometry. When the vibrations were applied to the exposed bone surface of the mastoid, vibration levels increased by 10-25 dB compared with when soft tissues covered the point of application. This could be of advantage in bone-conduction ECoG performed at ear surgery.

Acoustic Impedance Tests↗

PubMedDate not supplied

Electrocochleography used as a clinical hearing test in difficult-to-test children.

Thirty difficult-to-test children have been tested with transtympanic ECoG. When possible, informal hearing tests and/or free-field testing were performed. Children in whom no action potential (AP) could be recorded were submitted to conventional radiography of the inner ear, and vestibular tests. The correlation between free-field test thresholds and AP "thresholds" was good, especially in subjects with relatively good hearing. Response amplitude increased, and latency decreased, with increasing frequency of the stimulus implying that different parts of the basilar membrane are stimulated according to the frequency of the stimulus. Input-output curves of response amplitude and latency were plotted, and three different types were distinguished. ECoG can contribute to the evaluation of peripheral hearing in difficult-to-test children, and vestibular tests should always be performed on a child with suspected deafness or sensorineural hearing loss. Conventional radiography of the inner ear, however, seems to be of little value.

Action Potentials↗

PubMedDate not supplied

Peroperative temporary threshold shift in ear surgery. An electrocochleographic study.

TTS resulting from drilling in the temporal bone was detected by means of pre- and post-exposure ECoG recordings taken during ear surgery for chronic otitis media. The TTS obtained varied between 5 and 40 dB at 4 and 8 kHz. The correlation between duration of noise exposure and magnitude of TTS was statistically significant. The results indicate that drill-induced noise in ear surgery may result in postoperative high-tone sensorineural hearing loss, and support the view that manipulation of the ossicular chain during ear surgery causes mainly a threshold shift at the lower frequencies.

Acoustic Stimulation↗

PubMedDate not supplied

Skull distortion of bone conducted signals.

A previously essentially unknown type of distortion of bone conduction (BC) signal has been studied on the skulls of four human cadavers. The method was based on a miniature accelerometer, rigidly attached to the cranial bone, converting the skull vibration close to the cochlea into an electrical signal which was analysed with regard to harmonic distortion. The BC signals, pure tones, were presented by means of a high-quality vibrator. The distortion was found to be limited to the lower audiometric frequencies, with a maximum around 500 Hz, and of such a degree as to be able to significantly influence the results of BC audiometry. The distortion is probably caused by nonlinear mechanical properties of the human skull.

Audiometry↗

PubMedDate not supplied

Electrocochleography with bone-conducted stimulation. A comparative study of different methods of stimulation.

Due to the shortcomings of the conventional bone vibrators available at the present, electrocochleography with bone conducted acoustic stimulation has not found any clinical application despite the fact that methods for the procedure have been developed for some time. The most striking deficiencies of these vibrators are their unsatisfactory stimulus intensities and their lack of frequency specificity due to distortion. Driven by an a.c. signal, a piezoceramic accelerometer (A21T, D. J. Birchall Ltd.) was found to meet the requirements of clinical use giving satisfactory stimulus intensities with a minimum of distortion when attached to the mastoid process by means of a modified bone screw.

Acoustic Stimulation↗

PubMedDate not supplied

Survival of the cortical bone columella in ear surgery.

Twenty-six partial and twenty-four ossicular replacement grafts were removed from patients because of hearing problems, cholesteatoma or re-perforation. The ossicles had been inserted in the middle ear between 7 and 121 months. The removed grafts were analysed with histology, enzyme histochemistry and, in 5 cases, tetracycline labelling. The results demonstrated that the majority (78%) of the grafts consisted at the time of removal of a mixture of living and dead bone. In 13% of the cases there were no indications of bone survival, while 9% of the removed grafts were found to consist of mainly vital bone. It is concluded that the fate of ossicular replacement grafts resembles that previously described for cortical bone grafts used in orthopaedic surgery.

Bone Transplantation↗