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Biomedical subjects

R Häusler

Publications and source records attributed to R Häusler.

At least 37 records · Page 2Linked to original sources
PubMed2000

Electromagnetic interference of bone-anchored hearing aids by cellular phones.

We report a case of electromagnetic interference between a bone-anchored hearing aid (BAHA) and a cellular phone. A 54-year-old women was successfully treated for severe mixed conductive and sensorineural hearing loss with a BAHA. Five years after implantation, the patient experienced a sudden feeling of dizziness, accompanied by a loud buzzing sound and by a sensation of head pressure while examining a digital mobile phone. During a subsequent experiment, the buzzing sound could be reproduced and was identified as electromagnetic interference between the BAHA and digital cellular phones. Seventeen adult BAHA users from our clinic participated in a subsequent survey. Of the 13 patients with some experience of digital cellular phones, 11 reported hearing annoying noises elicited by these devices. However, no other sensation, such as dizziness, was described. Owing to the increasing number of users of both hearing aids and cellular phones, the incidence of electromagnetic interference must be expected to increase as well. Although to date there is no evidence that such interference may be harmful or dangerous to users of conventional or bone-anchored hearing aids, unexpected interference can be a frightening experience.

Electromagnetic Fields↗
PubMed2000

[Stapes surgery in anomalies of the course of the facial nerve].

In 548 stapes operations performed in Berne during the period 1994-1998, an anomaly of the course of the facial nerve was observed in 37 cases. 29 exhibited partial prolapse of the nerve over the oval window, with or without dehiscence of the bony canal, while 5 showed total prolapse of the nerve over the oval window. In one case the nerve was duplicated round the oval window and in a further instance the facial nerve was situated over the promontory and also over the oval window. In one other case the nerve was spread widely over the oval window. Concomitant anomalies of the stapes were frequently observed. The following surgical techniques were employed: in the case of partial prolapse of the nerve, a small piston was placed in the lower part of or in the oval window, which was widened towards the promontory. In cases of total prolapse of the facial nerve the prosthesis was drilled straight into the promontory. Where the nerve was duplicated the prosthesis was placed in the footplate between the nerve branches, and where the nerve ran over the promontory and over the oval window the prosthesis was placed above the oval window. In the case where the nerve was spread widely over the oval window, no prosthesis was inserted. 78% of patients had a residual air-bone gap of 20 dB or less; in only three cases did hearing fail to improve. One patient with Crouzon disease involving a complex anomaly had a hearing impairment of 22 dB. There was no deafness, facial paralysis or vertigo with nystagmus.

Auditory Threshold↗
PubMed2000

[Atypical pneumatization of the paranasal sinus system].

200 CT scans of adult patients with paranasal sinus problems seen in the ENT Department either in the University Hospital in Berne, Switzerland, or in the University Hospital in Munich, Germany, were analysed. Among these we found 9 striking abnormalities of paranasal sinus anatomy. We found abnormalities which caused clinical symptoms, such as an infected concha bullosa, a fine-septated infected maxillary sinus, a pneumosinus dilatans of the frontal sinus with aesthetic problems, and a cellula orbito-ethmoidalis with sinusitis. Some of these abnormalities were found by coincidence, such as a cellula orbito-sphenoidalis and an extreme pneumatisation of the sinus sphenoidalis with a pneumatised processus pterygoideus. 2 cases show the importance of preoperative evaluation of a possible abnormal sinus to avoid operative complications: a sinus sphenoidalis with a pneumatisated clivus and an intraluminal a. carotis interna. The other case involved an optic nerve running free through the sphenoidal sinus. In conclusion we stress the importance of preoperative CT examination and the choice of a coronary or axial CT scan, which reveals any abnormal anatomy of the paranasal sinus pneumatisation and thus increases the safety and efficiency of paranasal sinus surgery.

Adult↗
PubMed2000

Unilateral choanal atresia. A possible indication for computer aided surgery? "A report of two cases".

Choanal atresia (CA) is a congenital obstruction of the posterior nose. Bilateral CA is a paediatric emergency and must be treated surgically in the first few weeks after birth. This is in contrast to unilateral CA, because surgical management can be planned more selectively. Transpalatinal surgery for CA is a safe procedure. The endonasal technique is minimally invasive and less traumatic; however, a major disadvantage is a limited field of vision. Computer aided surgery using images acquired by computer tomography (CT) or magnetic resonance imaging (MRI) is an application that has emerged in the last few years. This application provides an additional safety factor for endoscopic surgery to resolve choanal atresia, especially in cases of another malformation. We report results from two cases of unilateral CA who were surgically managed with Computer aided surgery.

Adolescent↗
PubMed2000

Practical aspects for optimal registration (matching) on the lateral skull base with an optical frameless computer-aided pointer system.

HYPOTHESIS: Paired-point matching and surface matching are highly accurate when used on the lateral skull base with an optical computer-aided surgery system. BACKGROUND: Computer-aided surgery on the lateral skull base can be done with a pointer system or with the microscope. An optical pointer system that uses anatomic landmarks and surface points has been developed in Bern, Switzerland. METHODS: Axial computed tomography of a cadaver skull was performed. The images were processed on a computer workstation. An infrared camera was used. A reference base mounted on the head and a needle pointer, both equipped with light-emitting diodes, were used. Different anatomic landmarks were determined on the computer image of the skull and were compared with the actual anatomic markers taken on the bone or on the skin simulation material, and the target error was defined. In a second step, additional surface points on different regions of the skull were taken, and the inaccuracy from the target was redetermined. RESULTS: The authors found a mean average error in accuracy from the target with paired-point matching alone in the best series of 0.79 mm. Under skin simulation, they found a deterioration with paired-point matching alone but an improvement in accuracy with surface matching. CONCLUSION: For this navigation system, it is recommended that the following five anatomic points be selected for matching of the lateral skull base: the tip of the mastoid, the mastoid foramen, the umbo, the frontozygomatic suture, and the anterior nasal spine. For additional accuracy in clinical situations, surface matching is recommended.

Microscopy↗
PubMed2000

[Stapedotomy and anatomical variations of the facial nerve].

Among the 595 stapedotomies performed between 1992 and 1999 (surgeon R. Häusler), there were 40 cases (6.7%) where the facial nerve had an abnormal course. In 32, a partial nerve prolapse over the oval window was noted with (6 cases, 1 being a duplicated nerve around the oval window) or without (26 cases) dehiscence in the long bony canal. In 8 cases, there was a total prolapse of the nerve over the oval window, with 2 special cases: facial nerve having an inferior course over the oval window and the promontory; facial nerve being widely spread over the oval window and the promontory. Concomitant anomalies of the stapes were seen and several patients had dysmorphic syndromes with conductive hearing loss since early childhood. Stapedotomy was performed in 39 patients. In the 32 cases of partial nerve prolapse, a small piston (0.4 mm) was placed in the lower part of the oval window which was sometimes enlarged towards the promontory, except when the nerve was duplicated: the prosthesis was placed into the footplate between the nerve branches. In the 8 patients with total facial nerve prolapse, the prosthesis was either placed directly in a burr hole into the promontory just below the oval window (6 cases), or, when the nerve ran over the promontory and over the oval window, the prosthesis was placed above the oval window at the site where the facial nerve is usually located (1 case). In the case where the nerve was spread widely over the oval window and the promontory, no prosthesis was placed. In the 39 patients where a stapedotomy was performed, the average hearing level gain ranged from -15 dB to 40 dB (average: 18 dB) at 0.5, 1, 2 and 4 kHz. The average residual air-bone gap was < 30 dB in 36 patients (92.3%), < 20 dB in 30 (77%) and < 10 dB in 16 (41%). A post-operative additional hearing loss > or = 10 dB occurred in 3 cases (10, 12.5 and 12.5 dB). There were no cases of post-operative deafness or facial palsy. This analysis shows that in many cases with an aberrant course of the facial nerve, stapedotomy using adequate and sometimes non-conventional techniques can give post-operative hearing improvement.

Adult↗
PubMed2000

[Bezold's abscess with wide extension to the lateral skull base].

The case of a 72-year-old woman suffering from chronic otitis media is presented. This insulin dependent diabetic patient was under steroid therapy for collagenosis and suffered from chronic polysinusitis. After two preceding drainages of the mastoid (antrotomy and mastoidectomy), the patient developed putrid mastoiditis followed by Bezold's abscess, an epidural abscess and thrombosis of the sigmoid sinus. Lateral petrosectomy and drainage of the neck were performed, but the patient again developed an abscess with extension to the lateral skull base, the foramen magnum and the upper cervical spine. After a further operation with extensive drainage and a three-month course of antibiotic treatment with ceftriaxon, the infection finally healed. A germ of the Streptococcus milleri group was identified.

Aged↗
PubMed2000

[Diagnosis and treatment of temporal paragangliomas: an analysis of 21 cases treated in Bern between 1992 and 1999].

INTRODUCTION: Paragangliomas are usually benign tumours stemming from the neural crest which may have neuroendocrine activity. Because of hypervascularisation they usually lead to pulsatile tinnitus. Local expansion initially causes middle ear and later inner ear hearing loss, and cranial nerve dysfunction. PATIENTS/METHODS: Signs and symptoms, demographic data, tumour stages, treatments and outcomes were analysed for the 21 patients treated at our clinic between 1992 and 1999. Among 16 surgically treated patients 3 type A and 4 type B tumours were treated by mastoidectomy and middle ear reconstruction. For the 8 type C and one type D tumours, angiography was performed preoperatively, usually followed by selective embolisation of tumour vessels, in 7 cases with additional permanent occlusion of the internal carotid artery. These 9 tumours were removed through an infratemporal approach with partial petrosectomy, preservation of the inner ear and facial nerve rerouting, followed in 8 cases by middle ear occlusion. The patient with a type D2 tumour had a two-stage otological and neurosurgical operation. One patient with type C3 tumour only underwent radiation therapy. 4 patients have had no treatment so far: 2 had small type A tumours and one a type C3 tumour but contraindications for surgery. A last patient with a slowly growing type D2 tumour cannot be operated on due to general health problems. RESULTS: All patients with type A and B tumours had normal to subnormal postoperative hearing and normal facial nerve function. In one case with a type C tumour the middle ear reconstruction led to normal hearing thresholds. After rerouting of the facial nerve, transient palsy was noted in 6 out of 9 cases. In 3 patients a slight permanent impairment of facial nerve function (House-Brackman II) remained. 4 patients had some dysfunction of cranial nerves IX-XII postoperatively. After a follow-up of up to 8 years (mean 5 years) no recurrence was observed in the surgically treated patients. The patient treated by radiation had further tumour growth and another treatment is being planned. Among the 4 patients followed without treatment, no tumour growth has been observed up to now in 3 patients. DISCUSSION: Our study confirms that the well standardised conservative surgical treatment allows reliable removal of paragangliomas in most cases, and involves low morbidity.

Cranial Nerve Diseases↗
PubMed2000

[Excision and drainage of cholesterol granulomas of the petrous apex with preservation of hearing under computer-assisted navigation surgery (CANS)].

Diagnosis of cholesterol granuloma of the petrous apex has become easier today with new imaging techniques such as MRI and CT. The therapy of choice is surgery, which is still considered a delicate procedure. The objective is to demonstrate hearing-preserving excision and drainage of cholesterol granulomas of the petrous apex using the Bernese system of computer-assisted navigation surgery. Between 1995 and 1999, 3 patients with severe temporal headache, tinnitus and nonspecific vertigo had surgery for cholesterol granuloma of the petrous apex with drainage and excision in the University ENT Clinic, Berne. In the first patient, a combined transmastoidal and transtemporal approach was adopted with infralabyrinthine and subcochlear partial petrosectomy and extirpation of the granuloma in the petrous apex (surgery time 7 h). In the following 2 patients computer-assisted navigation surgery was used and transmastoidal infralabyrinthine-subcochlear drainage and excision of the granuloma in the petrous apex was performed after antefacial hypotympanal drilling with partial exposure of the internal carotid artery (surgery time 2.5 h). After surgery patients were rapidly releaved of symptoms. Postoperative CT showed the newly aerated cells in the petrous apex with permanent drainage. Hearing was preserved with slight residual conductive loss. The surgical method of choice for hearing-preserving excision and drainage is made through an infralabyrinthine-subcochlear approach. The application of computer-assisted navigation surgery in the lateral skull base allows permanent intraoperative monitoring of the precise position of the microsurgical instruments (accuracy < 1 mm) giving a high security level for minimally invasive function preserving surgery.

Adult↗
PubMed1999

[Objective value of adenotonsillectomy in the child. A prospective study of incidence of tonsillitis, snoring, pulse oximetry and polysomnography and general development before and after adenotonsillectomy].

65 children were analysed prospectively before and after adeno-tonsillectomy to determine the incidence of upper airway infections, snoring and nocturnal obstructive symptoms. The weight and height percentiles were also determined before and after adeno-tonsillectomy. The Oxygen Desaturation Index (ODI) was measured in 27 children suspected of having a sleep apnea syndrome. In six of these children polysomnographic studies were carried out. A statistically significant reduction (p < 0,005) of upper airway infections could be seen six to twelve months after adeno-tonsillectomy. In 25 children (38%), we observed a postoperative weight gain and in eight cases (12%) a height gain. The obstructive symptoms, especially snoring and respiratory apneas, disappeared or were significantly reduced in 90% of the cases after adeno-tonsillectomy. All preoperatively pathological ODI and AHI normalised after the operation (p < 0,005).

Adenoidectomy↗
PubMed1999

The "Bernese" frameless optical computer aided surgery system.

OBJECTIVE: We report on two years of clinical experience with a frameless Computer Aided Surgery system developed in Bern, Switzerland. MATERIAL AND METHODS: Our navigation system is based on a preoperative computer-tomography (CT) scan (without markers) and an intraoperative optical tracking of head movements and of the surgical instruments. Using landmark and surface-based registration, the skull can be accurately correlated to the CT images. The three-dimensional positions of the surgical instruments, as well as the endoscopic images, are displayed in real time on a monitor. RESULTS: In the last two years, 109 computer-aided interventions have been successfully performed: 89 on the anterior skull base/paranasal sinuses, 15 on the lateral skull base, and 5 minimally invasive procedures on other locations in the skull. No complications occurred. The practical accuracy on the cadaver skull is between 0.5 mm and 1.2 mm, and the clinical accuracy is between 0. 5 mm and 2 mm. CONCLUSIONS: Our navigation system has proven its accuracy and usability. Surgeons feel very comfortable with the increased safety provided by the unequivocal identification of important anatomical structures.

Cadaver↗
PubMed1999

Biomechanical properties of sterilized human auditory ossicles.

Bone allograft material is treated with sterilization methods to prevent the transmission of diseases from the donor to the recipient. The effect of some of these treatments on the integrity of the bone is unknown. This study was performed to evaluate the effect of several sterilization methods on the mechanical behaviour of human middle ear bones. Due to the size and composition of the bones (approximately 1.5 mm diameter by 4 mm long), mechanical testing options were limited to the traditional platens compression test. Experiments were first performed with synthetic bone to evaluate the precision of this test applied to small specimens. Following this, fresh frozen human ossicles were thawed and sterilized with (i) 1 N NaOH (n = 12); (ii) 0.9% LpH, a phenolic solution (n = 12); or (iii) steam at 134 degrees C (n = 18). A group of 26 control specimens did not receive any sterilization treatment. Material and structural properties were determined from axial compression testing. Results from the synthetic bone showed that the test was reproducible, with standard deviations less than 20% of the means. Significant differences occurred in stiffness and ultimate force values between NaOH-treated and autoclaved bones when compared to normals (p<0.05), but not for LpH-treated bones. LpH is not approved for medical use, so NaOH is the most appropriate of the treatments studied for the sterilization of ossicle allografts.

Analysis of Variance↗
PubMed1999

Surgical treatment of Zenker's diverticulum: transcutaneous diverticulectomy versus microendoscopic myotomy of the cricopharyngeal muscle with CO2 laser.

In a retrospective study, we analyzed 97 patients who were treated by either transcutaneous diverticulectomy (n = 66) or microendoscopic myotomy of the cricopharyngeal muscle with CO(2) laser (n = 31). Two (6.4%) of 31 patients in the microendoscopic myotomy group had complications, compared with 10 (15%) of 66 patients in the diverticulectomy group. In addition, the complications observed in the microendoscopic myotomy group were less severe than those observed in the transcutaneous diverticulectomy group. The average length of hospitalization was shorter in the microendoscopic myotomy group than in the diverticulectomy group (8 days versus 11.4 days). We conclude that microendoscopic CO(2)-laser myotomy is a less invasive, more precise, and safer procedure, which results in a shortened period of hospitalization and complete relief of symptoms in the vast majority of cases.

Adult↗
PubMed1999

Performance of compressed analogue (CA) and continuous interleaved sampling (CIS) coding strategies for cochlear implants in quiet and noise.

Speech understanding with compressed analogue (CA) and continuous interleaved sampling (CIS) coding strategies for cochlear implants was compared in quiet and in noise at signal-to-noise ratios (SNRs) of 15, 10 and 5 dB. The speech recognition of three experienced users of the Ineraid cochlear implant (CA coding strategy) was assessed using a set of sentence, vowel and consonant tests. Three weeks after the fitting of a CIS processor, the tests were repeated with the new device. Speech recognition scores for the sentence and consonant tests tended to be higher with the CIS processor in no or little noise, but lower in the test situations with less favourable SNRs, when compared to the CA processor (average score differences for the consonant test: +7.8% correct at 15 dB SNR; -6.8% correct at 5 dB SNR; p = 0.05). Results for the vowel test were slightly lower on average for the CIS processing strategy at all SNRs. A possible explanation for the differences in performance between CIS and CA in the consonant and sentence tests at different SNRs is the generally higher free-field threshold associated with the CA coding strategy, which may act as a single-channel noise suppression.

Adolescent↗
PubMed1999

Advantages and dangers of erbium laser application in stapedotomy.

Among different types of lasers, the erbium laser exhibits particularly favourable characteristics for ear surgery. Experiments with application of erbium laser pulses to the isolated stapes connected to an inner ear model confirmed that there was virtually no thermal effect to the inner ear liquid and that the border damage zone on the stapes footplate perforation did not exceed 5-10 microm. Erbium laser pulses, however, produce pressure waves due to the explosive ablation of tissue. Pulses of 10 to 17 J/cm2 producing pressure waves between 140 and 160 dB appear to be a limit for clinical application. With these criteria, an in-house built erbium YAG laser with a fiberoptic delivery device was used in 15 patients for stapedotomy. A special microhandpiece, where a zirconium fluoride fiber was connected to a quartz tip, was developed. In addition, three patients had stapedotomy with a commercially available Zeiss (Opmi TwinER) microscope equipped with a micromanipulator-operated erbium laser beam. One year after surgery, the air-bone gap was closed in all patients to within 20 dB between 0.5 and 3 kHz with only minor permanent bone conduction threshold losses (< 20 dB). However, we observed an immediate postoperative middle and high frequency loss of up to 75 dB on bone conduction threshold measurements 2 h after surgery, suggesting an acoustic traumatization by the erbium laser. This threshold shift recovered close to preoperative values within 6 h. These observations prompted us to discontinue the clinical use of erbium laser for stapedotomy until the problem of temporary acoustic traumatization is resolved.

Adult↗
PubMed1999

Radiologic and mechanical properties of inactivated ossicle homografts.

OBJECTIVE: This study examined the effects of old and new inactivation (sterilization) techniques on the radiologic and mechanical properties of ossicle homografts. MATERIALS AND METHODS: Ninety normal incuses and malleuses received either treatment with 1) 5% formaldehyde/cialit, 2) 1N NaOH, 3) 0.9% LpH, or 4) autoclaving at 134'C, or no treatment. All ossicles were assessed radiologically by high-resolution computed tomography. After imaging, all ossicles underwent mechanical testing by destructive axial compression in a mechanical testing machine measuring force and displacement. RESULTS: Ossicles treated with cialit, NaOH, or autoclaving showed a significant decrease of ultimate force and stiffness compared with controls. LpH treatment caused no such changes in these structural properties. Material properties of yield strength, ultimate strength, and elastic modulus were also altered by cialit, NaOH, and autoclaving, but were much more difficult to assess because of uncertainty in parameter estimates. There was a significant increase in radiologic density in autoclaved ossicles, a reduction in cialit- and LpH-treated ossicles, and no change in NaOH-treated ossicles. CONCLUSIONS: All tested inactivation procedures changed the biomechanical and/or radiologic properties of ossicle homografts. However, the new procedures used to inactivate infectious agents produced changes similar to the older treatments with formaldehyde/cialit. Human allografts are able to withstand harsh but safe sterilization procedures. The NaOH treatment seems to be the most suitable method for the future. The biologic (osteogenic) potentials of ossicle homografts treated with these new preservation/inactivation methods are still unknown. Further investigations are necessary to re-evaluate the clinical use of ossicle homografts in middle ear reconstructive surgery.

Adult↗