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Biomedical subjects

J Helms

Publications and source records attributed to J Helms.

At least 19 recordsLinked to original sources
PubMed2000

[Universal hearing screening of newborn infants with the BERA-phone].

BACKGROUND: Unidentified and untreated early infant hearing loss leads to speech-language deficits as well as to cognitive, intellectual, emotional and psychosocial handicaps. Targeted hearing screening programs may miss approximately 50% of all hearing impaired children. METHODS: In an universal hearing screening program with a two stage protocol, 1349 newborns were examined using the CRESCENDO Newborn Hearing Screener according to Finkenzeller and a clinical ABR system operating with a time course step stimulus algorithm. RESULTS: Five newborns that failed the two stage screening protocol were diagnosed as hearing impaired so that therapy was initiated before the age of six months. The specificity of the method was 98.8%. The CRESCENDO method only required a short examination time and was easy to apply. CONCLUSIONS: Hearing screening programs using ABR offer advantages when compared to evoked otoacoustic emission testing. ABR threshold detection with the time course step stimulus algorithm is a quick and easy to apply method with high specificity that can be recommended for newborn hearing screening.

Algorithms↗
PubMed1999

[Selection of a cochlear implant and results of implantation].

BACKGROUND: The cochlear implant is the therapy of choice for completely deaf patients. With this concept speech communication can be restored or developed. METHODS: The selection of the implant system may depend on different factors. As long as speech competence is thought to be of highest importance, a fast stimulation strategy involving a state of the art cochlear implant that provides 1500 Hz for every single electrode is close to the optimum. Further parameters include deep insertion into the cochlea (normally 30 mm) and other technical details. RESULTS: With these conditions fulfilled, about 2/3 of the adult deaf patients will later be able to use a telephone. Children who received implants in due time and do not have other cerebral defects will be partly able to meet with the requirements of normal schools.

Adolescent↗
PubMed1999

Technical developments in intra-operative monitoring for the preservation of cranial motor nerves and hearing in skull base surgery.

Although EMG recordings from mimic muscles have become the standard for intra-operative facial nerve monitoring, few data are available concerning other motor cranial nerves (MCN). Auditory brainstem responses (ABR) are a proven tool for intra-operative hearing preservation, but have their limitations, suggesting the application of supplementary methods. This paper describes new developments of MCN and cochlear nerve monitoring in skull base surgery. Up to 2 x 8 EMG channels were recorded after bipolar stimulation of MCN using concentric coaxial probes. A special software enabled event-dependent registrations of all signals exceeding a definable threshold level. Selective recordings from masticatory muscles (N.V) were obtained using rectangular Teflon-insulated needle electrodes. For oculomotor (Nn.III/ VI) nerve recordings bipolar needle electrodes were precisely placed by orbital ultrasound guidance. Lower cranial nerves were monitored inserting needle electrodes into the soft palate (N.IX), tongue (N.XII) and vocal muscles (N.X) during laryngoscopy using a special applicator. For ABR recordings, click stimuli (95 dB HL) were applied monaurally through insert earphones. Electrocochleography was simultaneously recorded as a near-field potential without averaging after promontory (transtympanic) electrode placement using otomicroscopy. Regarding the ABR biosignal, a characteristic response pattern was detected following bipolar electrical stimulation of the auditory nerve possibly useful for its intra-operative identification.

Cochlear Nerve↗
PubMed1998

Epidural application of ionomeric cement implants. Experimental and clinical results.

During setting and hardening, the hybrid bone substitute ionomeric cement (Ionocem) achieves a stable and durable bond with the apatite of the adjacent bone without interpository soft tissue. Fluid contact during setting results in the release of aluminium ions which may reach critical levels as high as 3000 micrograms/l. On epidural application it is, therefore, essential to prevent cement constituents from gaining access to the intradural space. After the cement has hardened, the presence of aluminium is demonstrable in the adjacent bone to a maximum depth of 20 microns (EDX microanalysis). In rabbits, epidural placement of freshly mixed cement causes slight thickening of the dura. There is reason to believe that human dura, with a thickness 10 times greater, is impermeable to components of the cement. After epidural application of the freshly mixed cement in the frontobasal and laterobasal regions and at the skull cap and petrous apex, 76 patients in all have been followed for up to 6.5 years. During this period no complications have arisen and functional (and cosmetic) results are promising. The availability of preformed implants (Ionoroc, Ionocast) permitted the peridural placement of minimal quantities of freshly mixed cement. These implants were fixed to localized sites on the adjacent calvarial bone by use of Ionocem. Notwithstanding the stringent manufacturer guidelines, there have been reports in the literature that during the vulnerable stage of setting neurotoxic aluminium ions were released into the dural space with a fatal outcome in two cases. In view of potential intradural complications, such as may occur in case of dural leaks, it was considered that further application of the material adjacent to the dura was no longer warranted. The production of Ionocem was discontinued in May 1995.

Aluminum Silicates↗
PubMed1998

[Postoperative results of stapes revision].

BACKGROUND: In this retrospective study indications, intraoperative findings, reconstruction techniques and postoperative hearing results in revision stapes surgery were evaluated. PATIENTS: Between March 1988 and January 1996, 150 patients underwent stapes revision. Indications for surgery were the presence of conductive hearing loss (132), dizziness (12), sensorineural hearing loss (3), deafness (2), and tinnitus (1). RESULTS: Intraoperative findings were lateral migration of the implant, regrowth of bone in the oval window niche, erosion of incus, cholesteatoma, and others. In most cases a new prosthesis (gold piston) was inserted between incus and vestibulum. In cases with incus erosion, a malleovestibulopexy was performed. Seventy-three percent of patients who underwent revision stapes surgery because of conductive hearing loss showed a hearing improvement of 20 dB or more. All patients who underwent revision stapes surgery because of dizziness reported an improvement of their symptoms postoperatively. CONCLUSIONS: Revision stapes surgery should be approached by experienced surgeons, because the risk of severe sensorineural hearing loss is higher than at the time of primary stapedectomy. Informed consent is mandatory.

Adolescent↗
PubMed1998

[Reliable fixation of cochlear implant electrode mountings in children and adults--initial experiences with a new titanium clip].

BACKGROUND: There is a reported 1% incidence of delayed migration of extrusions of the electrode arrays out of the cochlea. METHODS: A titanium clip to fix the electrode array of the MED EL Combi 40 Cochlear Implant System is described. The clip is designed and shaped in a double U configuration. The clip material allows easy adaption to the individual anatomical situation. The clip is fixed to a bony bridge at the incus bar and fixes the electrode in a plane parallel to the chorda facial angle. It is closed around the electrode similarly to a stapes piston around the incus. Additional tests which examined the possible risk of damaging the electrode carrier and clinical findings are described. RESULTS: The clip was used in 23 cases with a follow-up period up to 1 year. No signs for dislocation of the electrode were found. In one revision case the clip was covered with a thin mucosal layer. The electrode array showed no signs of damage. Intraoperative findings confirmed the experimental tests on the electrode fixation. CONCLUSION: The titanium clip facilitates safe and quick fixation of the electrode array and prevents dislocation. its flexibility and shape minimizes the risk of damage.

Adult↗
PubMed1998

[Long-term outcome after reconstruction of the cranial base with ionomer cement].

BACKGROUND: Congenital, posttraumatic, inflammatory or tumours skull base lesions with CSF leakage require reconstruction to mechanically stabilize the CNS and to securely seal the CSF space. PATIENTS AND METHODS: Ionomeric cement was used from 1988 until 1994 in 44 patients for skull base reconstruction at the Department of Otolaryngology-Head and Neck Surgery, University of Würzburg. Thirty-five patients were reexamined. The longest follow-up time was 8 years. The program for the present follow-up study comprised a general ENT and neurological examination as well as CT scans of the skull base, MRI tomography of the CNS, and the determination of the aluminium plasma concentration. RESULTS: None of the patients reexamined presented with complaints. Neurological examinations and MRI tomography in all patients did not reveal any pathological finding related to ionomeric cement application. Aluminium plasma concentrations in patients who received ionomeric cement implantations were not significantly elevated when compared to controls. General ENT examinations and CT scans in thirty-two patients demonstrated regular postoperative findings. The cement at the anterior skull base was not covered completely by mucosa in three patients. In one these cases, CT scans revealed dislocation of the ionomeric cement so that revision surgery was performed for removal. None of the patients to date presented with a CSF leak. CONCLUSION: Long-term results of the present study show that ionomeric cement is a suitable material for closure of osseous skull base lesions to permanently seal the CSF space. These results, however, can only be obtained when handling and application of the material is adequate. Unfortunately, the production of ionomeric cement has been stopped since 1995 following four cases of aluminium encephalopathy reported in the literature.

Adult↗
PubMed1997

Stapes surgery in osteogenesis imperfecta patients.

Osteogenesis imperfecta (OI), or the Van der Hoeve-de Kleyn syndrome, is a heterogeneous group of connective tissue disorders. The key features in this disease are bone fragility with a tendency to spontaneous fractures and deformations. The classical traid of symptoms involves a conductive and/or sensorineural hearing impairment together with a tendency to spontaneous bone fractures and blue sclerae. Between January 1988 and December 1994, ear surgery was performed on eight ears of six OI patients who presented with mixed hearing loss preoperatively. Pathological changes observed in the middle ear were atrophy and/or fractures of the stapedial crura in combination with thickening and fixation of the stapes footplate. Partial stapedectomy was performed in seven cases and a neo-window was created in the promontory of one patient when an overhanging facial canal obscured visualization of the oval window niche. Pre- and postoperative bone conduction thresholds did not differ in any of the patients. Postoperatively, mean values of the air-bone gap in the main speech frequency range were below 10 dB. Functional results following stapes surgery in patients with otosclerosis during the same time interval (n = 857) did not differ significantly. These data indicate that stapes surgery in OI patients can be performed with the same functional predictability as in otosclerosis patients, even though the underlying etiology is considerably different.

Adult↗
PubMed1997

[Ionomer cement prostheses in reconstructive middle ear surgery].

Animal experiments with microbiologic examinations and studies in cell cultures have shown that ionomer cement is a biocompatible and biostable bone replacement material in the head and neck region. Clinical and functional results of its use in the human middle ear have proven to be satisfactory during a maximal period of 2.5 years observation. The present trial was continued in order to determine the long-term behavior of ionomer cement (Ionos partial and total ossicles) after reconstruction of the ossicular chain. The ossicular chain was reconstructed in 343 cases and included various losses of one or more of the ossicles (i.e., incus, incus and malleus, incus and stapes superstructure, and malleus, incus and stapes superstructure). Follow-up extended over a maximum period of 5.5 years. Patients were examined under a surgical microscope and a pure-tone audiogram was performed at regular intervals. Clinical and audiological results were obtained 3 months postoperatively in all reconstructive procedures performed (partial and total ossicular replacement prostheses). These were mainly stable but revision surgery was necessary in 9% of the cases. In 5% the prosthesis was displaced and in 3% the prosthesis had partially migrated through the eardrum. Complete rejection of the implants was observed in the course of infections in 1% of the cases. Ionomer cement as a bone replacement material was found to have all required criteria for its use in the middle ear (biocompatibility, biostability, stable audiologic results and easy workability). These findings show that ionomer cement can be recommended in all cases of ossicular reconstruction.

Adolescent↗