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Biomedical subjects

R Laszig

Publications and source records attributed to R Laszig.

At least 37 records · Page 2Linked to original sources
PubMed2004

[Evaluation of the insertion-trauma of the Nucleus Contour Advance electrode-array in a human temporal bone model].

BACKGROUND: The development of intracochlear electrode arrays is aiming at a placement close to the modiolus with an insertion as atraumatic as possible. A new perimodiolar electrode model the Nucleus Contour Advance was to be evaluated regarding the possible intracochlear trauma. METHODS: The implantation of the Contour Advance electrode was performed in 11 frozen native temporal bones. Beneath a regular insertion in 5 temporal bones in 6 cases the insertion was carried out using the "advance-off-stylett" technique with a fixed stylett. The temporal bones were embedded in metacrylate based resin for histomorphological evaluation. The evaluation was performed regarding to the intracochlear placement close to the modiolus and the damage to intracochlear fine structures (basilar membrane, osseus spiral lamina). RESULTS: In 2 out of 11 cases we found a perforation from the scala tympani to the scala vestibuli independent of the insertion-technique. A severe intracochlear trauma was observed in one case with fracture of osseus spiral lamina using the AOS-technique. A close position to the modiolus could be achieved by insertion the scala tympani without perforation of the basilar membrane. CONCLUSIONS: The Nucleus Contour Advance electrode array showed minimal trauma in human temporal bones by using a standard insertion technique. By using the freehand AOS-technique a severe cochlear trauma is possible. Therefore further development in electrode design and the use of an insertion-tool is recommended.

Basilar Membrane↗
PubMed2004

Navigation as a tool to visualize bone-covered hidden structures in transfrontal approaches.

A retrospective analysis of 10 patients was performed to evaluate navigation systems in extranasal frontal skull base surgery. When performing a craniotomy following a bicoronal skin incision, the surgeon has to calculate the extent of the frontal sinus to avoid unnecessary damage to the dura or mucoceles later. Due to surgical morbidity including compression of the frontal lobe, many skull base surgeons have refused to use such an approach. Malformation or bone-destruction complicates the identification of the borders and increases the risk of side-effects. Navigation systems can be an alternative for calculating the frontal sinus outlines during surgery. In the authors' surgical procedure two different navigation systems were used. Conventional surgery using the transfrontal, transbasal or subcranial approach consisting of trepanation and craniotomy were performed, while the navigated surgical procedure was evaluated. The analysis showed that computer-assisted surgery (CAS) is applicable to extranasal frontal skull base surgery. In comparison to X-ray beam-controlled craniotomy, CAS is beneficial as it constitutes a noninvasive instrument of quality management. Furthermore, the analysis indicated that under the guidance of a navigation system a precise pre-surgical simulation is available in order to perform an optimal craniotomy and reconstruction of the frontal skull base.

Adult↗
PubMed2004

Imaging procedures in cochlear implant patients--evaluation of different radiological techniques.

The purpose of this study was to evaluate the feasibility and usability of different radiologic methods (single-slice computed tomography (CT), multi-slice CT and rotational tomography (RT)) for assessment of the position of cochlear implant electrodes. Cochlear implants in an isolated human temporal bone and in a complete formalin-fixed cadaver head were examined and the electrode position was determined. Subsequently, the labyrinth bone was isolated out of the cadaver head and histologically examined to compare the results of histology with imaging. Single-slice CT reliably identifies the electrode inside the human cochlea; however, due to the technically based large electrode artifact its position inside the cochlear spaces (e.g. electrode position in scala tympani or scala vestibuli) cannot be detected. Multi-slice CT of the cadaver head also showed artifacts that complicate the assessment of electrode position. Using RT the electrode artifact is small and therefore the electrode position within the cochlear spaces, scala tympani versus scala vestibuli, can be assessed. This technique was also applicable in a complete cadaver head, which is in contrast with former studies. In conclusion, CT allows the identification of electrode arrays inside the human cochlea. Multi-slice CT permits a much more precise depiction of the electrode inside the cochlea. RT alone has minimized electrode artifacts to a high extent and permits the assessment of the electrode position within the scala tympani or scala vestibuli. As RT was performed successfully in a complete cadaver head, further studies for evaluation of the intracochlear electrode position can now be performed in patients.

Angiography, Digital Subtraction↗
PubMed2001

In vivo visualization of the cochlear nerve and nuclei with fluorescent axonal tracers.

In recent years multichannel neuroprostheses have been developed which directly stimulate the central auditory pathway. Substantially these have been used in cases of total hearing loss caused by neurofibromatosis type 2 where bilateral damage to the auditory nerve prevents more peripheral stimulation. The electrode carrier of the auditory brainstem implant (ABI) is designed to be placed on the cochlear nucleus complex residing at the lateral brainstem surface. Despite altered anatomy due to tumor growth or preceding surgery, correct electrode placement is essential to maximize the variety of pitch percept elicited during electrical stimulation with the ABI without producing side-effects. In order to assist intraoperative identification of the proximal auditory nerve and cochlear nuclei, the non-toxic fluorescent axonal tracers Fast Blue or Fluorogold were injected into the cochlea of rats and Java monkeys. Four to seven days after tracer application, labeling of the eighth cranial nerve, its entrance into the brainstem and the primary radiation of auditory fibers into the cochlear nucleus could be demonstrated as colored fluorescence on the living brain under appropriate ultraviolet illumination. Additional histological processing revealed groups of retrogradely labeled neuronal cell bodies in both species. Our results suggest that this method could also be used in humans in order to aid surgeons with the proper positioning of the electrode array.

Amidines↗
PubMed2001

The Nucleus Contour electrode array: a radiological and histological study.

OBJECTIVES: To evaluate the handling and insertion trauma of the recently developed Nucleus perimodiolar Contour electrode array (Cochlear Ltd., Pty, Lane Cove, New South Wales, Australia) in human temporal bones compared with the Nucleus standard straight electrode array. STUDY DESIGN: E-perimental control group. METHODS: Twenty-nine fresh-frozen bones were implanted with different electrode arrays by an experienced cochlear implant surgeon, and evaluated both radiologically and histologically. RESULTS: Intracochlear insertion of the standard Nucleus straight electrode array was found to be atraumatic, confirming previous findings in the literature. Insertion of the Nucleus Contour electrode array resulted in instances of localized basilar membrane penetration causing the electrode array to move from the scala tympani into the scala vestibuli. However, this trauma did not result in any observable damage to the osseous spiral lamina or the modiolus. Basilar membrane penetration was observed in six of eight cochlear bones when a standard cochleostomy size (approximately 0.8 mm) and site (anterior and superior to the round window) were used. However, when the surgical technique was modified to use a slightly larger cochleostomy ( approximately 1.8 mm) situated closer to the round window and employ a partial stylet withdrawal technique during electrode insertion, the frequency of penetrations was restricted to two of seven bones. This trauma rate is comparable to that observed with other cochlear implants designs. CONCLUSIONS: Following our results, the design of the Nucleus Contour electrode appears to fulfill the safety requirements for an intracochlear electrode array, provided that the surgical insertion technique is modified in the manner outlined.

Basilar Membrane↗
PubMed2001

Cochlear structures after implantation of a perimodiolar electrode array.

OBJECTIVE: A perimodiolar prototype electrode array has been evaluated on 12 human temporal bone specimens. To achieve modiolar proximity, a fine Teflon positioner is attached to the tip and base of a conventional Nucleus 22 electrode array. METHODS: Intracochlear electrode position was examined by macroscopic preparation and confirmed by a cochlear view x-ray after insertion into human temporal bones. The temporal bones were examined with light microscopy for intracochlear trauma after insertion, explantation, and re-implantation of the perimodiolar array. RESULTS: Macroscopic preparation and x-ray confirmed close proximity of the intracochlear electrodes to the modiolar wall. In some bones, electrode insertion and positioning was performed without significant damage to intracochlear structures, but explantation caused varying degrees of trauma depending on the explantation technique used. Re-implantation and repeat explantation appeared to destroy most of the intracochlear architecture. CONCLUSIONS: The perimodiolar electrode array prototype with Teflon positioner cannot be recommended for clinical use, especially in children in whom the possibility for re-implantation is high.

Child↗
PubMed2001

Brainstem response in cerebellopontine angle tumors.

OBJECTIVE: To evaluate the auditory brainstem response (ABR) findings in cerebellopontine angle (CPA) tumors and focus on those with normal ABR results. STUDY DESIGN: This was a retrospective evaluation of ABR findings. All subjects with diagnosed CPA tumors who were referred for treatment were included. PATIENTS: All 309 patients with radiographically confirmed (computed tomography or magnetic resonance imaging [MRI]) CPA tumors (153 before 1993 and 156 after 1993). INTERVENTION: All patients underwent complete audiologic examination, electronystagmography, ABR testing, and ipsilateral transtympanic electrocochleography. All tumors were histologically confirmed. MAIN OUTCOME MEASURES: The patients were categorized according to ABR results (normal or pathologic findings or no response); according to histology (vestibular schwannomas or meningiomas); and according to tumor size by MRI (small, up to 15 mm; medium, 16-25 mm; large, 26-40 mm; and very large, over 40 mm). RESULTS: Normal ABR results were found in 18.4%; pathologic ABR results in 31.4%; and no response in 50.2%. Small vestibular schwannomas (under 15 mm) showed a higher incidence of normal ABR results (41.7%). CPA tumors with normal ABR results (n = 57) caused no hearing loss (n = 12), symmetrical hearing loss (n = 11), or ipsilateral hearing loss with Short Increment Sensitivity Index 100% and normal acoustic reflex (cochlear deafness, n = 34). Caloric response was normal in 59.7% of these tumors. CONCLUSION: Because validation of ABR as screening for acoustic tumors is based on diagnosed tumors, and because MRI allows detection of very small tumors, the incidence of normal ABR increases and its sensitivity would be expected to decrease. ABR is not sufficient for early detection of small CPA tumors.

Audiometry, Evoked Response↗
PubMed2001

Transsphenoidal computer-navigation-assisted deflation of a balloon after endovascular occlusion of a direct carotid cavernous sinus fistula.

SUMMARY: A 49-year-old woman with a direct posttraumatic carotid cavernous fistula (CCF) was treated with detachable balloons via a transcarotid route. After the procedure, her intracranial bruit, conjunctival injection, and orbital congestion were cured, but the preexistent sixth nerve palsy deteriorated. CT showed one balloon positioned in the posterior portion of the right cavernous sinus and was regarded to be responsible for nerve compression. After surgical exposure by use of a transnasal-transsphenoidal approach under 3D navigation control, this balloon was deflated by puncture with a 22-gauge needle. The previously described symptoms resolved after balloon deflation. This report presents a rare complication of endovascular treatment of direct CCF and a new microsurgical approach to a balloon in a case of nerve compression.

Abducens Nerve Diseases↗
PubMed2000

[Psychological stress, knowledge and treatment expectation of parents with a child managed by cochlear implant].

UNLABELLED: ESTABLISHED KNOWLEDGE: It is known that parents of hard-of-hearing children suffer from an increase in psychosocial stress. SCIENTIFIC QUESTION: How does the psychosocial situation of parents with children who have cochlear implants change during rehabilitation? AIM OF STUDY: It was the aim of this study to demonstrate how parents evaluate retrospectively their own psychological well-being during the process of rehabilitation. METHODS AND RESULTS: We interviewed 87 parents by questionnaires which were mailed to them. Fifty-seven mothers and 46 fathers responded (59% return rate). Parents reported a significant increase in stress, as perceived by themselves, after the time of diagnosis. Of the parents, 25% continued to suffer from psychic stress during rehabilitation as could be demonstrated by the SCL-90-R questionnaire criteria. The expectations by parents were realistic prior to implantation but thereafter increased significantly with time. CONCLUSIONS: The psychological state of parents during the critical phase, after a diagnosis of deafness has been made for their child, has to be considered. Even after an initial phase of shock, parents seemed to be stressed to an extent that required therapeutic intervention.

Adaptation, Psychological↗
PubMed2000

[Parotid involvement in cat scratch disease: a differential diagnosis with increased significance].

BACKGROUND: Bartonella henselae is the causative agent of cat-scratch disease (CSD), an inflammatory infection of the lymph nodes. So far, only few cases of atypical manifestations in the head and neck, especially manifestations in the parotid gland have been reported. PATIENTS AND METHODS: Between January 1997 and June 1999 seven patients with manifestations of CSD in the parotid gland were observed at the ENT-department Freiburg. The positive diagnosis was confirmed serologically by an indirect immunofluorescence assay and by detection of Bartonella henselae-DNA with PCR-amplification and subsequent hybridization or sequencing. RESULTS: An intraglandular abscessed lymphadenitis was found in five patients, two of these cases were based on a Parinaud's oculoglandular syndrome. A diffuse affection of the parotid gland, initially misinterpreted as a parotid tumor, was seen in two patients. CONCLUSIONS: Antibiotic treatment is recommended in order to reduce the duration of the disease, in cases of pain and lymph node abscesses. In uncommon manifestations of CSD, the nosological assignment can be difficult on the basis of the heterogeneous symptomatic in the individual patient and the CSD diagnosis can only be confirmed by serology or PCR-based techniques. CSD should be considered in the differential diagnosis of all equivocal masses in the head and neck, even in unusual localisations like the parotid gland.

Abscess↗
PubMed2000

Topodiagnosis of deafness: strategy for treatment of neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) causes bilateral hearing loss due to tumour growth in the cerebellopontine angle. We report the results of promontory testing and transtympanic electrocochleography on subjects with deafness due to NF2 referred for an auditory brainstem implant. All 19 ears tested revealed loss of cochlear microphonics. Nine ears (mainly without previous treatment) revealed auditory perception during promontory stimulation, indicating cochlear deafness. One of these subjects has been successfully provided with a cochlear implant. The other 10 ears (mainly after previous surgery) revealed negative promontory stimulation, indicating additional retrocochlear deafness. These findings indicate that neurofibromas initially cause a cochlear deafness, so that a cochlear implant can be used if the auditory nerve can be preserved. This option has to be considered in rehabilitating patients with bilateral tumours due to NF2.

Adolescent↗
PubMed2000

Surgical experiences in 58 cases using the Nucleus 22 multichannel auditory brainstem implant.

Patients with bilateral total deafness due to lesions of the vestibulocochlear nerve can be treated by electrical stimulation of the second auditory neuron. A 22-channel multi-electrode implant with transcutaneous transmission was developed that allows the selection of the most useful electrodes. Acoustic neuromas were removed from 49 out of 58 patients by ENT surgeons and neurosurgeons working in collaboration and using either a translabyrinthine or suboccipital approach. The central electroauditory prosthesis was implanted in the same procedure. Six patients were deaf after previous acoustic neuroma surgery without recurrence, three had diagnoses other than neurofibromatosis type 2 (NF2). There were no complications due to the implantation procedure. Side effects could be excluded by stimulation of the auditory electrodes alone. Most of the patients used their ABI daily. They reported perception of different sounds and frequencies, enhancement of lip-reading ability, and three of the patients were able to use the telephone.

Adolescent↗
PubMed2000

Stimulation of the cochlear nucleus with multichannel auditory brainstem implants and long-term results: Freiburg patients.

Since 1992 18 patients with bilateral retrocochlear deafness have been provided with a multichannel auditory brainstem implant (ABI). The surgical procedure implies tumour removal and ABI implantation in one stage. Most implantations were via the translabyrinthine approach. The long-term follow-up varied between nine and 80 months. In one case auditory perception could not be achieved and in a second case post-operative stimulation was not possible as the subject died due to lung emboli. In all the other cases auditory perception was achieved and only two subjects became non-users during the follow-up period. The presented long-term results suggest that deaf neurofibromatosis type 2 patients regain acoustic contact with the environment, enlarge their communication skills and improve their quality of life by using a multichannel auditory brainstem prosthesis.

Adolescent↗