Biomedical subjects

P Lohnstein

Publications and source records attributed to P Lohnstein.

3 recordsLinked to original sources

PubMed2004

[Obliterated cochlea in Cogan's syndrome -- implications for cochlear implant surgery].

BACKGROUND: Acute, often bilateral deafness in Cogan's syndrome or other autoimmune diseases is caused by autoimmune mediated inflammatory attack on the membranous labyrinth. Auditory rehabilitation in case of bilateral deafness can be achieved by cochlear implant surgery. METHODS: A retrospective analysis of all patients suffering from Cogan's syndrome that had received a cochlear implant, was carried out. RESULTS: 6 of 295 adult patients (2.6 %) that had received a cochlear implant, had become deaf due to Cogan's syndrome. Partial obliteration or ossifikation was encountered in all cases and influenced surgical procedure. In one case a fibrous obliteration of the scala tympani was found 8 weeks after acute onset of complete deafness. CONCLUSIONS: The course of obliteration is unknown. With regard to our results a fibrous obliteration may occur as early as 8 weeks after complete deafness. This has to be considered in counseling of patients. Only early cochlear implant surgery facilitates best possible rehabilitation results.

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

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↗