Helge Rask-Andersen

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Time lapse video recordings of cultured adult human and guinea pig spiral ganglion (hSG and gpSG) show that mitogen responsive progenitor/stem cells develop in the form of spheres that proliferate and differentiate into mature neurons and glia cells. Neurospheres, cultured with EGF and bFGF showed expression of nestin and incorporation of(More)
OBJECTIVE This study was designed to investigate the perceptual benefits and potential risks of implanting the Nucleus(R) multichannel auditory brainstem implant. DESIGN Between September 1992 and October 1997 a total of 27 subjects received a Nucleus 20- or 21-channel Auditory Brainstem Implant (ABI). All subjects involved in the trial had bilateral(More)
HYPOTHESIS To study variations in human cochlea anatomy with potential implications for cochlear implantation surgery. BACKGROUND A comprehension of the anatomic variations of the human cochlea is essential for understanding the degree of surgical trauma induced by inserting various electrode arrays in cochlear implantation surgery. Variations in anatomy(More)
The electrical potential difference (PD) between cerebrospinal fluid (CSF) and blood has been studied extensively in animals. To obtain data from man the PD and impedance were recorded from the lumbar subarachnoid space of thirteen unanaesthetized patients with a presumably normal blood--brain barrier. The spontaneous PD ranged from 1 mV to 5 mV, CSF(More)
Aquaporins are membrane water channel proteins that have also been identified in the cochlea. Auditory function critically depends on the homeostasis of the cochlear fluids perilymph and endolymph. In particular, the ion and water regulation of the endolymph is essential for sensory transduction. Within the cochlear duct the lateral wall epithelium has been(More)
Human spiral ganglion (SG) neurons show remarkable survival properties and maintain electric excitability for a long time after complete deafness and even separation from the organ of Corti, features essential for cochlear implantation. Here, we analyze and compare the localization and distribution of gap junction (GJ) intercellular channels and connexin 43(More)
This study was based on high-resolution SEM assessment of freshly fixed, normal-hearing, human inner ear tissue. In addition, semiquantitative observations were made in long-term deafened temporal bone material, focusing on the spiral ganglia and nerve projections, and a detailed study of the fine bone structure in macerated tissues was performed. Our main(More)
Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder whose hallmark is bilateral vestibular schwannoma. It displays a pronounced clinical heterogeneity with mild to severe forms. The NF2 tumor suppressor (merlin/schwannomin) has been cloned and extensively analyzed for mutations in patients with different clinical variants of the disease.(More)
The anatomy of the adult human cochlear aqueduct and its surrounding structures, and their normal variations at tomography, microdissection and plastic molding are described. The mean length of the aqueduct is 12.9 mm and the mean width of its funnel-shaped external aperture 4.2 mm. The mean width of the narrowest portion is 0.14 mm. No difference in(More)
A TEM study was performed on freshly fixed human spiral ganglions (HSG) collected during skull base surgery. This technique gives well preserved tissue for ultrastructural analysis. Unlike spiral ganglion cells in mature animals so far studied, most HSG cells lack a myelin coat, but are surrounded by a thin rim of Schwann cell (SC) cytoplasm. In the region(More)