caa a22 4500 475848993 CHVBK 20180406123923.0 cr unu---uuuuu 170329e20000901xx s 000 0 eng 10.1007/s004050000258 doi (NATIONALLICENCE)springer-10.1007/s004050000258 Morphological evidence that impaired intraneural microcirculation is a possible mechanism of eighth nerve conduction block in acoustic neuromas [Elektronische Daten] [T. Matsunaga, J. Kanzaki] In an attempt to better understand the mechanism of eighth nerve dysfunction in acoustic neuromas (vestibular schwannomas), we have morphologically examined microvessels and nerve fibers in the intracanalicular portion of eighth nerve specimens attached to these tumors. At the light microscopic level, microvessels were well preserved in all the specimens, even in the extremely flattened or markedly small nerve fascicles. However, the density of microvessels was quite variable in the different specimens, presumably as the result of different levels of compression by the tumors and the subsequent formation of a collateral microcirculation in each nerve. Focal areas of mild endoneurial fibrosis were found in 9 out of 22 specimens examined, but severe and widespread degeneration or demyelination was not found in any of the specimens. Ultrastructural studies frequently revealed mild to moderate abnormalities in myelin sheaths, and occasionally showed endothelial hyperplasia and hypertrophy in all the specimens. These findings are consistent with the slight to moderate reduction of endoneurial blood flow in the eighth nerves. The resultant ischemic condition in the eighth nerve may account for the eighth nerve conduction block in acoustic neuromas. Springer-Verlag Berlin Heidelberg, 2000 Key words Acoustic neuroma nationallicence Compression nationallicence Conduction block nationallicence Eighth nerve nationallicence Intraneural ¶microvessels nationallicence Matsunaga T. Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan, JP aut Kanzaki J. Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan, JP aut https://doi.org/10.1007/s004050000258 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004050000258 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Matsunaga T. Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan, JP aut NATIONALLICENCE 700 1- Kanzaki J. Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan, JP aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer