Biochemical Studies of Inner Ear Fluid in Man: Changes in Otosclerosis, Meniere's Disease, and Acoustic Neuroma

Clinical Significance of an Increased Cochlear 3D Fluid-Attenuated Inversion Recovery Signal Intensity on an MR Imaging Examination in Patients with Acoustic Neuroma

“…7,[10][11][12] The most plausible mechanisms include blockage of the neuroaxonal transport of proteins caused by compression of the vestibulocochlear nerve, cochlear membrane damage caused by arterial stasis and a consequent increased permeability, and a cell-mediated immune reaction to the inner ear caused by the antigenic properties of AN. [7][8][9][10][11][12]23 Among the 3 hypotheses, protein blockage from compression of the corresponding nerve is considered to be the dominant mechanism, with the others being minor in their contribution. Given that the cochlear signal reflecting the protein concentration correlates well with the degree of hearing loss represented by PTA in AN IAC but not in AN CPA , we could hypothesize that the degree of nerve compression is a major contribution to increasing the protein concentration while the tumor is confined to the internal auditory canal.…”

“…[1][2][3][4][5][6] The increased cochlear signal on FLAIR images in patients with ANs is explained by an increased concentration of protein in the perilymphatic space. [7][8][9][10][11][12] FLAIR MR imaging is sensitive to fluids with a high protein content. [13][14][15][16][17] Furthermore, 3D-FLAIR imaging can minimize the undesired inflow artifacts of CSF flow, has a higher signal-tonoise ratio and spatial resolution, and allows recognition of subtle compositional changes of the inner ear fluid.…”

Increased Cochlear Fluid-Attenuated Inversion Recovery Signal in Patients with Vestibular Schwannoma

“…In 1966, Silverstein and Schuknecht 6 reported that in patients with vestibular schwannoma, total perilymph protein was approximately 9 times more than that in normal perilymph. 6 On the basis of perilymph protein analysis from a large number of patients with vestibular schwannoma, Silverstein proposed the labyrinthine tap as a diagnostic test for vestibular schwannoma.…”

“…6 On the basis of perilymph protein analysis from a large number of patients with vestibular schwannoma, Silverstein proposed the labyrinthine tap as a diagnostic test for vestibular schwannoma. 7 The labyrinthine tap was performed by obtaining a sample of inner ear fluids through a hole in the stapes footplate by using a micropipet.…”

“…4 The pathogenesis of increased inner ear perilymph protein has been a matter of considerable investigation in the past. 4,[6][7][8][9] However, to date, no one agrees on a satisfactory explanation for this phenomenon. Furthermore, it has also remained unclear if protein levels in perilymph correlate with the degree of hearing loss and abnormal eighth nerve action potentials in patients with vestibular schwannoma.…”