Takumi Okuda

Case Report of Atlantoaxial Rotatory Fixation after Cochlear Implantation

Atlantoaxial rotatory fixation (AARF) is a relatively rare condition and is mainly seen in children. We report of a 7-year-old girl suffering from AARF after cochlear implantation (CI). Fortunately, early diagnosis based on three-dimensional computed tomography (3DCT) was made, and the patient was cured with conservative therapy. Nontraumatic AARF, which is also known as Grisels syndrome and occurs subsequent to neck infections or ear, nose, and throat (ENT) surgery, represents only a small fraction of AARF cases. Two factors are mainly thought to contribute to the pathogenesis of the condition estimated, namely, (i) neck immaturity in children and (ii) infiltration by inflammatory mediators around the upper neck joint, easily permitted by the neck vasculature. AARF should be suspected in case of torticollis developing after ENT surgery.

Late pneumolabyrinth may be induced by old penetrating injury: possibility of undiagnosed posttraumatic perilymphatic fistula.

Traumatic pneumolabyrinth is a relatively rare entity. We report the case of a unilaterally deaf woman with pneumolabyrinth who had suffered penetrating injury 15 years ago. This past history indicated that the case was late pneumolabyrinth occurring from undiagnosed old posttraumatic perilymphatic fistula. In Japan, most cases of traumatic pneumolabyrinth are caused by penetrating injury with an ear pick. Dizziness often improves within several months. Immediate surgical intervention is recommended for hearing loss, but the hearing outcome is not satisfactory. An appropriate strategy should be selected based on the interval to surgery, bone conduction hearing level at disease onset, stapes lesions, and location of air.

Glutamate induced currents in isolated inner hair cells from guinea-pig cochlea

We investigated the direct action of glutamate (Glu) on the membrane current of isolated inner hair cells of guinea-pig cochlea. Glu elicited inward currents at a holding potential of -70 mV. Eight of 13 cells showed a steady inward current, while five of 13 cells showed a fast and rapidly desensitized current. I-V relationships demonstrated that the reversal potential of Glu-induced current was near 0 mV. Glu-induced currents were dose-dependent, where the half maximum concentration (K(d)) was 41 microM and Hill coefficient (n) was 1.75.