Electrode impedances in children with cochlear implants: Comparison between intra-operative Switch ON and post-operative Switch ON.

INTRODUCTION: Intra-operative Switch ON (IOSO) is a novel clinical approach of activating the cochlear implant during the surgery adopted at our cochlear implantation center.We compared the electrode impedances in two conditions of Switch ON of cochlear implants; IOSO and post-operative Switch ON (POSO, 21st day of surgery). METHODS: Electrode impedances of 185 cochlear implants, 93 of whom received IOSO and 92 POSO, recorded over 10 years were analyzed retrospectively. RESULTS: Electrode impedances of IOSO group were significantly lower than POSO group at Switch ON and 3rd, 6th, 9th, and 12th months post cochlear implantation. In IOSO group, 3rd month's electrode impedances were high when compared to electrode impedances at Switch ON. Beyond the 3rd months, electrode impedance remained unchanged. In POSO group, there were no significant differences in electrode impedances between any measurement schedule. CONCLUSIONS: To our knowledge, this is the first study to investigate in detail the electrode impedances of the two above-said conditions of Switch ON in the process of cochlear implantation. This study concludes that timing of CI Switch ON has a significant effect on the electrode impedances. These results may affect the choice of cochlear implant Switch ON timing.

A study of anatomy of frontal recess in patients suffering from 'chronic frontal sinus disease'.

A study designed to describe the anatomical features of the frontal recess area in patients suffering from chronic frontal sinusitis. A prospective study done in adult patients admitted in our hospital between July 2009 to June 2011. Tertiary level, private ENT care centre. 50 adult patients of chronic frontal sinusitis who did not have history of previous sinus surgery. The frontal recess anatomy was studied by 2 mm slice CT scans pre-operatively. CT findings were confirmed intra operatively by meticulous dissection in frontal recess area endoscopically with aid of image guided system. A chart prepared for each patient of different anatomical variations present in frontal recess on each nasal side and analyzed. Agger nasi cell was found in 94 % of cases. The superior attachment of the uncinate was to the lamina papyraceae in 82 % of cases. Type 1 frontal recess cells were found in 44 %, type 2 in 8 %, type 3 in 48 % and type 4 in 2 % of the cases. Over all 74 % of cases had frontal recess cells. The management of frontal sinusitis is a challenge to endoscopic surgeon and as more and more rhinologists got expertise in endoscopic sinus surgery skills; the next challenge is management of frontal sinus. Hence, the need arises for more precise study of frontal recess anatomy. Detailed studies of anatomic features of the frontal recess by coronal and sagittal CT scans are very important and helpful for endoscopic frontal sinus surgery. Our study suggests that there is high prevalence of frontal recess cells in Indian population suffering from frontal sinusitis.