The effect of inflammation on spiral ganglion cell density measurements in the cat cochlea.
The quantitative analysis of spiral ganglion cells is important in assessing the biological safety of cochlear implants. Quantitative analysis of ganglion cells in a histological section is conventionally expressed as cell density, the number of ganglion cells within Rosenthal's canal being divided by its area. The area of Rosenthal's canal conventionally excludes the area of blood vessels within it. Previous work has shown that the blood vessel area within Rosenthal's canal increases with cochlear inflammation. Consequently, excluding this area may result in an underestimate of ganglion cell loss and a tested implant parameter may be wrongly passed as safe. This study investigates whether the increase in blood vessel area with grade of inflammation has an effect on ganglion cell density measurements made by excluding blood vessel area. Eighteen implanted and stimulated cat cochleae were serially sectioned. Using computer image analysis we measured ganglion cell number, the area of Rosenthal's canal and its blood vessels. A 'blind' histologist graded the inflammation in each cochlea. Ganglion cell densities calculated by excluding and including blood vessel area showed no divergence with increasing inflammation (B = -163, P = 0.001 and B = -160, P = 0.001). The increase in the blood vessel area with inflammation has no effect on cell density measurements made by excluding that area.
Moralee
S J
SJ
Department of Otolaryngology, Royal Infirmary, Edinburgh, UK.
D000818:Animals; D002415:Cats; D002452:Cell Count; D016923:Cell Death; D003051:Cochlea / Q000473:pathology*; D007249:Inflammation; D013136:Spiral Ganglion / Q000473:pathology*