Use of the trimmed Shah permavent tube in the management of glue ear.

Twenty-five children (mean age six years) with de novo bilateral ear effusions received a 'trimmed' high grade silicone (HGS) Shah permavent ventilation tube in one ear and a conventional polyethylene Shah grommet in the other. The extrusion rate and the degree of tympanosclerosis formation was examined. At 29 months the conventional grommet had extruded in 90 per cent of children and a recurrent middle ear effusion was found in over 50 per cent of these ears. The average length of stay for the conventional grommet was 12.5 months. Five permavent tubes had extruded, one was extruding but the remainder were all in place and patent. Comparing ears on each side the amount of tympanosclerosis was worse in the ear with the conventional grommet in 47 per cent of children and worse on the permanent side in 11 per cent of the children. The 'trimmed permavent' appears to act as a medium to long-term grommet which self extrudes without serious complications. Its use at the primary operation in young children may save repeated insertions of conventional grommets.