Nonhuman primate model of cleft palate and its implications for middle ear pathology

The present study is a preliminary report on the development of a nonhuman primate model of cleft palate and middle ear (ME) disease. The causal relationship between a surgical cleft of the soft palate only or a cleft of the hard and soft palate and otitis media with effusion (OME) was investigated in rhesus monkeys. Prior to clefting, ME status was documented by pneumatic otoscopy or otomicroscopic examination and tympanometry over a period of at least five months. A minimum of four preoperative eustachian tube (ET) function evaluations were performed employing the inflation-deflation and the forced-response tests. These procedures were repeated following surgery and during a long-term follow-up. Seventeen of the 18 ears developed a recurrent OME. Postoperative ME pressures were initially high negative values. After the first two postoperative months, high positive ME pressures were recorded. The forced-response test showed little to no long-term changes in passive and active tubal resistances or in the efficiency of tubal dilation as a result of surgery. The inflation-deflation test showed higher opening and closing pressures and a limited and more variable ability to equilibrate applied positive and negative ME pressures following surgery. Both ME status and ET function appeared to improve with time. These findings indicated that the pathogenesis of recurrent OME in this animal model may have been due to changes in ET function associated with an abnormal nasopharynx rather than aberrant tensor veli palatini (TVP) muscle function.