Aural exostoses (surfer's ear) provide vital fossil evidence of an aquatic phase in Man's early evolution

Transcanal Excision of Exostoses: Large Series Comparing Bone Removal Methods

OBJECTIVE

External auditory exostosis (EAE) is a condition of progressive temporal bone growth into the external auditory canal most commonly from repeat cold water and wind exposure. Several tools have been utilized for EAE excision with varying implications for intra- and postoperative complications. However, comparisons of osteotome and microdrill are made difficult due to the few published cases and intervariability between surgeons. Furthermore, evidence is needed to analyze the safety of novel supplemental tools such as the piezoelectric bone-cutting device.

STUDY DESIGN

Retrospective chart review.

SETTING

Medical clinic and surgery center.

METHODS

A total of 413 subjects representing 472 ears met the inclusion criteria. Of which 159 ears were operated on using osteotome alone (OA), 271 using osteotome with a drill (OD), and 42 with osteotome with piezoelectric (OP). Charts were analyzed for the most reported intraoperative complications and postoperative symptoms and complications.

RESULTS

There were no significant differences in the rate of tympanic membrane perforations nor in total intraoperative complications between OA, OD, or OP. The OD group contained the only nonperforation intraoperative event. OA had the lowest or near lowest incidence of all symptoms analyzed. OA showed a significantly lower incidence of tinnitus when compared to OD and OP.

CONCLUSION

We found that OA performed the best, though not statistically significant in most measures, with regard to mitigating rates of complications postsurgery. Our findings suggest OA provides lower risk intraoperatively and postoperatively for patients undergoing transcanal exostosis excision.

A revision of the conductive hearing loss in Cranium 4 from the Middle Pleistocene site of Sima de los Huesos (Burgos, Spain)

Pathological conditions have been previously documented in the Middle Pleistocene Sima de los Huesos hominins from northern Spain, and several of these have clear behavioral implications. Within this fossil assemblage, Cranium 4 shows bilateral external auditory exostoses which have been preliminarily interpreted as causing a significant hearing loss in this individual. If confirmed, this would be the oldest recorded case of deafness in human history and could have important implications for the antiquity of this condition, as well as social interactions. To further investigate this case, the current study presents 3D reconstructions of the entire outer and middle ear, based on computed tomography scans of both temporal bones in Cranium 4. We established the degree of stenosis in both external auditory canals, showing that in both cases the degree of stenosis is less than 52% of the original cross-sectional area of each canal. Based on clinical studies in living humans, the buildup of wax due to the degree of stenosis in Cranium 4 is unlikely to have caused frequent external ear infections. In addition, we estimated the pattern of sound power transmission up to 5 kHz in both ears relying on a comprehensive model developed in the bioengineering literature and which has been applied previously to the Sima de los Huesos hominins. The model was modified to account for the peculiar shape of the pathological external ear canals in Cranium 4. The results show that this pathology had little to no influence on the sound power transmission in this individual. Thus, we conclude that the exostoses present in both ears of Cranium 4 did not significantly affect their hearing.