Anlage und Pneumatisation

Histomorphological study on hypocellularity in mastoid processes from archaeological human skeletons

OBJECTIVE

To evaluate processes causing two types of mastoid hypocellularity (Type 1 and Type 3), and to provide histomorphological criteria for a differential diagnosis in archaeological human bone.

MATERIALS AND METHODS

Eight human crania from the early medieval cemetery in Dirmstein (Rhineland-Palatinate, Germany) displaying secondary obliteration of mastoid air cells were analyzed using light-microscopy and backscattered electron imaging.

RESULTS

In Type 1 hypocellularity, obliteration starts in the non-pneumatized portion of the mastoid process and extends into the pneumatized portion. The findings could represent a chronic, maybe recurrent condition related to a pathologically altered middle ear mucosa in early childhood. In Type 3, a sequence of resorptive and proliferative processes are present and are consistent with a healing stage of mastoiditis.

CONCLUSIONS

Using histomorphology, in vivo processes resulting in different types of mastoid hypocellularity can be assessed, even in bones that have undergone some degree of diagenesis.

SIGNIFICANCE

The study provides methods to evaluate the etiology of histomorphological changes of the mastoid process, which potentially provides insight into the presence of infection and inflammation in past populations.

LIMITATIONS

Diagenetic modifications of archaeological bone can hinder assessment of histomorphological change, requiring careful evaluation during analysis.

SUGGESTIONS FOR FURTHER RESEARCH

Including histomorphology in future studies on archaeological human crania can contribute to an improved differential diagnosis of pathological conditions in the middle ear region.

Differential diagnosis of mastoid hypocellularity in human skeletal remains

Mastoid hypocellularity is frequently used as an indicator of chronic otits media in paleopathological investigations. The condition can be caused by a poor development of air cells during infancy and early childhood (primary hypocellularity) or by obliteration of air cells with bone during later life (secondary hypocellularity). We performed a macroscopic, radiographic, and microscopic study of pneumatization patterns in 151 mastoid processes of individuals from an early-medieval cemetery in Germany, with emphasis on the architecture of the nonpneumatized portion of hypocellular mastoid processes. Two types of primary mastoid hypocellularity were distinguished. The first was characterized by a poorly defined boundary between the pneumatized portion and the nonpneumatized portion and a trabecular thickening in the spongy bone of the latter. The second showed a well-defined boundary between the pneumatized portion and the nonpneumatized portion and normal spongy bone architecture in the latter. The key feature for the diagnosis of secondary hypocellularity was the recognition of the walls of former air cells. Our observations closely match the histopathological findings by Wittmaack (Wittmaack: Uber die normale und die pathologische Pneumatisation des Schläfenbeins. Jena: Gustav Fischer [1918]), who developed a concept of the normal pneumatization process of the temporal bone and the pathogenesis of aberrant pneumatization. We agree with Wittmaack's view that two types of primary mastoid hypocellularity can be distinguished morphologically. Regarding the pathogenesis of these types, we, however, conclude that Wittmaack's concept needs to be revised and updated. Further studies are required to establish the relationship between morphological findings in cases of mastoid hypocellularity and the health status of individuals.