Cribra orbitalia in an archaeological context: new insights from micro-CT analysis of the Christchurch Spitalfields collection

Palaeopathological analyses are key within bioarchaeological research because skeletal lesions on ancient human remains are a direct product of interactions between biological, social and environmental factors. Evaluating the proportional representation of disease and nutritional deficiencies from skeletal remains can therefore help to identify different pressures acting within and between populations. Cribra Orbitalia (CO), a porous appearance within the orbital roofs, is one of the most commonly occurring pathologies to be used in this manner. For many years they were considered synonymous with a diagnosis of anaemia, whether genetic or acquired. However, recent histological research demonstrated that infection and nutritional deficiencies can create the same morphological appearance as anaemia. This has widespread implications for previous interpretations derived from these lesions, and indeed for the utility of the lesions at a macroscopic level. Palaeopathological methods are currently limited given our poor understanding of the underlying biology and pathophysiology of CO, and reliance on macrostructural examination techniques. The goal of this study was to address whether the accuracy of macroscopic analyses can be improved by using a novel, non-destructive micro-CT analysis. Macroscopic and micro-CT analyses were undertaken on a unique sample of sub-adult individuals of known biological age. Postcranial and cranial skeletal remains representing n = 23 individuals of less than 5 years of age, deriving from the Christ Church Spitalfields (1729-1859AD) collection (London,UK), were studied. Two research aims were evaluated: 1) whether the expression of CO within this sample was associated with other cranial or postcranial expressions of pathology; and 2) how the gross expression of CO in this sample relates to internal features within the bone of the orbits. It was found that the type of CO lesion was more strongly associated with the presence of cranial and postcranial pathologies than location of the lesion within the orbital roof. Neither type nor location of CO was found to be statistically related to three attributes (trabecular thickness, size and shape of diploic spaces, and outer table thickness) of internal bony architecture that were qualitatively evaluated using micro-CT. Approximately 70% of the diagnoses made by analysis of cranial and postcranial macroscopic attributes of pathology were found to have internal bony characteristics consistent with the macroscopic diagnosis. However, the diagnosis could not have been made on the basis of CO type or location alone. Results indicate that macroscopic interpretations of CO may be incorrect, and that further research is necessary to identify whether the results are applicable to older individuals with CO, as well as other populations with this pathology. It is vital to investigate whether other aspects of macroscopic and/or microscopic lesion morphology have a stronger relationship with lesion cause. This PhD contributes to the field by clarifying the complexity of interpretation of CO, and identifying that further research to improve understanding of these lesions, as accuracy of lesion diagnosis is key to making meaningful comparisons of patterns of disease within and between ancient human populations