- CT —
- computed tomography
American Indian children suffer from chronic otitis media at a rate 3 times greater than the general population.1 The reason that this population has been so vulnerable to middle ear infections, and for how long they have been vulnerable, is unknown.2 Chronic ear infections can lead to permanent hearing loss3,4 and contribute to lifelong problems communicating with others. Repeated middle ear infections, which typically begin during early childhood, often lead to radiographic findings such as decreased mastoid air cell pneumatization5 that persist throughout life and are best observed by computed tomography (CT) scanning.
The lead author (J.W.O.) practiced for a time in the remote high desert of the Navajo Reservation in Shiprock, New Mexico, where he was the sole otolaryngologist for over 80 000 American Indians.6 He saw firsthand how frequently these people suffered in school and at work from hearing loss caused by chronic ear infections and wondered if American Indians who lived in this area centuries ago also struggled with this burden. To investigate this question, we used CT scanning on a set of ancient American Indian skulls to see if there were findings indicative of chronic middle ear disease.
Study specimens are from 2 archaeological sites located on the 12 000-acre B-Square Ranch in Farmington, New Mexico, which is owned by Tommy Bolack. These ancestral Puebloan habitation sites (ad 850–1300) were excavated by Mr Bolack between 1967 and 1989. The 1978 New Mexico Cultural Properties Act provided for protection of archaeological sites on state land. Private landowners were allowed to conduct field archeology on their property until the “unmarked burial statute”7 was added in late 1989, requiring that a professional archaeologist excavate unmarked burials on private land with a permit from the Cultural Properties Act committee. The study specimens were obtained before the unmarked burial statute and were not subject to these regulations.
In addition, there are no direct descendants of the ancestral Puebloans today, although the Hopi, Zuni, Acoma, and the northern Rio Grande Pueblos are distantly related8; thus, consent for this study was not requested of existing American Indians in New Mexico or Arizona. The University of California San Diego Institutional Review Board determined that our study did not qualify as human subject research and required no review. Throughout the study, we were keenly sensitive to the concerns of first peoples and treated the skulls studied with the utmost respect. One of us (L.W.) is an experienced and knowledgeable professional archeologist who personally oversaw handling of the specimens to ensure this was done properly.
Each skull was labeled as to its cultural “provenance” (origin) and its archaeological “provenience” (site of archaeological recovery). We performed CT scanning by using a Siemens Biograph TruePoint positron emission tomography and CT scanner with a 190-mm field of view, 200-mA seconds, and 120-kV peaks. A volume acquisition was obtained, and 0.6-mm–thick axial slices were constructed with 0.3-mm overlap; 3-mm–thick sagittal and coronal reconstructions were performed with 0.5 mm between slices.
A total of 20 ancient American Indian skulls were included in this study (Table 1): 1 male, 7 female, and 12 of unknown sex. Fourteen skulls could be assigned a broad age category, with 6 remaining unknown. Five of the 20 specimens (25%) showed evidence of arrested mastoid pneumatization on 1 or both sides (Figs 1 and 2), a finding commonly associated with chronic otitis media. Three of the 20 skulls (15%) exhibited expanded marrow space, or porotic hyperostosis (Figs 3 and 4). Almost all specimens had some degree of flattening of the occiput (Fig 5) caused by carrying infants strapped to cradleboards, a practice that continues in the American Indian culture today.
The ossicles and mastoid air cells are tiny, delicate, and fragile. Fortunately, these structures are encased in bone and were therefore well protected over the centuries from being damaged.9 In fact, the bone that encases the middle and inner ears is the densest in the human skeleton.10 To keep the specimens intact and completely undisturbed, we used CT scanning to peer inside the ancient temporal bones for evidence of chronic otitis media.
We chose mastoid pneumatization as the main evidence for past chronic otitis media in our study. There are other radiographic findings associated with chronic ear infections, such as ossicular discontinuity or erosion of the lateral semicircular canal or tegmen.11 A major analytic challenge was to determine with reasonable confidence that the temporal bone changes had not occurred during the many centuries of being buried under tons of earth. Mastoid pneumatization covers a relatively large area of the temporal bone and is a gradual change associated with chronic otitis media.12
An obvious drawback of our study is its small sample size, which means that our findings cannot be generalized. Twenty-five percent of the 20 skulls displayed arrested mastoid pneumatization; therefore, it can be inferred from our results that chronic ear infections were not unknown to the ancient American Indians. Another limitation is that the ancestral Puebloan specimens in this study were not related to the Navajo who currently occupy this area.
Despite these limitations, we felt these skulls presented a rare opportunity to look for signs of chronic middle ear disease in ancient American Indians. One theory regarding the appearance of chronic middle ear disease in this population is that Europeans exposed American Indians to virulent new strains of bacteria to which they had not evolved immunity, causing chronic otitis media.13 All individuals in our study lived and died well before Europeans were introduced to American Indians in this area; thus, bacteria that might have arrived with these newcomers did not cause the ear infections.
Chronic middle ear disease often arrests mastoid pneumatization. There is some evidence in the archaeological crania of American Indians14 and Greenlandic Inuit,15 suggesting an increase in the incidence of poor mastoid air cell development after exposure to Europeans. The authors of these and other studies,16 performed at least 20 years ago, generally relied on plain films, whereas we used present-day CT technology, which affords greater clarity and precision than plain film.
Iron deficiency anemia may have increased these individuals’ susceptibility to otitis media. Recurrent otitis media in children has been linked to iron-deficiency anemia.17 Porotic hyperostosis is characterized by localized areas of spongy or porous bone tissue, and in our study, was interpreted as increased marrow space. This may result from iron deficiency anemia, and was found in 3 of 20 specimens. Indeed, porotic hyperostosis has been identified in 45.2% to 82.0% of the ancient American Indian skeletal specimens found in this region of the Southwest.18
Today, American Indians have the highest incidence of hearing loss of any ethnic group,19 likely because of suffering from chronic otitis media at a much greater rate than the general population.1 American Indians have the lowest graduation rate from high school20; the high frequency of hearing loss along with other factors may contribute to this underachievement. Hearing loss and poor academic achievement may also be connected to the unemployment rate of American Indians, the highest of any American ethnic group.21
The evidence identified in our study suggests that chronic otitis media was common in ancient American Indian populations before European contact; additional research is needed to confirm these findings in a larger sample. Work is required to help present-day American Indians avoid the long-term sequelae of chronic middle ear disease.
We thank Mr Tommy Bolack for granting us access to his unique archaeological collection. We are also grateful to Mr Bolack and Mr Charles LaNasa for their financial support, Mr Gary Wildfong for his logistical contributions, and Ms Jane Buchwald, Chief Scientific Research Writer at Medwrite Medical Communications, for her editorial suggestions.
- Accepted November 1, 2017.
- Address correspondence to James W. Ochi, MD, Division of Otolaryngology, Sharp Rees-Stealy Medical Group, 10243 Genetic Center Dr, San Diego, CA 92121. E-mail:
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
FUNDING: No external funding.
POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.
- National Institutes of Health
- National Institute on Deafness and Other Communication Disorders (NIDCD)
- US Department of Health and Human Services, Northern Navajo Medical Center
- ↵New Mexico Cultural Properties Act, N.M. Stat § 18-6-11.2 (1989)
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