Possible Clinical Implications of Geographic Differences in Prevalence of Double Transverse Foramen.

BACKGROUND: The double transverse foramen (DBLTF) is a cervical spine anatomic variant. Current literature has presented prevalence values of DBLTF in Caucasian Mediterranean subjects that seem to be higher than those observed in other samples of subjects. Therefore we aimed to test if Caucasian Mediterranean subjects present a higher prevalence of the DBLTF than sub-Saharan African subjects. METHODS: We analyzed the presence of DBLTF in cervical spines of 100 skeletons from Caucasian Mediterranean subjects and 91 skeletons from sub-Saharan African subjects, resulting in a total of 1337 cervical vertebrae having been studied. RESULTS: No DBLTF was found in vertebrae C1, C2, and C3. The pattern of prevalence observed in all samples analyzed indicated the prevalence ranged from exhibiting the most to the least prevalence as C6 > C5 > C7 > C4. The sub-Saharan African subjects presented a significant reduced DBLTF prevalence of 2.2%, 14.3%, 19.8%, and 3.3% in C4 (P = 0.043), C5 (P = 0.004), C6 (P < 0.001), and C7 (P = 0.041), respectively, than that presented by Caucasian Mediterranean subjects (9.0%, 32.0%, 45.0%, 11.0% in C4, C5, C6, and C7, respectively). CONCLUSIONS: Our study has revealed that this anatomic variation is more frequently found in Caucasian Mediterranean subjects than in sub-Saharan African subjects.

The Decreasing Prevalence of the Arcuate Foramen.

BACKGROUND: The arcuate foramen (AF), or ponticulus posticus, is an anatomic variant of the first cervical vertebra that consists of a complete or partial osseous bridge over the groove for the vertebral artery and extends from the posterior aspect of the superior articular facet to the superior lateral border of the posterior arch. The AF has been associated with clinical symptoms, such as headache, migraine, neck pain, shoulder pain, arm pain, and vertebral artery dissection. We aimed to test whether the prevalence of the AF has decreased in the modern human population over the past centuries as a result of reduction in inbreeding and endogamy. METHODS: Possible reduction in the prevalence of the AF was assessed by comparing a 17th century rural sample (n = 108) with a 20th century modern urban sample (n = 192). RESULTS: When comparing the 17th and the 20th century samples, we found a statistically significant (P = 0.003) reduction of 14.5% (95% confidence interval 4.5-24.5) in the prevalence of the AF. CONCLUSIONS: Prevalence of the AF has been decreasing over the past centuries.