Normal Atlanto-Occipital Interval in Adults of Southeast Nigeria: An Evaluation of the Effect of Age, Sex, and Race.

BACKGROUND: Imaging of the craniocervical junction (CCJ) after trauma is crucial for injury detection and description. Of all the anatomic measurements of the CCJ, the normal value of atlanto-occipital interval (AOI) is not yet well established in adults. The aim of our study is to determine the normal values of the AOI in Nigerians aged between 21 and 60 years using multidetector computed tomography (MDCT) scan and to determine racial, age, and sex differences. METHODS: This was a prospective observational study done at Memfys Hospital for Neurosurgery, Enugu, Nigeria, between May 2016 and April 2017. There were 240 subjects (120 men and 120 women) divided into the following age groups: 21-30, 31-40, 41-50, and 51-60 years. Non-Nigerians and those with preexisting CCJ abnormalities were excluded. Normal values were those within the 95% confidence interval. Results were analyzed for possible sex and age variations and compared with the available literature for racial differences. Ethical approval was obtained for this study. RESULTS: The measured normal computed tomography value of the AOI in adult Nigerians was 1.181 ± 0.018 mm. The values in the age groups of 21-30, 31-40, 41-50, and 51-60 years were 1.279 ± 0.038, 1.164 ± 0.033, 1.151 ± 0.029, and 1.133 ± 0.033 mm, respectively (P < 0.05). The average normal values in men and women were 1.188 ± 0.025 and 1.174 ± 0.026 mm, respectively. The interobserver reliability test using the Cronbach α was 0.938. CONCLUSIONS: AOI values in this study were higher than previous MDCT-based values in non-African populations. The AOI decreased linearly with age and did not show any sex difference.

A Rare Case of Pediatric Lumbar Spinal Ependymoma Mimicking Meningitis.

Spontaneous acute subarachnoid hemorrhage (SAH) from lumbar ependymoma in children is rare. We report a case of a 14-year-old boy who developed sudden radicular low back pain while playing baseball. He was initially managed conservatively in a local hospital for suspected lumbar disc herniation, but he later developed meningeal symptoms and fever before being referred to our hospital. He underwent a diagnostic lumbar puncture in the emergency department; his cerebrospinal fluid suggested an SAH. Physical examination showed meningeal signs and cauda equina features. Cerebrospinal fluid analysis was negative for bacterial meningitis. Lumbar magnetic resonance imaging revealed a mass characterized as a hemorrhagic lesion. The patient had an emergent evacuation of the mass through the posterior approach. Postoperatively, his symptoms resolved completely. The histologic diagnosis was, surprisingly, an ependymoma (World Health Organization grade II). This case is particularly interesting because of its rarity in children, and its pattern of presentation. Although bacterial or viral meningitis is the most frequent cause of meningeal features in children, SAH from a hemorrhagic spinal tumor should be considered. Ultimately, a high index of suspicion is needed for prompt diagnosis.