Morphology And Morphometry Of The Transverse Foramina Of Cervical Vertebrae In An Adult Kenyan Population: A Radiological Study

Abstract

Background: Transverse foramina are canals in cervical transverse processes that transmit the vertebral artery, the vertebral vein and the accompanying sympathetic plexus. These foramina exhibit side, sex and population specific variations such as those of size, shape and number. The knowledge of these variations is important for cervical surgical procedures such as pedicle screw fixation, anterior and lateral decompression and cervical discectomy and fusion. Variations in the transverse foramina are also vital in the prediction of variations of the vertebral artery. However, there remains a dearth in literature on the morphological and morphometric variations of cervical transverse foramina in an adult Kenyan population. Methods: Ninety-four neck CT scan images of 2 mm slice thickness in an axial view were used to assess the presence, number, completeness and shape of the cervical transverse foramina. Anteroposterior and transverse lengths of the foramina were also measured using an inbuilt ruler in the CT imaging software NeusoftTM. Measurements were tabulated and analyzed using SPSS (Version 28.0, Chicago Illinois). Normalcy of data was assessed using Kolmogorov-Smirnov and Shapiro-Wilk tests. Means, standard deviations and frequency tables of the morphometric data were generated. Paired and independent t-tests were used to compare the morphometric parameters for side and sex respectively. A one-way ANOVA was used to determine differences in transverse foramina down the cervical spine. A p-value of ≤ 0.05 was considered statistically significant. Chi-square tests were used to assess associations between categorical data. Data was presented in the form of photographs, tables and graphs. Results: Transverse foramina had a prevalence of 98.78% (1300/1316 transverse foramina). 3.64% of transverse foramina were duplicated. The morphology of the transverse foramina was identified as type 1 (circular), type 2 (elongated antero-posteriorly), type 3 (elongated transversely), type 4 (oblique left to right elongation) and type 5 (oblique right to left elongation) in 69.62%, 3.62%, 13.38%, 7.23% and 6.15% of the transverse foramina respectively. 0.46% foramina were noted as incomplete and 3.19% as constricted. Statistically significant side and level differences were noted in anteroposterior and transverse diameters of the transverse foramina. The mean right antero-posterior and transverse diameters were 4.72 ± 1.45 mm and 5.43 ± 1.48 mm respectively. The mean left antero-posterior and transverse diameters were 4.48 ± 1.60 mm and 5.26 ± 1.67 mm respectively. Foraminal dimensions on the right side were generally larger than the left. The first cervical transverse foramina were the largest and those of the seventh, the smallest. The diameters decreased from C2 to C3 then increased to C6. Conclusion: Transverse foramina display side and level dependent morphologic and morphometric variations. This is of clinical importance to spine surgeons to prevent intraoperative damage of the vertebral vessels when operating in the cervical region. It is also useful to radiologists for image analysis as well as to neurosurgeons for neurological diagnosis.