Angulation Between the Occipital Condyle and the Hypoglossal Canal: An Anatomical Study With Application in Transcondylar Approaches and Occipital Condyle Screw Placement

Humza Faisal Siddiqui; Juan J Cardona; Arada Chaiyamoon; Aishwarya Gilkes; Mathangi Rajaram-Gilkes; Sassan Keshavarzi; Joe Iwanaga; Aaron S Dumont; R Shane Tubbs

doi:10.7759/cureus.32326

Angulation Between the Occipital Condyle and the Hypoglossal Canal: An Anatomical Study With Application in Transcondylar Approaches and Occipital Condyle Screw Placement

Cureus. 2022 Dec 8;14(12):e32326. doi: 10.7759/cureus.32326. eCollection 2022 Dec.

Authors

Humza Faisal Siddiqui¹, Juan J Cardona², Arada Chaiyamoon³, Aishwarya Gilkes⁴, Mathangi Rajaram-Gilkes⁵, Sassan Keshavarzi², Joe Iwanaga^{2

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7}, Aaron S Dumont², R Shane Tubbs^{2

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Affiliations

¹ Department of Neurosurgery, Jinnah Postgraduate Medical Centre, Karachi, PAK.
² Department of Neurosurgery, Tulane University School of Medicine, New Orleans, USA.
³ Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, THA.
⁴ Department of Anatomical Sciences, St. George's University, St. George's, GRD.
⁵ Department of Medical Education, Geisinger Commonwealth School of Medicine, Scranton, USA.
⁶ Department of Neurology, Tulane University School of Medicine, Tulane Center for Clinical Neurosciences, New Orleans, USA.
⁷ Department of Structural & Cellular Biology, Tulane University School of Medicine, New Orleans, USA.
⁸ Department of Surgery, Tulane University School of Medicine, New Orleans, USA.
⁹ Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, USA.

Abstract

Background A detailed understanding of the relationship between the occipital condyle (OC) and the deeper-lying hypoglossal canal (HC) is necessary for surgeons who place screws into the OC or drill through or around the HC. Therefore, this anatomical study was performed. Methodology A total of 30 skulls (60 sides) underwent an analysis of the angle formed between the long axis of the OC and the HC, i.e., the OC/HC angle. Additionally, the lengths and widths of the OCs and foramen magnum (FM) of each skull were measured using a micrometer. Statistical analyses were performed between the left and right sides, and a Pearson's correlation coefficient was calculated between OC/HC angles and the sizes of the OCs and FM of the skulls. Results The OC/HC angle for the left and right sides ranged from 30 to 56 degrees (mean 46 degrees). The width of the OCs ranged from 9 to 18 mm (mean 13 mm). The length of the OCs was 18 to 31 mm (mean 24 mm). The mean length and width of the FM were 36 mm and 30 mm, respectively. There was no statistically significant difference between the OC/HC angle comparing left and right sides or male or female specimens. Additionally, no statistically significant differences were found between septated and non-septated HC. Pearson's correlation coefficient for left and right OC/HC angles and left and right OC lengths was r = 0.4056 and r = 0.2378, respectively. Pearson's correlation coefficient for left and right OC/HC angles and left and right OC width was r = 0.3035 and r = 0.3530, respectively. Pearson's correlation coefficient for left and right OC/HC angles and the width of the FM was r = 0.2178 and r = 0.2048, respectively. Pearson's correlation coefficient for left and right OC/HC angles and the length of the FM was r = 0.3319 and r = 0.2683, respectively. Conclusions The OC/HC angle as measured here was relatively consistent with no statistically significant differences between sides. We did not find a strong correlation between the width or length of the OC or the width or length of the FM and the OC/HC angles. Therefore, based on our study, surgeons can expect that this angle will range between 30 and 56 degrees (mean 46 degrees). Such knowledge might decrease patient morbidity following invasive procedures involving the OC.

Keywords: anatomical study; craniovertebral junction; hypoglossal canal; occipital condyles; transcondylar approach.