A Stepwise Posterolateral Approach for Computed Tomography Guided C2 (Axis) Transpedicular Biopsy: A Technical Note

INTRODUCTION: Minimally invasive percutaneous CT-guided biopsies of the spine are well established. Although, technical difficulties with CT-guided percutaneous intervention of the C2 body present due to the smaller size of the vertebral elements and potential injury of the critical adjacent structures such as Carotid arteries laterally, vertebral artery, and cervical nerve posterolaterally, pharynx and larynx anteriorly, and spinal cord in the cervical spinal canal. Routinely transoral approach is used for the percutaneous intervention of the C2 body. Literature on the posterolateral approach for biopsies of the C2 vertebral body is sparse as compared to other approaches. This case report presents a case of adenocarcinoma diagnosed with CT-guided percutaneous biopsy of the C2 body using a posterolateral approach under local anesthesia. CASE REPORT: A 70-year-old female presented to our outpatient clinic with complaints of progressively increasing neck pain with a visual analog score (VAS) 7/10. Neck pain was radiating to the base of the occiput and aggravated by neck movements. On clinical examination, there was axial tenderness at the base of the skull and the upper part of the cervical spine. Neurological examinations of sensory and power in all the limbs were normal. Systemic examination and laboratory parameters did not reveal any abnormality. X-rays and MRI revealed a fracture of the odontoid process with marrow edema with differentials of metastasis. PET scan revealed left lung lesion likely to be primary lesion and lesion in C2 vertebral body as likely metastasis. A minimally invasive percutaneous CT-guided posterolateral approach for biopsy proved moderately differentiated adenocarcinoma from the lung with metastasis to C2 vertebrae. The patient was started on an appropriate Chemotherapy regimen as per the Immunohistochemistry (IHC) and Genomic studies with adjuvant radiotherapy. CONCLUSION: Understanding the detailed anatomy prior to CT guided minimally invasive percutaneous C2 biopsy procedure helps in increasing its safety, precision, and high yield. Stepwise approach to the procedure aids in getting repeatable and high-yielding results especially in a technically challenging area such as C2 vertebrae.