1484. Anteromedial Approach To The Occipito-Cervical Junction. Anatomical Study And Microsurgical Technique.

Authors: Felix Pastor Escartin; Fernando Talamantes Escribá; Vicent Quilis Quesada; Esteban Vega Torres; Pau Capilla Guasch; Guillermo García Oriola; Cristina Oller; José Manuel González Darder; Diego Tabarés Palacín; Luis Real Peña; José Luis León Guijarro; Jorge Torres Gaya (valencia, Spain)

Introduction: Describe the anatomical structures of the upper cervical region and the technical aspects of the anteromedial approach to the occipito-cervical junction, the anterior edge of the foramen magnum and the upper cervical segments for the microsurgical treatment of lesions in this specific location. Demonstrate its practical application through a surgical case. Methods: Sixteen cadaveric specimens previously fixed with formaline were dissected in the microsurgical neuroanatomy laboratory of our institution. The technique described in the literature was performed with the aid of a surgical microscope and specific instrumentation. We demonstrate the feasibility of this approach in vivo, in the microsurgical treatment of two metastasis and one chordoma of the axis with epidural extension from the atlas to C3. It required a radical excision and posterior reconstruction with C1-C3 instrumentation and arthrodesis using tricortical iliac crest graft and an anterior cervical plate . Results: The anatomical structures related to the approach are identified, from the pharyngeal tubercle of the clivus (rostral limit) to the fourth cervical vertebra (caudal limit). Lateromedially, both lateral masses of the atloaxoidal complex were observed. The platysma muscle, the submandibular gland, the digastric muscle, the hypoglossal and superior laryngeal nerves, the hyoid bone and the prevertebral and retropharyngeal fasciae were identified and preserved in all specimens. During surgery, the aforementioned structures could be visualized, obtaining optimal exposure for the treatment of an axis chordoma. This technique is anatomically more conservative and with less morbidity than the classic approaches described for this region. Conclusion: The retropharyngeal anteromedial approach allows a safe and optimal exposure of lesions located from the clivus to C4, both in cadaver specimens and microsurgical procedures. This approach is a valid option for treating lesions located at upper cervical segments,equivalent to the Smith Robinson approach for subaxial cervical segment.