LAUSR

The anterior foramen magnum area, ventral to the brainstem is one of the most difficult regions to access surgically, and the extent of osseous drilling through the far-lateral or transcondylar approach should be planned in each case based on the tumor extension.1,2 This video, reproduced after informed consent of the patient, demonstrates a case of a ventral foramen magnum neurenteric cyst surgically treated using the partial transcondylar approach. A 27-yr-old woman presented with gait disturbance, oscillopsia, and transient arm numbness. Neuroimaging revealed a ventral foramen magnum cystic tumor involving the basilar and bilateral vertebral arteries. The tumor extended inferiorly from the middle clivus to the C1 level, and occupied the whole premedullary cistern compressing the bilateral lower cranial nerves. The left partial transcondylar approach was performed with drilling the condylar fossa, superior part of the occipital condyle, C1 posterior arch, and posterior part of the jugular process to achieve the sufficient surgical view from the inferolateral side. The drilling of the occipital condyle was minimized so that the articular facet of the occipital condyle was preserved. The tumor on the bilateral side was completely removed as enabled by the sufficient surgical field without new neurological deficits. Three-dimensional reconstructed images based on the postoperative computed tomography scans demonstrated the appropriate extent of the osseous drilling.