LAUSR

PURPOSE C1 lateral mass reconstruction is recommended, in cases of instability caused by tumor involvement or extensive C1 lateral mass resection. However, because of the anatomical complexity of the area and, most importantly, the proximity to vertebral arteries, few cases of reconstruction have been reported to date. The purpose of this report is to present technical details of C1 lateral mass reconstruction in conjunction with vertebral artery preservation from a posterior approach. METHODS Two cases of one stage craniovertebral junction instrumentation and C1 lateral mass reconstruction in conjunction with vertebral artery preservation from a posterior approach are presented. RESULTS In both cases of extensive resection of lateral mass due to tumor involvement, an expandable cage was used for C1 lateral mass reconstruction, which has been used only in one patient in literature. Complementary pathological examinations of the two cases indicated two rare tumors that had been reported in the upper cervical region so far. The first case became an unknown origin metastatic cancer and the second was reported to be a primary non- Hodgkin lymphoma. CONCLUSIONS C1 lateral mass reconstruction with an expandable cage together with VA preservation is recommended in cases of extensive C1 lateral mass resection to increase the total strength and to shorten the length of the posterior device and probably better fusion. The expandable cage is preferred because of safer placement under compression instead of the lateral mass.