Minimally invasive surgical treatment for Kimmerle anomaly

INTRODUCTION: Kimmerle anomaly is the bony ridge between the lateral mass of atlas and its posterior arch or transverse process. This bony tunnel may include the V3 segment of the vertebral artery, vertebral vein, posterior branch of the C1 spinal nerve, and the sympathetic nerves, which results in the clinical symptoms of this disease. Reports on the surgical treatment of Kimmerle anomaly are rare. There are no reports on minimally invasive surgical treatment of this pathology. MATERIALS AND METHODS: Six patients with Kimmerle anomaly were treated from 2015 until 2016. Three patients underwent routine surgery through the posterior midline (posterior midline approach [PMA] group). The other three patients underwent decompression with a paravertebral transmuscular approach (PTMA group). The operation time, intraoperative blood loss, clinical symptoms before and after surgery as well as intra- and post-operative complications were compared between the PTMA and PMA groups. RESULTS: The results of the surgical treatments were assessed at discharge and 1 year later. Blood loss, operation time, and intensity of pain at the postoperative wound area were lower in the PTMA group. There were no postoperative complications. The delayed surgical treatment outcomes did not depend on the method of artery decompression. CONCLUSIONS: Surgical treatment of vertebral artery compression in patients with Kimmerle anomaly is preferable in cases where conservative treatment is inefficient. A minimally invasive PTMA is an alternative to the routine midline posterior approach, providing direct visualization of the compressed V3 segment of the vertebral artery and minimizing postoperative pain.