Far lateral approach with intraoperative ultrasound Doppler identificationof the vertebral artery

A 69-year-old woman presented with right hemiparesis and magnetic resonance imaging revealed a meningioma at the ventral aspect of the foramen magnum. We used a retromastoid curvilinear incision down the lateral aspect of the neck to expose the semispinalis and other muscles. Guided by ultrasound to avoid damage to the vertebral artery beneath the semispinalis, we incised the semispinalis muscle in a U-shape that hinged at the retromastoid curvil inear incision with its one limb along the border of the foremen magnum and the other limb along the posterior arch of the atlas. The other muscles we re divided in line with the curvilinear incision and retracted posteriorly with the bulk of semispinalis to expose the bones, not disturbing the U-sha ped piece of semispinalis that covered the vertebral artery. Similarly guid ed by ultrasound, we performed far lateral suboccipital craniectomy and lam inectomy, exposed the dura above and below the dural entry of the vertebral artery, opened the dura cephalad and caudal to the dural entry of the vert ebral artery, and excised the tumor. This method provided adequate exposure to the lateral aspect of the cranio-vertebral junction and minimized the r isks of dissecting the whole extradural segment of vertebral artery. It req uires more cases to determine whether the results of this patient can be ge neralized. (C) 1999 Elsevier Science B.V. All rights reserved.