Table 2. Possible complications during occipital condyle screw placement and tips to prevent them.

Complications	Preventive strategies/management
Posterior condylar emissary vein injury	This can be avoided by meticulous dissection along the condylar fossa to identify the vein
	When injured, the bleeding can be controlled using bone wax and oxidized cellulose polymer or the vein can be safely coagulated without neurologic sequelae
Vertebral artery (V3 segment) injury	Prevented by having a working knowledge of the course of the vertebral artery and its anatomical variations on preoperative 3D CT angiography
	Meticulous dissection along the posterior arch of C1 using blunt dissection, and protecting the artery by inferior retraction during drilling, tapping and screw insertion
Hypoglossal nerve injury	Preoperative CT analysis of the position of hypoglossal canal and estimation of the effective height available for OCS placement
	Bilateral EMG monitoring during surgery
Spinal cord injury	Meticulous subperiosteal blunt dissection
Jugular bulb injury	Avoided by adopting a medial angulation in the axial plane
Pseudarthrosis	Decortication and judicious use of allograft and autograft from iliac crest