Transient headache related to enlargement of the contralateral vertebral artery after vertebral artery occlusion.

Background: Endovascular proximal parent artery occlusion has been performed for VA dissection. We describe a case that presented with headache associated with transient enlargement of contralateral VA after VA occlusion.
Case Description: A 54-year-old man presented with constant occipital headache on the left due to left VA dissection. Proximal parent artery occlusion of the left VA with detachable coils was performed, and the headache disappeared after coil occlusion. However, the patient presented with occipital headache on the right 1 week later. The MRI showed enlargement of the right VA compared with before the procedure. Four weeks later, the right occipital headache disappeared, and MRI showed improvement of enlargement of the right VA.
Conclusion: The patient might present with right occipital headache related to transient enlargement of contralateral VA after VA occlusion. Careful postoperative neuroradiological examination of the contralateral VA is required because contralateral VA enlargement may be caused by hemodynamic stress after VA occlusion.