I was wondering what are the side effects of a radical neck dissection?

Depends on cause: Most often radical neck dissections are done by ENT surgeons for cancer. Side effects are dependent on the location of the cancer and invasiveness. Some of the potential side effects based on the anatomy of the region include damage/injury to the large vessels-ie. Carotid artery, jugular vein. This can lead to stroke. Damage can occur to nerves that control swallowing or the ability to speak.