 A common sign is a constricted pupil (Horner's syndrome) on the ipsilateral side due to loss of sympathetic innervation to the eye, caused by damage to the sympathetic trunk in the neck.The C2 fracture accounts for nearly 19% of spinal fractures and 55% of cervical fractures (in patients with head injury).Within C2 fractures, the hangman's fracture accounts for 23% of occurrences while the odontoid or dens fracture accounts for 55% of them.