Blunt carotid injury associated with cervical spine fractures is a rare entity but potentially lethal. An initial, clinically silent period can be misleading. Prompt diagnosis and treatment are mandatory to avoid neurological damages and death. We present the case of a 36-year-old man diagnosed with an isolated cervical spine fracture, where an associated carotid artery lesion was initially overlooked and diagnosis was made after development of a neurological deterioration secondary to a posterior reversible encephalopathy syndrome (PRES). We discuss a simple algorithm that can be used to make the diagnosis, even during the clinically asymptomatic period of this injury.