A 29 yo male presents from a high speed MCV.  He was the unhelmeted driver of a motorcycle.  He was  unresponsive and intubated prior to arrival.  CT of the cervical spine is shown below.  What's the diagnosis?  Scroll down for answer

Answer:  Atlanto-occiptal dislocation (internal decapitation)

• Most commonly from high energy mechanisms as in this case
• Mechanism is hyperextension/distraction
• Only about 1/3 of cases do not result in immediate death, and overall surival is rare
• Children have a higher predisposition but also have a higher incidence of survival
• Roughly half of the survivors will have residual neurological deficits
• Lateral cervical spine xrays may be unremarkable aside froom pre-vertebal swelling
• While presentation, as in this case, is usual not subtle, some patients may present awake and alert with complaint neck pain
• CT plus MRI are used to evaluate ligamentous injury
• CT angiogram is appropriate as concurrent vascular injuries are common
• Early neurosurgical occipitocervical fusion is recommended, while traction/halo is not 

Nelson, A.  Traumatic Atlanto-Occipital Dislocation in Children.  Journal of the American Academy of Orthopaedic Surgeons. 2014; 22(5):275-282.

Tintinalli J, et al.  Tintinalli's Emergency Medicine: A Comprehensive Study Guide 8th Ed. New York: McGraw Hill Education, 2016.