Clearance of the cervical spine (CS) in obtunded trauma patients in an intensive care unit is problematic. Patients with no osseous injuries have potential unstable extradural supportive soft tissue injury. Evaluation of the supporting structures involves dynamic fluoroscopy or MRI both of which have inherent risks and convenience issues. Defining which of these patients are at highest risk for severe supportive structure injury may improve resource utilization for CS clearance. The purpose of this study was to evaluate clinical factors that may predict the probability of CS supportive soft tissue injury in patients with traumatic brain injury. Patients who sustained traumatic brain injury with intracranial pathology, absence of CS osseous injury, and a limited cervical spine MRI within 72 hours of injury were included. Potential clinical predictors included the severity of the traumatic brain injury defined by the Abbreviated Injury Severity Score for the cerebrum and initial Glasgow Coma Scale, the Injury Severity Score (ISS), mechanism of injury, and high versus low-velocity mechanism. Severity of soft tissue/ligament injury was graded by MRI findings. One hundred twenty-five patients met the study criteria; 81 had negative MRI findings and in 44 the MRI study was positive for potentially unstable injuries. High-velocity mechanisms of injury and ISS--not the severity of the traumatic brain injury or initial Glasgow Coma Scale score--were statistically significant predictors of severe CS supportive soft tissue injuries. Obtunded blunt trauma patients who have been involved in high-velocity-mechanism incidents and have high ISS are at greatest risk for extradural supportive soft tissue CS injuries. These patients should either remain in CS immobilization until clinical evaluation can be completed or undergo further evaluation of their supportive soft tissue structures by MRI or fluoroscopic flexion/extension.