Incidence and pattern of cervical spine injury in blunt assault: it is not how they are hit, but how they fall.

BACKGROUND: The injury mechanism of blunt cervical spine injury (CSI) involves two forces: (1) an acceleration-deceleration force or change in velocity (delta v) that causes significant head and neck movement, resulting in flexion-extension injury pattern and (2) a direct force to the head or face against an immovable object with force transmitted down the cervical spine. Combining those two forces creates what bioengineers call imparted energy (IE). In blunt assault to the head or face, IE is low; hence, the reported incidence of CSI is low. The goal of our study was to identify the incidence, pattern, and outcome of CSI in blunt assaulted patients.

METHOD: We queried the trauma registry at our Level I trauma center for patients admitted with the diagnosis of blunt assault over a 5-year period (2005-2009). Patients with CSI were identified by International Classification Diagnosis (Ninth Revision) codes of 805, 806, 839, or 952. We only included the patients who received the blow to the head and face. For eligible patients, we extracted data from trauma registry and inpatient chart review, including radiographic reports. A single author (N.K.) reviewed computed tomography (CT) scan of all individuals with CSI. We performed summary and Spearman rank correlation statistical analysis with p value <0.05 considered significant.

RESULTS: During the study period, 1,335 patients met our study inclusion criteria. All underwent CT of the head, cervical spine, and/or face. CSI was suspected in 78 patients; however, 65 had normal CT results and were diagnosed instead with a cervical sprain. Of the remaining 13 patients, two had a herniated disc, two had spinal stenosis, and nine had a fracture or dislocation, yielding a CSI incidence of 0.7%. We found no correlation between an increased incidence of CSI and either severe head trauma (low Glasgow Coma Scale [GCS] score) (r = -0.02, p = 0.58) or severe facial trauma (high face Abbreviated Injury Scale score [f-AIS]) (r = 0.02, p = 0.59). Three patients had significant subluxation; only two had associated spinal cord injury (SCI). All three required surgical fusion, and all three reported a fall after assault without significant head or face trauma.

CONCLUSION: The incidence of CSI after blunt assault is very low, and the pattern of injury and severity is related to a fall occurring after the assault. Our results should encourage clinicians to find out if patient falls after the assault.