Discussion

This study demonstrated a low frequency of cervical spine fractures in isolated craniofacial GSWs; GSWs to the head are highly morbid and are frequently lethal injuries. Self-inflicted GSWs to the head have an overall survival of only 10%-15%.^{Reference Selden, Goodman and Cordell3} Gunshot wounds crossing midline (as in many SI cases), involving multiple lobes, or significant intraventricular hemorrhage are identified as highly lethal injury patterns. The majority of patients die on-scene, and of those surviving to the hospital, approximately 50% will die in the emergency department.^{Reference Cavaliere, Cavenago and Siccardi2} Within this severely injured population, this study identified a low incidence of concurrent cervical spine fractures.

The current results of a four percent prevalence of cervical spine fractures in GSW to the head as identified by CT parallels previous literature reporting on radiographic and cadaveric studies. This body of research predominantly used plain radiographs as the imaging modality for cervical spine evaluation with less frequent flexion-extension x-rays, fluoroscopy, or CT. Kennedy, et al noted a 10% incidence of cervical spine fractures with GSW trajectory involving the face or neck.^{Reference Kennedy, Gonzalez and Beitler11} Kaups and Davis reported a 93% cervical clearance rate with radiographs, with three direct bullet injuries suggested by trajectory and no evidence of indirect spinal column injuries.^{Reference Kaups and Davis4} Cervical spine fractures have not been identified when the trajectory is limited to the cranium.^{Reference Klein, Cohn and Soffer8,Reference Lanoix, Gupta and Leak9,Reference Kennedy, Gonzalez and Beitler11,Reference Chong, Ware and Harris12} Thus, it is logical that the rate of cervical spine fractures in the SI cohort is lower than the assault population, as most SI tracts (bitemporal, transoral, or submental) would be limited to the cranium. Similarly, penetrating spinal injuries rarely results in instability, thus, the very low overall rate of spinal surgery in this population. A review of over 300 GSWs with bony spinal column injury identified only two cases (<1%) requiring decompression of spinal canal and no cases of instability requiring operative intervention.^{Reference DuBose, Teixeira and Hadjizacharia7}

The frequency of cervical spine fractures in patients with craniofacial GSW was four percent in a review of five years of NTDB data. The higher frequency of cervical spine fracture in non-SI GSW patients was similar to frequencies in the NTDB cohort. The single case of SI-GSW with a cervical spine fracture was caused by an unusual trajectory through the mandible, hyoid bone, and into the spinal column at the C5 level, and was identified on CT scan. No cervical spine fractures were observed in SI patients with the more common submental, transoral, or bitemporal trajectories.

Spinal immobilization is suggested to have limited benefit and high potential for harm. A retrospective analysis of the NTDB demonstrated twice the risk of death from penetrating trauma in spine-immobilized patients.^{Reference Haut, Kalish and Efron6} Similarly, the Eastern Association for the Surgery of Trauma (EAST; Chicago, Illinois USA) practices management guideline for spinal immobilization found a risk ratio of 2.4 for mortality and no benefit on mitigating neurologic defects.^{Reference Velopulos, Shihab and Lottenberg13} Prehospital spine immobilization is not cost-effective for penetrating torso or extremity injuries and is unlikely to be advantageous for penetrating head injuries.^{Reference Garcia, Liu and Victorino5} Cervical spine immobilization has the potential to mask potentially life-threatening conditions and impede airway or hemorrhage management. Specifically, cervical spine immobilization has been associated with an increased number of intubation attempts.^{Reference Kaups and Davis4} Given these findings, it is recommended to delay or omit cervical spine immobilization in favor of airway and hemorrhage management.^{Reference DuBose, Teixeira and Hadjizacharia7,Reference Velopulos, Shihab and Lottenberg13,Reference Medzon, Rothenhaus and Bono14}

Despite these concerns, one-half of the GSWs to the head presenting at this institution arrived in SMR, with no difference in frequency between SI and assault cases. Contraindications for SMR in the local EMS protocols include penetrating trauma to the head or neck with no evidence of spinal injury; cases where airway management, ventilation, or hemorrhage control is compromised; and cardiac arrest.¹⁵ Patients that were hypotensive or receiving CPR had lower rates of SMR, in line with these guidelines. Apart from hemodynamic instability, there were no other factors consistently associated with SMR use. Not surprisingly, the presence of SMR increased the frequency of dedicated cervical spine imaging.