Clearing the cervical spine in unconscious head injured patients - the evidence

Cervical spine injury occurs in 5-10% of patients with traumatic brain injury (TBI) and the consequences of missing significant cervical injuries in unconscious blunt trauma patients are potentially devastating. An adequate cervical spine clearance protocol for unconscious patients must avoid missed injuries, but must also avoid unnecessary cervical immobilisation and the associated morbidity. Existing protocols include various combinations of plain X-rays, helical CT, dynamic flexion-extension X-rays and MRI. Some clinicians also maintain immobilisation until clinical clearance is eventually enabled by the return of an adequate conscious state. Plain X-rays alone are inadequate and miss 12-16% of cervical injuries. Swimmer's views and/or oblique views identify more injuries, but are frequently inadequate. Helical CT is sensitive to fractures and subluxation/dislocation injuries but may be insufficient to exclude unstable ligamentous injuries. Dynamic flexion-extension fluoroscopy may better identify unstable ligamentous injuries, but at The Alfred Hospital Trauma Centre in Melbourne, this modality was insensitive in the routine protocol and repeatedly missed significant cervical instability. Furthermore at The Alfred Hospital, when routine dynamic flexion/ extension fluoroscopy and helical CT reconstructions were directly compared, flexion/extension identified no new injuries that had not already been diagnosed by early helical CT reconstructions. Cervical MRI is intuitively appealing as it detects ligament, disc interspace, and cord injury more efficiently than other imaging modalities, but MRI also increases cervical clearance times, increases the risks associated with complex transports and is not an ideal acute screening tool. Nevertheless, recently at The Alfred Hospital, extremely high-risk TBI patients have had unstable cervical injuries detected solely by MRI. Current generation multi-slice CT with reconstructions may obviate the need for MRI even in these patients. The current Alfred Hospital cervical clearance protocol for unconscious patients, and the evolutionary steps in its development, will be discussed.