Cervical Spine Clearance : A Review and Understanding of the Concepts

Cervical spine injury is relatively rare, occurring in only 2% to 3% of patients with blunt trauma who undergo imaging studies. However, timely and accurate recognition of cervical spine injury is essential for the optimal management of patients with blunt trauma as subsequent morbidity includes prolonged immobilization. Evaluation of cervical spine injuries should begin in the emergency department and involves a combination of pediatric, trauma, orthopedic, and neurosurgeons for definitive management. Knowing which patients are at highest risk for injuries will undoubtedly influence decisions on how aggressively to pursue a potential cervical spine injury and can be achieved by establishing a multidisciplinary team approach that provides cervical spine immobilization, assessment, and clearance. Implementation of such guidelines will decrease time for cervical spine clearance and incidence of missed injuries. In this article different aspects of cervical spine injuries and cervical spine clearance protocols are reviewed.


INtRODUCtION
Historically imaging the cervical spine in blunt trauma has been controversial.The debate has been dominated by the problem of ruling out a spinal injury in the unconscious trauma patient.There have been several reports of spinal instability despite normal radiographs, but maintaining immobilization on the intensive care unit 'just in case' has been associated with significant morbidity.New imaging techniques have become available, but did not solve the problem, adding their own 'baggage', such as cost, availability, logistic difficulties, radiation dosage, lack of specificity and evidence of effectiveness or safety. 1 Timely and accurate recognition of cervical spine injury is essential to the optimal management of patients with blunt trauma as subsequent morbidity may cause prolonged immobilization. 2

Epidemiology
Cervical spine injury is relatively rare, occurring in only 2% to 3% of patients with blunt trauma who undergo imaging studies. 3,4Existing epidemiologic studies of patients with cervical spine injury typically focus on admitted patients or populations seen at referral centers.][7]

Different guidelines
Knowing which patients are at highest risk for injuries will undoubtedly influence decisions on how aggressively to pursue a potential cervical spine injury, however no published studies have yet identified the relative risks of injury to the cervical spine in different patient groups.Analysis of the TARN database shows that the relative risk of cervical spine fracture, or cord injury, is greatly increased by the presence of a depressed level of consciousness, severe injuries to other body systems, head injury and chest injury. 11

NEXUS study
The National Emergency X-Radiography Utilization Study validated the use of a 5-point decision-making instrument for identifying trauma patients in whom cervical spine radiography is required. 12e points identified were Absence of all 5 of these had a negative predictive value of 99.9% (95% confidence interval 99.8-100%). 13e Canadian C-Spine Rule 14 The Canadian C-Spine Rule 14 has recently been developed to reduce radiography of cervical spine injuries.In alert, stable patients, X-rays are deemed to be unnecessary if the patient is less than 65 years of age and does not have a dangerous mechanism of injury and does not have paraesthaesia in the extremities and was involved in a simple rear end shunt or is in a sitting position in the Emergency Department or has been ambulatory at any time since injury or has delayed onset of neck pain or has absence of midline cervical spine tenderness and is able to rotate the head by 45 O to both sides.
A dangerous mechanism of injury is defined as-• Fall >1 m or 5 stairs • Axial load to the head • RTA >100 km/h, rollover or ejection • Motorized recreational vehicles

• Bicycle collision
This rule was derived solely in a cohort of adult patients, and has not been validated in children and therefore, the rule is not applicable in pediatric practice. 14ndemark: criteria for high-risk patients 15 1. High velocity blunt trauma

Clinical
• Cervical spine pain, spasm, deformity or neurology • Significant closed head injury; • Pelvic or multiple extremity fractures

Role of imaging
Imaging plays an important part in the diagnosis of spinal injuries.In view of the potentially disastrous consequences of a missed spinal injury, imaging is employed to diagnose or, more frequently, to rule out a spinal injury.Over the last decade there has been a rapid change in clinical and imaging practice for the diagnosis of potential injuries of the cervical spine.This is driven by the standardization of health care, with definition of clinical protocols aided by the rapid advances in imaging Agrawal.Cervical Spine Clearance: A Review and Understanding of the Concepts technology. 179][20][21] One should remember that no imaging modality is accurate 100% of the time, and the combination of accurate history taking, physical examination, and appropriate spinal imaging is required to minimize missed CSI. 1

Plain radiography
Despite the availability of newer technologies, there is still an important role for plain films and all staff needs a basic understanding of the principles.They are ubiquitous, cheaper than CT and the radiation dose is much less for the full spine.Standard radiographic evaluation of the cervical spine in such patients typically consists of cross-table lateral, anteroposterior, and openmouth odontoid views, supplemented at some centers with oblique imaging. 2 Some authors have stated that the odointoid peg view is unhelpful in young children (notwithstanding the practical difficulties that may be encountered). 18Little information can be gleaned from static views regarding the stability of the cervical spine.Static flexion-extension radiographs have been advocated in adults to determine the stability of the cervical spine.• No neck pain or tenderness

• Normal neurological examination Adequacy of the films
There is often a difference in quality between portable films and those taken on a fixed departmental machine, although new portable digital units are a great improvement.Good radiographic technique is essential if subtle signs are to be revealed.To be adequate, the films should show the full extent of the cervical spine, from the occiput to the upper border of T1, and should not be rotated (Figure 1).The penetration should be sufficient to show bone architecture without losing soft tissue detail.The films must be evaluated by a competent practitioner who maintains sufficient activity to maintain skills.

Computed tomography
Role of CT scan has not been compared with plain radiography, other than in small case series (Figure 2).CT scans may, however, miss important injuriestransverse slices, may not detect the presence of a Salter Harris I fracture through the odointoid synchondrosis, and as seen below, significant soft tissue lesions may be detected on MR scan that have been missed by CT.
Dynamic CT has been used to confirm the presence, or absence, of atlanto-axial rotatory fixation in a child presenting with torticollis, following injury to the neck. 23

Magnetic resonance imaging
Utility of MR for imaging the patient with an acute spinal injury is widely accepted, despite a relative paucity of technology assessment studies addressing accuracy of MR findings.MR imaging is used to evaluate two different aspects of spinal injury.One is the extent of injury to neural tissues.Extent of spinal cord and root injury and the likelihood of improvement are the neurologic questions, which need to be answered.Neurological function can be correlated to the imaging appearance of the spinal cord.Assessment of biomechanical integrity of the ligamentous-osseous skeleton is the second aspect of MR evaluation.Identification of injury to specific soft tissues of the spine and their distribution (pattern) reflect mechanisms and extent of injury, and guide treatment planning.Addressing both aspects is necessary in most patients. 24

Limitations of imaging
The evidence from a large prospective study strongly suggests that adequate screening radiographs identify the large majority of patients with bony cervical spine injuries and that the overwhelming majority of patients with blunt trauma with an adequate screening series that shows no injury are indeed without bony injury.Nevertheless, in a small number of patients with blunt trauma, important cervical spine injury can be missed, even on adequate screening plain films.Furthermore, in many patients with blunt trauma, plain films are not adequate, and adjunctive studies are required before cervical spine injury can be excluded.Any strategy designed to improve the identification of such injuries must attempt to achieve a balance between detecting a small number of additional injuries and exposing large numbers of patients with trauma to the costs and radiation associated with additional imaging. 25

Pediatric perspective
Due to the higher frequency of adult trauma, clinicians are exposed on a regular basis to adults with potential cervical spine injury, but have relatively little exposure to, and experience in, the management of children with Agrawal.Cervical Spine Clearance: A Review and Understanding of the Concepts a potential for these injuries. 26The incidence of cervical spine injury (CSI) in children is low (1% to 2%) and failure to recognize a CSI can produce catastrophic neurologic disability. 27,28

Anatomical considerations
There are several features peculiar to the paediatric cervical spine, when compared to that of adults. 29,30A relatively large head leading to a fulcrum of flexion at C2/3 rather than at C5/6, as in adults • Horizontally aligned facet joints, compared to oblique orientation in adults.This is most noticeable in upper cervical vertebrae • Underdeveloped uncinate processes of C3-C7, leading to flatter articular surfaces • Anterior ''wedging'' of the vertebral bodies • Synchondrosis at the junction of the odontoid peg and C2 vertebral body, allowing physeal injuries to occur • Less rigid ligamentous support and weaker supportive muscles, allowing greater displacement for a given force These anatomical differences can be expected to lead to different patterns of injuries in children.Horizontal facet joints, increased ligamentous laxity and weaker musculature make the child's bony cervical spine more mobile, with a lower expectation of bony injury.The higher fulcrum of flexion would be expected to lead to injuries occurring at a higher level than those seen in adults.Although there is inevitably some individual variation, the cervical spine is believed to take on a more adult structure and behaviour at around the age of 8-9 years. 31,32

Clinical evaluation
Evaluation of the stability of the cervical spine in pediatric patients has been inconsistent and controversial.Pediatric surgeons as well as emergency room physicians and trauma, orthopedic, and neurologic surgeons often are asked to rule out cervical spine injuries. 1ubsequent variability in the diagnostic approach and management of CSI in children includes issues such as who to perform cervical spine radiographs on, which radiographs to obtain, duration of immobilization, when to contact subspecialists, when to obtain computed tomography (CT) and magnetic resonance imaging (MRI) scans, and how to show the absence of a ligamentous injury in comatose patients. 1The solution often is the overuse of cervical spine radiographs.However, guidelines as to which patients require imaging as well as what constitutes "routine screening" are variable and still evolving. 9,33Pediatric patients with the following risk factors for cervical spine injury undergo cervical immobilization and radiographic evaluation:

Clearing the c-spine
Clearing the c-spine of injury is an area that requires strict rules and guidelines.[14][15][16]

Who
If the patient is to be discharged from the emergency department, the Registrar from the following units may clear the c-spine after discussion with the emergency department- If the patient is an inpatient the c-spine can only be cleared after consultation with the Neurosurgical or Orthopedic consultant, or the Emergency consultant if the patient is still in the emergency department.

How
Several questions need to be asked when attempting to clear the c-spine.These are questions that need to be asked of adult and paediatric patients.These are: • Can pain and tenderness be assessed?
• Are there other distracting (painful) injuries?
• Is there neck pain?
• Is there tenderness over the cervical spine?
• Are there any motor or sensory abnormalities?
• Is there limitation of active neck movement?
• Is there limitation to head control?

Who to immobilize
In identifying who to immobilize patients can be devided into two groups' i.e. conscious and unconscious patients.The unconscious patient is by far the most difficult to assess but for obvious reasons easier to immobilize.Patients with an alteration in their level of consciousness are at increased risk for cervical spine fracture hence 'the unconscious patient with a history of possible trauma must be immobilized'. 34,35It is important to note here that for cooperative patients who arrive with a hard collar in situ and who do not have a mechanism of injury warranting continued immobilization, the collar should be removed whilst a senior staff member maintains the head alignment.The neck is palpated for tenderness, and if none elicited, assessed for pain on active movement.[38]

How to immobilize
Immobilization of the patients with cervical spine is a very difficult and at times controversial task.Method for immobilizing these patients was put together with (at best) general agreement from all teams. 34,35,38There is little literature available that documents the methods used for immobilizing young children.It has been shown that small children can be immobilize flat on a spine board in a semi rigid one piece cervical collar and a head immobilizer, and for children less than two year of age use of towels and staff or parents holding the head.Sedation is not used, but if the patient is head injured and uncooperative anesthesia, paralysis and intubation are used to aid assessment and imaging. 39

C-spines and spine boards
Patients with suspected cervical spine injury should be placed in supine position, flat on their backs, in such a way as to avoid potential airway compromise.[42]

Collars
In addition to spine boards and the ever-popular towels and tape, cervical collars are an integral part of spinal immobilization in adults. 43,44][45][46] Unfortunately, many pediatric cervical collars simply do not fit children.
Agrawal.Cervical Spine Clearance: A Review and Understanding of the Concepts An apparently normal magnetic resonance image can conclusively exclude cervical spine injury and is established as a gold standard for clearing the cervical spine in a clinically suspicious or unevaluatable blunt trauma patient. 47MRI may be unnecessary if the CT scan is negative. 48,49Spinal cord injury treatment with intrathecal autologous bone marrow stromal cell transplantation: the first clinical trial case report. 50

CONCLUSION
Clearing the cervical spine is a vital part of the treatment of trauma patients and if undetected an injury to the cervical spine can result in paralysis and even death.Establishing a multidisciplinary team provides standards for cervical spine immobilization, assessment, and clearance.Implementation of such guidelines will decrease time for cervical spine clearance, and ongoing analysis of sensitivity is encouraging.Team members consisted of pediatric surgeons, orthopedic surgeons, neurosurgeons, emergency room physicians, and trauma nurse practitioners.Cervical spine injuries in children are uncommon, but present many potential pitfalls in management.