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 Table of Contents  
SYMPOSIUM: CERVICAL SPINE TRAUMA
Year : 2022  |  Volume : 5  |  Issue : 1  |  Page : 10-23

Approach to upper cervical trauma


Department of Neurosurgery & Spine, Fortis Hospital Anandapur, Kolkata, West Bengal, India

Date of Submission12-Apr-2021
Date of Decision05-Jun-2021
Date of Acceptance21-Jun-2021
Date of Web Publication02-Feb-2022

Correspondence Address:
Gomatam R Vijay Kumar
Department of Neurosurgery & Spine, Fortis Hospital Anandapur, 1701 Tritiya, Upohar Luxury Complex, 2052 Chakgaria, Kolkata 700094, West Bengal.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ISJ.ISJ_31_21

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  Abstract 

Upper cervical spine injuries are relatively common and are often the result of blunt trauma. These injuries can be neurologically devastating and can have a high mortality. Management of these injuries requires an in-depth understanding of the complex anatomy of this region, delineation of the injury morphology, and classification after appropriate imaging. The treatment, surgical or conservative, is based on the neurological injury and structural instability.Bony injuries of the upper cervical spine, such as the occipital condylar fractures, fractures of the atlas, majority of odontoid fractures, and traumatic spondylolisthesis of the axis, respond well to nonsurgical management by external immobilization. In contrast, ligamentous injuries of the atlanto-occipital joints or the transverse atlantal ligament (TAL) have a poorer prognosis for healing and often require surgical intervention.

Keywords: Atlanto-axial, cranio-vertebral junction, cranio-cervical junction, fracture, occipito-atlantal, occipito-cervical, trauma, upper cervical spine


How to cite this article:
Vijay Kumar GR. Approach to upper cervical trauma. Indian Spine J 2022;5:10-23

How to cite this URL:
Vijay Kumar GR. Approach to upper cervical trauma. Indian Spine J [serial online] 2022 [cited 2022 May 25];5:10-23. Available from: https://www.isjonline.com/text.asp?2022/5/1/10/337141




  Introduction and Epidemiology Top


The upper cervical spine or the cranio-vertebral junction (CVJ) comprises the first two cervical vertebrae and the basiocciput, including the articulations of the occiput with the atlas and the atlas with the axis. The anatomy, embryology, and biomechanics of this region of the spine are different from the rest of the spinal column. Each vertebra of the upper cervical spine is unique and has a complex bony and ligamentous stabilizing anatomy. Injury to the upper cervical spine is usually the result of significant force applied to the head in a blunt trauma mechanism. Cervical spine injury is reported in 2.4% of victims of blunt trauma.[1],[2] The incidence rate of spine and spinal cord injuries as 64 per 100,000 population was identified in one of the few population-based demographic studies on the spinal column and spinal cord injury in the database.[3] This study looked at the Manitoba Health Services Insurance Plan Database during the years 1981–84. They identified two incidence peaks in young males and in elderly females. The incidence of upper cervical spine injuries was roughly half to one-third of the total cervical spine injuries in this study. Enhanced safety care features in automobiles and availability of better emergency care have contributed to reducing the morbidity and mortality from cervical injuries.[4] Kumar et al. performed a systematic review of all published studies between the years 2000 and 2016 to assess the global incidence of traumatic spinal injury and derived a worldwide rate of 10.5 cases per 100,000 population. They suggested that the rate was higher (13.7 per 100,000) in low- and middle-income countries compared with high-income countries (8.7 per 100,000).[5] In a population-based study from Taiwan, Yang et al. reported a much higher incidence of hospitalized acute spinal trauma of 61.6 cases per 100,000, which is closer to the Manitoba study.[6] In the same study, Yang et al. reported that 28.3% of patients admitted for spinal injury had a neurological deficit, giving a rate of 17.4 per 100,000 incidence of spinal cord injury. Patients older than 65 years of age, male sex, and white ethnicity were reported by Lowery et al. to have a higher risk of cervical spine injury after blunt trauma.[2] Young et al. report a cervical spine injury rate of 6.2%. However, this incidence is observed in patients reporting to specified trauma centers in the United States and is not a population-based estimate.[7]

Injuries to the upper cervical spine are easy to miss.[8],[9] The complex regional anatomy, the presence of overlying structures, and the quality of imaging in the emergency setting can lead to misinterpretation. Improper treatment due to delayed recognition of these injuries can have a serious impact on the outcome and can be a cause for litigation.[10],[11] The goals of treatment of these injuries are to protect the neural elements, reduce and align the bony structures, and ideally maintain segmental motion.


  Anatomy Top


Each level of the upper cervical spine is anatomically and biomechanically unique, unlike the subaxial spine. The CVJ is the level of transition from the cranium to the cervical spine. The brainstem and the upper cervical spinal cord, the spinal accessory nerve, and the vertebral arteries pass through the CVJ. The CVJ allows the weight of the head to be supported on the cervical spine, while allowing complex motion. The bony anatomy of the joints in the CVJ permits the range of motion, with stability being provided largely by the intrinsic and extrinsic ligaments, including the capsular ligaments. The muscles of the CVJ initiate and maintain the movement of the CVJ, but they do not limit the joint movements.[12]

The basi-occiput has a pair of bean-shaped occipital condyles, located just lateral to the foramen magnum, slightly anterior to the equator of the foramen. The atlas has paired lateral masses that are held together by a short anterior arch and a longer posterior arch. In the middle of the anterior arch is the anterior tubercle ventrally, which serves as the attachment for the anterior longitudinal ligament and the longus colli muscles. In the middle of the posterior arch is the posterior tubercle dorsally, which serves to attach the ligamentum nuchae. The superior aspect of the lateral mass is gently concave to accommodate the occipital condyles. The inferior aspect is flat, with a downward and lateral inclination, to articulate with the superior facet of the axis. The transverse process of the atlas lies laterally to the lateral mass and is perforated by the foramen transversarium, through which passes the vertebral artery cranially, to circle around the dorsal half of the lateral mass and creating a groove on the superior aspect of the posterior arch before going intracranial. The odontoid process extends cranially from the body of the axis and represents the vertebral body of the atlas. It articulates with the dorsal anterior arch of the atlas through a synovial joint. The axis has large facets, with the superior aspect articulating with the inferior aspect of the lateral mass of the atlas. The laminae join together at the spinous process of the axis, which is large and usually bifid.

The ligaments of the CVJ can be classified as extrinsic and intrinsic. The extrinsic ligaments include the ligamentum nuchae, which extends from the external occipital protuberance to the posterior tubercle of the atlas, the spinous process of the axis, and the subaxial cervical spine. The anterior longitudinal ligament is replaced by a fibroelastic membrane called the anterior atlanto-occipital membrane. The ligamentum flavum is replaced by a fibroelastic band called the posterior atlanto-occipital and the atlanto-axial ligament. The atlanto-occipital and atlanto-axial joint capsules are also classed in the extrinsic ligaments. The intrinsic ligaments are situated within the spinal canal and are responsible for the bulk of the ligamentous stability. They are located anterior to the dura in three layers. From dorsal to ventral, they are the tectorial membrane, the cruciate ligament, and the ligaments of the odontoid. The tectorial membrane extends from behind the body of the axis to the anterior rim of the foramen magnum [Figure 1]. It is the fibroelastic membranous continuation of the posterior longitudinal ligament. The cruciate ligament lies ventrally to the tectorial membrane, immediately behind the dens, and has two components: a transverse band behind the odontoid, which attaches to a bony tubercle on the medial aspect of the lateral mass of atlas on either side. This ligament is probably the strongest ligament in the body and is called the TAL [Figure 2]. It is covered with articular cartilage ventrally to allow articulation with the dens. It is responsible for keeping the dens in contact with the anterior arch of the atlas. Vertical extensions from the TAL attach superiorly to the foramen magnum and inferiorly to the body of the axis, forming the cruciate ligament. Further ventrally are the odontoid ligaments: apical and alar. The paired alar ligaments are strong bands, about 5–6 mm in diameter, which attach the dens to the occipital condyles on either side. The apical ligament attaches the tips of the odontoid to the foramen magnum.
Figure 1: Diagram depicting a sagittal view of the bones and ligaments of the CVJ

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Figure 2: Diagram depicting the ligaments of the odontoid on a coronal view

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The ligaments are the major stabilizers of the CVJ. The average range of motion of the joints in the upper cervical spine is described in [Table 1]. Flexion is restricted by the bony anatomy, whereas extension is limited by the tectorial membrane. Lateral flexion and rotation are restricted by the contralateral alar ligaments. Distraction more than 2 mm is resisted by the tectorial membrane and the alar ligaments. Translation of more than 1 mm is resisted by the capsular ligaments of the facet joints and the intact TAL.
Table 1: Range of motion of the joints in the upper cervical spine

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  Types of Injury Top


The types of upper cervical injury and their clinical/morphological classification have been discussed in detail in another review article in this symposium and are not repeated here.


  Evaluation Top


Although any traumatic event can result in a cervical spinal injury, it is most often the result of motor vehicle accidents, falls, and sporting injuries. There may also exist a predisposition in the form of congenital anomalies, degenerative conditions, and arthritis. Often, there may be an association between head trauma and an altered level of consciousness, complicating the evaluation due to difficult history taking and examination. Thus, all patients with significant polytrauma, head injury, or a history suggestive of significant blunt trauma force should be assumed to have a cervical spinal injury and evaluated accordingly. Older individuals are more likely to have an odontoid fracture or an axis body fracture compared with younger patients who are more likely to sustain a traumatic spondylolisthesis or a hyperextension teardrop fracture.[13] Children, particularly those younger than nine years of age, have anatomical and biomechanical differences compared with adults. The pediatric spine is much more elastic because of more shallow and horizontally orientated facet joints, stretchable ligaments and joint capsules, absent uncinate processes, and weaker neck muscles. Children younger than nine years of age are more likely to sustain upper cervical injuries, have a higher incidence of ligamentous injury with pseudosubluxation, and have spinal cord injury without radiographic abnormality. This is postulated to be due to the relatively large head in an infant or child compared with the body, leading to an upward shift of the cervical spine fulcrum of movement to C2/3.[14] The presence of atlantoaxial instability due to congenital anomalies of the cervical spine, particularly those affecting the odontoid, can increase the risk of neurological injury after blunt trauma. The true incidence of these anomalies is unknown; however, children with Down’s syndrome, Morquio’s syndrome, Klippel-Feil syndrome, or any other evident congenital anomaly should be considered to be at a higher risk for cervical spine and neurological injury.[15]

History should be obtained, if possible from the patient, if not from any witness or the first attender. Salient points in the history should include the mechanism of injury, presence or absence of restraints, loss of consciousness, transient motor or sensory deficits, and presence of neck pain or headache.

Initial management of all patients with trauma should be as per the Advanced Trauma Life Support protocol of Airway, Breathing and Circulation, with care being taken to maintain inline immobilization of the cervical spine. A thorough physical examination, including examination of the entire spine while maintaining head and neck stabilization in neutral alignment, should follow. The spinal column should be inspected for bruising, and it should be palpated for tenderness or deformity. A full neurological examination should be performed, including the cranial nerves and the perineum, for any sensory or motor deficit indicating a spinal cord injury.

Radiological evaluation with its implicit cost and radiation exposure must be weighed against the potential serious consequences of missed injuries. One approach to rationalize the use of imaging is to follow clinical algorithms to identify patients having a low probability of cervical spine injury and reserve imaging for the remainder. The two most widely used clinical algorithms are the Nexus Criteria[16],[17] [Table 2] and the Canadian C-spine rule[18] [Table 3]. Both these clinical algorithms have been validated in several large clinical studies to have a good sensitivity of 90%–100%. The Canadian C-spine rule has a slightly higher sensitivity on direct comparison to the Nexus criteria, but this has to be weighed against a more complicated application.[19]
Table 2: Nexus criteria for low risk

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Table 3: Canadian C-spine rule

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  Diagnostic Imaging Top


Conventional radiography

Conventional radiography has been the workhorse for cervical spine screening for a number of years. However, recent studies have flagged up its low sensitivity for picking up injuries, especially in the junctional regions.[20],[21] The increasing application of clinical algorithms has also made conventional radiography less relevant. A single cross-table lateral cervical spine radiograph is still considered an acceptable first-line screening tool, provided the whole cervical spine is clearly visualized.[22] Radiographs of the cervical spine in static flexion and extension have not been shown to add any value and may increase the risk of a neurological deficit.[22],[23],[24] An open-mouth odontoid view may be obtained to get an AP visualization of the upper cervical spine. This view will demonstrate the occipital condyles, the atlas lateral masses, and the odontoid process. There should be <2 mm of asymmetry of the lateral atlanto-dental interval (ADI), and the total lateral mass overhang should be less than 7 mm.[25] Radiographic studies of the pediatric spine present special challenges in interpretation. In a study by Cattell and Filtzer, pseudosubluxation at C2/3 and C3/4 was reported in 40% and 14% of patients.[26] The presence of synchondroses can also create confusion by mimicking fracture, especially at C2 dens/arch and in the subaxial vertebrae between the posterior and anterior elements. If the clinical picture is suggestive of the possibility of a significant injury, an MRI examination should be considered since 20% of pediatric cervical spine injuries are ligamentous and may not be excluded by a CT scan.[27],[28]

CT scan

Over the past decade, CT scan of the whole cervical spine has increasingly replaced conventional radiography as the primary screening test.[20],[21] CT scans are now available round the clock in most trauma centers. CT scans provide better visualization of the junctional areas such as the CVJ and cervicothoracic region and allow for sagittal, coronal, and 3D reconstructions. CT scans have high sensitivity and specificity for bony and disco-ligamentous injuries. When compared with MRI, the sensitivity for any cervical spine injury is 87.5% with an almost 100% sensitivity for an unstable lesion.[29] Unlike the MRI, which requires special equipment and is contraindicated in patients with pacemakers or severe claustrophobia, CT scanning can be performed in practically all patients. In addition, the short examination time makes it an ideal screening test in the often unstable, intubated, ventilated, and immobilized trauma patient.

MRI

The MRI can be a good option for cervical spine screening in patients in whom radiation exposure is a concern, such as children, adolescents, and pregnant women. It is valuable in certain specific clinical situations where ligamentous injuries are suspected and confirmation may change the clinical management, such as the presence of TAL injury in atlas or odontoid fractures or C2/3 disc injury in a hangman’s fracture. The other common indication is screening of patients with neurological deficit who do not have a significant injury on CT scan, the eponymous SCIWORET (spinal cord injury without radiological evidence of trauma).[29] The MRI can detect minor injuries such as bone bruises that are often not visible on CT scans. Although some studies in the past have shown a missed cervical spine injury rate of up to 5% for CT scans as opposed to MRI,[30] more recent studies and meta-analyses have not shown any added benefit of MRI over CT scans for cervical spinal injury detection.[31],[32]

Vascular imaging

The intimate anatomical proximity of the vertebral arteries makes them susceptible to injury in upper cervical trauma. Any surgical intervention at the atlanto-axial region is benefited by clear visualization of the vascular anatomy before screw placement.[22] Vascular imaging is also recommended when fractures involve the foramen transversarium of the atlas, in severe atlanto-axial dislocations, and where there is neurological deficit that is suggestive of cerebral or brainstem hypoperfusion. Both CT- and MR-angiography have similar diagnostic potential and can be chosen based on convenience.[33],[34]

Radiographic measurements

All the diagnostic imaging studies obtained should be thoroughly evaluated to visualize bony landmarks such as the basion, the opisthion, the odontoid, the occipital condyles, atlas arches with lateral masses, the axis with its facets, for any fractures, alterations in normal anatomy or alignment, and for changes in spatial relationships. A number of eponymously named measurement tools in the cranio-cervical junction are routinely mentioned in the radiographic assessment of the upper cervical spine. However, a number of these measurements were described for assessing instability in patients with cranial settling and rheumatoid arthritis and these are probably not of relevance to the acute assessment of patients with trauma and are not listed in this article.

Widening of the prevertebral soft tissue shadow may be indicative of an underlying trauma. Detecting a cranio-cervical dissociation is extremely important. Of the number of radiographic measurements described, the one that has shown the most sensitivity and specificity is the revised cranio-cervical interval (CCI) described by Pang et al.[35] This is measured as the distance between the occipital condyle and the superior surface of the lateral mass of the atlas in the sagittal plane [Figure 3]. Any value greater than 2.5 mm indicates instability. The Harris lines and their “rule of 12” comprise another sensitive indicator of occipito-atlantal instability.[36] The basion-dens interval (BDI or Wholey Line) as measured by a line drawn from the tip of the dens to the basion should be less than 12 mm. The basion-posterior axial line interval (BAI) is the distance between a line projected cranially from the dorsal body of the axis to the tip of the basion anteriorly. This measurement should also be ≤12 mm. The anterior ADI is the distance measured between the posterior cortex of the anterior arch of the atlas and the anterior surface of the odontoid [Figure 4]. The normal measurement is <3 mm in an adult and <5 mm in children. Any value more than 3–5 mm is indicative of a lesion of the TAL. The measurement of the distance between the posterior cortex of the odontoid and the anterior cortex of the posterior arch of atlas is called the posterior atlanto-dental interval (PADI). This represents the space available for the spinal cord at C1/C2 and should normally be ≥13 mm. A TAL rupture can also be identified by the “rule of Spence,” which describes measuring the lateral overlap of the lateral mass of the atlas over the facet joint of the axis on an open-mouth AP view or in a coronal CT image [Figure 5]. According to Spence, a value ≥7 mm was stated to be predictive of a TAL rupture.[37] A more recent study has questioned this absolute value and suggested that lower values of even 3.8 mm may be significant.[38] Retropharyngeal soft tissue swelling can be an indirect sign of upper cervical injury. A soft-tissue thickness >5 mm at C3 may denote underlying trauma. A recent study has shown this sign to have poor sensitivity, but very good specificity, especially at C6.[39]
Figure 3: Sketch demonstrating measurement of the revised cranio-cervical interval for assessing occipito-atlantal dislocation; any measurement >2.5 mm is significant

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Figure 4: Sketch showing measurement of the anterior atlanto-dental interval. A figure >3 mm in an adult is suggestive of transverse atlantal ligament failure

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Figure 5: Sketch showing measurement of the overhang of atlas lateral mass over axis on coronal view: “rule of Spence”

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  Treatment of Upper Cervical Spine Injuries Top


Conservative care

Conservative treatment is indicated in the patients who have upper cervical fractures without dislocation and in the absence of any other evidence of instability. Conservative care usually comprises ambulatory cervical immobilization in a cervical orthosis. The various cervical orthoses available range from the soft and the hard cervical collar (Philadelphia collar) to the more elaborate and restrictive devices such as the SOMI brace, Four-post brace, and the Halo brace. It is undeniable that the Halo brace is more effective than the hard collar at restricting motion in the upper cervical spine for flexion/extension, lateral bending, and rotation. However, there are a number of issues to consider before halo fixation. It is cumbersome, with often poor patient compliance and is prone to a number of minor and major complications such as pin-site infection, loosening, loss of reduction, cranial perforation, brain abscess, cerebrospinal fluid leakage, and dysphagia. Some studies have reported serious adverse effects in elderly patients managed with halo fixation, with high morbidity and mortality due to cardiopulmonary complications.[40] In a study by Tashjian et al., cardiac arrest and aspiration pneumonia were the leading causes of a mortality rate of 42%.[41] At the other age extreme, children with cervical spine fractures are often managed with halo fixation, either primarily or often in addition to surgical intervention. Children tolerate halo fixation well, and most studies report compliance to the completion of the treatment goal. The common complications are pin-site infections and loosening. Dural penetration, supraorbital nerve injury, and unsightly scarring are other reported complications.[42] Some authors have recommended custom rings with upto eight pins for fixation for younger children, especially those younger than three years of age.[43] Alternative methods of effective external immobilization have been studied in view of the serious compliance and complication issues with halo fixation. Some studies have suggested similar clinical efficacy for both the hard collar and the Halo vest immobilization.[44]

Conservative treatment maybe considered for the following upper cervical spine injuries:

  • Occipital condylar fractures: Anderson Montesano Types I and II


  • Atlas fractures: Gehweiler Types 1, 2, 3a, 4 (with some exceptions), 5


  • Odontoid fractures: Anderson D’Alonzo Types 1, 3, Grauer Subtype 2a


  • Hangman fracture: Effendi Levine Types I, II


  • Conservative treatment usually includes 6–12 weeks of ambulatory external immobilization, analgesic medication, and physiotherapy as needed.

    Surgical treatment options

    The different surgical treatment options that can be used for the management of these often complex injuries are described next.

    Occipito-cervical fixation/fusion

    This is a procedure in which the occiput is fixated to the cervical spine. Over the years, the technique has progressed from onlay of fibular or iliac crest graft, to wire and bent Steinman pin/contoured threaded rod fixation, to the current techniques of plate and screw fixation. The onlay grafts required prolonged external immobilization in a Halo or Minerva jacket for at least 12 weeks. The wire and rod/plate techniques also do not confer immediate rigid fixation. Also, the sublaminar and suboccipital wiring techniques risk dural and neural injury. The patient is positioned prone. A midline occipito-cervical incision is made to expose the occiput and as much of the upper cervical spine as needed. A plate is fixed on the occipital bone, just dorsal to the foramen magnum, with screws that are best placed in the midline suboccipital keel where the bone is the thickest, or in the paramedian where the bone is thicker than in the squamous part. It is useful to assess the thickness of the suboccipital bone in the preoperative CT scan. In the midline, the thickness can be as much as 12–14 mm in an adult. The paramedian bone thickness is about 6 mm. The position of the screws (usually three screws in a standard suboccipital plate) can be marked out after seating the suboccipital plate on the bone. Bicortical purchase can be obtained by drilling a pilot hole with a hand drill with a stop set to 8–12 mm for a midline screw. The holes are then tapped, and the screws are inserted over the plate to obtain a rigid fixation of the suboccipital plate. This plate is connected with rods to polyaxial screws that are placed in the cervical spine.[45],[46] The cervical screw options range from lateral mass screws at C1, C2 pedicle or pars screws or C1-C2 trans-articular screws. If further levels of fixation are needed, the construct can be extended down to lateral mass or pedicle screws placed in the subaxial cervical spine. The procedure will result in a significant loss of flexion/extension, lateral bending, and more than 50% loss of rotation of the cervical spine.[47] It is important to fix the spine in a neutral alignment, so that the patient’s eyes are able to look forward and slightly downward when upright.

    This procedure is indicated in all patients with an occipito-cervical instability, especially the Anderson/Montesano Type 3 [Figure 6] or the Horn grade II injuries. It would also be a reasonable option for patients with an unstable atlas ring fracture associated with comminuted or split fractures of the lateral mass, precluding screw fixation (Gehweiler types 3b and 4 combined) [Figure 7], [Figure 8].
    Figure 6: Sketches depicting the patterns of occipital condyle fractures as classified by Anderson and Montesano

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    Figure 7: Sketches depicting the Gehweiler classification of atlas fractures

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    Figure 8: A 28-year-old man involved in a motor vehicle accident: unrestrained passenger in a vehicle rollover. A: Lateral X-ray showing increased anterior ADI. B: Open-mouth cervical spine X-ray demonstrating “rule of Spence.” C: CT sagittal reconstruction showing bilateral atlanto-axial lateral subluxation and partial occipito-atlantal subluxation. D: Axial CT showing a Gehweiler Type 3b atlas fracture. E: Intraoperative photograph showing an occipito-cervical fixation. F: Postoperative lateral cervical X-ray showing an occipito-cervical fixation with C2 pedicle screw and C3 lateral mass screws

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    Atlanto-axial fixation/fusion

    In this procedure, the atlas and axis are fixed together. There are a variety of techniques that are described. The earlier descriptions of sublaminar wires/cables (Gallie, Brookes-Jenkins, Sonntag) have been supplanted by the more biomechanically robust screw fixation techniques. The C1/C2 transarticular screw fixation described by Grob and Magerl involves putting a cortical bone screw across the C1/C2 facet joint on either side.[48] This achieves a very rigid biomechanical fixation of the atlanto-axial complex. However, the procedure has a steep learning curve and a significant risk of injuring the vertebral artery. The Goel/Harms technique describes inserting a lateral mass screw at C1 and a pars or pedicle screw at C2 connected by rods on both sides[49],[50] [Figure 9]. In patients with unsuitable vertebral artery anatomy, the C2 pedicle screw can be replaced by a C2 translaminar screw with similar biomechanical results.[51] More recently, there are a number of descriptions of the C1/C2 transarticular fixation being done through minimally invasive techniques.[52] The procedure is indicated in patients with unstable or dislocated odontoid fractures (Anderson/D’Alonzo Type 2, Grauer Type 2c), old or non-united odontoid fractures, and unstable atlas ring fractures (Gehweiler type 3b).
    Figure 9: A 30-year-old man who fell off a tree. Severe neck pain with transient numbness from neck downward. A: Open-mouth AP and lateral cervical radiograph. B: CT sagittal reconstruction showing a type 2 (Grauer type 2c) odontoid fracture, with the fracture line angled antero-inferior to postero-superior. C: Postoperative lateral cervical spine and AP open-mouth X-ray showing a posterior Goel/Harms type C1 lateral mass, C2 pedicle screw fixation

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    Anterior odontoid screw fixation

    This technique preserves atlanto-axial motion and is applicable for certain odontoid fractures: a displaced Anderson/D’Alonzo type 2 (Grauer Type 2a or 2b) [Figure 10], [Figure 11]. Type 2 odontoid fractures have reported non-union rates of 26%–85%. Anatomical factors that contribute to poor healing of type 2 fractures include less volume of the trabecular bone, distraction of the fragment by the apical ligament, and poor periosteal blood supply due to the surrounding synovium.[53] Higher rates of non-union were associated with age >50 years, displacement >5 mm, posterior displacement of the fragment, angulation >11°, fracture comminution, and inability to achieve or maintain reduction of the fracture.[54],[55],[56] Anterior odontoid screw fixation is also an option for patients with an undisplaced type 2 fracture or some type 3 fractures who are not suitable for or compliant with external immobilization. Good fusion rates are obtained in young patients/good bone stock, recent injury, and absence of comminution. The procedure is a minimally invasive anterior cervical approach of accessing the C2/3 interspace and inserting a cancellous lag screw through the body of the axis, across the fracture line, and into the dens [Figure 12]. Careful patient selection is necessary for good results: patients with good bone quality, Grauer type 2a or type 2b fracture, anaesthetic fitness and suitable body habitus (the procedure is technically difficult in short necked or barrel-chested individuals). Non-union after anterior odontoid screw fixation is reported in about 9.7% of patients in a systematic review and meta-analysis by Lvov.[57] The rate of non-union is not reduced by inserting two screws instead of one.[57],[58] Other complications of an anterior odontoid screw fixation include dysphagia in 10%, hoarseness in 1.2%, wound hematoma in 0.2%, and a reoperation rate of 5%. The incidence of esophageal injury and spinal cord injury was very low.[59]
    Figure 10: Sketches depicting the Anderson and D’Alonzo classification of odontoid fractures

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    Figure 11: Sketches depicting the Grauer classification of type 2 odontoid fractures

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    Figure 12: A 63-year-old woman who had a fall at home in the bathroom two weeks earlier. Increasing neck pain. No neurological deficit. A: Lateral cervical spine X-ray showing a type 2 odontoid fracture with posterior displacement. B: Sagittal T2-weighted MRI showing the odontoid fracture, without any spinal cord compression. C: CT sagittal reconstruction demonstrating a transverse fracture line with posterior displacement of the dens. D: Postoperative lateral cervical spine X-ray showing an anterior odontoid screw fixation

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    Other procedures

    Hangman’s fractures are usually treated conservatively. However, the type 2a and the type 3 fractures usually warrant surgery and the options include C2/3 anterior cervical discectomy and fusion [Figure 13], C1-C3 posterior fixation, C2-C3 posterior arthrodesis, and C2 interfragmentary fixation across the fracture.
    Figure 13: A 44-year-old man who sustained a motorcycle accident. Was wearing a helmet. Severe neck pain, but no neurological deficit. A: Lateral cervical spine X-ray showing a type II Hangman’s fracture with C2/3 subluxation. B: CT sagittal reconstruction showing the bilateral C2 pars fracture with separation >3 mm. C: Sagittal T1 MR image demonstrating C2/3 disc disruption and retropulsion. D: Postoperative lateral cervical spine X-ray showing cage and plate fixation after a C2/3 anterior cervical discectomy showing marked reduction in displacement of the C2 pars fracture

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    A summary of the various injury types commonly seen in clinical practice is provided in [Table 4].
    Table 4: Summary of upper cervical injury types, epidemiology, treatment decision modifiers, management principles, and relevant studies

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      Conclusions Top


    Injury to the upper cervical spine occurs in about a third of the patients sustaining a cervical spine trauma. The consequences can be severe, with neurological disturbance and fatal outcome. Risk assessment is based on the history, mechanism of injury, and the neurological examination, aided by a clinical algorithm such as the Nexus criteria. Conventional radiography has been supplemented by CT scanning of the cervical spine, which has a very high sensitivity and specificity, for identifying these injuries. Accurate identification and classification of the bony and ligamentous injuries is critical for evaluating the presence of instability. Conservative management is done by external ambulatory immobilization in a cervical orthosis. Surgical management is needed for neural decompression and fixation of instability, especially ligamentous instability. Surgical stabilization in the upper cervical spine will usually lead to restriction of cervical spinal movement, especially rotation and flexion/extension, depending on the type of surgery. The often aberrant vascular anatomy should be evaluated prior to any surgical intervention.[80]

    Ethical policy and institutional review board statement

    Not applicable.

    Financial support and sponsorship

    Nil.

    Conflicts of interest

    There are no conflicts of interest.

    Declaration of patient consent

    The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.



     
      References Top

    1.
    Goldberg W, Mueller C, Panacek E, Tigges S, Hoffman JR, Mower WR; Nexus Group. Distribution and patterns of blunt traumatic cervical spine injury. Ann Emerg Med 2001;38:17-21.  Back to cited text no. 1
        
    2.
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        Figures

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        Tables

      [Table 1], [Table 2], [Table 3], [Table 4]



     

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