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The modified odontoid view: An alternative visualization of the atlantoaxial joint
The Journal
ofEmergency Medione,
Vol.
1,pp.321-325,
1984
Pnnted in the USA
Copyright 0 1984 Pergamon Press Ltd
??
THE MODIFIED ODONTOID VIEW: AN ALTERNATIVE VISUALIZATION OF THE ATLANTOAXIAL JOINT John E. Turns,
MD,*
*Department
Mark A. Shaffer, of Emergency
MD,**
and Peter E. Doris
MD***
Medicine, University of Chicago, IL;
* *Hinsdale Hospital; Department of Emergency Medicine, University of Chicago, IL; and * **Departments of Radiology, University of Chicago, IL; and St. James Hospital Chicago Heights, IL Reprint address: John E. Turns, MD, Department of Emergency Medicine, University of Chicago Affiliated Hospitals and Clinics, 950 East 59th Street, Chicago, IL 60637
0 Abstract-The sensitivity of the cross table lateral view (CTLV) alone, as a determinant in the radiographic disposition ln patients with cervical spine fracture/dislocation has been challenged. A cervical spine trauma series that includes the CTLV, the anteroposterior view (APV), and the open-mouth view (OMV) has been suggested. Whereas the CTLV and APV present no difficulty, the OMV is often not possible in the uncooperative or unconscious patient, or in those patients with rigid forms of neck support. The modified odontoid view (MOV) can replace the OMV in these patients. The MOV allows for satisfactory visualization of the Cl/C2 complex and is easily obtained as a portable technique. In addition, it requires neither patient cooperation nor neck movement. The technique is described and its interpretation reviewed. •! Keywords-cross table lateral view; open mouth odontoid view; modified odontoid view
Introduction At the present time, little consensus exists regarding the radiographic approach to the patient with possible cervical spine injury. Some authors recommend that several views of the cervical spine be obtained before the
RECEIVED: 13
patient is moved from the stretcher.‘-“ Others maintain the cross table lateral view is sufficient to determine radiographic disposition of patients in most situations.5-8 Many emergency physicians rely exclusively on the CTLV for making diagnostic and therapeutic decisions that may require subsequent head and neck mobilization. Recent literature suggests that the CTLV is falsely negative or difficult to interpret in up to 25% of the cases reviewed.q Thus, to permit head and neck motion following a single, normal cross table lateral view increases the risk for morbidity for a significant number of patients. Authors now suggest that a trauma series, consisting of CTLV, APV, and OMV, be performed in all cases of suspected cervical spine injury. 2,q,10This trauma series, obtained in entirety during head and neck immobilization, will increase the diagnostic yield of detecting significant occult fracture/ dislocations.q Whereas the CTLV and APV can be performed with ease in all patients without head or neck movement, the final trauma series view, the OMV, requires patient cooperation to hold the mouth open. Many individuals evaluated following trauma are unconscious or uncooperative and thus un-
April 1983; ACCEPTED:6 October 1983 321
0736-4679/84 $3.00 + .OO
322
J. E. Turns, M. A. Shaffer, and P. E. Doris
Figure 1. Technical factors for this view on a standard, single-phase portable unit are 80 kV (peak) at 100 mAs, using a grid or Bucky technique.
able or unwilling to cooperate for the openmouth technique. Furthermore, those patients with rigid forms of neck support (four poster or Philadelphia collars) are physically incapable of holding their mouths open. For this group of patients, the modified odontoid view can replace the OMV in the cervical spine trauma series.
Technique and Interpretation The original axial supine odontoid view, described in traditional textbooks of radiographic positioning, requires neck extension to visualize the Cl/C2 complex.” The modified odontoid view can easily be performed without head and neck movement. With the patient in the supine position and the head and neck in a neutral position, the cassette is placed under the base of the patient’s skull. Using a small localizing cone, the central ray is angled 30 degrees cephalad, centering on the midline, and directed 4 cm (1.5 in.) below the symphysis menti.
In this position the central ray should enter the neck under the patient’s chin, pass through the dens, exit through the foramen magnum, and strike the center of the cassette. The angIe of 30 degrees cephalad permits visualization of the Cl/C2 complex without head or neck movement or overshadowing of the mandibular bony densities. Figure 1 demonstrates the proper positioning for the modified odontoid view. The modified odontoid view can be interpreted in a fashion similar to the traditional open-mouth view (see Figure 2). For example, in both views the classical compression fracture described by Jefferson, usually following a direct blow to the vertex of the head, demonstrates the characteristic lateral displacement of one or both lateral masses of Cl with respect to the dens or the body of C2. In the MOV, symmetry around the dens is measured from the medial or lateral edge of each lateral mass of Cl to the midline of the odontoid. The lateral edge of each lateral mass should also align with the lateral edge of the body of C2. If
323
Modified Odontoid View
(4 MANDIBLE
BODY
\
BODY ODONTOID POSTERIOR
ARCH ci CCIPITAL BONE
@I
Figure 2. (a) A representative YOV radiograph obtained on a volunteer in a four-poster support and (b) an accompanying medical illustration with approprlate anatomy Identified.
the body of C2 is obscured in this view, lateral mass alignment can be compared with the vertebral body of C3, usually wellvisualized. Neural arch fractures of Cl, commonly following marked hyperextension, are seen
as unilateral or bilateral clefts in the ring of atlas. This is more frequently seen in the posterior arch and only rarely in the anterior arch. Similarly, a fracture through either transverse process of C 1, may be clearly seen on the OMV. The odontoid process is
324
well-visualized in this view. Horizontal and vertical fractures of the odontoid and fractures through the base of the dens are clearly demonstrated. It has the added advantage of dens visualization without overlapping of the upper incisors, commonly seen in the routine OMVs. Total dislocation of the atlantooccipital articulation reveals a gross distortion of the relationship between the posterior arch of Cl and the posterior rim of the foramen magnum.
Discussion The emergency medicine physician faces an increasing number of patients with suspected head and neck traumas. A rise in the number of cervical spine injuries parallels increasing reliance on the automobile for rapid, high-speed transportation.12*13 In addition, new recreational interests such as diving, tobogganing, skateboarding, and gymnastics have contributed significantly to this number.14’1S Emergency departments face an increasing number of suspected head and neck traumas. Characteristically, these patients are young and otherwise healthy. In a recent review of patients with cervical spine fractures/dislocations it was found that 80% of these patients have no neurological deficit; 20% of these patients failed to complain of specific neck symptoms at the time of initial evaluation.16 Errors in patient management in cases of cervical fracture/dislocation can result in truly tragic consequences. The potential for physical, economic, and emotional devastation is perhaps without parallel in medicine. A review of the literature regarding the radiographic approach to suspected cervical injury yields few absolutes. That movement is deleterious to a patient suspect of cervical injury is, however, widely recognized.” Current practice often permits movement of the head and neck following a single, unremarkable CTLV. The reliability of this single view to predict cervical
J. E. Turns, M. A. Shaffer, and P. E. Doris
fracture/dislocation has been seriously questioned. A trauma series (CTLV, APV, OMV) performed with complete head and neck immobilization can increase diagnostic yield for significant pathology at a minimal risk to the patient. Because the open-mouth view is not possible in all patients, the modified odontoid view allows an alternative visualization of the Cl/C2 complex. The radiographic technique is simple, quick, and can easily be described to a technician previously unfamiliar with the view. The head and neck can be maintained in rigid support. Interpretation of the MOV requires the basic understanding of the occipito-atlantoaxial articulations. The fundamental principles used to evaluate cortical integrity and symmetry around the dens in the traditional open-mouth view facilitate interpretation of the MOV. Once the emergency physician determines the need for cervical spine radiography, it is recommended that a CTLV, APV, and OMV be obtained (in that order) under complete head and neck immobilization. The MOV can replace the OMV when applicable. If the trauma series is unremarkable for fracture/dislocation, immobilization can be removed and further diagnostic and therapeutic modalities pursued. When possible, all cervical spine series should be completed to include both oblique views and flexion extension views when indicated.
Summary The modified odontoid view is an excellent alternative to the open-mouth technique as the third view in a cervical spine trauma series. It is easily performed as a portable technique, and does not require patient cooperation. This view allows for the alternative visualization of the Cl/C2 complex with clarity. It is used as an adjunct to the CTLV and APV for the diagnostic and therapeutic disposition of trauma patients requiring cervical spine radiography.
Modified Odontoid View
1. Abel MS: Occult TraumaticLesions of the Cervical Vertebrae. St. Louis, MO, Warren H. Green Inc, 1971, pp 3-22, 44-83. 2. Charlton OP, Gehweeker JA Jr, Martinez S: Roentgenographic evaluation of cervical spine trauma. JAMA 1979; 242:1073-1075. 3. McCall IW, Park WM, McSweeney T: The radiological demonstration of acute lower cervical injury. Clin Radio1 1973; 24:235-240. 4. Fielding JW, Hawkins RJ: Roentgenographic diagnosis of the injured neck, in American Academy of OrthopedicSurgeons: InstructionalCourse Lectures. St Louis, MO, CV Mosby Co, 1975, vol 25, pp 149-170. 5. Dolan DK: Cervical spine injuries below the axis. Radio1 Ciin North Am 1977; 15:247-259. 6. Babcock JL: Cervical spine injuries: Diagnosis and classification. Arch Surg 1976; 3646-651. 7. Harris JH Jr. Harris WH: The Radiolonv of Emergency Medicine. Baltimore, Williams &-Wiikins Co, 1975, pp 60-77. 8. Ayella RA: Radiologic Management of the Massively TraumatizedPatient. Baltimore, Williams Jr Wilkins Co, 1978, pp 51-72. 9. Shaffer MA, Doris PE: Limitation of the cross table lateral view in detecting cervical spine injuries: A retrospective analysis. Ann Emerg Med 1981; 10:508-513. 10. Wales LR, Knopp RK, Morishima MS: Recom-
325
mendations for evaluation of the acutely injured cervical spine: A Clinical radiographic algorithm. Ann Emerg Med 1980; 8:422-428. 11. McInnes J: Clarke’s Positioning in Radiology. Chicago, Yearbook Medical Publishers, 1973, vol 1, p 178. 12. Karwacki JJ, Baker SP: Children in motor vehicles: Never too young to die. JAMA 1979; 242: 2848-285 1. 13. Hall MM: Road traffic accidents. Practitioner 1979; 222:754-764. 14. Herkowitz HN, Samberg LC: Vertebral column injuries associated with tobogganing. J Trauma 1978; 18:806-810. 15. Bouzarth WF: Spinal injuries: Principles and practices in emergency medicine, in Harris JH, Harris WH (eds): The Radiology of Emergency Medicine. Baltimore, WiJliams & Wilkins Co, 1975, pp 60-67. 16. Walter J, Shaffer MA, Doris PE: Unreliability of clinical criterion in predicting cervical spine injuries. Presented at University Association for Emergency Medicine Scientific Assembly, Salt Lake City Utah, April 1982. 17. Black P: Injuries of the spinal cord: Management in the acute phase, in Zuidema GD, Rutherford RB, Ballinger WF (eds): The Management of Trauma, ed 3. Philadelphia, WB Saunders 1979, pp 226-253.
ofEmergency Medione,
Vol.
1,pp.321-325,
1984
Pnnted in the USA
Copyright 0 1984 Pergamon Press Ltd
??
THE MODIFIED ODONTOID VIEW: AN ALTERNATIVE VISUALIZATION OF THE ATLANTOAXIAL JOINT John E. Turns,
MD,*
*Department
Mark A. Shaffer, of Emergency
MD,**
and Peter E. Doris
MD***
Medicine, University of Chicago, IL;
* *Hinsdale Hospital; Department of Emergency Medicine, University of Chicago, IL; and * **Departments of Radiology, University of Chicago, IL; and St. James Hospital Chicago Heights, IL Reprint address: John E. Turns, MD, Department of Emergency Medicine, University of Chicago Affiliated Hospitals and Clinics, 950 East 59th Street, Chicago, IL 60637
0 Abstract-The sensitivity of the cross table lateral view (CTLV) alone, as a determinant in the radiographic disposition ln patients with cervical spine fracture/dislocation has been challenged. A cervical spine trauma series that includes the CTLV, the anteroposterior view (APV), and the open-mouth view (OMV) has been suggested. Whereas the CTLV and APV present no difficulty, the OMV is often not possible in the uncooperative or unconscious patient, or in those patients with rigid forms of neck support. The modified odontoid view (MOV) can replace the OMV in these patients. The MOV allows for satisfactory visualization of the Cl/C2 complex and is easily obtained as a portable technique. In addition, it requires neither patient cooperation nor neck movement. The technique is described and its interpretation reviewed. •! Keywords-cross table lateral view; open mouth odontoid view; modified odontoid view
Introduction At the present time, little consensus exists regarding the radiographic approach to the patient with possible cervical spine injury. Some authors recommend that several views of the cervical spine be obtained before the
RECEIVED: 13
patient is moved from the stretcher.‘-“ Others maintain the cross table lateral view is sufficient to determine radiographic disposition of patients in most situations.5-8 Many emergency physicians rely exclusively on the CTLV for making diagnostic and therapeutic decisions that may require subsequent head and neck mobilization. Recent literature suggests that the CTLV is falsely negative or difficult to interpret in up to 25% of the cases reviewed.q Thus, to permit head and neck motion following a single, normal cross table lateral view increases the risk for morbidity for a significant number of patients. Authors now suggest that a trauma series, consisting of CTLV, APV, and OMV, be performed in all cases of suspected cervical spine injury. 2,q,10This trauma series, obtained in entirety during head and neck immobilization, will increase the diagnostic yield of detecting significant occult fracture/ dislocations.q Whereas the CTLV and APV can be performed with ease in all patients without head or neck movement, the final trauma series view, the OMV, requires patient cooperation to hold the mouth open. Many individuals evaluated following trauma are unconscious or uncooperative and thus un-
April 1983; ACCEPTED:6 October 1983 321
0736-4679/84 $3.00 + .OO
322
J. E. Turns, M. A. Shaffer, and P. E. Doris
Figure 1. Technical factors for this view on a standard, single-phase portable unit are 80 kV (peak) at 100 mAs, using a grid or Bucky technique.
able or unwilling to cooperate for the openmouth technique. Furthermore, those patients with rigid forms of neck support (four poster or Philadelphia collars) are physically incapable of holding their mouths open. For this group of patients, the modified odontoid view can replace the OMV in the cervical spine trauma series.
Technique and Interpretation The original axial supine odontoid view, described in traditional textbooks of radiographic positioning, requires neck extension to visualize the Cl/C2 complex.” The modified odontoid view can easily be performed without head and neck movement. With the patient in the supine position and the head and neck in a neutral position, the cassette is placed under the base of the patient’s skull. Using a small localizing cone, the central ray is angled 30 degrees cephalad, centering on the midline, and directed 4 cm (1.5 in.) below the symphysis menti.
In this position the central ray should enter the neck under the patient’s chin, pass through the dens, exit through the foramen magnum, and strike the center of the cassette. The angIe of 30 degrees cephalad permits visualization of the Cl/C2 complex without head or neck movement or overshadowing of the mandibular bony densities. Figure 1 demonstrates the proper positioning for the modified odontoid view. The modified odontoid view can be interpreted in a fashion similar to the traditional open-mouth view (see Figure 2). For example, in both views the classical compression fracture described by Jefferson, usually following a direct blow to the vertex of the head, demonstrates the characteristic lateral displacement of one or both lateral masses of Cl with respect to the dens or the body of C2. In the MOV, symmetry around the dens is measured from the medial or lateral edge of each lateral mass of Cl to the midline of the odontoid. The lateral edge of each lateral mass should also align with the lateral edge of the body of C2. If
323
Modified Odontoid View
(4 MANDIBLE
BODY
\
BODY ODONTOID POSTERIOR
ARCH ci CCIPITAL BONE
@I
Figure 2. (a) A representative YOV radiograph obtained on a volunteer in a four-poster support and (b) an accompanying medical illustration with approprlate anatomy Identified.
the body of C2 is obscured in this view, lateral mass alignment can be compared with the vertebral body of C3, usually wellvisualized. Neural arch fractures of Cl, commonly following marked hyperextension, are seen
as unilateral or bilateral clefts in the ring of atlas. This is more frequently seen in the posterior arch and only rarely in the anterior arch. Similarly, a fracture through either transverse process of C 1, may be clearly seen on the OMV. The odontoid process is
324
well-visualized in this view. Horizontal and vertical fractures of the odontoid and fractures through the base of the dens are clearly demonstrated. It has the added advantage of dens visualization without overlapping of the upper incisors, commonly seen in the routine OMVs. Total dislocation of the atlantooccipital articulation reveals a gross distortion of the relationship between the posterior arch of Cl and the posterior rim of the foramen magnum.
Discussion The emergency medicine physician faces an increasing number of patients with suspected head and neck traumas. A rise in the number of cervical spine injuries parallels increasing reliance on the automobile for rapid, high-speed transportation.12*13 In addition, new recreational interests such as diving, tobogganing, skateboarding, and gymnastics have contributed significantly to this number.14’1S Emergency departments face an increasing number of suspected head and neck traumas. Characteristically, these patients are young and otherwise healthy. In a recent review of patients with cervical spine fractures/dislocations it was found that 80% of these patients have no neurological deficit; 20% of these patients failed to complain of specific neck symptoms at the time of initial evaluation.16 Errors in patient management in cases of cervical fracture/dislocation can result in truly tragic consequences. The potential for physical, economic, and emotional devastation is perhaps without parallel in medicine. A review of the literature regarding the radiographic approach to suspected cervical injury yields few absolutes. That movement is deleterious to a patient suspect of cervical injury is, however, widely recognized.” Current practice often permits movement of the head and neck following a single, unremarkable CTLV. The reliability of this single view to predict cervical
J. E. Turns, M. A. Shaffer, and P. E. Doris
fracture/dislocation has been seriously questioned. A trauma series (CTLV, APV, OMV) performed with complete head and neck immobilization can increase diagnostic yield for significant pathology at a minimal risk to the patient. Because the open-mouth view is not possible in all patients, the modified odontoid view allows an alternative visualization of the Cl/C2 complex. The radiographic technique is simple, quick, and can easily be described to a technician previously unfamiliar with the view. The head and neck can be maintained in rigid support. Interpretation of the MOV requires the basic understanding of the occipito-atlantoaxial articulations. The fundamental principles used to evaluate cortical integrity and symmetry around the dens in the traditional open-mouth view facilitate interpretation of the MOV. Once the emergency physician determines the need for cervical spine radiography, it is recommended that a CTLV, APV, and OMV be obtained (in that order) under complete head and neck immobilization. The MOV can replace the OMV when applicable. If the trauma series is unremarkable for fracture/dislocation, immobilization can be removed and further diagnostic and therapeutic modalities pursued. When possible, all cervical spine series should be completed to include both oblique views and flexion extension views when indicated.
Summary The modified odontoid view is an excellent alternative to the open-mouth technique as the third view in a cervical spine trauma series. It is easily performed as a portable technique, and does not require patient cooperation. This view allows for the alternative visualization of the Cl/C2 complex with clarity. It is used as an adjunct to the CTLV and APV for the diagnostic and therapeutic disposition of trauma patients requiring cervical spine radiography.
Modified Odontoid View
1. Abel MS: Occult TraumaticLesions of the Cervical Vertebrae. St. Louis, MO, Warren H. Green Inc, 1971, pp 3-22, 44-83. 2. Charlton OP, Gehweeker JA Jr, Martinez S: Roentgenographic evaluation of cervical spine trauma. JAMA 1979; 242:1073-1075. 3. McCall IW, Park WM, McSweeney T: The radiological demonstration of acute lower cervical injury. Clin Radio1 1973; 24:235-240. 4. Fielding JW, Hawkins RJ: Roentgenographic diagnosis of the injured neck, in American Academy of OrthopedicSurgeons: InstructionalCourse Lectures. St Louis, MO, CV Mosby Co, 1975, vol 25, pp 149-170. 5. Dolan DK: Cervical spine injuries below the axis. Radio1 Ciin North Am 1977; 15:247-259. 6. Babcock JL: Cervical spine injuries: Diagnosis and classification. Arch Surg 1976; 3646-651. 7. Harris JH Jr. Harris WH: The Radiolonv of Emergency Medicine. Baltimore, Williams &-Wiikins Co, 1975, pp 60-77. 8. Ayella RA: Radiologic Management of the Massively TraumatizedPatient. Baltimore, Williams Jr Wilkins Co, 1978, pp 51-72. 9. Shaffer MA, Doris PE: Limitation of the cross table lateral view in detecting cervical spine injuries: A retrospective analysis. Ann Emerg Med 1981; 10:508-513. 10. Wales LR, Knopp RK, Morishima MS: Recom-
325
mendations for evaluation of the acutely injured cervical spine: A Clinical radiographic algorithm. Ann Emerg Med 1980; 8:422-428. 11. McInnes J: Clarke’s Positioning in Radiology. Chicago, Yearbook Medical Publishers, 1973, vol 1, p 178. 12. Karwacki JJ, Baker SP: Children in motor vehicles: Never too young to die. JAMA 1979; 242: 2848-285 1. 13. Hall MM: Road traffic accidents. Practitioner 1979; 222:754-764. 14. Herkowitz HN, Samberg LC: Vertebral column injuries associated with tobogganing. J Trauma 1978; 18:806-810. 15. Bouzarth WF: Spinal injuries: Principles and practices in emergency medicine, in Harris JH, Harris WH (eds): The Radiology of Emergency Medicine. Baltimore, WiJliams & Wilkins Co, 1975, pp 60-67. 16. Walter J, Shaffer MA, Doris PE: Unreliability of clinical criterion in predicting cervical spine injuries. Presented at University Association for Emergency Medicine Scientific Assembly, Salt Lake City Utah, April 1982. 17. Black P: Injuries of the spinal cord: Management in the acute phase, in Zuidema GD, Rutherford RB, Ballinger WF (eds): The Management of Trauma, ed 3. Philadelphia, WB Saunders 1979, pp 226-253.