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Computed tomography in the initial evaluation of the cervical spine
ORIGINAL CONTRIBUTION cervical spine, computed tomography; computed tomography, cervical spine
Computed Tomography in the Initial Evaluation of the Cervical Spine Unstable injury of the cervical spine must be considered in all victims of blunt trauma. To evaluate the role of limited, directed computed tomography (CT) in the initial evaluation of the cervical spine, a one-year study involving 104 high-risk patients was undertaken. Sensitivity was O. 78 overall, but in the group of patients scanned after inadequate plain radiographs, CT had a sensitivity of 1.0 ,for unstable cervical injury All falsenegative studies involved atlantoaxial rotary subiuxation. We conclude that limited, directed CT of the cervical spine is appropriate in the initial evaluation of patients at risk, particularly if plain radiographs are inadequate, but is of limited value in the evaluation of ligamentous injury of the upper cervical spine. [Schleehauf K, Ross SE, Civil If), Schwab CW: Computed tomography in the initial evaluation of the cervical spine. Ann Emerg Med August 1989;18:815-817.] INTRODUCTION The early identification of unstable cervical spine injury remains essential in the management of blunt trauma patients. Difficulties in obtaining adequate, plain radiographs of the neck have made the use of other radiographic modalities mandatory. At the Southern New Jersey Regional Trauma Center, evaluation of the cervical spine includes limited, directed computed tomography (CT). This is used to anatomically delineate fractures suspected or identified on plain radiographs or to rule out cervical spine injury when plain radiographs are inadequate. To determine its effectiveness in suspected spinal injury, we undertook a one-year study of all patients undergoing CT of the cervical spine.
Karen Schleehauf, MD Steven E Ross, MD, FACS lan D Civil, MBChB C William Schwab, MD, FACS Camden, New Jersey From the Department of Surgery, UMDNJ/ Robert Wood Johnson Medical School -Camden/Cooper Hospital-University Medical Center, Camden, New Jersey. Received for publication May 20, 1987. Revisions received August 15, 1988, and February 20, 1989. Accepted for publication April 24, 1989. Presented at the University Association for Emergency Medicine Annual Meeting in Philadelphia, May 1987. Address for reprints: Steven E Ross, MD, Department of Surgery, 3 Cooper Plaza, Suite 411, Camden, New Jersey 08103.
MATERIALS A N D METHODS All patients admitted to the multiple trauma service suffering blunt, high-energy transfer injury who present with loss or alteration of consciousness, facial laceration or clinically apparent fracture above the clavicle, neurologic deficit suggestive of cervical spine injury, or neck pain or tenderness undergo radiographic evaluation of the cervical spine. Initial cervical spine radiographs include lateral-cervical, anteroposterior, and open-mouth odontoid views, which are obtained in the trauma resuscitation area. CT is obtained when these views are inadequate (eg, inability to obtain open-mouth odontofd view or lack of visualization of the C7-T1 junction on a lateral view). In addition, when confirmation of injuries that are suspected on plain radiographs is required, z CT of the specific regions of the neck involved is obtained. All patients surviving resuscitation with injury diagnosed on plain radiography also undergo limited CT to further delineate the pathologic anatomy. All CTs are performed with a SOMATOM 2 CT Scanner (Seimans, Erlungen, West Germany) using sections 4 m m thick at intervals of 3 mm. The angle of coronal section varied from 5 ° to 20 ° (average, 16°). Transverse reconstructions were performed on all subjects. Coronal and sagittal reconstructions were performed as required for the level and type of injury suspected. All plain radiographs and scans are interpreted by an attending traumatologist as well as an attending radiologist and orthopedic or neurologic surgeon.
18:8 August 1989
Annals of Emergency Medicine
815/45
CT EVALUATION Schleehauf et al
C l i n i c a l data regarding p a t i e n t evaluation diagnosis and treatment were collected on all patients prospectively in a computerized trauma registry. The cervical radiographs of all patients undergoing cervical spine CT for a 12-month period ending April 15, 1986, were subsequently reviewed by a traumatologist and a radiologist with consensus recorded for adequacy and interpretation. The diagnosis at the completion of cervical spine evaluation (including plain radiography, CT, thin-section tomography, video cineradiography, radionuclide bone scan, and stress views as required for individual p a t i e n t management) was accepted as defining presence or absence of unstable cervical spine injury. Unstable injury was defined by the criteria established by White et al. 3 Patients suffering rotary subluxation of the atlantoaxial joint were also defined as having unstable injury. All patients in w h o m unstable cervical spine injury was ruled out were followed for a m i n i m u m of two weeks after hospital discharge by outpatient recheck for signs or symptoms of cervical spine injury. Specificity and sensitivity were calculated for CT on the population as a whole and on each subgroup.
RESULTS Six hundred six patients suffering from blunt, high-energy transfer injury were admitted to the t r a u m a center during the study peIiod. Three hundred forty-three of them fulfilled the criteria for high risk for cervical spine injury. One hundred four patients underwent CT as part of their e v a l u a t i o n . S e v e n t y - f i v e of t h o s e were victims of m u l t i s y s t e m or severe head trauma - 49 with Abbreviated Injury Scale 4 or 5 head injury 4 and 26 w i t h m u l t i s y s t e m i n j u r y without severe head injury. Seventythree CTs of the cervical spine were performed on an emergency basis, 11 w i t h i n 24 hours of admission, 17 within four days of admission, and three on a delayed basis (ten days to one m o n t h ) . . Eighty of these patients were men, and 24 were women. The average age was 34 years (range, 13 to 88 years). Mechanism of injury included motor v e h i c l e a c c i d e n t (77), p e d e s t r i a n struck by motor vehicle (six), motorcycle accidents (five), assault (five), fall from heights (eight), and bicycle 46/816
accidents (three). Eighteen (17%) of these 104 patients sustained unstable cervical spine injury. G r o u p 1 i n c l u d e d 56 p a t i e n t s scanned after inadequate plain radiographs (Table). Included in this group were 34 patients without visualization of the C7-T1 junction on lab erocervical view, 14 with inadequate visualization of the C1-C2 junction on open-mouth odontoid view, and eight with neither region seen on plain radiography. Four of these patients had positive scans. One patient whose CT was interpreted as displaying rotary subluxation of C1-C2 was later determined to be free of spine injury after thorough mobility studies. Sensitivity of CT, for bony injury, in this clinical setting was 1.0. Suspicious but nondiagnostic radiographs were the indications for neck CT in 31 patients (group 2). Seven studies were positive, and 24 were negative. All positive studies were true-positives. Two studies, thought to be negative with regard to C1-C2, were later determined to conceal a rotary subluxation following cinevideo stress views. When plain radiographs were suspicious for injury but not diagnostic, CT had a sensitivity of 0.78 and specificity of 0.91. Identification of unstable injury on plain radiograph was the indication for CT in 12 patients (group 3). Five studies were positive for unstable injury and seven were negative. One CT involving a case of ligamentous injury at the cervicocephalic junction was falsely negative. This injury had been previously identified on lateralcervical view and was clinically apparent. CT had a sensitivity of 0.83 when unstable injury had been identified on plain films. Five patients with normal plain radiographs but persistent neck pain or neurologic deficit underwent late CT as part of complete evaluation (group 4). Two of these scans were performed with intrathecal contrast; all were negative with regard to acute injury. Sensitivity was undefined in this group. For the entire population in which CT of the cervical spine was used, the sensitivity of CT for unstable cervical spine injury was 0.81. No unstable injuries have been detected subsequently in any patient in w h o m they were not detected in the hospital. Annals of Emergency Medicine
DISCUSSION Patients p r e s e n t i n g w i t h blunt, high-energy transfer injury, particularly these with major blunt head or m u l t i s y s t e m trauma, must be considered to be at high risk for unstable cervical spine injury. From 10% to 20% of all patients with major head injury had been reported to have concomitant cervical spine injury.S, 6 To avoid missed, unstable cervical spine injury and possible iatrogenic spinal cord injury, a high index of suspicion as well as extremely sensitive radiologic evaluation is necessary. The full cervical spine series has a reported sensitivity of 0.921 to 1.0.7 Although 100% sensitive when complete and technically adequate, I technically adequate films cannot be obtained in significant numbers of patients. Body habitus, upper extremity injuries, chest injuries, or lack of patient cooperation frequently preclude visualization of the C7-T1 junction. Because 18% of cervical spine injuries occur at this level, 8 it is of param o u n t importance that it be visualized. Despite the use of caudad arm traction, in our previously reported experience, the incidence of inadequate lateral-cervical view in blunt, h i g h - e n e r g y t r a n s f e r v i c t i m s was 25%.1 Similarly, facial and mandibular injuries, endotracheal intubation, or lack of patient cooperation may lead to inadequate visualization of the C1-C2 j u n c t i o n in the openmouth odontoid view. From 23% 9 to 33% 8 of cervical spine injuries occur at this level. To effectively deal with these difficulties in plain radiography, some authors have advocated the use of thinsection tomography to and CT H in patients with radiographic suspicion of injury. More recently, Streitwieser and associates 9 have advocated the use of thin-section tomography in all patients with clinical findings susp i c i o u s of cervical spine injury. Mace ~2 has further suggested that all patients at risk for cervical spine injury undergo CT of the neck. T h i n - s e c t i o n t o m o g r a p h y is a time-consuming procedure involving special patient positioning often impossible in m u l t i s y s t e m trauma patients. In addition, in most institutions, this modality is available on a routine, working-day basis only. In contrast, limited, directed CT requires little additional time, especially in patients undergoing emer18:8 August 1989
the cervical spine: Initial radiologic cwduation. ] Trauma 1987;27:1055.
TABLE. A c c u r a c y o f C T o f c e r v i c a l s p i n e
Group
No. of Patients
Positive/ False +
Negative/ False -
Sensitivity
Specificity
1
56
3/1
53/0
1.0
0.98
2
31
7/2
24/2
0.71
0.92
3
12
5/0
7/1
0.83
1.0
4
5
0/0
5/0
Undefined
1.0
104
15.4
89/3
0.78
0.95
Total
g e n c y C T e v a l u a t i o n of h e a d or abdom e n (65% of this series); in Level I and II t r a u m a c e n t e r s f u n c t i o n i n g under A m e r i c a n C o l l e g e of S u r g e o n s g u i d e l i n e s , it is a v a i l a b l e o n a 24h o u r basis. 13 T h e s e n s i t i v i t y of C T of t h e cervical spine in our s e l e c t e d p o p u l a t i o n w a s 0.81, w e l l b e l o w t h e r e p o r t e d s e n s i t i v i t y of a full c e r v i c a l spine series.l A l t h o u g h h i g h l y specific, C T is n o t s e n s i t i v e e n o u g h for u s e as a s c r e e n i n g study. W h e n used as an adj u n c t to p l a i n r a d i o g r a p h s , p a r t i c u l a r l y w h e n t h o s e r a d i o g r a p h s are t e c h n i c a l l y i n a d e q u a t e , it p r o v e s to be b o t h h i g h l y s e n s i t i v e and specific. All i n a c c u r a t e studies in our series i n v o l v e d l i g a m e n t o u s injuries at t h e c e r v i c o c e p h a l i c and C1-C2 levels. N o l i g a m e n t o u s i n j u r i e s at t h e s e l e v e l s w e r e a c c u r a t e l y i d e n t i f i e d by CT. Alt h o u g h b o n y i n j u r y is w e l l d e l i n e a t e d in this region by CT, it appears t h a t this is n o t the o p t i m a l s t u d y for soft-
18:8 August 1989
t i s s u e injury. W h e n t h e r e is suspic i o n of l i g a m e n t o u s i n j u r y , o t h e r studies, s u c h as stress v i e w s or cineradiography, m a y be n e c e s s a r y in add i t i o n to CT. CONCLUSION We c o n c l u d e t h a t l i m i t e d , d i r e c t e d C T of t h e n e c k is appropriate in t h e e v a l u a t i o n of b l u n t t r a u m a p a t i e n t s at risk for c e r v i c a l spine i n j u r y after plain radiographs, particularly when t h e s e i n i t i a l s t u d i e s are t e c h n i c a l l y i n a d e q u a t e , b u t it is n e i t h e r s e n s i t i v e e n o u g h n o r l o g i s t i c a l l y p r a c t i c a l to replace t h o s e p l a i n radiographs. Limited C T is u s e f u l in t h e i n v e s t i g a t i o n of p a t h o l o g i c a n a t o m y w h e n specific injuries are s u s p e c t e d or " i d e n t i f i e d " on p l a i n radiographs; t h e v a l u e of C T in t h e d i a g n o s i s of l i g a m e n t o u s inj u r y in t h e u p p e r c e r v i c a l s p i n e is limited.
REFERENCES 1. Ross SE, Schwab CW, David E, et al: Clearing
Annals of Emergency Medicine
2. Wales LR, Knopp RK, Morishima MS: Recommendations for evaluation of the acutely injured cervical spine: A clinical radiologic algorithm. Ann Emerg Med 1980;9:422-428. 3. White AA, Southwick WO, Pantabi MM: Clinical instability in the lower cervical spine: A review of past and current concepts. Spine 1976;1:15-27. 4. Joint Committee on Injury Scaling (1980t: The Abbreviated Injury ScaJe (AIS), 1985 revi-
sion. Park Ridge, Illinois, American Association for Automotive Medicine, 1985. 5. Roberts FR: Trauma of the cervical spine. Topics Emerg Med 1979;1:63-77. 6. Rockswold GL: Evaluation and resuscitation in head trauma. Minn Med 1981;64:81-84. 7. Shaffer MA, Doris PE: Limitation of the cross table lateral view in defecting cervical spine injuries: A retrospective analysis. Ann Emerg Med 1981;10:508-513. 8. Miller MD, Gehweiler JA, Martinez S, et al: Significant new observations on cervical spine trauma. A JR 1978;130:659-663. 9. Strietwieser DR, Knopp R, Wales LR, et ah Accuracy of standard radiographic views in detecting cervical spine fractures. Arm Emerg Med 1983;12:538-549,. 10. Maravilla DR, Cooper PR, Sklar FH: Thin section of tomography in the treatment of cervical spine iniury. Radiology 1978;127:131-139. 11. Post M, Green B, Quencer R, et al: The value of computed tomography in spinal trauma. Spine 1982;7:417-431. 12. Mace SE: Emergency evaluation of cervical spine injuries: CT versus plain radiographs. Ann Emerg Med 1975i14:973-975. 13. Committee on Trauma of the American College of Surgeons: Hospital and prehospital resources for optimal care of the injured patient. BuII Am Coil Surg 1986;71:4-12.
817/47
Computed Tomography in the Initial Evaluation of the Cervical Spine Unstable injury of the cervical spine must be considered in all victims of blunt trauma. To evaluate the role of limited, directed computed tomography (CT) in the initial evaluation of the cervical spine, a one-year study involving 104 high-risk patients was undertaken. Sensitivity was O. 78 overall, but in the group of patients scanned after inadequate plain radiographs, CT had a sensitivity of 1.0 ,for unstable cervical injury All falsenegative studies involved atlantoaxial rotary subiuxation. We conclude that limited, directed CT of the cervical spine is appropriate in the initial evaluation of patients at risk, particularly if plain radiographs are inadequate, but is of limited value in the evaluation of ligamentous injury of the upper cervical spine. [Schleehauf K, Ross SE, Civil If), Schwab CW: Computed tomography in the initial evaluation of the cervical spine. Ann Emerg Med August 1989;18:815-817.] INTRODUCTION The early identification of unstable cervical spine injury remains essential in the management of blunt trauma patients. Difficulties in obtaining adequate, plain radiographs of the neck have made the use of other radiographic modalities mandatory. At the Southern New Jersey Regional Trauma Center, evaluation of the cervical spine includes limited, directed computed tomography (CT). This is used to anatomically delineate fractures suspected or identified on plain radiographs or to rule out cervical spine injury when plain radiographs are inadequate. To determine its effectiveness in suspected spinal injury, we undertook a one-year study of all patients undergoing CT of the cervical spine.
Karen Schleehauf, MD Steven E Ross, MD, FACS lan D Civil, MBChB C William Schwab, MD, FACS Camden, New Jersey From the Department of Surgery, UMDNJ/ Robert Wood Johnson Medical School -Camden/Cooper Hospital-University Medical Center, Camden, New Jersey. Received for publication May 20, 1987. Revisions received August 15, 1988, and February 20, 1989. Accepted for publication April 24, 1989. Presented at the University Association for Emergency Medicine Annual Meeting in Philadelphia, May 1987. Address for reprints: Steven E Ross, MD, Department of Surgery, 3 Cooper Plaza, Suite 411, Camden, New Jersey 08103.
MATERIALS A N D METHODS All patients admitted to the multiple trauma service suffering blunt, high-energy transfer injury who present with loss or alteration of consciousness, facial laceration or clinically apparent fracture above the clavicle, neurologic deficit suggestive of cervical spine injury, or neck pain or tenderness undergo radiographic evaluation of the cervical spine. Initial cervical spine radiographs include lateral-cervical, anteroposterior, and open-mouth odontoid views, which are obtained in the trauma resuscitation area. CT is obtained when these views are inadequate (eg, inability to obtain open-mouth odontofd view or lack of visualization of the C7-T1 junction on a lateral view). In addition, when confirmation of injuries that are suspected on plain radiographs is required, z CT of the specific regions of the neck involved is obtained. All patients surviving resuscitation with injury diagnosed on plain radiography also undergo limited CT to further delineate the pathologic anatomy. All CTs are performed with a SOMATOM 2 CT Scanner (Seimans, Erlungen, West Germany) using sections 4 m m thick at intervals of 3 mm. The angle of coronal section varied from 5 ° to 20 ° (average, 16°). Transverse reconstructions were performed on all subjects. Coronal and sagittal reconstructions were performed as required for the level and type of injury suspected. All plain radiographs and scans are interpreted by an attending traumatologist as well as an attending radiologist and orthopedic or neurologic surgeon.
18:8 August 1989
Annals of Emergency Medicine
815/45
CT EVALUATION Schleehauf et al
C l i n i c a l data regarding p a t i e n t evaluation diagnosis and treatment were collected on all patients prospectively in a computerized trauma registry. The cervical radiographs of all patients undergoing cervical spine CT for a 12-month period ending April 15, 1986, were subsequently reviewed by a traumatologist and a radiologist with consensus recorded for adequacy and interpretation. The diagnosis at the completion of cervical spine evaluation (including plain radiography, CT, thin-section tomography, video cineradiography, radionuclide bone scan, and stress views as required for individual p a t i e n t management) was accepted as defining presence or absence of unstable cervical spine injury. Unstable injury was defined by the criteria established by White et al. 3 Patients suffering rotary subluxation of the atlantoaxial joint were also defined as having unstable injury. All patients in w h o m unstable cervical spine injury was ruled out were followed for a m i n i m u m of two weeks after hospital discharge by outpatient recheck for signs or symptoms of cervical spine injury. Specificity and sensitivity were calculated for CT on the population as a whole and on each subgroup.
RESULTS Six hundred six patients suffering from blunt, high-energy transfer injury were admitted to the t r a u m a center during the study peIiod. Three hundred forty-three of them fulfilled the criteria for high risk for cervical spine injury. One hundred four patients underwent CT as part of their e v a l u a t i o n . S e v e n t y - f i v e of t h o s e were victims of m u l t i s y s t e m or severe head trauma - 49 with Abbreviated Injury Scale 4 or 5 head injury 4 and 26 w i t h m u l t i s y s t e m i n j u r y without severe head injury. Seventythree CTs of the cervical spine were performed on an emergency basis, 11 w i t h i n 24 hours of admission, 17 within four days of admission, and three on a delayed basis (ten days to one m o n t h ) . . Eighty of these patients were men, and 24 were women. The average age was 34 years (range, 13 to 88 years). Mechanism of injury included motor v e h i c l e a c c i d e n t (77), p e d e s t r i a n struck by motor vehicle (six), motorcycle accidents (five), assault (five), fall from heights (eight), and bicycle 46/816
accidents (three). Eighteen (17%) of these 104 patients sustained unstable cervical spine injury. G r o u p 1 i n c l u d e d 56 p a t i e n t s scanned after inadequate plain radiographs (Table). Included in this group were 34 patients without visualization of the C7-T1 junction on lab erocervical view, 14 with inadequate visualization of the C1-C2 junction on open-mouth odontoid view, and eight with neither region seen on plain radiography. Four of these patients had positive scans. One patient whose CT was interpreted as displaying rotary subluxation of C1-C2 was later determined to be free of spine injury after thorough mobility studies. Sensitivity of CT, for bony injury, in this clinical setting was 1.0. Suspicious but nondiagnostic radiographs were the indications for neck CT in 31 patients (group 2). Seven studies were positive, and 24 were negative. All positive studies were true-positives. Two studies, thought to be negative with regard to C1-C2, were later determined to conceal a rotary subluxation following cinevideo stress views. When plain radiographs were suspicious for injury but not diagnostic, CT had a sensitivity of 0.78 and specificity of 0.91. Identification of unstable injury on plain radiograph was the indication for CT in 12 patients (group 3). Five studies were positive for unstable injury and seven were negative. One CT involving a case of ligamentous injury at the cervicocephalic junction was falsely negative. This injury had been previously identified on lateralcervical view and was clinically apparent. CT had a sensitivity of 0.83 when unstable injury had been identified on plain films. Five patients with normal plain radiographs but persistent neck pain or neurologic deficit underwent late CT as part of complete evaluation (group 4). Two of these scans were performed with intrathecal contrast; all were negative with regard to acute injury. Sensitivity was undefined in this group. For the entire population in which CT of the cervical spine was used, the sensitivity of CT for unstable cervical spine injury was 0.81. No unstable injuries have been detected subsequently in any patient in w h o m they were not detected in the hospital. Annals of Emergency Medicine
DISCUSSION Patients p r e s e n t i n g w i t h blunt, high-energy transfer injury, particularly these with major blunt head or m u l t i s y s t e m trauma, must be considered to be at high risk for unstable cervical spine injury. From 10% to 20% of all patients with major head injury had been reported to have concomitant cervical spine injury.S, 6 To avoid missed, unstable cervical spine injury and possible iatrogenic spinal cord injury, a high index of suspicion as well as extremely sensitive radiologic evaluation is necessary. The full cervical spine series has a reported sensitivity of 0.921 to 1.0.7 Although 100% sensitive when complete and technically adequate, I technically adequate films cannot be obtained in significant numbers of patients. Body habitus, upper extremity injuries, chest injuries, or lack of patient cooperation frequently preclude visualization of the C7-T1 junction. Because 18% of cervical spine injuries occur at this level, 8 it is of param o u n t importance that it be visualized. Despite the use of caudad arm traction, in our previously reported experience, the incidence of inadequate lateral-cervical view in blunt, h i g h - e n e r g y t r a n s f e r v i c t i m s was 25%.1 Similarly, facial and mandibular injuries, endotracheal intubation, or lack of patient cooperation may lead to inadequate visualization of the C1-C2 j u n c t i o n in the openmouth odontoid view. From 23% 9 to 33% 8 of cervical spine injuries occur at this level. To effectively deal with these difficulties in plain radiography, some authors have advocated the use of thinsection tomography to and CT H in patients with radiographic suspicion of injury. More recently, Streitwieser and associates 9 have advocated the use of thin-section tomography in all patients with clinical findings susp i c i o u s of cervical spine injury. Mace ~2 has further suggested that all patients at risk for cervical spine injury undergo CT of the neck. T h i n - s e c t i o n t o m o g r a p h y is a time-consuming procedure involving special patient positioning often impossible in m u l t i s y s t e m trauma patients. In addition, in most institutions, this modality is available on a routine, working-day basis only. In contrast, limited, directed CT requires little additional time, especially in patients undergoing emer18:8 August 1989
the cervical spine: Initial radiologic cwduation. ] Trauma 1987;27:1055.
TABLE. A c c u r a c y o f C T o f c e r v i c a l s p i n e
Group
No. of Patients
Positive/ False +
Negative/ False -
Sensitivity
Specificity
1
56
3/1
53/0
1.0
0.98
2
31
7/2
24/2
0.71
0.92
3
12
5/0
7/1
0.83
1.0
4
5
0/0
5/0
Undefined
1.0
104
15.4
89/3
0.78
0.95
Total
g e n c y C T e v a l u a t i o n of h e a d or abdom e n (65% of this series); in Level I and II t r a u m a c e n t e r s f u n c t i o n i n g under A m e r i c a n C o l l e g e of S u r g e o n s g u i d e l i n e s , it is a v a i l a b l e o n a 24h o u r basis. 13 T h e s e n s i t i v i t y of C T of t h e cervical spine in our s e l e c t e d p o p u l a t i o n w a s 0.81, w e l l b e l o w t h e r e p o r t e d s e n s i t i v i t y of a full c e r v i c a l spine series.l A l t h o u g h h i g h l y specific, C T is n o t s e n s i t i v e e n o u g h for u s e as a s c r e e n i n g study. W h e n used as an adj u n c t to p l a i n r a d i o g r a p h s , p a r t i c u l a r l y w h e n t h o s e r a d i o g r a p h s are t e c h n i c a l l y i n a d e q u a t e , it p r o v e s to be b o t h h i g h l y s e n s i t i v e and specific. All i n a c c u r a t e studies in our series i n v o l v e d l i g a m e n t o u s injuries at t h e c e r v i c o c e p h a l i c and C1-C2 levels. N o l i g a m e n t o u s i n j u r i e s at t h e s e l e v e l s w e r e a c c u r a t e l y i d e n t i f i e d by CT. Alt h o u g h b o n y i n j u r y is w e l l d e l i n e a t e d in this region by CT, it appears t h a t this is n o t the o p t i m a l s t u d y for soft-
18:8 August 1989
t i s s u e injury. W h e n t h e r e is suspic i o n of l i g a m e n t o u s i n j u r y , o t h e r studies, s u c h as stress v i e w s or cineradiography, m a y be n e c e s s a r y in add i t i o n to CT. CONCLUSION We c o n c l u d e t h a t l i m i t e d , d i r e c t e d C T of t h e n e c k is appropriate in t h e e v a l u a t i o n of b l u n t t r a u m a p a t i e n t s at risk for c e r v i c a l spine i n j u r y after plain radiographs, particularly when t h e s e i n i t i a l s t u d i e s are t e c h n i c a l l y i n a d e q u a t e , b u t it is n e i t h e r s e n s i t i v e e n o u g h n o r l o g i s t i c a l l y p r a c t i c a l to replace t h o s e p l a i n radiographs. Limited C T is u s e f u l in t h e i n v e s t i g a t i o n of p a t h o l o g i c a n a t o m y w h e n specific injuries are s u s p e c t e d or " i d e n t i f i e d " on p l a i n radiographs; t h e v a l u e of C T in t h e d i a g n o s i s of l i g a m e n t o u s inj u r y in t h e u p p e r c e r v i c a l s p i n e is limited.
REFERENCES 1. Ross SE, Schwab CW, David E, et al: Clearing
Annals of Emergency Medicine
2. Wales LR, Knopp RK, Morishima MS: Recommendations for evaluation of the acutely injured cervical spine: A clinical radiologic algorithm. Ann Emerg Med 1980;9:422-428. 3. White AA, Southwick WO, Pantabi MM: Clinical instability in the lower cervical spine: A review of past and current concepts. Spine 1976;1:15-27. 4. Joint Committee on Injury Scaling (1980t: The Abbreviated Injury ScaJe (AIS), 1985 revi-
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