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Physiologic anterior subluxation: Case report of occurrence at C5 to C6 and C6 to C7 spinal levels
PEDIATRICS/CASE REPORT
Physiologic Anterior Subluxation: Case Report of Occurrence at C5 to C6 and C6 to C7 Spinal Levels
Mark E. Ralston, MD, MPH From the Department of Emergency Medicine, Naval Medical Center, Portsmouth, VA.
Physiologic anterior subluxation is a phenomenon that is common to the upper pediatric cervical spine and characterized by the normal forward displacement of one cervical vertebra relative to the subjacent one. Physiologic anterior subluxation can be seen in children in the setting of trauma, when it must be distinguished from pathologic subluxation. Physiologic anterior subluxation has not been reported at lower cervical spinal levels (C5 to C6 or C6 to C7). This is a report of physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels distinguished from pathologic subluxation in a 9-yearold child evaluated in the acute setting after cervical spine injury. [Ann Emerg Med. 2004;44:472-475.]
INTRODUCTION
Physiologic anterior subluxation of the cervical spine refers to the normal forward displacement of one cervical vertebra relative to the subjacent one and has been called ‘‘pseudosubluxation.’’ It represents true, minor subluxation of the cervical spine, which occurs normally in children because of unique anatomic and biomechanical characteristics compared with that of adults. Physiologic anterior subluxation most commonly occurs in the upper cervical spine of infants and children1-12 but occasionally persists into adolescence3,6,8,10,11 and young adulthood.8 Physiologic anterior subluxation can be seen in children admitted with multiple trauma,11 when it must be distinguished from pathologic subluxation. The phenomenon is most often isolated to the C2 or C3 spinal level1-6,8-12 but is also described at other spinal levels, including C2 to C43,6 and C2 to C53,8,12 levels. Physiologic anterior subluxation has not been reported at lower cervical spinal levels (C5 to C6 or C6 to C7). This is a report of physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels in a 9-year-old child evaluated acutely in a tertiary hospital emergency department (ED) after cervical spine injury. CASE REPORT
doi:10.1016/ j.annemergmed.2004.05.024
4 7 2
A 9-year-old girl presented to a tertiary hospital ED for evaluation of headache and neck pain approximately 16 hours after a motor vehicle collision. The patient was a seatbeltrestrained front-seat passenger in a slowly moving vehicle hit broadside on the left front fender by a vehicle moving at approximately 20 miles per hour. The patient had a right frontal head injury without loss of consciousness and experienced immediate, severe neck pain with subsequent limited neck range of motion. She was taken directly to the
ANNALS OF EMERGENCY MEDICINE
44:5
NOVEMBER 2004
P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
Emergency Medicine Department at Naval Medical Center, Portsmouth, VA. Medical history was unremarkable. Physical examination was significant for a 2 3 4-cm right frontal scalp contusion, torticollis, and cervical spine tenderness, both midline and over the bilateral paraspinal musculature. Neurologic examination results were normal. A 3-view cervical spine radiographic series (anteroposterior/lateral/odontoid views) was obtained. The lateral radiograph (neutral position) demonstrated anterior subluxation at 2 spinal levels: C5 to C6 (1.5 mm) and C6 to C7 (3.3 mm; Figure 1). Flexionextension radiographs were obtained in active neck flexion and extension under physician supervision. The flexion view demonstrated segmental kyphosis (10.3 degrees anterior angulation) at the C3 to C4 spinal level and anterior subluxation at 3 levels: C2 to C3 (3.6 mm), C3 to C4 (1.8 mm), and C6 to C7 (2.6 mm; Figure 2). Complete reduction of anterior subluxation was observed on the extension view (Figure 3). A neck magnetic
Figure 1. Lateral cervical spine plain radiograph demonstrating physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels (neutral view).
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resonance image (MRI) showed no evidence of ligamentous injury but confirmed the anterior subluxation seen on lateral cervical spine radiographs. The patient was given the diagnosis of cervical strain and physiologic anterior subluxation. She was discharged home with symptomatic treatment. A follow-up visit at 1.5 weeks revealed significant decrease in neck pain and improvement in active neck range of motion. DISCUSSION
Physiologic anterior subluxation is thought to be the result of normal hypermobility of primarily the upper cervical spine in children, likely caused by a number of factors: a wedged anterior contour of the upper cervical spine vertebral bodies,1,3 ligamentous laxity,5,6,8,12 horizontally configured apophyseal facets,3,5,8 and a higher fulcrum of motion in the cervical spine of young children (C2/C3 level) up to age 10 years compared with
Figure 2. Lateral cervical spine plain radiographs demonstrating physiologic anterior subluxation at C2 to C3, C3 to C4, and C6 to C7 spinal levels and segmental kyphosis at C3 to C4 spinal level (flexion view).
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P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
lower levels (C4/C5 or C5/C6) in older children and adolescents.5,8,12 The term ‘‘pseudosubluxation’’ is commonly assigned to the phenomenon reported here.5-11 ‘‘Physiologic anterior subluxation’’ is a more accurate term to describe the normal forward displacement of vertebral bodies in the immature cervical spine because the subluxation is a real phenomenon. Moreover, the term distinguishes itself from physiologic posterior subluxation, which is also, but less frequently, observed in the pediatric cervical spine, typically at the C2 to C3 spinal level in extension.5,6,12 All normal anterior movement of the pediatric cervical spine may be referred to as physiologic anterior subluxation. The amount of vertebral displacement in physiologic anterior subluxation has been reported to vary from less than 1 mm to 5 mm3,5 and may be accompanied by acute forward angulation of vertebral segments (segmental kyphosis).5 Additionally, vertebral displacement in physiologic anterior subluxation may be proportional to the degree of neck flexion,1,2,5 including flexion induced by
Figure 3. Lateral cervical spine plain radiographs demonstrating complete reduction of physiologic anterior subluxation (extension view).
4 7 4
a stiff collar. Correction of the displacement with the neck in neutral and extension positions has also been described.5,8 Physiologic anterior subluxation may be accentuated by muscle spasm.2 In the patient reported here, anterior displacement was isolated to the lower cervical spine on the neutral lateral view, measured less than 4 mm, emerged in the upper cervical spine with accompanying segmental kyphosis in flexion, resolved completely in extension, and was confirmed as physiologic by a normal MRI. The necessity of additional radiographic imaging in the evaluation of an acutely injured patient with findings consistent with physiologic anterior subluxation on a lateral cervical spine radiograph has not been defined but likely depends on mechanism of injury, clinical risk, and presence of associated radiographic findings. In the patient at low risk for ligamentous injury (ie, minor mechanism, normal level of consciousness, without neck pain or posterior midline tenderness, normal neurologic examination, and without distracting injury), the findings should be recognized as physiologic without need of further imaging. On the other hand, any patient at high risk for ligamentous injury (ie, with additional radiographic abnormalities such as divergence of spinous processes, narrowing of anterior disc space, displacement of apophyseal joints, excessive vertebral body displacement, or paravertebral soft tissue swelling) should undergo MRI to evaluate for pathologic subluxation. Less clear is the role of further imaging in clinically difficult cases (ie, the patient with obvious findings of physiologic anterior subluxation but also severe mechanism, significant neck pain, concerning physical examination such as posterior midline neck tenderness or torticollis, or equivocal findings on standard cervical spine plain radiographs). Currently, no absolute criterion standard exists for verifying physiologic anterior subluxation short of a normal MRI, which is neither practical nor available in most EDs. If the findings are located at the C2 or C3 level, satisfactory alignment of the posterior cervical line is helpful but not always sufficient to rule out a pathologic subluxation.12,13 Flexion-extension radiographs have been shown to have a limited role in the acute evaluation of blunt cervical spine injury14,15 but may have a useful indication here in that physiologic anterior subluxation observed in neutral or flexion may correct in extension.5,7,8 If this tool were validated, it could be used to verify physiologic anterior subluxation at all levels of the cervical spine, from C2 to C7 where the phenomenon can occur, thereby saving referral or transfer
ANNALS OF EMERGENCY MEDICINE
44:5
NOVEMBER 2004
P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
for MRI. However, evidence for a normal extension radiograph as verification of physiologic anterior subluxation currently does not exist beyond the level of case report, and with the exception of the child in this report, patients in previous case reports did not have confirmatory normal MRI results.5,8 The performance of a normal extension radiograph compared with normal MRI as a criterion standard for physiologic anterior subluxation needs to be evaluated prospectively. Without this evaluation, anterior subluxation in clinically difficult cases cannot be assumed to be physiologic and should be differentiated from ligamentous injury by MRI.16 Whether cases with findings occurring solely at the C2 to C3 level could be managed as an exception to this is unfounded in the literature. In summary, physiologic anterior subluxation is a phenomenon common to the upper pediatric cervical spine but has now been reported to occur at every spinal level from C2 to C7. All normal anterior movement of the pediatric cervical spine may be referred to as physiologic anterior subluxation, a more accurate term to describe the phenomenon than ‘‘pseudosubluxation’’ because the subluxation is real. Physiologic anterior subluxation can be seen in children in the setting of trauma, when it must be distinguished from pathologic subluxation. In this report, physiologic anterior subluxation was confirmed for the first time at C5 to C6 and C6 to C7 spinal levels in a 9-yearold child evaluated in the acute setting after cervical spine injury.
4. Dunlap JP, Morris M, Thompson RG. Cervical-spine injuries in children. J Bone Joint Surg. 1958;40A:681-686. 5. Jacobson G, Bleecker HH. Pseudosubluxation of the axis in children. Am J Roentgenol. 1959;82:472-481. 6. Cattell HS, Filtzer DL. Pseudosubluxation and other normal variations in the cervical spine in children. J Bone Joint Surg. 1965;47A:1295-1309. 7. Penning L. Normal movements of the cervical spine. Am J Roentgenol. 1978;130: 317-326. 8. Harrison RB, Keats TE, Winn HR, et al. Pseudosubluxation of the axis in young adults. J Can Assoc Radiol. 1980;31:176-177. 9. Fechtel SG. Pseudosubluxation of the cervical spine in adolescents: a case report. J Manipulat Physiol Ther. 1983;6:81-83. 10. Goni Orayen C, Perez Martinez A, Martin Martinez C, et al. Pseudosubluxation of C2-C3 during childhood: a common clinical-radiological misdiagnosis. Ann Exp Pediatr. 1992;36:390-392. 11. Shaw M, Burnett H, Wilson A, et al. Pseudosubluxation of C2 on C3 in polytraumatized children: prevalence and significance. Clin Radiol. 1999;54:377-380. 12. Swischuk L. Emergency Imaging of the Acutely Ill or Injured Child. 4th ed. Baltimore, MD: Williams & Wilkins; 2000. 13. Ralston ME, Chung K, Barnes PD, et al. Role of flexion-extension radiographs in blunt pediatric cervical spine injury. Acad Emerg Med. 2001;8:237-245. 14. Swischuk LE. Anterior displacement of C2 in children: physiologic or pathologic? A helpful differentiating line. Radiology. 1977;122:759-763. 15. Pollack CV, Hendey GW, Martin DR, et al. Use of flexion-extension radiographs of the cervical spine in blunt trauma. Ann Emerg Med. 2001;38:8-11. 16. Slack SE, Clancy MJ. Clearing the cervical spine of paediatric trauma patients. Emerg Med J. 2004;21:189-193.
I thank Kirsten Ecklund, MD, for her helpful advice. Received for publication April 28, 2004. Revision received May 24, 2004. Accepted for publication May 26, 2004. Available online September 11, 2004. The views expressed in this article are those of the author and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States government. The author reports this study did not receive any outside funding or support. Address for reprints: Mark E. Ralston, MD, MPH, 1117 Rainier Circle, Oak Harbor, WA 98277; 360-240-8714, fax 360-257-9662; E-mail [email protected].
REFERENCES 1. Bailey DK. The normal cervical spine in infants and children. Radiology. 1952;59: 712-719. 2. Townsend EH, Rowe ML. Mobility of the upper cervical spine in health and disease. Pediatrics. 1952;10:567-572. 3. Sullivan CR, Bruwer AJ, Harris LE. Hypermobility of the cervical spine in children: a pitfall in the diagnosis of cervical dislocation. Am J Surg. 1958;95: 636-640.
NOVEMBER 2004
44:5
ANNALS OF EMERGENCY MEDICINE
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Physiologic Anterior Subluxation: Case Report of Occurrence at C5 to C6 and C6 to C7 Spinal Levels
Mark E. Ralston, MD, MPH From the Department of Emergency Medicine, Naval Medical Center, Portsmouth, VA.
Physiologic anterior subluxation is a phenomenon that is common to the upper pediatric cervical spine and characterized by the normal forward displacement of one cervical vertebra relative to the subjacent one. Physiologic anterior subluxation can be seen in children in the setting of trauma, when it must be distinguished from pathologic subluxation. Physiologic anterior subluxation has not been reported at lower cervical spinal levels (C5 to C6 or C6 to C7). This is a report of physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels distinguished from pathologic subluxation in a 9-yearold child evaluated in the acute setting after cervical spine injury. [Ann Emerg Med. 2004;44:472-475.]
INTRODUCTION
Physiologic anterior subluxation of the cervical spine refers to the normal forward displacement of one cervical vertebra relative to the subjacent one and has been called ‘‘pseudosubluxation.’’ It represents true, minor subluxation of the cervical spine, which occurs normally in children because of unique anatomic and biomechanical characteristics compared with that of adults. Physiologic anterior subluxation most commonly occurs in the upper cervical spine of infants and children1-12 but occasionally persists into adolescence3,6,8,10,11 and young adulthood.8 Physiologic anterior subluxation can be seen in children admitted with multiple trauma,11 when it must be distinguished from pathologic subluxation. The phenomenon is most often isolated to the C2 or C3 spinal level1-6,8-12 but is also described at other spinal levels, including C2 to C43,6 and C2 to C53,8,12 levels. Physiologic anterior subluxation has not been reported at lower cervical spinal levels (C5 to C6 or C6 to C7). This is a report of physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels in a 9-year-old child evaluated acutely in a tertiary hospital emergency department (ED) after cervical spine injury. CASE REPORT
doi:10.1016/ j.annemergmed.2004.05.024
4 7 2
A 9-year-old girl presented to a tertiary hospital ED for evaluation of headache and neck pain approximately 16 hours after a motor vehicle collision. The patient was a seatbeltrestrained front-seat passenger in a slowly moving vehicle hit broadside on the left front fender by a vehicle moving at approximately 20 miles per hour. The patient had a right frontal head injury without loss of consciousness and experienced immediate, severe neck pain with subsequent limited neck range of motion. She was taken directly to the
ANNALS OF EMERGENCY MEDICINE
44:5
NOVEMBER 2004
P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
Emergency Medicine Department at Naval Medical Center, Portsmouth, VA. Medical history was unremarkable. Physical examination was significant for a 2 3 4-cm right frontal scalp contusion, torticollis, and cervical spine tenderness, both midline and over the bilateral paraspinal musculature. Neurologic examination results were normal. A 3-view cervical spine radiographic series (anteroposterior/lateral/odontoid views) was obtained. The lateral radiograph (neutral position) demonstrated anterior subluxation at 2 spinal levels: C5 to C6 (1.5 mm) and C6 to C7 (3.3 mm; Figure 1). Flexionextension radiographs were obtained in active neck flexion and extension under physician supervision. The flexion view demonstrated segmental kyphosis (10.3 degrees anterior angulation) at the C3 to C4 spinal level and anterior subluxation at 3 levels: C2 to C3 (3.6 mm), C3 to C4 (1.8 mm), and C6 to C7 (2.6 mm; Figure 2). Complete reduction of anterior subluxation was observed on the extension view (Figure 3). A neck magnetic
Figure 1. Lateral cervical spine plain radiograph demonstrating physiologic anterior subluxation at C5 to C6 and C6 to C7 spinal levels (neutral view).
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ANNALS OF EMERGENCY MEDICINE
resonance image (MRI) showed no evidence of ligamentous injury but confirmed the anterior subluxation seen on lateral cervical spine radiographs. The patient was given the diagnosis of cervical strain and physiologic anterior subluxation. She was discharged home with symptomatic treatment. A follow-up visit at 1.5 weeks revealed significant decrease in neck pain and improvement in active neck range of motion. DISCUSSION
Physiologic anterior subluxation is thought to be the result of normal hypermobility of primarily the upper cervical spine in children, likely caused by a number of factors: a wedged anterior contour of the upper cervical spine vertebral bodies,1,3 ligamentous laxity,5,6,8,12 horizontally configured apophyseal facets,3,5,8 and a higher fulcrum of motion in the cervical spine of young children (C2/C3 level) up to age 10 years compared with
Figure 2. Lateral cervical spine plain radiographs demonstrating physiologic anterior subluxation at C2 to C3, C3 to C4, and C6 to C7 spinal levels and segmental kyphosis at C3 to C4 spinal level (flexion view).
4 7 3
P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
lower levels (C4/C5 or C5/C6) in older children and adolescents.5,8,12 The term ‘‘pseudosubluxation’’ is commonly assigned to the phenomenon reported here.5-11 ‘‘Physiologic anterior subluxation’’ is a more accurate term to describe the normal forward displacement of vertebral bodies in the immature cervical spine because the subluxation is a real phenomenon. Moreover, the term distinguishes itself from physiologic posterior subluxation, which is also, but less frequently, observed in the pediatric cervical spine, typically at the C2 to C3 spinal level in extension.5,6,12 All normal anterior movement of the pediatric cervical spine may be referred to as physiologic anterior subluxation. The amount of vertebral displacement in physiologic anterior subluxation has been reported to vary from less than 1 mm to 5 mm3,5 and may be accompanied by acute forward angulation of vertebral segments (segmental kyphosis).5 Additionally, vertebral displacement in physiologic anterior subluxation may be proportional to the degree of neck flexion,1,2,5 including flexion induced by
Figure 3. Lateral cervical spine plain radiographs demonstrating complete reduction of physiologic anterior subluxation (extension view).
4 7 4
a stiff collar. Correction of the displacement with the neck in neutral and extension positions has also been described.5,8 Physiologic anterior subluxation may be accentuated by muscle spasm.2 In the patient reported here, anterior displacement was isolated to the lower cervical spine on the neutral lateral view, measured less than 4 mm, emerged in the upper cervical spine with accompanying segmental kyphosis in flexion, resolved completely in extension, and was confirmed as physiologic by a normal MRI. The necessity of additional radiographic imaging in the evaluation of an acutely injured patient with findings consistent with physiologic anterior subluxation on a lateral cervical spine radiograph has not been defined but likely depends on mechanism of injury, clinical risk, and presence of associated radiographic findings. In the patient at low risk for ligamentous injury (ie, minor mechanism, normal level of consciousness, without neck pain or posterior midline tenderness, normal neurologic examination, and without distracting injury), the findings should be recognized as physiologic without need of further imaging. On the other hand, any patient at high risk for ligamentous injury (ie, with additional radiographic abnormalities such as divergence of spinous processes, narrowing of anterior disc space, displacement of apophyseal joints, excessive vertebral body displacement, or paravertebral soft tissue swelling) should undergo MRI to evaluate for pathologic subluxation. Less clear is the role of further imaging in clinically difficult cases (ie, the patient with obvious findings of physiologic anterior subluxation but also severe mechanism, significant neck pain, concerning physical examination such as posterior midline neck tenderness or torticollis, or equivocal findings on standard cervical spine plain radiographs). Currently, no absolute criterion standard exists for verifying physiologic anterior subluxation short of a normal MRI, which is neither practical nor available in most EDs. If the findings are located at the C2 or C3 level, satisfactory alignment of the posterior cervical line is helpful but not always sufficient to rule out a pathologic subluxation.12,13 Flexion-extension radiographs have been shown to have a limited role in the acute evaluation of blunt cervical spine injury14,15 but may have a useful indication here in that physiologic anterior subluxation observed in neutral or flexion may correct in extension.5,7,8 If this tool were validated, it could be used to verify physiologic anterior subluxation at all levels of the cervical spine, from C2 to C7 where the phenomenon can occur, thereby saving referral or transfer
ANNALS OF EMERGENCY MEDICINE
44:5
NOVEMBER 2004
P H Y S I O L O G I C A N T E R I O R S U B L U X A T I O N Ralston
for MRI. However, evidence for a normal extension radiograph as verification of physiologic anterior subluxation currently does not exist beyond the level of case report, and with the exception of the child in this report, patients in previous case reports did not have confirmatory normal MRI results.5,8 The performance of a normal extension radiograph compared with normal MRI as a criterion standard for physiologic anterior subluxation needs to be evaluated prospectively. Without this evaluation, anterior subluxation in clinically difficult cases cannot be assumed to be physiologic and should be differentiated from ligamentous injury by MRI.16 Whether cases with findings occurring solely at the C2 to C3 level could be managed as an exception to this is unfounded in the literature. In summary, physiologic anterior subluxation is a phenomenon common to the upper pediatric cervical spine but has now been reported to occur at every spinal level from C2 to C7. All normal anterior movement of the pediatric cervical spine may be referred to as physiologic anterior subluxation, a more accurate term to describe the phenomenon than ‘‘pseudosubluxation’’ because the subluxation is real. Physiologic anterior subluxation can be seen in children in the setting of trauma, when it must be distinguished from pathologic subluxation. In this report, physiologic anterior subluxation was confirmed for the first time at C5 to C6 and C6 to C7 spinal levels in a 9-yearold child evaluated in the acute setting after cervical spine injury.
4. Dunlap JP, Morris M, Thompson RG. Cervical-spine injuries in children. J Bone Joint Surg. 1958;40A:681-686. 5. Jacobson G, Bleecker HH. Pseudosubluxation of the axis in children. Am J Roentgenol. 1959;82:472-481. 6. Cattell HS, Filtzer DL. Pseudosubluxation and other normal variations in the cervical spine in children. J Bone Joint Surg. 1965;47A:1295-1309. 7. Penning L. Normal movements of the cervical spine. Am J Roentgenol. 1978;130: 317-326. 8. Harrison RB, Keats TE, Winn HR, et al. Pseudosubluxation of the axis in young adults. J Can Assoc Radiol. 1980;31:176-177. 9. Fechtel SG. Pseudosubluxation of the cervical spine in adolescents: a case report. J Manipulat Physiol Ther. 1983;6:81-83. 10. Goni Orayen C, Perez Martinez A, Martin Martinez C, et al. Pseudosubluxation of C2-C3 during childhood: a common clinical-radiological misdiagnosis. Ann Exp Pediatr. 1992;36:390-392. 11. Shaw M, Burnett H, Wilson A, et al. Pseudosubluxation of C2 on C3 in polytraumatized children: prevalence and significance. Clin Radiol. 1999;54:377-380. 12. Swischuk L. Emergency Imaging of the Acutely Ill or Injured Child. 4th ed. Baltimore, MD: Williams & Wilkins; 2000. 13. Ralston ME, Chung K, Barnes PD, et al. Role of flexion-extension radiographs in blunt pediatric cervical spine injury. Acad Emerg Med. 2001;8:237-245. 14. Swischuk LE. Anterior displacement of C2 in children: physiologic or pathologic? A helpful differentiating line. Radiology. 1977;122:759-763. 15. Pollack CV, Hendey GW, Martin DR, et al. Use of flexion-extension radiographs of the cervical spine in blunt trauma. Ann Emerg Med. 2001;38:8-11. 16. Slack SE, Clancy MJ. Clearing the cervical spine of paediatric trauma patients. Emerg Med J. 2004;21:189-193.
I thank Kirsten Ecklund, MD, for her helpful advice. Received for publication April 28, 2004. Revision received May 24, 2004. Accepted for publication May 26, 2004. Available online September 11, 2004. The views expressed in this article are those of the author and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States government. The author reports this study did not receive any outside funding or support. Address for reprints: Mark E. Ralston, MD, MPH, 1117 Rainier Circle, Oak Harbor, WA 98277; 360-240-8714, fax 360-257-9662; E-mail [email protected].
REFERENCES 1. Bailey DK. The normal cervical spine in infants and children. Radiology. 1952;59: 712-719. 2. Townsend EH, Rowe ML. Mobility of the upper cervical spine in health and disease. Pediatrics. 1952;10:567-572. 3. Sullivan CR, Bruwer AJ, Harris LE. Hypermobility of the cervical spine in children: a pitfall in the diagnosis of cervical dislocation. Am J Surg. 1958;95: 636-640.
NOVEMBER 2004
44:5
ANNALS OF EMERGENCY MEDICINE
4 7 5