CLINICAL
IMAGING
1992;16:31-33
31
CERVICAL FRACTURE IN ANKYLOSING SPONDYLITIS: VALUE OF MULTIDIMENSIONAL IMAGING ELLIOT K. FISHMAN,
MD
AND DONNA MAGID,
creates a rigid spinal Ankylosing spondylitis column that cannot easily accommodate to altered or increased forces. Fractures or fracture-subluxation may be seen following apparently trivial injury. Assessment of the lower cervical and cervicothoracic spine can be limited in the kyphotic, ankylosed spine. However, reformatted computed tomography (CT] data can be manipulated to provide true orthogonal (sagittal, coronal) planar images of the obliqued spine, and can be used to provide a three-dimensional overview of anatomy prior to treatment. One such case is presented. KEY WORDS:
Ankylosing spondylitis; Cervical spine; Computed tomography
MD
spine in the AS patient may be particularly difficult to evaluate with routine radiographs. Marked kyphosis at the cervicothoracic junction and inability to comply with positioning are two factors contributing to such difficulties. Computed tomography is less position-dependent than standard radiographs but can also be limited in these patients due to difficulty positioning them in the scanning gantry. Images may be obtained at unusual obliquities and be somewhat difficult to interpret. However, reformation of the acquired CT data into multiple orthogonal planes can prove helpful in detection of known or suspected fractures. In addition, three-dimensional display of the data set can help in interpreting the full extent of injury. We present a case of a posterior cervical ring fracture with subluxation documented on twodimensional (2D) and three-dimensional (3D) imaging and discuss its use in this group of patients.
INTRODUCTION Fractures at the cervicothoracic junction are one of the recognized complications in the patient with ankylosing spondylitis (AS). Approximately 75% of spinal fractures in AS occur in the cervical spine (l3). Hyperextension is the most common mechanism of injury, with significant fractures often resulting from trivial trauma. Detection of these fractures is important as cervical fractures are associated with a high morbidity and mortality. However, the cervical
From the Russell H. Morgan Department of Radiology and Radiological Science (E.K.F., D.M.), and the Department of Orthopaedic Surgery (D.M.). The Johns Hopkins Medical Institutions, Baltimore, Maryland. Address reprint requests to Donna Magid, MD, Department of Radioloav. The lohns Hookins Hosuital. 600 N. Wolfe Street. Bal. ’ timore, %D 212~5. Received April 1991; revised June 1991: accepted July 1991. 0 1992 by Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0&?99-7071/92/$5.00
CASE HISTORY The patient was a 75-year-old man with a 30-year history of alcohol and tobacco abuse. On the day of admission the patient was in a family altercation and was thrown against the refrigerator, after which he noted that he could neither walk nor move his hands. The patient stated that for the past several years his head had “been stuck in position with his chin nearly fixed to his chest.” Cervical spine films in the emergency room were suboptimal due to the patient’s fixed flexion. A CT scan with two-dimensional and three-dimensional reconstruction was ordered [Figures 1 and 2). The CT scan demonstrated a fracture of the anterior syndesmophyte at C6-7 with approximately 3 mm of subluxation. The fracture and subluxation were best seen on the edited 3D views in the spinal axis, and on sagittal 2D views. A subsequent myelo-
32
CLINICAL IMAGING VOL. 16, NO. 1
FISHMAN AND MAGID
DISCUSSION Ankylosing spondylitis is an inflammatory arthropaAlthy that occurs in up to 1.6% of the population. though sacroiliac and thoracolumbar spinal involve-
B FIGURE 1. (A) Orthotool@) display of transaxial (top left), coronal (bottom left) and sagittal (bottom right) images, AS patient with C6-7 fracture. Transaxial and coronals are obliqued due to patient’s rigid kyphosis. True sagittal image shows the C6-7 fracture (arrow) with focal step-off in posterior vertebral body. (B) Zoomed sagittal again demonstrates fracture (arrows).
gram demonstrated a partial block at the C6-7 level. The patient was taken to surgery for a cervical laminectomy for C5-Tl with C6-7 fusion with bone graft, followed by halo fixation. By three month follow-up, the patient was pain-free and ambulating with a walker.
ment are most common, cervical spine disease is seen in patients with long-standing or extensive disease. Up to 75% of patients develop cervical ankylosis, often as a late manifestation (4). Ankylosing spondylitis may be complicated by a number of skeletal and neurologic complications including spinal cord compression, spinal fractures due to injury to the rigid spine, cauda equina syndrome, or solitary lumbosacral or thoracic nerve lesions (l-5). The ankylosed spine has no mobility to accommodate forces of weight bearing. This magnifies even trivial forces acting on the rigid spine. Fractures may appear through the anterior or posterior columns, although they often originate in flexion and affect the posterior elements (5). Because the AS patient often has a baseline of discomfort or pain, fractures following minor trauma may be under evaluated. It may be impossible to obtain adequate plain films. Increased thoracic kyphosis blocks visualization of the lower cervical spine, which is obscured by the shoulder girdle. Magnetic resonance imaging (MRI) has been used to evaluate cervicothoracic spinal trauma. It can provide excellent direct visualization of the cord, ligaments, and disc (6). It may be more limited, however, in assessing complex fracture patterns or in defining densely ossified or calcified structures. It is also limited by metal hardware or life-support equipment, and in most institutions is far less readily available as an after-hours emergency procedure. CT is rapid, relatively available in most settings, and less expensive. Computed tomography has been shown to be an excellent modality for evaluating fractures of the cer-
FIGURE
2. 3D view step-off at that level.
again profiles
C6-7
fracture
with
JANUARY-MARCH
1992
vital spine. In the AS patient with inadequate plain films, it may be particularly helpful. Unfortunately, due to the difficulty in positioning the patient in the CT scanning gantry, the axis of the images may be atypical and therefore difficult to interpret. By reformatting the data into a three-dimensional data set for rotation along any axis, one can overcome this problem and create accurate orthogonal images that display the spinal column including the vertebral bodies and posterior elements. This enhances the detection of subtle fractures and subluxation. The additional time required for acquiring adequate data is minimal. In our institution, the transfer and reformatting time is also trivial (about 3 and 1 min, respectively). Our obliquing time is approximately 10 sec. All commercially available CT scanners now offer reformatting software to allow coronal and sagittai reconstructions; most also allow adjustment of those planes to accommodate obliqued transaxial data. This may require 5 to 15 min additional console time, for most CT equipment. In conclusion, we present a case of cervical fracture in a patient with ankylosing spondylitis in which the extent of injury was best defined on refor-
CT IN ANKYLOSING
SPONDYLITIS
33
matted orthogonal and three-dimensional CT displays. Accurate visualization of such complications of AS can allow more precise therapeutic management and follow up (7-8). REFERENCES 1. Thomas
volvement 150.
DJ, Kendall MJ, Whitfield AGW. Nervous system inin ankylosing spondylitis. Br Med J 1971;1:148-
2. Lee MLH, Waters DJ. Neurological spondylitis. Br Med J 1962;1:798.
complication
of ankylosing
3. Mitchell MJ, Sartoris DJ, Moody 13, Resnick D. Cauda Equina syndrome complicating ankylosing spondylitis. Radiology 1990;175:521-525. 4. Hunter Semin
T. The spinal complications of ankylosing Arthritis Rheum 1989;19:172-182.
5. Gelineck J, DeCarvalho AD. Fractures ing spondylitis. Fortschr Rontgenstar
spondylitis.
of the spine in ankylos1990;152(3):307-310.
6. Goldberg AL, Rothfus WE. Deeb ZL, et al. The impact of magnetic resonance on the diagnostic evaluation of acute cervicothoracic spinal trauma. Skeletal Radio1 1988;17:89-95. 7. Harding JR, McCall IW, Park WM. Jones BP. Fracture cervical spine in ankylosing spondylitis. Br J 1985;58:3-7.
of the Radio1
8. Murray G, Persellin R. Cervical fracture complicating ankylosing spondylitis: a report of eight cases and review of literature. Am J Med 1981:70:1033-1041.
IMAGING
1992;16:31-33
31
CERVICAL FRACTURE IN ANKYLOSING SPONDYLITIS: VALUE OF MULTIDIMENSIONAL IMAGING ELLIOT K. FISHMAN,
MD
AND DONNA MAGID,
creates a rigid spinal Ankylosing spondylitis column that cannot easily accommodate to altered or increased forces. Fractures or fracture-subluxation may be seen following apparently trivial injury. Assessment of the lower cervical and cervicothoracic spine can be limited in the kyphotic, ankylosed spine. However, reformatted computed tomography (CT] data can be manipulated to provide true orthogonal (sagittal, coronal) planar images of the obliqued spine, and can be used to provide a three-dimensional overview of anatomy prior to treatment. One such case is presented. KEY WORDS:
Ankylosing spondylitis; Cervical spine; Computed tomography
MD
spine in the AS patient may be particularly difficult to evaluate with routine radiographs. Marked kyphosis at the cervicothoracic junction and inability to comply with positioning are two factors contributing to such difficulties. Computed tomography is less position-dependent than standard radiographs but can also be limited in these patients due to difficulty positioning them in the scanning gantry. Images may be obtained at unusual obliquities and be somewhat difficult to interpret. However, reformation of the acquired CT data into multiple orthogonal planes can prove helpful in detection of known or suspected fractures. In addition, three-dimensional display of the data set can help in interpreting the full extent of injury. We present a case of a posterior cervical ring fracture with subluxation documented on twodimensional (2D) and three-dimensional (3D) imaging and discuss its use in this group of patients.
INTRODUCTION Fractures at the cervicothoracic junction are one of the recognized complications in the patient with ankylosing spondylitis (AS). Approximately 75% of spinal fractures in AS occur in the cervical spine (l3). Hyperextension is the most common mechanism of injury, with significant fractures often resulting from trivial trauma. Detection of these fractures is important as cervical fractures are associated with a high morbidity and mortality. However, the cervical
From the Russell H. Morgan Department of Radiology and Radiological Science (E.K.F., D.M.), and the Department of Orthopaedic Surgery (D.M.). The Johns Hopkins Medical Institutions, Baltimore, Maryland. Address reprint requests to Donna Magid, MD, Department of Radioloav. The lohns Hookins Hosuital. 600 N. Wolfe Street. Bal. ’ timore, %D 212~5. Received April 1991; revised June 1991: accepted July 1991. 0 1992 by Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0&?99-7071/92/$5.00
CASE HISTORY The patient was a 75-year-old man with a 30-year history of alcohol and tobacco abuse. On the day of admission the patient was in a family altercation and was thrown against the refrigerator, after which he noted that he could neither walk nor move his hands. The patient stated that for the past several years his head had “been stuck in position with his chin nearly fixed to his chest.” Cervical spine films in the emergency room were suboptimal due to the patient’s fixed flexion. A CT scan with two-dimensional and three-dimensional reconstruction was ordered [Figures 1 and 2). The CT scan demonstrated a fracture of the anterior syndesmophyte at C6-7 with approximately 3 mm of subluxation. The fracture and subluxation were best seen on the edited 3D views in the spinal axis, and on sagittal 2D views. A subsequent myelo-
32
CLINICAL IMAGING VOL. 16, NO. 1
FISHMAN AND MAGID
DISCUSSION Ankylosing spondylitis is an inflammatory arthropaAlthy that occurs in up to 1.6% of the population. though sacroiliac and thoracolumbar spinal involve-
B FIGURE 1. (A) Orthotool@) display of transaxial (top left), coronal (bottom left) and sagittal (bottom right) images, AS patient with C6-7 fracture. Transaxial and coronals are obliqued due to patient’s rigid kyphosis. True sagittal image shows the C6-7 fracture (arrow) with focal step-off in posterior vertebral body. (B) Zoomed sagittal again demonstrates fracture (arrows).
gram demonstrated a partial block at the C6-7 level. The patient was taken to surgery for a cervical laminectomy for C5-Tl with C6-7 fusion with bone graft, followed by halo fixation. By three month follow-up, the patient was pain-free and ambulating with a walker.
ment are most common, cervical spine disease is seen in patients with long-standing or extensive disease. Up to 75% of patients develop cervical ankylosis, often as a late manifestation (4). Ankylosing spondylitis may be complicated by a number of skeletal and neurologic complications including spinal cord compression, spinal fractures due to injury to the rigid spine, cauda equina syndrome, or solitary lumbosacral or thoracic nerve lesions (l-5). The ankylosed spine has no mobility to accommodate forces of weight bearing. This magnifies even trivial forces acting on the rigid spine. Fractures may appear through the anterior or posterior columns, although they often originate in flexion and affect the posterior elements (5). Because the AS patient often has a baseline of discomfort or pain, fractures following minor trauma may be under evaluated. It may be impossible to obtain adequate plain films. Increased thoracic kyphosis blocks visualization of the lower cervical spine, which is obscured by the shoulder girdle. Magnetic resonance imaging (MRI) has been used to evaluate cervicothoracic spinal trauma. It can provide excellent direct visualization of the cord, ligaments, and disc (6). It may be more limited, however, in assessing complex fracture patterns or in defining densely ossified or calcified structures. It is also limited by metal hardware or life-support equipment, and in most institutions is far less readily available as an after-hours emergency procedure. CT is rapid, relatively available in most settings, and less expensive. Computed tomography has been shown to be an excellent modality for evaluating fractures of the cer-
FIGURE
2. 3D view step-off at that level.
again profiles
C6-7
fracture
with
JANUARY-MARCH
1992
vital spine. In the AS patient with inadequate plain films, it may be particularly helpful. Unfortunately, due to the difficulty in positioning the patient in the CT scanning gantry, the axis of the images may be atypical and therefore difficult to interpret. By reformatting the data into a three-dimensional data set for rotation along any axis, one can overcome this problem and create accurate orthogonal images that display the spinal column including the vertebral bodies and posterior elements. This enhances the detection of subtle fractures and subluxation. The additional time required for acquiring adequate data is minimal. In our institution, the transfer and reformatting time is also trivial (about 3 and 1 min, respectively). Our obliquing time is approximately 10 sec. All commercially available CT scanners now offer reformatting software to allow coronal and sagittai reconstructions; most also allow adjustment of those planes to accommodate obliqued transaxial data. This may require 5 to 15 min additional console time, for most CT equipment. In conclusion, we present a case of cervical fracture in a patient with ankylosing spondylitis in which the extent of injury was best defined on refor-
CT IN ANKYLOSING
SPONDYLITIS
33
matted orthogonal and three-dimensional CT displays. Accurate visualization of such complications of AS can allow more precise therapeutic management and follow up (7-8). REFERENCES 1. Thomas
volvement 150.
DJ, Kendall MJ, Whitfield AGW. Nervous system inin ankylosing spondylitis. Br Med J 1971;1:148-
2. Lee MLH, Waters DJ. Neurological spondylitis. Br Med J 1962;1:798.
complication
of ankylosing
3. Mitchell MJ, Sartoris DJ, Moody 13, Resnick D. Cauda Equina syndrome complicating ankylosing spondylitis. Radiology 1990;175:521-525. 4. Hunter Semin
T. The spinal complications of ankylosing Arthritis Rheum 1989;19:172-182.
5. Gelineck J, DeCarvalho AD. Fractures ing spondylitis. Fortschr Rontgenstar
spondylitis.
of the spine in ankylos1990;152(3):307-310.
6. Goldberg AL, Rothfus WE. Deeb ZL, et al. The impact of magnetic resonance on the diagnostic evaluation of acute cervicothoracic spinal trauma. Skeletal Radio1 1988;17:89-95. 7. Harding JR, McCall IW, Park WM. Jones BP. Fracture cervical spine in ankylosing spondylitis. Br J 1985;58:3-7.
of the Radio1
8. Murray G, Persellin R. Cervical fracture complicating ankylosing spondylitis: a report of eight cases and review of literature. Am J Med 1981:70:1033-1041.
