- Email: [email protected]
Cervical Disk Prolapse
C5J
Cervical Disk Prolapse O. WAYNE HOUSER, M.D., BURTON M. ONOFRIO, M.D., GARY M. MILLER, M.D., W. NEATH FOLGER, M.D., AND PATSY
L.
SMITH,
R.N.
• Objective: To correlate the findings on computed tomographic myelography (CTM) with surgically and pathologically proven prolapsed cervical disks, mention other pertinent cross-sectional imaging studies, and note the clinical relevance of certain CTM features. • Design: We retrospectively reviewed the medical and radiologic records of Mayo patients with suspected degenerative cervical disk disease during a 4year period. • Material and Methods: Between January 1986 and December 1989, 734 patients with possible cervical disk disease underwent assessment by CTM. An extruded disk was noted in 297 of these patients. In this study group, magnetic resonance (MR) imaging was also done in 28 patients and plain computed tomography was performed in 14, and we summarized those findings. • Results: Of the 297 study patients, 280 had a cervical radiculopathy and 17 had a myelopathy. The literature on imaging of cervical disk disease is convoluted, if not confusing. Articles that advocate the use of computed tomography (CT),1 intravenous contrast-enhanced computed tomography (IVCT),2-4 computed tomographic myelography (CTM),5-12 and magnetic resonance (MR)13,14 have been published, including some comparative studies. 15-21 In a 1990 review of the radiologic literature on cervical disk disease, Russell" concluded that (1) cervical myelopathy should be imaged by MR; (2) MR is less accurate than IVCT or CTM in defining the cervical spinal canal and foramina; (3) IVCT is more versatile than MR in distinguishing between soft disk and bony spur; and (4) CTM is the examination of choice for cervical disk disease. Kido and associates" mentioned that Kent and colleagues" were frustrated by attempting to determine the accuracy of various
From the Department of Diagnostic Radiology (O.W.H., G.M.M., P.L.S.), Department of Neurologic Surgery (B.M.O.), and Department of Neurology (W.N,F.), Mayo Clinic Rochester, Rochester, Minnesota. Address reprint requests to Dr. O. W. Houser, Department of Diagnostic Radiology, Mayo Clinic Rochester, 200 First Street SW, Rochester, MN 55905. Mayo Clin Proc 1995; 70:939-945
CTM identified more than 90% of the extruded cervical disks. CTM could not distinguish between an osteophytic cartilaginous cap and a disk, and CTM could not identify the source of a cervical radiculopathy in 102 patients. Although only a few imaging studies other than CTM were performed, those modalities were less sensitive in the detection of prolapsed disks. • Conclusion: Imaging of cervical disk prolapse continues to be difficult, and the results are not always specific. CTM is the most sensitive imaging examination, but the number of MR studies in the current series of patients was insufficient for a reasonable comparison between the two modalities. (Mayo Clin Proc 1995; 70:939-945) CT = computed tomography; CTM = computed tomographic myelography; IVCT = intravenous contrast-enhanced computed tomography; MPGR = multiplanar gradient-recalled; MR =magnetic resonance
diagnostic studies. Furthermore, their personal efforts to perform a meta-analysis of cervical disk disorders had also been stymied, and they noted that the available data on disk prolapse were insufficient when they used the combination of a large series and surgical confirmation as a criterion. It is puzzling why more effort may have been expended on comparing CTM with MR or describing the evolving MR scanning techniques-':" than on correlating the findings from either of these techniques with surgical and pathologic findings. The purpose of this article is to correlate CTM with surgically and pathologically proven prolapsed cervical disk and to focus on the CTM features of prolapsed disk. STUDY SUBJECTS From January 1986 to December 1989, 734 patients with suspected degenerative disease of the cervical intervertebral disk underwent assessment clinically and by CTM. Among 494 patients, surgical intervention revealed disk prolapse in 297, neural foraminal stenosis in 95, spondylotic myelopathy in 93, calcifying pseudotumor in 1, spinal cord atrophy in 1, and no identified disease in 7. The 297 patients with 299 prolapsed disks are the subject of this report. All 939
© 1995 Mayo Foundation/or Medical Education and Research
For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,
940
Mayo Clin Proc, October 1995, Vol 70
CERVICAL DISK PROLAPSE
patients were assessed by a neurologist and a neurosurgeon, who agreed that CTM was warranted. All extruded disk fragments in the 278 patients who had a laminectomy and the 19 patients who had an anterior diskectomy were surgically confirmed and pathologically verified except in two instances, in which a tiny disk fragment was inadvertently aspirated intraoperatively. Additional cross-sectional preoperative imaging studies included MR in 28 patients and plain CT in 14. Either the clinical symptoms or the CTM findings were similar in 233 additional patients; thus, they will be mentioned to provide a more complete perspective. This group consisted of 181 nonsurgical patients and 52 surgical patients who had foraminal stenosis." In the nonoperative group, the final clinical diagnosis was cervical radiculopathy in 102, cervical neuropathy in 13, and neck or arm pain (or both) of undetermined cause in 40. The CTM studies in these patients were either nonrevealing or showed mild to moderate spondylosis. In contrast, CTM disclosed an apparent prolapsed disk that did not correspond to the patient's clinical symptoms in the other 26 nonoperative patients. All 52 surgical patients had a radiculopathy due to foraminal stenosis. Their CTMs revealed an apparent prolapsed disk at the entrance to the foraminal canal, but at operation, these apparent disks proved to be a cartilaginous cap superimposed on a bony osteophyte in 42 patients and only a cartilaginous cap in 10.
METHODS All histories, CTM, preoperative CT scans, and preoperative MR scans were retrospectively reviewed. The final clinical diagnosis, site of a radiculopathy, surgical findings, weight of disk, and pertinent radiologic findings were noted. Spondylosis, including bulging annulus and bony spurs that did not cause clinical symptoms, was too ubiquitous to be tabulated. CTM technique consisted of a lumbar intrathecal injection of 12 to 20 mL of iohexol or iopamidol, 180 or 200 mg of iodine/mL, respectively, followed by filming of the entire spinal canal and either 3-mm or 1.5-mm CT (GE 9800) oblique scans parallel to the intervertebral disks. Oblique axial sections parallel to the intervertebral disk were obtained through the clinically suspected pathologic site and any obvious abnormality noted by film examination. Plain CT examinations were performed by obtaining 3-mm or 5mm sections through the cervical spine. MR examinations (1.5-T magnet and 12.7-cm surface coil) included Tl and T2W or T2*W sagittal scanning sequences and either T2*W or Tl W (or both) oblique axial sections parallel to the intervertebral disk with use of 5-mm or 4-mm sections at the site of the patient's suspected clinical lesion or any abnormality noted on sagittal MR scans.
RESULTS Clinical, Surgical, and Pathologic Findings.-The study group consisted of 197 men and 100 women. Their ages ranged from 27 to 87 years (Table 1), but most patients were in the fifth or sixth decade of life. Clinically, a cervical radiculopathy was evident in 280 patients and a myelopathy in 17. The surgical reports for the 297 patients noted one or more prolapsed disks in 258 (87%), a prolapsed disk with a bony spur in 38 (13%) (Fig. 1), and a prolapsed disk with a fractured inferior facet in 1. The 297 patients had 299 extruded disks, from the third through the seventh cervical interspaces. The level was C-6 in 57%, C-5 in 21%, C-7 in 13%, C-4 in 8%, and C-3 in 1%. One patient had three concurrent extruded cervical disks. When a laminectomy was performed, the weight of the extruded disk ranged from 10 to 1,008 mg. Most extruded disks were at and inferior to the nerve roots; only a few had migrated superior to the nerve roots. If an anterior diskectomy was performed, the disk was continuous with the adjacent tissue and its weight was difficult to ascertain. Of the 19 anterior diskectomies, 11 were performed for midline disks in patients with myelopathy, and 8 were performed in patients whose prolapsed disk lay far enough laterally to incite a radiculopathy but did not extend sufficiently beyond the spinal cord to allow line-of-sight exposure with use of a posterior surgical approach. CT Myelography.-The size of the myelographic defect did not always correlate with the weight of the pathologic specimen because a relatively large disk that is predominantly in the axilla of the nerve root may produce only a small extradural defect. CTM findings corresponded to the surgical findings in 277 instances (in all 17 cases of myelopathy and in 260 cases of radiculopathy) when an extradural soft tissue mass encroached on the root sleeve or thecal sac; they were disparate in 22 instances in which a soft tissue mass was not evident despite the presence of a clinical radiculopathy (Table 2). The bulk of the extradural mass lay Table I.-Sex and Age Distribution of 297 Patients With Prolapsed Disks Factor
Sex Male Female Decade of life 3 4 5 6 7 8 9
No. of patients
197 100 4
54 102 73 49 12 3
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
CERVICAL DISK PROLAPSE
Mayo Clin Proc, October 1995, Vol 70
Fig. I. Computed tomographic myelogram. showing extruded 110mg left C-5 disk superimposed on bony spur.
at the level of the cervical foramen in 260 instances, encroached on or obliterated the adjacent root sleeve, and sometimes even displaced the adjacent spinal cord. In 190 instances, a prolapsed disk was suggested when the extradural defect extruded from the level of the adjacent disk superiorly into the region of the cervical foramen. In the other 70 instances, an extradural mass opposite the cervical foramen suggested a sequestered disk. The spinal cord was compressed by the disk extrusion in the other 17 patients. When compressed, the spinal cord did not have the configuration characteristically noted when it is chronically compressed by spondylosis." In 13 patients, a large midline or predominantly midline disk deformed the adjacent cervical spinal cord; in 3 patients with a congenitally narrow cervical spinal canal, the disk fragments were smaller and weighed 38, 340, and 540 mg. In the other patient, the extruded disk was superimposed on degenerative cervical stenosis. The weight of the disk fragment in this patient could not be determined because the entire disk was
excised during the anterior diskectomy plus fusion. Of interest, 3 of 6 C-3 and 4 of 17 C-4 disk extrusions were associated with myelopathy. In 22 patients, surgical exploration was done on the basis of clinical findings only. Among 19 of these patients , the surgeon found an extruded disk at C-4 in 2, C-5 in 6, C-6 in 7, and C-7 in 6; the surgical exploration was negative in 3 patients (Table 2). CTM revealed slight spondylosis without a definite soft tissue mass in 19 patients and no abnormalities in 3. In contrast, a soft tissue extradural deformity appeared to be present on CTM in seven patients who had no cervical abnormalities on surgical exploration. In 52 patients, myelography showed an apparent extruded disk (in 10) or a bony spur that seemed to be associated with an extruded disk (in 42). At surgical exploration, the apparent disk proved to be simply a cap of cartilage (Fig. 2).28 Finally, an extradural soft tissue mass was evident on CTM in 26 additional patients whose symptoms did not correlate with the lesion, which was at a level remote from any symptoms or even affected the asymptomatic side. In this group, no patients underwent surgical exploration. Similarly, none of the 155 patients who had a final diagnosis of a cervical radiculopathy, neuropathy, or neck and arm pain, and either no abnormal findings or slight to moderate spondylosis on CfM, underwent surgical exploration. MR lmaging.-MR data were limited to 28 patients. The imaging sequences obtained were Tl W in 27 patients, multiplanar gradient-recalled (MPGR) in 19, and T2W spin echo in 15. Relative to cerebrospina l fluid, extruded cervical disks varied from being hyperintense to isointense on Tl W images and from hypointense to isointense on T2W images. Extruded disks were hyperintense in comparison with cerebrospinal fluid on Tl W images in 14 patients and hypointense on T2W or MPGR sequences in 9. In addition, these disks may (Fig. 3) or may not (Fig. 4) be covered by a thin hypointense line, representing the posterior longitudinal ligament and dura. In this series, the extruded disk was depicted by its inherent signal or both Tl W and MPGR sequences in 11 patients, by Tl W hyperintensity alone in 3, and by MPGR hypointensity in 3. A thin hypointense dural
Table 2.-Myelograph ic Findings in Cervical Disk Prolapse (299 Disks) Soft tissue mass and associated symptoms
Cervical site
Radiculopathy
C-3 C-4 C-5 C-6 C-7 Total
3 13 55 156 33 260
Myelopathy 3 4 5 5 0 17
941
Errorspondylosis only 0 2 5 7 5 19
Negative
Total
0 0 I I
6 19 66 169 39 299
1
3
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
942
CERVICAL DISK PROLAPSE
Mayo Clio Proc, October 1995, Vol 70
The study revealed an extruded disk in six patients and foraminal stenosis in one; in seven patients, no abnormalities were detected.
Fig. 2. Computed tomographic myelogram of stenosis at entrance to foraminal canal due to cartilaginous cap at C-5 on the right. No extruded disk was found.
posterior longitudinal ligament covered an isointense disk on T1W images in one patient and an isointense disk on MPGR sequences in another patient. The most useful studies were the 19 MPGR axial sequences, which revealed a hypointense disk in nine patients and a posterior ligament-dural line covering six isointense disks. Plain CT.-Plain CT of the cervical spine was performed in 14 patients who had a suspected extruded cervical disk.
DISCUSSION Clinically, cervical degenerative disk disease usually involves multiple vertebral levels, has a preponderance in male patients, and occurs in middle-aged and older patients. One type of cervical disk disease-disk prolapse-differs. Disk prolapse is virtually always limited to a single disk level, usually involves the fifth and sixth cervical disks, typically manifests during the fifth and sixth decades of life, and is characterized clinically by either a radiculopathy or, less frequently, a myelopathy.s-" In the current series, a radiculopathy occurred in 94%, a myelopathy in 6%, a C-6 extrusion in 57%, and a C-5 extrusion in 21%. The site of a prolapsed disk relative to the cervical spinal cord may influence the surgical approach. Typically, lateral cervical disks are removed by the posterior approach. The surgical exposure of prolapsed midline disks that compromise the spinal cord, or some paramedian disks that compromise either the spinal cord or the nerve root but do not extend beyond the lateral margin of the cervical cord, is usually impossible without excessive manipulation of the spinal cord. Such disks should be removed by the anterior approach. Our finding of myelopathy in 50% of C-3 and almost 25% of C-4 disk extrusions agrees with the observations reported by O'Laoire and Thomas." Our surgical findings of disk extrusion do not match those of Aldrich,' who noted sequestration in all 36 of his patients with
Fig. 3. A, Computed tomographic myelogram, demonstrating extruded 250-mg left C-6 disk. B, Multiplanar gradientrecalled magnetic resonance image, showing disk slightly hypointense in comparison with cerebrospinal fluid and an overlying posterior longitudinal ligament-dural line. (Echo time, 20 ms; repetition time 600 ms.)
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
Mayo Clin Proc, October 1995, Vol 70
CERVICAL DISK PROLAPSE
943
Fig. 4. A, Computed tomogram, showing 200-mg right C-6 extruded disk. Band C, Magnetic resonance scans, with (B) and without (C) diethylenetriamine pentaacetic acid , do not show a T1W extruded disk because it is isointense in comparison with cerebrospinal fluid. D, Multiplanar gradient-recalled imaging fails to show same extruded disk, which is also isointense in comparison with cerebrospinal fluid .
posterolateral disk disorders. The only other surgical finding of note was that 13% of cervical disks in our series were superimposed on an osteophyte . Pathologically, the initial manifestations of cervical disk disease can include prolapsed disk, prolapsed disk superimposed on an osteophyte, cartilaginous cap, cartilaginous cap superimposed on an osteophyte, bony osteophyte, synovial cyst, hypertrophy of flaval ligaments, and bulging annulus. Current imaging techniques, however, do not always distinguish among the possibilities in this spectrum. " Furthermore, these manifestations , by virtue of their size or site of involvement, do not invariably cause clinical symptoms. Therefore, both imaging of the pathologic condition and correlating the imaging, clinical, and surgical findings remain somewhat difficult despite recent advances in CTM and MR.
The literature reveals a CTM detection rate for cervical prolapsed disk that ranges from 75 to 100%; most published rates are between these two extreme s. Our detection rate of approximately 90% is similar to the 87% reported by Modic and colleagues . I ? Our error rate included an undercall rate of more than 7% when surgical exploration showed a clinically suspected prolapsed disk that CTM failed to identify. This discrepancy included about 15% of cases of prolapsed disk at C-7, where shoulder artifact degrades the results of examination. Conversely , the overcall rate of slightly more than 2% is more distressing because surgical exploration disclosed no abnormality and did not benefit patients who had an apparent prolapsed disk on CTM that matched the site of the patient's radiculopathy. Intrinsically, CTM does not facilitate distinction between prolapsed disks and cartilaginous caps of an osteophyte.
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
944
CERVICAL DISK PROLAPSE
Both findings have the appearance of soft tissue that mayor may not be superimposed on a bony spur. Our 52 patients with stenosis at the entrance to the foraminal canal and CTM features that resembled a prolapsed disk with or without an associated osteophyte were not considered errors because the patients had a radiculopathy due to nerve root compression that was relieved by the surgical intervention. Similarly, those nonsurgical patients who had an apparent prolapsed disk that did not correspond to symptoms also were not included as errors. This limited MR survey suggests that a single sequence, whether Tl W, T2W, or MPGR, will reveal an inherent disk signal that differs from that for cerebrospinal fluid in approximately half the prolapsed cervical disks, a combination of two sequences will disclose almost two-thirds, and a combined sequence plus a posterior longitudinal ligamentdural line will detect slightly more than two-thirds. The detection rate of about 68% in this series approaches but does not match the 75% rate noted by Brown and coworkers 15 and Modic and associates." Because cerebrospinal fluid provides the background for identification of disk prolapse, edema within the extruded disk reduces the sensitivity of both Tl W and MPGR sequences. Furthermore, the absence of fat within the cervical spinal canal, noted in recent anatomic studies, may contribute to the lack of Tl W sensitivity. The hypodense posterior longitudinal ligamentdural line was useful in confirming 12 extruded disks and identifying 2 disks; thus, failure to detect this structure also affects sensitivity. The reason for its absence is unknown. The description of sequestered disks reported by Aldrich" indicates that this structure may be tom, and the incidence of disk extrusion in this series suggests that the overlying posterior longitudinal ligament and dura may be attenuated. CONCLUSION CTM, although not always specific, was the imaging procedure of choice for diagnosing cervical degenerative disk disease, including prolapsed disk, at our institution from January 1986 to December 1989. Whether the CTM preponderance persists will depend on technologic advances. CTM is a mature modality that is unlikely to improve dramatically. In contrast, MR is evolving. New imaging sequences'<" may advance MR but will need pathologic correlation. Review of the literature by Kent and colleagues" and Kido and coworkers" has led them to suggest that published findings on cervical degenerative spinal disorders are flawed because of the paucity of large patient series with pathologic and surgical verification. Radiologists should be concerned and contribute appropriate data. Newer, perhaps stricter investigations with outcome analysis may dictate what future role, if any, imaging will have in the evaluation of disk prolapse.
Mayo Clin Proc, October 1995, Vol 70
REFERENCES 1. Daniels DL, Grogan JP, Johansen JG, Meyer GA, Williams AL, Haughton VM. Cervical radiculopathy: computed tomography and myelography compared. Radiology 1984; 151:109-113 2. Baleriaux D, Noterman J, Ticket L. Recognition of cervical soft disk herniation by contrast-enhanced CT. AJNR Am J Neuroradiol 1983; 4:607-608 3. Heinz ER, Yeates A, Burger P, Drayer BP, Osborne D, Hill R. Opacification of epidural venous plexus and dura in evaluation of cervical nerve roots: CT technique. AJNR Am J Neuroradiol 1984; 5:621-624 4. Russell EJ, D'Angelo CM, Zimmerman RD, Czervionke LF, Huckman MS. Cervical disk herniation: CT demonstration after contrast enhancement. Radiology 1984; 152:703712 5. Aldrich F. Posterolateral microdiscectomy for cervical monoradiculopathy caused by posterolateral soft cervical disc sequestration. J Neurosurg 1990; 72:370-377 6. Jahnke RW, Hart BL. Cervical stenosis, spondylosis, and herniated disc disease. Radiol Clin North Am 1991; 29:777-791 7. Landman JA, Hoffman JC Jr, Braun IF, Barrow DL. Value of computed tomographic myelography in the recognition of cervical herniated disk. AJNR Am J Neuroradiol 1984; 5:391-394 8. Masaryk TJ, Ross JS, Modic MT, Boumphrey F, Bohlman H, Wilber G. High-resolution MR imaging of sequestered lumbar intervertebral disks. AJNR Am J Neuroradiol 1988; 9:351-358 9. Modic MT, Masaryk TJ, Ross JS, Mulopulos GP, Bundschuh CV, Bohlman H. Cervical radiculopathy: value of oblique MR imaging. Radiology 1987; 163:227-231 10. Nakagawa H, Okumura T, Sugiyama T, Iwata K. Discrepancy between metrizamide CT and myelography in diagnosis of cervical disk protrusions. AJNR Am J Neuroradiol 1983; 4:604-606 11. Penning L, Wilmink JT, Specificity of CT myelographic findings in cervical nerve root symptoms. Neurosurg Rev 1986; 9:99-101 12. Russell EJ, Cervical disk disease. Radiology 1990; 177:313-325 13. Hedberg MC, Drayer BP, Flom RA, Hodak JA, Bird CR. Gradient echo (GRASS) MR imaging in cervical radiculopathy. AJR Am J Roentgenol 1988; 150:683-689 14. Ross JS, Ruggieri PM, Glicklich M, Obuchowski N, Dillinger J, Masaryk TJ, et a1. 3D MRI of the cervical spine: low flip angle FISP vs. Gd-DTPA turboFLASH in degenerative disk disease. J Comput Assist Tomogr 1993; 17:26-33 15. Brown BM, Schwartz RH, Frank E, Blank NK. Preoperative evaluation of cervical radiculopathy and myelopathy by surface-coil MR imaging. AJR Am J Roentgenol 1988; 151:1205-1212 16. Larsson E-M, HoMs S, Cronqvist S, Brandt L. Comparison of myelography, CT myelography and magnetic resonance imaging in cervical spondylosis and disk herniation: pre- and postoperative findings. Acta Radiol 1989; 30:233-239 17. Modic MT, Masaryk TJ, Mulopulos GP, Bundschuh C, Han JS, Bohlman H. Cervical radiculopathy: prospective evaluation with surface coil MR imaging, CT with metrizamide, and metrizamide myelography. Radiology 1986; 161:753759
For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,
CERVICAL DISK PROLAPSE
Mayo Clin Proc, October 1995, Vol 70
18.
Neuhold A, Stiskal M, Platzer C, Pernecky G, Brainin M. Combined use of spin-echo and gradient-echo MR-imaging in cervical disk disease: comparison with myelography and intraoperative findings. Neuroradiology 1991; 33:422426 19. Schipper J, Kardaun JWPF, Braakman R, van Dongen KJ, Blaauw G. Lumbar disk herniation: diagnosis with CT or myelography? Radiology 1987; 165:227-231 20. Sobel DF, Barkovich AJ, Munderloh SH. Metrizamide myelography and postmyelographic computed tomography: comparative adequacy in the cervical spine. AJNR Am J Neuroradiol 1984; 5:385-390 21. Yousem DM, Atlas SW, Hackney DB. Cervical spine disk herniation: comparison of CT and 3DFT echo MR scans. J Comput Assist Tomogr 1992; 16:345-351 22. Kido DK, Mushin AI, Thornbury JR, Littenberg B, Rothenberg BM. A meta-analysis of imaging procedures for lumbar disc herniation. Presented at the American Society of Neuroradiology Annual Meeting; 1993 May 16-20; Vancouver, British Columbia, Canada 23. Kent DL, Haynor DR, Larson EB, Deyo RA. Diagnosis of lumbar spinal stenosis in adults: a metaanalysis of the accuracy of CT, MR, and myelography. AJR Am J Roentgenol 1992; 158:1135-1144 24. Ross JS, Ruggieri PM, Tkach JA, Masaryk TJ, Paranandi L, Dillinger Jf, et al. Gd-DTPA-enhanced 3D MR imaging of
25.
26.
27.
28.
29.
30.
945
cervical degenerative disk disease: initial experience. AJNR Am J Neuroradiol 1992; 13:127-136 Tsuruda JS, Norman D, Dillon W, Newton TH, Mills DG. Three-dimensional gradient-recalled MR imaging as a screening tool for the diagnosis of cervical radiculopathy. AJNR Am J Neuroradiol 1989; 10:1263-1271 Van Dyke C, Ross JS, Tkach J, Masaryk TJ, Modic MT. Gradient-echo MR imaging of the cervical spine: evaluation of extradural disease. AJNR Am J Neuroradiol 1989; 10:627-632 Yousem DM, Atlas SW, Goldberg HI, Grossman RI. Degenerative narrowing of the cervical spine neural foramina: evaluation with high-resolution 3DFT gradient-echo MR imaging. AJNR Am J Neuroradiol 1991; 12:229-236 Houser OW, Onofrio BM, Miller GM, Folger WN, Smith PL, Kallman DA. Cervical neural foraminal canal stenosis: computerized.tornographic myelography diagnosis. J Neurosurg 1993; 79:84-88 Houser OW, Onofrio BM, Miller GM, Folger WN, Smith PL. Cervical spondylotic stenosis and myelopathy: evaluation with computed tomographic myelography. Mayo Clin Proc 1994; 69:557-563 O'Laoire SA, Thomas DGT. Spinal cord compression due to prolapse of cervical intervertebral disc (herniation of nucleus pulposus): treatment in 26 cases by discectomy without interbody bone graft. J Neurosurg 1983; 59:847-853
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
Cervical Disk Prolapse O. WAYNE HOUSER, M.D., BURTON M. ONOFRIO, M.D., GARY M. MILLER, M.D., W. NEATH FOLGER, M.D., AND PATSY
L.
SMITH,
R.N.
• Objective: To correlate the findings on computed tomographic myelography (CTM) with surgically and pathologically proven prolapsed cervical disks, mention other pertinent cross-sectional imaging studies, and note the clinical relevance of certain CTM features. • Design: We retrospectively reviewed the medical and radiologic records of Mayo patients with suspected degenerative cervical disk disease during a 4year period. • Material and Methods: Between January 1986 and December 1989, 734 patients with possible cervical disk disease underwent assessment by CTM. An extruded disk was noted in 297 of these patients. In this study group, magnetic resonance (MR) imaging was also done in 28 patients and plain computed tomography was performed in 14, and we summarized those findings. • Results: Of the 297 study patients, 280 had a cervical radiculopathy and 17 had a myelopathy. The literature on imaging of cervical disk disease is convoluted, if not confusing. Articles that advocate the use of computed tomography (CT),1 intravenous contrast-enhanced computed tomography (IVCT),2-4 computed tomographic myelography (CTM),5-12 and magnetic resonance (MR)13,14 have been published, including some comparative studies. 15-21 In a 1990 review of the radiologic literature on cervical disk disease, Russell" concluded that (1) cervical myelopathy should be imaged by MR; (2) MR is less accurate than IVCT or CTM in defining the cervical spinal canal and foramina; (3) IVCT is more versatile than MR in distinguishing between soft disk and bony spur; and (4) CTM is the examination of choice for cervical disk disease. Kido and associates" mentioned that Kent and colleagues" were frustrated by attempting to determine the accuracy of various
From the Department of Diagnostic Radiology (O.W.H., G.M.M., P.L.S.), Department of Neurologic Surgery (B.M.O.), and Department of Neurology (W.N,F.), Mayo Clinic Rochester, Rochester, Minnesota. Address reprint requests to Dr. O. W. Houser, Department of Diagnostic Radiology, Mayo Clinic Rochester, 200 First Street SW, Rochester, MN 55905. Mayo Clin Proc 1995; 70:939-945
CTM identified more than 90% of the extruded cervical disks. CTM could not distinguish between an osteophytic cartilaginous cap and a disk, and CTM could not identify the source of a cervical radiculopathy in 102 patients. Although only a few imaging studies other than CTM were performed, those modalities were less sensitive in the detection of prolapsed disks. • Conclusion: Imaging of cervical disk prolapse continues to be difficult, and the results are not always specific. CTM is the most sensitive imaging examination, but the number of MR studies in the current series of patients was insufficient for a reasonable comparison between the two modalities. (Mayo Clin Proc 1995; 70:939-945) CT = computed tomography; CTM = computed tomographic myelography; IVCT = intravenous contrast-enhanced computed tomography; MPGR = multiplanar gradient-recalled; MR =magnetic resonance
diagnostic studies. Furthermore, their personal efforts to perform a meta-analysis of cervical disk disorders had also been stymied, and they noted that the available data on disk prolapse were insufficient when they used the combination of a large series and surgical confirmation as a criterion. It is puzzling why more effort may have been expended on comparing CTM with MR or describing the evolving MR scanning techniques-':" than on correlating the findings from either of these techniques with surgical and pathologic findings. The purpose of this article is to correlate CTM with surgically and pathologically proven prolapsed cervical disk and to focus on the CTM features of prolapsed disk. STUDY SUBJECTS From January 1986 to December 1989, 734 patients with suspected degenerative disease of the cervical intervertebral disk underwent assessment clinically and by CTM. Among 494 patients, surgical intervention revealed disk prolapse in 297, neural foraminal stenosis in 95, spondylotic myelopathy in 93, calcifying pseudotumor in 1, spinal cord atrophy in 1, and no identified disease in 7. The 297 patients with 299 prolapsed disks are the subject of this report. All 939
© 1995 Mayo Foundation/or Medical Education and Research
For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,
940
Mayo Clin Proc, October 1995, Vol 70
CERVICAL DISK PROLAPSE
patients were assessed by a neurologist and a neurosurgeon, who agreed that CTM was warranted. All extruded disk fragments in the 278 patients who had a laminectomy and the 19 patients who had an anterior diskectomy were surgically confirmed and pathologically verified except in two instances, in which a tiny disk fragment was inadvertently aspirated intraoperatively. Additional cross-sectional preoperative imaging studies included MR in 28 patients and plain CT in 14. Either the clinical symptoms or the CTM findings were similar in 233 additional patients; thus, they will be mentioned to provide a more complete perspective. This group consisted of 181 nonsurgical patients and 52 surgical patients who had foraminal stenosis." In the nonoperative group, the final clinical diagnosis was cervical radiculopathy in 102, cervical neuropathy in 13, and neck or arm pain (or both) of undetermined cause in 40. The CTM studies in these patients were either nonrevealing or showed mild to moderate spondylosis. In contrast, CTM disclosed an apparent prolapsed disk that did not correspond to the patient's clinical symptoms in the other 26 nonoperative patients. All 52 surgical patients had a radiculopathy due to foraminal stenosis. Their CTMs revealed an apparent prolapsed disk at the entrance to the foraminal canal, but at operation, these apparent disks proved to be a cartilaginous cap superimposed on a bony osteophyte in 42 patients and only a cartilaginous cap in 10.
METHODS All histories, CTM, preoperative CT scans, and preoperative MR scans were retrospectively reviewed. The final clinical diagnosis, site of a radiculopathy, surgical findings, weight of disk, and pertinent radiologic findings were noted. Spondylosis, including bulging annulus and bony spurs that did not cause clinical symptoms, was too ubiquitous to be tabulated. CTM technique consisted of a lumbar intrathecal injection of 12 to 20 mL of iohexol or iopamidol, 180 or 200 mg of iodine/mL, respectively, followed by filming of the entire spinal canal and either 3-mm or 1.5-mm CT (GE 9800) oblique scans parallel to the intervertebral disks. Oblique axial sections parallel to the intervertebral disk were obtained through the clinically suspected pathologic site and any obvious abnormality noted by film examination. Plain CT examinations were performed by obtaining 3-mm or 5mm sections through the cervical spine. MR examinations (1.5-T magnet and 12.7-cm surface coil) included Tl and T2W or T2*W sagittal scanning sequences and either T2*W or Tl W (or both) oblique axial sections parallel to the intervertebral disk with use of 5-mm or 4-mm sections at the site of the patient's suspected clinical lesion or any abnormality noted on sagittal MR scans.
RESULTS Clinical, Surgical, and Pathologic Findings.-The study group consisted of 197 men and 100 women. Their ages ranged from 27 to 87 years (Table 1), but most patients were in the fifth or sixth decade of life. Clinically, a cervical radiculopathy was evident in 280 patients and a myelopathy in 17. The surgical reports for the 297 patients noted one or more prolapsed disks in 258 (87%), a prolapsed disk with a bony spur in 38 (13%) (Fig. 1), and a prolapsed disk with a fractured inferior facet in 1. The 297 patients had 299 extruded disks, from the third through the seventh cervical interspaces. The level was C-6 in 57%, C-5 in 21%, C-7 in 13%, C-4 in 8%, and C-3 in 1%. One patient had three concurrent extruded cervical disks. When a laminectomy was performed, the weight of the extruded disk ranged from 10 to 1,008 mg. Most extruded disks were at and inferior to the nerve roots; only a few had migrated superior to the nerve roots. If an anterior diskectomy was performed, the disk was continuous with the adjacent tissue and its weight was difficult to ascertain. Of the 19 anterior diskectomies, 11 were performed for midline disks in patients with myelopathy, and 8 were performed in patients whose prolapsed disk lay far enough laterally to incite a radiculopathy but did not extend sufficiently beyond the spinal cord to allow line-of-sight exposure with use of a posterior surgical approach. CT Myelography.-The size of the myelographic defect did not always correlate with the weight of the pathologic specimen because a relatively large disk that is predominantly in the axilla of the nerve root may produce only a small extradural defect. CTM findings corresponded to the surgical findings in 277 instances (in all 17 cases of myelopathy and in 260 cases of radiculopathy) when an extradural soft tissue mass encroached on the root sleeve or thecal sac; they were disparate in 22 instances in which a soft tissue mass was not evident despite the presence of a clinical radiculopathy (Table 2). The bulk of the extradural mass lay Table I.-Sex and Age Distribution of 297 Patients With Prolapsed Disks Factor
Sex Male Female Decade of life 3 4 5 6 7 8 9
No. of patients
197 100 4
54 102 73 49 12 3
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
CERVICAL DISK PROLAPSE
Mayo Clin Proc, October 1995, Vol 70
Fig. I. Computed tomographic myelogram. showing extruded 110mg left C-5 disk superimposed on bony spur.
at the level of the cervical foramen in 260 instances, encroached on or obliterated the adjacent root sleeve, and sometimes even displaced the adjacent spinal cord. In 190 instances, a prolapsed disk was suggested when the extradural defect extruded from the level of the adjacent disk superiorly into the region of the cervical foramen. In the other 70 instances, an extradural mass opposite the cervical foramen suggested a sequestered disk. The spinal cord was compressed by the disk extrusion in the other 17 patients. When compressed, the spinal cord did not have the configuration characteristically noted when it is chronically compressed by spondylosis." In 13 patients, a large midline or predominantly midline disk deformed the adjacent cervical spinal cord; in 3 patients with a congenitally narrow cervical spinal canal, the disk fragments were smaller and weighed 38, 340, and 540 mg. In the other patient, the extruded disk was superimposed on degenerative cervical stenosis. The weight of the disk fragment in this patient could not be determined because the entire disk was
excised during the anterior diskectomy plus fusion. Of interest, 3 of 6 C-3 and 4 of 17 C-4 disk extrusions were associated with myelopathy. In 22 patients, surgical exploration was done on the basis of clinical findings only. Among 19 of these patients , the surgeon found an extruded disk at C-4 in 2, C-5 in 6, C-6 in 7, and C-7 in 6; the surgical exploration was negative in 3 patients (Table 2). CTM revealed slight spondylosis without a definite soft tissue mass in 19 patients and no abnormalities in 3. In contrast, a soft tissue extradural deformity appeared to be present on CTM in seven patients who had no cervical abnormalities on surgical exploration. In 52 patients, myelography showed an apparent extruded disk (in 10) or a bony spur that seemed to be associated with an extruded disk (in 42). At surgical exploration, the apparent disk proved to be simply a cap of cartilage (Fig. 2).28 Finally, an extradural soft tissue mass was evident on CTM in 26 additional patients whose symptoms did not correlate with the lesion, which was at a level remote from any symptoms or even affected the asymptomatic side. In this group, no patients underwent surgical exploration. Similarly, none of the 155 patients who had a final diagnosis of a cervical radiculopathy, neuropathy, or neck and arm pain, and either no abnormal findings or slight to moderate spondylosis on CfM, underwent surgical exploration. MR lmaging.-MR data were limited to 28 patients. The imaging sequences obtained were Tl W in 27 patients, multiplanar gradient-recalled (MPGR) in 19, and T2W spin echo in 15. Relative to cerebrospina l fluid, extruded cervical disks varied from being hyperintense to isointense on Tl W images and from hypointense to isointense on T2W images. Extruded disks were hyperintense in comparison with cerebrospinal fluid on Tl W images in 14 patients and hypointense on T2W or MPGR sequences in 9. In addition, these disks may (Fig. 3) or may not (Fig. 4) be covered by a thin hypointense line, representing the posterior longitudinal ligament and dura. In this series, the extruded disk was depicted by its inherent signal or both Tl W and MPGR sequences in 11 patients, by Tl W hyperintensity alone in 3, and by MPGR hypointensity in 3. A thin hypointense dural
Table 2.-Myelograph ic Findings in Cervical Disk Prolapse (299 Disks) Soft tissue mass and associated symptoms
Cervical site
Radiculopathy
C-3 C-4 C-5 C-6 C-7 Total
3 13 55 156 33 260
Myelopathy 3 4 5 5 0 17
941
Errorspondylosis only 0 2 5 7 5 19
Negative
Total
0 0 I I
6 19 66 169 39 299
1
3
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
942
CERVICAL DISK PROLAPSE
Mayo Clio Proc, October 1995, Vol 70
The study revealed an extruded disk in six patients and foraminal stenosis in one; in seven patients, no abnormalities were detected.
Fig. 2. Computed tomographic myelogram of stenosis at entrance to foraminal canal due to cartilaginous cap at C-5 on the right. No extruded disk was found.
posterior longitudinal ligament covered an isointense disk on T1W images in one patient and an isointense disk on MPGR sequences in another patient. The most useful studies were the 19 MPGR axial sequences, which revealed a hypointense disk in nine patients and a posterior ligament-dural line covering six isointense disks. Plain CT.-Plain CT of the cervical spine was performed in 14 patients who had a suspected extruded cervical disk.
DISCUSSION Clinically, cervical degenerative disk disease usually involves multiple vertebral levels, has a preponderance in male patients, and occurs in middle-aged and older patients. One type of cervical disk disease-disk prolapse-differs. Disk prolapse is virtually always limited to a single disk level, usually involves the fifth and sixth cervical disks, typically manifests during the fifth and sixth decades of life, and is characterized clinically by either a radiculopathy or, less frequently, a myelopathy.s-" In the current series, a radiculopathy occurred in 94%, a myelopathy in 6%, a C-6 extrusion in 57%, and a C-5 extrusion in 21%. The site of a prolapsed disk relative to the cervical spinal cord may influence the surgical approach. Typically, lateral cervical disks are removed by the posterior approach. The surgical exposure of prolapsed midline disks that compromise the spinal cord, or some paramedian disks that compromise either the spinal cord or the nerve root but do not extend beyond the lateral margin of the cervical cord, is usually impossible without excessive manipulation of the spinal cord. Such disks should be removed by the anterior approach. Our finding of myelopathy in 50% of C-3 and almost 25% of C-4 disk extrusions agrees with the observations reported by O'Laoire and Thomas." Our surgical findings of disk extrusion do not match those of Aldrich,' who noted sequestration in all 36 of his patients with
Fig. 3. A, Computed tomographic myelogram, demonstrating extruded 250-mg left C-6 disk. B, Multiplanar gradientrecalled magnetic resonance image, showing disk slightly hypointense in comparison with cerebrospinal fluid and an overlying posterior longitudinal ligament-dural line. (Echo time, 20 ms; repetition time 600 ms.)
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
Mayo Clin Proc, October 1995, Vol 70
CERVICAL DISK PROLAPSE
943
Fig. 4. A, Computed tomogram, showing 200-mg right C-6 extruded disk. Band C, Magnetic resonance scans, with (B) and without (C) diethylenetriamine pentaacetic acid , do not show a T1W extruded disk because it is isointense in comparison with cerebrospinal fluid. D, Multiplanar gradient-recalled imaging fails to show same extruded disk, which is also isointense in comparison with cerebrospinal fluid .
posterolateral disk disorders. The only other surgical finding of note was that 13% of cervical disks in our series were superimposed on an osteophyte . Pathologically, the initial manifestations of cervical disk disease can include prolapsed disk, prolapsed disk superimposed on an osteophyte, cartilaginous cap, cartilaginous cap superimposed on an osteophyte, bony osteophyte, synovial cyst, hypertrophy of flaval ligaments, and bulging annulus. Current imaging techniques, however, do not always distinguish among the possibilities in this spectrum. " Furthermore, these manifestations , by virtue of their size or site of involvement, do not invariably cause clinical symptoms. Therefore, both imaging of the pathologic condition and correlating the imaging, clinical, and surgical findings remain somewhat difficult despite recent advances in CTM and MR.
The literature reveals a CTM detection rate for cervical prolapsed disk that ranges from 75 to 100%; most published rates are between these two extreme s. Our detection rate of approximately 90% is similar to the 87% reported by Modic and colleagues . I ? Our error rate included an undercall rate of more than 7% when surgical exploration showed a clinically suspected prolapsed disk that CTM failed to identify. This discrepancy included about 15% of cases of prolapsed disk at C-7, where shoulder artifact degrades the results of examination. Conversely , the overcall rate of slightly more than 2% is more distressing because surgical exploration disclosed no abnormality and did not benefit patients who had an apparent prolapsed disk on CTM that matched the site of the patient's radiculopathy. Intrinsically, CTM does not facilitate distinction between prolapsed disks and cartilaginous caps of an osteophyte.
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
944
CERVICAL DISK PROLAPSE
Both findings have the appearance of soft tissue that mayor may not be superimposed on a bony spur. Our 52 patients with stenosis at the entrance to the foraminal canal and CTM features that resembled a prolapsed disk with or without an associated osteophyte were not considered errors because the patients had a radiculopathy due to nerve root compression that was relieved by the surgical intervention. Similarly, those nonsurgical patients who had an apparent prolapsed disk that did not correspond to symptoms also were not included as errors. This limited MR survey suggests that a single sequence, whether Tl W, T2W, or MPGR, will reveal an inherent disk signal that differs from that for cerebrospinal fluid in approximately half the prolapsed cervical disks, a combination of two sequences will disclose almost two-thirds, and a combined sequence plus a posterior longitudinal ligamentdural line will detect slightly more than two-thirds. The detection rate of about 68% in this series approaches but does not match the 75% rate noted by Brown and coworkers 15 and Modic and associates." Because cerebrospinal fluid provides the background for identification of disk prolapse, edema within the extruded disk reduces the sensitivity of both Tl W and MPGR sequences. Furthermore, the absence of fat within the cervical spinal canal, noted in recent anatomic studies, may contribute to the lack of Tl W sensitivity. The hypodense posterior longitudinal ligamentdural line was useful in confirming 12 extruded disks and identifying 2 disks; thus, failure to detect this structure also affects sensitivity. The reason for its absence is unknown. The description of sequestered disks reported by Aldrich" indicates that this structure may be tom, and the incidence of disk extrusion in this series suggests that the overlying posterior longitudinal ligament and dura may be attenuated. CONCLUSION CTM, although not always specific, was the imaging procedure of choice for diagnosing cervical degenerative disk disease, including prolapsed disk, at our institution from January 1986 to December 1989. Whether the CTM preponderance persists will depend on technologic advances. CTM is a mature modality that is unlikely to improve dramatically. In contrast, MR is evolving. New imaging sequences'<" may advance MR but will need pathologic correlation. Review of the literature by Kent and colleagues" and Kido and coworkers" has led them to suggest that published findings on cervical degenerative spinal disorders are flawed because of the paucity of large patient series with pathologic and surgical verification. Radiologists should be concerned and contribute appropriate data. Newer, perhaps stricter investigations with outcome analysis may dictate what future role, if any, imaging will have in the evaluation of disk prolapse.
Mayo Clin Proc, October 1995, Vol 70
REFERENCES 1. Daniels DL, Grogan JP, Johansen JG, Meyer GA, Williams AL, Haughton VM. Cervical radiculopathy: computed tomography and myelography compared. Radiology 1984; 151:109-113 2. Baleriaux D, Noterman J, Ticket L. Recognition of cervical soft disk herniation by contrast-enhanced CT. AJNR Am J Neuroradiol 1983; 4:607-608 3. Heinz ER, Yeates A, Burger P, Drayer BP, Osborne D, Hill R. Opacification of epidural venous plexus and dura in evaluation of cervical nerve roots: CT technique. AJNR Am J Neuroradiol 1984; 5:621-624 4. Russell EJ, D'Angelo CM, Zimmerman RD, Czervionke LF, Huckman MS. Cervical disk herniation: CT demonstration after contrast enhancement. Radiology 1984; 152:703712 5. Aldrich F. Posterolateral microdiscectomy for cervical monoradiculopathy caused by posterolateral soft cervical disc sequestration. J Neurosurg 1990; 72:370-377 6. Jahnke RW, Hart BL. Cervical stenosis, spondylosis, and herniated disc disease. Radiol Clin North Am 1991; 29:777-791 7. Landman JA, Hoffman JC Jr, Braun IF, Barrow DL. Value of computed tomographic myelography in the recognition of cervical herniated disk. AJNR Am J Neuroradiol 1984; 5:391-394 8. Masaryk TJ, Ross JS, Modic MT, Boumphrey F, Bohlman H, Wilber G. High-resolution MR imaging of sequestered lumbar intervertebral disks. AJNR Am J Neuroradiol 1988; 9:351-358 9. Modic MT, Masaryk TJ, Ross JS, Mulopulos GP, Bundschuh CV, Bohlman H. Cervical radiculopathy: value of oblique MR imaging. Radiology 1987; 163:227-231 10. Nakagawa H, Okumura T, Sugiyama T, Iwata K. Discrepancy between metrizamide CT and myelography in diagnosis of cervical disk protrusions. AJNR Am J Neuroradiol 1983; 4:604-606 11. Penning L, Wilmink JT, Specificity of CT myelographic findings in cervical nerve root symptoms. Neurosurg Rev 1986; 9:99-101 12. Russell EJ, Cervical disk disease. Radiology 1990; 177:313-325 13. Hedberg MC, Drayer BP, Flom RA, Hodak JA, Bird CR. Gradient echo (GRASS) MR imaging in cervical radiculopathy. AJR Am J Roentgenol 1988; 150:683-689 14. Ross JS, Ruggieri PM, Glicklich M, Obuchowski N, Dillinger J, Masaryk TJ, et a1. 3D MRI of the cervical spine: low flip angle FISP vs. Gd-DTPA turboFLASH in degenerative disk disease. J Comput Assist Tomogr 1993; 17:26-33 15. Brown BM, Schwartz RH, Frank E, Blank NK. Preoperative evaluation of cervical radiculopathy and myelopathy by surface-coil MR imaging. AJR Am J Roentgenol 1988; 151:1205-1212 16. Larsson E-M, HoMs S, Cronqvist S, Brandt L. Comparison of myelography, CT myelography and magnetic resonance imaging in cervical spondylosis and disk herniation: pre- and postoperative findings. Acta Radiol 1989; 30:233-239 17. Modic MT, Masaryk TJ, Mulopulos GP, Bundschuh C, Han JS, Bohlman H. Cervical radiculopathy: prospective evaluation with surface coil MR imaging, CT with metrizamide, and metrizamide myelography. Radiology 1986; 161:753759
For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,
CERVICAL DISK PROLAPSE
Mayo Clin Proc, October 1995, Vol 70
18.
Neuhold A, Stiskal M, Platzer C, Pernecky G, Brainin M. Combined use of spin-echo and gradient-echo MR-imaging in cervical disk disease: comparison with myelography and intraoperative findings. Neuroradiology 1991; 33:422426 19. Schipper J, Kardaun JWPF, Braakman R, van Dongen KJ, Blaauw G. Lumbar disk herniation: diagnosis with CT or myelography? Radiology 1987; 165:227-231 20. Sobel DF, Barkovich AJ, Munderloh SH. Metrizamide myelography and postmyelographic computed tomography: comparative adequacy in the cervical spine. AJNR Am J Neuroradiol 1984; 5:385-390 21. Yousem DM, Atlas SW, Hackney DB. Cervical spine disk herniation: comparison of CT and 3DFT echo MR scans. J Comput Assist Tomogr 1992; 16:345-351 22. Kido DK, Mushin AI, Thornbury JR, Littenberg B, Rothenberg BM. A meta-analysis of imaging procedures for lumbar disc herniation. Presented at the American Society of Neuroradiology Annual Meeting; 1993 May 16-20; Vancouver, British Columbia, Canada 23. Kent DL, Haynor DR, Larson EB, Deyo RA. Diagnosis of lumbar spinal stenosis in adults: a metaanalysis of the accuracy of CT, MR, and myelography. AJR Am J Roentgenol 1992; 158:1135-1144 24. Ross JS, Ruggieri PM, Tkach JA, Masaryk TJ, Paranandi L, Dillinger Jf, et al. Gd-DTPA-enhanced 3D MR imaging of
25.
26.
27.
28.
29.
30.
945
cervical degenerative disk disease: initial experience. AJNR Am J Neuroradiol 1992; 13:127-136 Tsuruda JS, Norman D, Dillon W, Newton TH, Mills DG. Three-dimensional gradient-recalled MR imaging as a screening tool for the diagnosis of cervical radiculopathy. AJNR Am J Neuroradiol 1989; 10:1263-1271 Van Dyke C, Ross JS, Tkach J, Masaryk TJ, Modic MT. Gradient-echo MR imaging of the cervical spine: evaluation of extradural disease. AJNR Am J Neuroradiol 1989; 10:627-632 Yousem DM, Atlas SW, Goldberg HI, Grossman RI. Degenerative narrowing of the cervical spine neural foramina: evaluation with high-resolution 3DFT gradient-echo MR imaging. AJNR Am J Neuroradiol 1991; 12:229-236 Houser OW, Onofrio BM, Miller GM, Folger WN, Smith PL, Kallman DA. Cervical neural foraminal canal stenosis: computerized.tornographic myelography diagnosis. J Neurosurg 1993; 79:84-88 Houser OW, Onofrio BM, Miller GM, Folger WN, Smith PL. Cervical spondylotic stenosis and myelopathy: evaluation with computed tomographic myelography. Mayo Clin Proc 1994; 69:557-563 O'Laoire SA, Thomas DGT. Spinal cord compression due to prolapse of cervical intervertebral disc (herniation of nucleus pulposus): treatment in 26 cases by discectomy without interbody bone graft. J Neurosurg 1983; 59:847-853
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.