- Email: [email protected]
Surgical Treatments of Myelopathy Caused by Cervical Ligamentum Flavum Ossification
PEER-REVIEW REPORTS BIN NI ET AL.
OS ODONTOIDEUM WITH ATLANTOAXIAL DISLOCATION
21. Naderi S, Crawford NR, Song GS, Sonntag VK, Dickman CA: Biomechanical comparison of C1-C2 posterior fixations: cable, graft, and screw combinations. Spine (Phila Pa 1976) 23:1946-55, 1998.
27. Platzer P, Vecsei V, Thalhammer G, Oberleitner G, Schurz M, Gaebler C: Posterior atlanto-axial arthrodesis for fixation of odontoid nonunions. Spine (Phila Pa 1976) 33:624-30, 2008.
22. Ni B, Chen H, Guo X, Tao C: Bilateral atlantoaxial transarticular screws combined with atlas laminar hooks fixation. Chin J Surg 43:1358-9, 2005.
28. Resnick DK, Benzel EC: C1-C2 pedicle screw fixation with rigid cantilever beam construct: case report and technical note. Neurosurgery 50:426-8, 2002.
23. Ni B, Zhu Z, Zhou F, Guo Q, Yang J, Liu J, Wang F: Bilateral C1 laminar hooks combined with C2 pedicle screws fixation for treatment of C1-C2 instability not suitable for placement of transarticular screws. Eur Spine J 19:1378-82, 2010.
29. Sankar WN, Wills BP, Dormans JP, Drummond DS: Os odontoideum revisited: the case for a multifactorial etiology. Spine (Phila Pa 1976) 31:979-984, 2006.
24. Olerud S, Olerud C: The C1 claw device: a new instrument for C1-C2 fusion. Eur Spine J 10:345-7, 2001.
30. Spierings EL, Braakman R: The management of os odontoideum: analysis of 37 cases. J Bone Joint Surg Br 64:422-8, 1982.
25. Os odontoideum. Neurosurgery 50:S148-55, 2002. 26. Plant JG, Ruff SJ: Migration of rod through skull, into brain following C1-C2 instrumental fusion for os odontoideum: a case report. Spine (Phila Pa 1976) 35:E90-2, 2010.
31. Stevens JM, Chong WK, Barber C, Kendall BE, Crockard HA: A new appraisal of abnormalities of the odontoid process associated with atlanto-axial subluxation and neurological disability. Brain 117(Pt 1):133-48, 1994.
32. Stillwell WT, Fielding JW: Acquired os odontoideum: a case report. Clin Orthop Relat Res (135):7173, 1978. 33. Sze G, Brant-Zawadzki MN, Wilson CR, Norman D, Newton TH: Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies. Radiology 161:391-4, 1986. 34. Zhou F, Ni B, Li S, Yang J, Guo X, Zhu Z: C2 translaminar screw as the optimal choice for atlantoaxial dislocation with C2-C3 congenital fusion. Arch Orthop Trauma Surg 2010, In press.
Bin Ni and Fengjin Zhou contributed equally to this work. received 13 April 2010; accepted 15 July 2010 Citation: World Neurosurg. (2011) 75, 3/4:540-546. DOI: 10.1016/j.wneu.2010.07.021 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
Surgical Treatments of Myelopathy Caused by Cervical Ligamentum Flavum Ossification Jian Yang1, Bin Ni1, Ning Xie1, Qunfeng Guo1, Liangzhe Wang2
Key words 䡲 Cervical 䡲 Ossification of the ligamentum flavum 䡲 Surgical treatment Abbreviations and Acronyms CSF: Cerebrospinal fluid CT: Computed tomography JOA: Japanese Orthopaedic Association MRI: Magnetic resonance imaging OLF: Ossification of the ligamentum flavum OPLL: Ossification of the posterior longitudinal ligament From the Departments of 1Orthopedics and 2 Pathology, Changzheng Hospital, The Second Military Medical University, Shanghai, People’s Republic of China To whom correspondence should be addressed: Bin Ni, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2011) 75, 3/4:546-550. DOI: 10.1016/j.wneu.2010.10.041 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
䡲 OBJECTIVE: To present a small case series reporting the outcomes of surgical treatment for myelopathy caused by cervical ossification of the ligamentum flavum (OLF). 䡲 METHODS: The authors assessed 15 cases of myelopathy caused by cervical OLF. Patients were eight women and seven men 37–75 years old (mean age 59.7 years). All patients underwent bilateral laminectomy, and the lesions were removed. The decompression range was confined within the medial sides of the bilateral facets and within the involved segments. Intraoperative specimens were examined histologically to confirm the diagnosis. During the operation, the extent of adherence of the lesions to the dura was recorded. The patients were followed for 3–70 months. Neurofunctional improvements were evaluated with the Japanese Orthopaedic Association (JOA) score. 䡲 RESULTS: Definite adherences were present in 67.7% of all cases. JOA score showed a 71.5% improvement after operation from a preoperative score of 5– 8 (mean 6.4) to a postoperative score of 10 –14 (mean 13.5). The operative outcomes were satisfactory without extensive decompression of adjacent segments. 䡲 CONCLUSIONS: A high rate of adherence to the dura was observed in patients with myelopathy caused by cervical OLF. Bilateral laminectomy and removal of the lesions, without extensive decompression of adjacent segments, provides an optimistic prognosis.
INTRODUCTION Ossification of the ligamentum flavum (OLF) occurs most frequently in the lower thoracic spine and is extremely rare in the
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cervical region (3, 5, 10, 14, 23). Features of cervical OLF, associated morbidity, and treatment have been previously described in
case reports (3, 8, 10, 13, 14). In the present study, we report the surgical treatment of 15 Chinese patients with cervical OLF.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.10.041
PEER-REVIEW REPORTS JIAN YANG ET AL.
MYELOPATHY CAUSED BY CERVICAL OLF
Table 1. Characteristics of 15 Patients with Cervical OLF No.
Gender/Age (years)
DC (months)
1
M/37
8
C5-6
⫺
2
F/63
52
C4-5, C5-6, C6-7
⫹
Level
Adhesion
Concomitant Diseases
Follow-up (months)
—
50
6/16 (90.9)
9
5/12 (58.3)
Dorsal OLF
JOA Score Preoperatively/ Follow-up (improvement %)
3
M/62
28
C6/7
⫹
4
F/50
20
C4-5, C5-6
⫺
5
M/63
36
C2-3, C3-4, C4-5
6
F/75
90
C3-4, C4-5, C5-6
7
F/58
66
C6-7, C7-T1
⫹
—
70
7/13 (60.0)
8
M/65
45
C4-5
⫹
OPLL, dorsal OLF
20
5/13 (66.7)
OPLL
12
8/15 (77.8)
Disc herniation
—
36
7/14 (70.0)
⫹
Disc herniation
12
6/13 (63.6)
⫹
Disc herniation
3
5/10 (41.7)
9
F/74
38
C3-4, C4-5, C5, C6
⫹
12
5/13 (66.7)
10
F/58
24
C3-4, C4-5
⫺
—
9
6/14 (72.3)
11
M/45
18
C6-7
⫺
—
12
7/16 (90.0)
12
M/58
22
C5-6, C6-7
⫺
—
54
8/14 (66.7)
13
M/55
28
C4-5, C5-6
⫹
Disc herniation
12
7/13 (60.0)
14
F/62
30
C6-7, C7-T1
⫹
Dorsal OLF
9
8/15 (77.8)
15
F/70
45
C3-4, C4-5, C5-6
⫹
Disc herniation
9
6/12 (54.5)
DC, disease course; JOA, Japanese Orthopaedic Association; OLF, ossification of the ligamentum flavum; OPLL, ossification of the posterior longitudinal ligament; ⫺, no or slight adhesion; ⫹, definite or severe adhesion.
MATERIALS AND METHODS This study included 15 consecutive Chinese patients admitted to our department from 1999 –2009. There were seven men and eight women 37–75 years old (mean age 59.7 years). Typical clinical features included sensory defect; decreased muscle strength; and disturbance in gait, urination, and defecation. The patients’ courses were prolonged, and the histories of the main complaints ranged from 8 months to 7.5 years. The distributions of the involved segments are shown in Table 1. Concomitant diseases included disc degeneration and herniation in five patients (33.3%), ossification of the posterior longitudinal ligament (OPLL) in two patients (13.3%), and thoracic OLF in three patients (20%). In our hospital, x-rays, computed tomography (CT), and magnetic resonance imaging (MRI) are obtained as routine preoperative imaging, and x-rays only are routinely obtained postoperatively. When planning each operation, preoperative images were studied to confirm the location and contour of the lesion and the degree of cord compression. Indications for operation included development of neurologic deficiency and definite imaging findings in accordance with the clinical manifesta-
tions. Nine patients underwent immediate operations, and six patients underwent conservative treatment for 3– 6 months that was ultimately ineffective, and operations were then required. Decompressive laminectomy was performed in all patients at the involved levels (Table 1). Operations were performed with a posterior approach and exposure of corresponding segments. The decompression range was the bilateral laminae within the medial sides of the facets and within the involved segments. A furrow was made along the range using a burr and a rongeur. The laminae were lifted from one side (from the intact side if the lesion was unilateral) to the other side to reveal the lesions. Care was taken to separate the adhesion. Lateral mass screws and rods were mounted in all the cases at one level above and below the involved segments. Dural tear occurred in two patients. In one case, the dura was torn, but there was no defect, and the dura was repaired in situ. In the other case, the dura was torn with a defect 4 mm wide ⫻ 1 cm long. The defect was patched with deep fascia sewn to the dura, and fibrin glue was sprinkled on the surface of the dura. When closing the incisions, rigorous layered sutures were per-
WORLD NEUROSURGERY 75 [3/4]: 546-550, MARCH/APRIL 2011
formed in all cases to prevent cerebrospinal fluid (CSF) leakage. No CSF leakage was observed. A cervical collar was used for 3 months postoperatively in all patients. Histologic examination of the intraoperative specimens was performed routinely to confirm the diagnosis. During the operation, the extent of adherence of the lesions to dura was recorded. Neurologic state and radiologic parameters were evaluated at 3–70 months’ follow-up. Neurologic deficiency was evaluated with the Japanese Orthopaedic Association (JOA) score, and x-rays were routinely obtained postoperatively.
RESULTS There were 31 segments in 15 patients, including 1 in C2-3 (3.2%), 5 in C3-4 (16.1%), 9 in C4-5 (29.0%), 8 in C5-6 (25.8%), 6 in C6-7 (19.4%), and 2 in C70T1 (6.4%) (Table 1). There were 11 cases with multiple segments and 4 cases with single segments. Preoperative imaging findings showed enlargement of the ligamentum flavum and compression of the spinal cord (Figure 1). The space-occupying lesions showed low-intensity signals on MRI T1-weighted and T2weighted sequences and high-density sig-
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MYELOPATHY CAUSED BY CERVICAL OLF
Figure 1. Appearance on magnetic resonance imaging (MRI) and computed tomography (CT) of a patient with multiple segments of cervical
nals in CT and x-rays. The lesions were shown definitively on MRI in 12 patients, on CT in all 15 patients, and on x-rays in only 1 case (Figure 2). Intraoperative findings indicated that the lesions definitely adhered to the dura in 10 (66.7%) patients; there was no or slight adherence in 5 (33.3%) patients. Dural tear occurred in two patients. Intraoperative repair was performed, and no sign of postoperative CSF leakage was observed.
The JOA score showed a 71.5% improvement from a preoperative score of 5– 8 (mean 6.4) to a postoperative score of 10 –14 (mean 13.5). Operative complications occurred in one patient with postoperative temporary neurologic deterioration who presented with an aggravation of preoperative body numbness and in one patient with C5 radiculopathy; these complications resolved over 1 week (first patient) and 2 weeks (second patient).
Figure 2. Occupying lesion solitarily located in C5-6 showed high density on computed tomography (CT) (A) and low intensity on magnetic resonance
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ossification of the ligamentum flavum (OLF).
No recurrence or other complications were observed in follow-up of up to 70 months (mean 23.1 months).
DISCUSSION Although the pathogenesis of OLF is unclear, there is evidence from thoracic spine cases that degeneration, trauma, inflamma-
imaging (MRI) (B). It is definitely revealed on x-ray (arrow) (C).
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.10.041
PEER-REVIEW REPORTS JIAN YANG ET AL.
MYELOPATHY CAUSED BY CERVICAL OLF
tion, metabolic abnormality, and genetics may play important roles (12, 17, 20). The differences in morbidities between the cervical and thoracic spine were suggested to result from different focal anatomic and force factors (9, 13, 14). In the cervical spine, OLF hardly occurs in the capsular portion because the ligamentum flavum does not adhere to the bony tissue directly in this area. Additionally, in contrast to in the cervical spine, the ligament in the thoracic region seldom becomes loose, and the tension is always static, which may play an important role in the process of ossification. Typical cervical OLF can be visualized on x-ray, CT, and MRI (4, 21). CT can define the contour of the ossification, three-dimensional CT helps to determine the precise location of the lesion, and MRI can reveal the degree of cord compression. Precise evaluation of the location and contour of the lesions and the degree of cord compression in preoperative images is crucial in planning the operation. In the present study, only one lesion was revealed on x-ray, whereas MRI and CT revealed 80% and 100% of all lesions. These data suggest that comprehensive imaging methods are required for patients with suspicion of OLF. There were three cases (20%) associated with thoracic OLF and two cases associated with OPLL, suggesting that consideration of other spinal regions is important when cervical OLF is observed (6). In cases with concomitant diseases, the responsible lesions must be confirmed by neurologic examinations.
of development of progressive deformity after laminectomy were reported to range from 14%– 47% (19) and 21%– 42% (11). Generally, a minor decompression range, especially in cases of intact facets, is less likely to result in late postoperative deformity (24). Mechanical factors may play an important role, however, in the morbidity of ossification of spinal ligaments. Marked progression of OPLL and ossification of the anterior longitudinal ligament after cervical laminectomy were reported (15, 22). Additionally, a case in which changes of focal mechanics led to secondary OLF at adjacent levels was described (2). We agree that posterior cervical laminectomy in which spinous process, interspinous ligaments, and laminae are ablated remains a risk factor for changing focal mechanics that may lead to ossification of other ligaments at the same level or ligaments at adjacent levels, even if postoperative deformity does not occur. Given the frequent coincidence of ossification of spinal ligaments (4, 18), we used internal fixation in all patients with the aim of preventing ossification of other ligaments at the same level or ligaments at adjacent levels (Figure 3). Further study of the impact of this technique is required. Operative outcome of cervical OLF showed an optimistic prognosis. Although adherence to the dura was observed in 66.7% of patients, a 71.5% improvement of JOA score was achieved. Two patients experienced complications including one temporary neurologic deterioration and one C5 radiculopathy; however, both complications resolved within 1–2 weeks postoperatively. We confined the decompression range within the involved segments and within the medial side of the bilateral facets as long as this was sufficient to remove the lesions. Satisfactory neurologic improvements were achieved without the requirement for extensive decompression of adjacent segments. The optimal outcome of surgical treatment may result from the low incidence of cervical OLF occurring in the capsular portion and the anterior flexion of the cervical spine leaving a large buffering space for the cervical spine cord to tolerate the compression of the lesions and procedural disturbances. To our knowledge, only two cases of cervical OLF were previously reported in Chinese patients (8, 13). In addition to the 15 cases of OLF we describe in the present
Figure 3. Postoperative x-rays of patient in Figure 1.
In the present study, six patients received conservative treatment for 3– 6 months before operation, without obvious neurologic improvement, and their condition seemed to develop progressively. There is some evidence from thoracic OLF cases that a longer disease course and a more severe preoperative neurologic deficiency represent a worse prognosis (1, 7, 16). In those studies, early diagnosis and surgical decompression were the only significant predictors of favorable outcome. When definite imaging evidence and corresponding neurologic deficiency are confirmed, an operation should performed. We observed a high rate (66.7% of patients) of adherence of the lesions to the dura. Although surgeons should be extremely careful when dissecting the adhesion, a dural tear can occasionally occur, particularly when the dura is severely adhered or even ossified and fused with the lesion. In such cases, the lesion may be excised with the adherent outer layer of the dura. In cases where the dura is torn but there is no defect, the dura can be repaired in situ. If the dura is torn with a defect, however, it should be patched with deep fascia or an artificial dural graft, rather than be sewn in situ, to avoid dural sac stenosis. Fibrin glue sprinkled on the surface of the dura and rigorous layered sutures when closing the incisions are also helpful. Using multiple surgical methods, most CSF leaks can be prevented. The indication for instrumentation for laminectomy is controversial (19). The rates
WORLD NEUROSURGERY 75 [3/4]: 546-550, MARCH/APRIL 2011
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PEER-REVIEW REPORTS JIAN YANG ET AL.
study, we encountered two other nonoperative outpatient cases with typical MRI and CT images. There seems to be a recent emergence of cervical OLF in China. We suggest that this phenomenon relates to the large population, the comparably small number of hospitals, and the development of economical and medical conditions allowing extensive use of CT and MRI. Nevertheless, the number of Chinese cases we treated from 1999 –2009 was 7.5 times more than previously reported from 1962– 2008 (8, 13). We suggest that the incidence of OLF in China is more common than previously reported.
CONCLUSIONS We observed a high rate of adherence to the dura in patients with myelopathy caused by cervical OLF. Bilateral laminectomy and removal of the lesions, without extensive decompression of adjacent segments, provides an optimistic prognosis.
REFERENCES 1. Aizawa T, Sato T, Sasaki H, Kusakabe T, Morozumi N, Kokubun S: Thoracic myelopathy caused by ossification of the ligamentum flavum: clinical features and surgical results in the Japanese population. J Neurosurg Spine 5:514-519, 2006. 2. Chen Y, Lu XH, Yang LL, Chen DY: Ossification of ligamentum flavum related to thoracic kyphosis after tuberculosis: Case report and review of the literature. Spine 34:E41-44, 2009. 3. Chou YC, Lee CC, Yen PS, Lin JF, Su CF, Lin SZ, Chen WF: Cough induced by ossification of the ligamentum flavum in the high cervical spine: case report. J Neurosurg 100:364-366, 2004. 4. Enomoto H, Kuwayama N, Katsumata T, Doi T: Ossification of the ligamentum flavum: a case report and its MRI finding. Neuroradiology 30:571-573, 1988.
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MYELOPATHY CAUSED BY CERVICAL OLF
5. Goodman JM, Kuzma BB: Ossification of the ligamentum flavum with myelopathy. Surg Neurol 46: 396-397, 1996.
17. Omojola MF, Cardoso ER, Fox AJ, Drake CG, Durward QJ: Thoracic myelopathy secondary to ossified ligamentum flavum. J Neurosurg 56:448-450, 1982.
6. Guo JJ, Luk KD, Karppinen J, Yang H, Cheung KM: Prevalence, distribution, and morphology of ossification of the ligamentum flavum: a population study of one thousand seven hundred thirty-six magnetic resonance imaging scans. Spine 35:51-56, 2010.
18. Ono K, Yonenobu K, Miyamoto S, Okada K: Pathology of ossification of the posterior longitudinal ligament and ligamentum flavum. Clin Orthop Relat Res 359:18-26, 1999.
7. Hur H, Lee JK, Lee JH, Kim JH, Kim SH: Thoracic myelopathy caused by ossification of the ligamentum flavum. J Korean Neurosurg Soc 46:189-194, 2009. 8. Kim K, Isu T, Nomura R, Kobayashi S, Teramoto A: Cervical ligamentum flavum ossification: two case reports. Neurol Med Chir (Tokyo) 48:183-187, 2008. 9. Kobayashi S, Okada K, Onoda K, Horikoshi S: Ossification of the cervical ligamentum flavum. Surg Neurol 35:234-238, 1991. 10. Kubota M, Baba I, Sumida T: Myelopathy due to ossification of the ligamentum flavum of the cervical spine: a report of two cases. Spine 6:553-559, 1981. 11. Lu JJ: Cervical laminectomy: technique. Neurosurgery 60:S149-S153, 2007. 12. Matsui H, Katoh Y, Tsuji H: Untreated hypophosphatemic vitamin D-resistant rickets with symptomatic ossification of the ligamentum flavum. J Spinal Disord 4:110-113, 1991. 13. Miyazawa N, Akiyama I: Ossification of the ligamentum flavum of the cervical spine. J Neurosurg Sci 51:139-144, 2007. 14. Mizuno J, Nakagawa H: Unilateral ossification of the ligamentum flavum in the cervical spine with atypical radiological appearance. J Clin Neurosci 9:462-464, 2002. 15. Nakamura H: A radiographic study of the progression of ossification of the cervical posterior longitudinal ligament: the correlation between the ossification of the posterior longitudinal ligament and that of the anterior longitudinal ligament. Nippon Seikeigeka Gakkai Zasshi 68:725-736, 1994. 16. Okada K, Oka S, Tohge K, Ono K, Yonenobu K, Hosoya T: Thoracic myelopathy caused by ossification of the ligamentum flavum: clinicopathologic study and surgical treatment. Spine 16:280-287, 1991.
19. Ryken TC, Heary RF, Matz PG, Anderson PA, Groff MW, Holly LT, Kaiser MG, Mummaneni PV, Choudhri TF, Vresilovic EJ, Resnick DK: Cervical laminectomy for the treatment of cervical degenerative myelopathy. J Neurosurg Spine 11:142-149, 2009. 20. Sakou T, Taketomi E, Matsunaga S, Yamaguchi M, Sonoda S, Yashiki S: Genetic study of ossification of the posterior longitudinal ligament in the cervical spine with human leukocyte antigen haplotype. Spine 16:1249-1252, 1991. 21. Sugimura H, Kakitsubata Y, Suzuki Y, Kakitsubata S, Tamura S, Uwada O, Kodama T, Yano T, Watanabe K: MRI of ossification of ligamentum flavum. J Comput Assist Tomogr 16:73-76, 1992. 22. Takatsu T, Ishida Y, Suzuki K, Inoue H: Radiological study of cervical ossification of the posterior longitudinal ligament. J Spinal Disord 12:271-273, 1999. 23. van Oostenbrugge RJ, Herpers MJ, de Kruijk JR: Spinal cord compression caused by unusual location and extension of ossified ligamenta flava in a Caucasian male: a case report and literature review. Spine 24:486-488, 1999. 24. Zdeblick TA, Abitbol JJ, Kunz DN, McCabe RP, Garfin S: Cervical stability after sequential capsule resection. Spine 18:2005-2008, 1993.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. This study was approved by the ethical committee of our hospital. received 12 April 2010; accepted 19 October 2010 Citation: World Neurosurg. (2011) 75, 3/4:546-550. DOI: 10.1016/j.wneu.2010.10.041 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.10.041
OS ODONTOIDEUM WITH ATLANTOAXIAL DISLOCATION
21. Naderi S, Crawford NR, Song GS, Sonntag VK, Dickman CA: Biomechanical comparison of C1-C2 posterior fixations: cable, graft, and screw combinations. Spine (Phila Pa 1976) 23:1946-55, 1998.
27. Platzer P, Vecsei V, Thalhammer G, Oberleitner G, Schurz M, Gaebler C: Posterior atlanto-axial arthrodesis for fixation of odontoid nonunions. Spine (Phila Pa 1976) 33:624-30, 2008.
22. Ni B, Chen H, Guo X, Tao C: Bilateral atlantoaxial transarticular screws combined with atlas laminar hooks fixation. Chin J Surg 43:1358-9, 2005.
28. Resnick DK, Benzel EC: C1-C2 pedicle screw fixation with rigid cantilever beam construct: case report and technical note. Neurosurgery 50:426-8, 2002.
23. Ni B, Zhu Z, Zhou F, Guo Q, Yang J, Liu J, Wang F: Bilateral C1 laminar hooks combined with C2 pedicle screws fixation for treatment of C1-C2 instability not suitable for placement of transarticular screws. Eur Spine J 19:1378-82, 2010.
29. Sankar WN, Wills BP, Dormans JP, Drummond DS: Os odontoideum revisited: the case for a multifactorial etiology. Spine (Phila Pa 1976) 31:979-984, 2006.
24. Olerud S, Olerud C: The C1 claw device: a new instrument for C1-C2 fusion. Eur Spine J 10:345-7, 2001.
30. Spierings EL, Braakman R: The management of os odontoideum: analysis of 37 cases. J Bone Joint Surg Br 64:422-8, 1982.
25. Os odontoideum. Neurosurgery 50:S148-55, 2002. 26. Plant JG, Ruff SJ: Migration of rod through skull, into brain following C1-C2 instrumental fusion for os odontoideum: a case report. Spine (Phila Pa 1976) 35:E90-2, 2010.
31. Stevens JM, Chong WK, Barber C, Kendall BE, Crockard HA: A new appraisal of abnormalities of the odontoid process associated with atlanto-axial subluxation and neurological disability. Brain 117(Pt 1):133-48, 1994.
32. Stillwell WT, Fielding JW: Acquired os odontoideum: a case report. Clin Orthop Relat Res (135):7173, 1978. 33. Sze G, Brant-Zawadzki MN, Wilson CR, Norman D, Newton TH: Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies. Radiology 161:391-4, 1986. 34. Zhou F, Ni B, Li S, Yang J, Guo X, Zhu Z: C2 translaminar screw as the optimal choice for atlantoaxial dislocation with C2-C3 congenital fusion. Arch Orthop Trauma Surg 2010, In press.
Bin Ni and Fengjin Zhou contributed equally to this work. received 13 April 2010; accepted 15 July 2010 Citation: World Neurosurg. (2011) 75, 3/4:540-546. DOI: 10.1016/j.wneu.2010.07.021 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
Surgical Treatments of Myelopathy Caused by Cervical Ligamentum Flavum Ossification Jian Yang1, Bin Ni1, Ning Xie1, Qunfeng Guo1, Liangzhe Wang2
Key words 䡲 Cervical 䡲 Ossification of the ligamentum flavum 䡲 Surgical treatment Abbreviations and Acronyms CSF: Cerebrospinal fluid CT: Computed tomography JOA: Japanese Orthopaedic Association MRI: Magnetic resonance imaging OLF: Ossification of the ligamentum flavum OPLL: Ossification of the posterior longitudinal ligament From the Departments of 1Orthopedics and 2 Pathology, Changzheng Hospital, The Second Military Medical University, Shanghai, People’s Republic of China To whom correspondence should be addressed: Bin Ni, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2011) 75, 3/4:546-550. DOI: 10.1016/j.wneu.2010.10.041 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
䡲 OBJECTIVE: To present a small case series reporting the outcomes of surgical treatment for myelopathy caused by cervical ossification of the ligamentum flavum (OLF). 䡲 METHODS: The authors assessed 15 cases of myelopathy caused by cervical OLF. Patients were eight women and seven men 37–75 years old (mean age 59.7 years). All patients underwent bilateral laminectomy, and the lesions were removed. The decompression range was confined within the medial sides of the bilateral facets and within the involved segments. Intraoperative specimens were examined histologically to confirm the diagnosis. During the operation, the extent of adherence of the lesions to the dura was recorded. The patients were followed for 3–70 months. Neurofunctional improvements were evaluated with the Japanese Orthopaedic Association (JOA) score. 䡲 RESULTS: Definite adherences were present in 67.7% of all cases. JOA score showed a 71.5% improvement after operation from a preoperative score of 5– 8 (mean 6.4) to a postoperative score of 10 –14 (mean 13.5). The operative outcomes were satisfactory without extensive decompression of adjacent segments. 䡲 CONCLUSIONS: A high rate of adherence to the dura was observed in patients with myelopathy caused by cervical OLF. Bilateral laminectomy and removal of the lesions, without extensive decompression of adjacent segments, provides an optimistic prognosis.
INTRODUCTION Ossification of the ligamentum flavum (OLF) occurs most frequently in the lower thoracic spine and is extremely rare in the
546
www.SCIENCEDIRECT.com
cervical region (3, 5, 10, 14, 23). Features of cervical OLF, associated morbidity, and treatment have been previously described in
case reports (3, 8, 10, 13, 14). In the present study, we report the surgical treatment of 15 Chinese patients with cervical OLF.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.10.041
PEER-REVIEW REPORTS JIAN YANG ET AL.
MYELOPATHY CAUSED BY CERVICAL OLF
Table 1. Characteristics of 15 Patients with Cervical OLF No.
Gender/Age (years)
DC (months)
1
M/37
8
C5-6
⫺
2
F/63
52
C4-5, C5-6, C6-7
⫹
Level
Adhesion
Concomitant Diseases
Follow-up (months)
—
50
6/16 (90.9)
9
5/12 (58.3)
Dorsal OLF
JOA Score Preoperatively/ Follow-up (improvement %)
3
M/62
28
C6/7
⫹
4
F/50
20
C4-5, C5-6
⫺
5
M/63
36
C2-3, C3-4, C4-5
6
F/75
90
C3-4, C4-5, C5-6
7
F/58
66
C6-7, C7-T1
⫹
—
70
7/13 (60.0)
8
M/65
45
C4-5
⫹
OPLL, dorsal OLF
20
5/13 (66.7)
OPLL
12
8/15 (77.8)
Disc herniation
—
36
7/14 (70.0)
⫹
Disc herniation
12
6/13 (63.6)
⫹
Disc herniation
3
5/10 (41.7)
9
F/74
38
C3-4, C4-5, C5, C6
⫹
12
5/13 (66.7)
10
F/58
24
C3-4, C4-5
⫺
—
9
6/14 (72.3)
11
M/45
18
C6-7
⫺
—
12
7/16 (90.0)
12
M/58
22
C5-6, C6-7
⫺
—
54
8/14 (66.7)
13
M/55
28
C4-5, C5-6
⫹
Disc herniation
12
7/13 (60.0)
14
F/62
30
C6-7, C7-T1
⫹
Dorsal OLF
9
8/15 (77.8)
15
F/70
45
C3-4, C4-5, C5-6
⫹
Disc herniation
9
6/12 (54.5)
DC, disease course; JOA, Japanese Orthopaedic Association; OLF, ossification of the ligamentum flavum; OPLL, ossification of the posterior longitudinal ligament; ⫺, no or slight adhesion; ⫹, definite or severe adhesion.
MATERIALS AND METHODS This study included 15 consecutive Chinese patients admitted to our department from 1999 –2009. There were seven men and eight women 37–75 years old (mean age 59.7 years). Typical clinical features included sensory defect; decreased muscle strength; and disturbance in gait, urination, and defecation. The patients’ courses were prolonged, and the histories of the main complaints ranged from 8 months to 7.5 years. The distributions of the involved segments are shown in Table 1. Concomitant diseases included disc degeneration and herniation in five patients (33.3%), ossification of the posterior longitudinal ligament (OPLL) in two patients (13.3%), and thoracic OLF in three patients (20%). In our hospital, x-rays, computed tomography (CT), and magnetic resonance imaging (MRI) are obtained as routine preoperative imaging, and x-rays only are routinely obtained postoperatively. When planning each operation, preoperative images were studied to confirm the location and contour of the lesion and the degree of cord compression. Indications for operation included development of neurologic deficiency and definite imaging findings in accordance with the clinical manifesta-
tions. Nine patients underwent immediate operations, and six patients underwent conservative treatment for 3– 6 months that was ultimately ineffective, and operations were then required. Decompressive laminectomy was performed in all patients at the involved levels (Table 1). Operations were performed with a posterior approach and exposure of corresponding segments. The decompression range was the bilateral laminae within the medial sides of the facets and within the involved segments. A furrow was made along the range using a burr and a rongeur. The laminae were lifted from one side (from the intact side if the lesion was unilateral) to the other side to reveal the lesions. Care was taken to separate the adhesion. Lateral mass screws and rods were mounted in all the cases at one level above and below the involved segments. Dural tear occurred in two patients. In one case, the dura was torn, but there was no defect, and the dura was repaired in situ. In the other case, the dura was torn with a defect 4 mm wide ⫻ 1 cm long. The defect was patched with deep fascia sewn to the dura, and fibrin glue was sprinkled on the surface of the dura. When closing the incisions, rigorous layered sutures were per-
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formed in all cases to prevent cerebrospinal fluid (CSF) leakage. No CSF leakage was observed. A cervical collar was used for 3 months postoperatively in all patients. Histologic examination of the intraoperative specimens was performed routinely to confirm the diagnosis. During the operation, the extent of adherence of the lesions to dura was recorded. Neurologic state and radiologic parameters were evaluated at 3–70 months’ follow-up. Neurologic deficiency was evaluated with the Japanese Orthopaedic Association (JOA) score, and x-rays were routinely obtained postoperatively.
RESULTS There were 31 segments in 15 patients, including 1 in C2-3 (3.2%), 5 in C3-4 (16.1%), 9 in C4-5 (29.0%), 8 in C5-6 (25.8%), 6 in C6-7 (19.4%), and 2 in C70T1 (6.4%) (Table 1). There were 11 cases with multiple segments and 4 cases with single segments. Preoperative imaging findings showed enlargement of the ligamentum flavum and compression of the spinal cord (Figure 1). The space-occupying lesions showed low-intensity signals on MRI T1-weighted and T2weighted sequences and high-density sig-
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Figure 1. Appearance on magnetic resonance imaging (MRI) and computed tomography (CT) of a patient with multiple segments of cervical
nals in CT and x-rays. The lesions were shown definitively on MRI in 12 patients, on CT in all 15 patients, and on x-rays in only 1 case (Figure 2). Intraoperative findings indicated that the lesions definitely adhered to the dura in 10 (66.7%) patients; there was no or slight adherence in 5 (33.3%) patients. Dural tear occurred in two patients. Intraoperative repair was performed, and no sign of postoperative CSF leakage was observed.
The JOA score showed a 71.5% improvement from a preoperative score of 5– 8 (mean 6.4) to a postoperative score of 10 –14 (mean 13.5). Operative complications occurred in one patient with postoperative temporary neurologic deterioration who presented with an aggravation of preoperative body numbness and in one patient with C5 radiculopathy; these complications resolved over 1 week (first patient) and 2 weeks (second patient).
Figure 2. Occupying lesion solitarily located in C5-6 showed high density on computed tomography (CT) (A) and low intensity on magnetic resonance
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ossification of the ligamentum flavum (OLF).
No recurrence or other complications were observed in follow-up of up to 70 months (mean 23.1 months).
DISCUSSION Although the pathogenesis of OLF is unclear, there is evidence from thoracic spine cases that degeneration, trauma, inflamma-
imaging (MRI) (B). It is definitely revealed on x-ray (arrow) (C).
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tion, metabolic abnormality, and genetics may play important roles (12, 17, 20). The differences in morbidities between the cervical and thoracic spine were suggested to result from different focal anatomic and force factors (9, 13, 14). In the cervical spine, OLF hardly occurs in the capsular portion because the ligamentum flavum does not adhere to the bony tissue directly in this area. Additionally, in contrast to in the cervical spine, the ligament in the thoracic region seldom becomes loose, and the tension is always static, which may play an important role in the process of ossification. Typical cervical OLF can be visualized on x-ray, CT, and MRI (4, 21). CT can define the contour of the ossification, three-dimensional CT helps to determine the precise location of the lesion, and MRI can reveal the degree of cord compression. Precise evaluation of the location and contour of the lesions and the degree of cord compression in preoperative images is crucial in planning the operation. In the present study, only one lesion was revealed on x-ray, whereas MRI and CT revealed 80% and 100% of all lesions. These data suggest that comprehensive imaging methods are required for patients with suspicion of OLF. There were three cases (20%) associated with thoracic OLF and two cases associated with OPLL, suggesting that consideration of other spinal regions is important when cervical OLF is observed (6). In cases with concomitant diseases, the responsible lesions must be confirmed by neurologic examinations.
of development of progressive deformity after laminectomy were reported to range from 14%– 47% (19) and 21%– 42% (11). Generally, a minor decompression range, especially in cases of intact facets, is less likely to result in late postoperative deformity (24). Mechanical factors may play an important role, however, in the morbidity of ossification of spinal ligaments. Marked progression of OPLL and ossification of the anterior longitudinal ligament after cervical laminectomy were reported (15, 22). Additionally, a case in which changes of focal mechanics led to secondary OLF at adjacent levels was described (2). We agree that posterior cervical laminectomy in which spinous process, interspinous ligaments, and laminae are ablated remains a risk factor for changing focal mechanics that may lead to ossification of other ligaments at the same level or ligaments at adjacent levels, even if postoperative deformity does not occur. Given the frequent coincidence of ossification of spinal ligaments (4, 18), we used internal fixation in all patients with the aim of preventing ossification of other ligaments at the same level or ligaments at adjacent levels (Figure 3). Further study of the impact of this technique is required. Operative outcome of cervical OLF showed an optimistic prognosis. Although adherence to the dura was observed in 66.7% of patients, a 71.5% improvement of JOA score was achieved. Two patients experienced complications including one temporary neurologic deterioration and one C5 radiculopathy; however, both complications resolved within 1–2 weeks postoperatively. We confined the decompression range within the involved segments and within the medial side of the bilateral facets as long as this was sufficient to remove the lesions. Satisfactory neurologic improvements were achieved without the requirement for extensive decompression of adjacent segments. The optimal outcome of surgical treatment may result from the low incidence of cervical OLF occurring in the capsular portion and the anterior flexion of the cervical spine leaving a large buffering space for the cervical spine cord to tolerate the compression of the lesions and procedural disturbances. To our knowledge, only two cases of cervical OLF were previously reported in Chinese patients (8, 13). In addition to the 15 cases of OLF we describe in the present
Figure 3. Postoperative x-rays of patient in Figure 1.
In the present study, six patients received conservative treatment for 3– 6 months before operation, without obvious neurologic improvement, and their condition seemed to develop progressively. There is some evidence from thoracic OLF cases that a longer disease course and a more severe preoperative neurologic deficiency represent a worse prognosis (1, 7, 16). In those studies, early diagnosis and surgical decompression were the only significant predictors of favorable outcome. When definite imaging evidence and corresponding neurologic deficiency are confirmed, an operation should performed. We observed a high rate (66.7% of patients) of adherence of the lesions to the dura. Although surgeons should be extremely careful when dissecting the adhesion, a dural tear can occasionally occur, particularly when the dura is severely adhered or even ossified and fused with the lesion. In such cases, the lesion may be excised with the adherent outer layer of the dura. In cases where the dura is torn but there is no defect, the dura can be repaired in situ. If the dura is torn with a defect, however, it should be patched with deep fascia or an artificial dural graft, rather than be sewn in situ, to avoid dural sac stenosis. Fibrin glue sprinkled on the surface of the dura and rigorous layered sutures when closing the incisions are also helpful. Using multiple surgical methods, most CSF leaks can be prevented. The indication for instrumentation for laminectomy is controversial (19). The rates
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study, we encountered two other nonoperative outpatient cases with typical MRI and CT images. There seems to be a recent emergence of cervical OLF in China. We suggest that this phenomenon relates to the large population, the comparably small number of hospitals, and the development of economical and medical conditions allowing extensive use of CT and MRI. Nevertheless, the number of Chinese cases we treated from 1999 –2009 was 7.5 times more than previously reported from 1962– 2008 (8, 13). We suggest that the incidence of OLF in China is more common than previously reported.
CONCLUSIONS We observed a high rate of adherence to the dura in patients with myelopathy caused by cervical OLF. Bilateral laminectomy and removal of the lesions, without extensive decompression of adjacent segments, provides an optimistic prognosis.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. This study was approved by the ethical committee of our hospital. received 12 April 2010; accepted 19 October 2010 Citation: World Neurosurg. (2011) 75, 3/4:546-550. DOI: 10.1016/j.wneu.2010.10.041 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.10.041