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The Asymptomatic Degenerative Cervical Disc: A Dilemma
Perspectives Commentary on: Inclusion of Asymptomatic Degenerative Discs in a Two-Level Anterior Cervical Discectomy and Fusion: A Decision Analysis by Boakye and Mindea pp. 339-343.
Volker K. H. Sonntag, M.D. Vice Chairman Emeritus, Division of Neurological Surgery Barrow Neurological Institute St. Joseph’s Hospital and Medical Center
The Asymptomatic Degenerative Cervical Disc: A Dilemma Volker K. H. Sonntag
A
nterior cervical discectomy and corpectomy for the treatment of cervical spondylosis, cervical disc herniation, and ossification of the posterior longitudinal ligament are associated with favorable rates of fusion and successful clinical outcomes. Although the complications from these procedures have been well described, the pathogenesis and clinical development of degenerative adjacent segment disease (ASD) are not fully understood. Intuitively, the mechanical and shearing motion exerted by the lever moment at adjacent levels after fusion should advance local degenerative changes. However, few large series on the treatment of cervical spondylosis with fusion have a long enough follow-up period to address ASD. One of the most common predisposing factors for developing asymptomatic ASD is predisposing degenerative changes at the adjacent segment before fusion. In most series, anterior cervical fusion was performed to treat cervical spondylosis. The lower cervical segments—C5-6 and C6-7—are typically the ones affected by degeneration and requiring subsequent surgical treatment. These lower levels may be vulnerable because of increased segmental motion and loading demands. One way of preventing ASD is to incorporate the adjacent level in the initial surgery if it exhibits degenerative disc disease. Some authors suggest supplementing anterior cervical discectomy with fusion for treatment of degenerative disease associated with the high risk of developing ASD at C5-6 and C6-7 (2, 7). Adjacent segment fusion is partly justified by the fact that patients with a multiple-level fusion of the degenerative segments experience a notable decrease in ASD. The incidence of ASD was reduced by using preoperative discography to identify degenerative discs before they are incorporated into the fusion (3). Nevertheless, Clements and O’Leary (1) “advocated not operating on adjacent level of patients, if patients had no clinical symptoms attributable to the radiographic degenerative disc.”
Key words 䡲 Anterior cervical discectomy 䡲 Asymptomatic degenerative discs 䡲 Spinal fusion
Every patient with cervical spondylosis needs to undergo a detailed history and physical examination to identify any signs or symptoms attributable to a degenerative disc. If the signs, symptoms, and clinical examination are consistent with the radiologic findings, anterior cervical discectomy should be performed on all symptomatic segments. In their article in this issue of WORLD NEUROSURGERY, Boakye and Mindea used a decision analysis model to compare single-level and two-level fusions in patients with asymptomatic discs adjacent to a symptomatic disc. The extensive application of probabilities and utilities of alternative outcomes in the decision tree was based on systematic review of the literature and on expert opinion. Their findings indicate that observation was the preferred management for asymptomatic adjacent degenerative disc. Although this conclusion seems reasonable, the needs of each individual patient must be treated separately. For example, in a young patient with significant ASD, including that segment with the initial surgery would seem a reasonable approach. In these patients, the risk of developing symptomatic radiculopathy or myelopathy over the life span is significant enough that early surgical intervention might be beneficial and should be discussed with the patient. Another major consideration for including the asymptomatic adjacent degenerative disc in the initial operation is the patient’s medical condition. If a patient is young or middle-aged and in excellent health, including the asymptomatic adjacent level in the initial operation should be considered. Another factor to be considered is the severity of ASD. If a patient has myelopathy and radiculopathy and one level has severe ASD, the seemingly asymptomatic adjacent level should be included in the initial intervention. Another factor to consider is the curvature of the spine. Is kyphosis or straightening of the spine present at the apparently asymptomatic adjacent level?
Abbreviations and Acronyms ASD: Adjacent segment disease
Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA To whom correspondence should be addressed: Volker K. H. Sonntag, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2012) 78, 3/4:241-242. DOI: 10.1016/j.wneu.2012.02.048
WORLD NEUROSURGERY 78 [3/4]: 241-242, SEPTEMBER/OCTOBER 2012
www.WORLDNEUROSURGERY.org
241
PERSPECTIVES
Finally, whether the adjacent level is hypermobile or subluxation is present at the adjacent level should be considered. These factors should also prompt the surgeon to consider including the adjacent degenerative disc in the initial operation. Strategies have been devised to prevent ASD from becoming symptomatic, such as anterior cervical discectomy without fusion. Fusion rates after anterior cervical discectomy ranged from 72%–100% (5, 6, 8). The development of kyphosis after anterior cervical discectomy ranged from 63%– 83% (5, 6). However, in a large series, Lunsford et al. (4) reported no difference in the development of ASD in patients undergoing anterior cervical discectomy without fusion compared with patients undergoing
REFERENCES 1. Clements DH, O’Leary PF: Anterior cervical discectomy and fusion. Spine (Phila Pa 1976) 15:1023-1025, 1990. 2. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH: Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 81:519-528, 1999. 3. Hubach PC: A prospective study of anterior cervical spondylodesis in intervertebral disc disorders. Eur Spine J 3:209-213, 1994.
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www.SCIENCEDIRECT.com
anterior cervical discectomy with fusion. An alternative way to prevent ASD is placement of an artificial disc. However, it seems reasonable to keep the segment mobile to prevent progression of ASD in an asymptomatic level. Only long-term follow-up will assess its efficacy at preventing the worsening or development of ASD. Nevertheless, this possibility holds enormous potential for preventing ASD from becoming symptomatic. Based on their decision analysis for managing asymptomatic ASD, Boakye and Mindea concluded that observation is the preferred strategy. Nonetheless, surgeons must consider each individual case before this recommendation is adopted on a global basis.
4. Lunsford LD, Bissonette DJ, Jannetta PJ, Sheptak PE, Zorub DS: Anterior surgery for cervical disc disease. Part 1: treatment of lateral cervical disc herniation in 253 cases. J Neurosurg 53:1-11, 1980. 5. Murphy MG, Gado M: Anterior cervical discectomy without interbody bone graft. J Neurosurg 37:71-74, 1972. 6. Savolainen S, Rinne J, Hernesniemi J: A prospective randomized study of anterior single-level cervical disc operations with long-term follow-up: surgical fusion is unnecessary. Neurosurgery 43:51-55, 1998. 7. Shinomiya K, Okamoto A, Kamikozuru M, Furuya K, Yamaura I: An analysis of failures in primary cervical
anterior spinal cord decompression and fusion. J Spinal Disord 6:277-288, 1993.
8. Wilson DH, Campbell DD: Anterior cervical discectomy without bone graft: report of 71 cases. J Neurosurg 47:551-555, 1977. Citation: World Neurosurg. (2012) 78, 3/4:241-242. DOI: 10.1016/j.wneu.2012.02.048 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2012 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2012.02.048
Volker K. H. Sonntag, M.D. Vice Chairman Emeritus, Division of Neurological Surgery Barrow Neurological Institute St. Joseph’s Hospital and Medical Center
The Asymptomatic Degenerative Cervical Disc: A Dilemma Volker K. H. Sonntag
A
nterior cervical discectomy and corpectomy for the treatment of cervical spondylosis, cervical disc herniation, and ossification of the posterior longitudinal ligament are associated with favorable rates of fusion and successful clinical outcomes. Although the complications from these procedures have been well described, the pathogenesis and clinical development of degenerative adjacent segment disease (ASD) are not fully understood. Intuitively, the mechanical and shearing motion exerted by the lever moment at adjacent levels after fusion should advance local degenerative changes. However, few large series on the treatment of cervical spondylosis with fusion have a long enough follow-up period to address ASD. One of the most common predisposing factors for developing asymptomatic ASD is predisposing degenerative changes at the adjacent segment before fusion. In most series, anterior cervical fusion was performed to treat cervical spondylosis. The lower cervical segments—C5-6 and C6-7—are typically the ones affected by degeneration and requiring subsequent surgical treatment. These lower levels may be vulnerable because of increased segmental motion and loading demands. One way of preventing ASD is to incorporate the adjacent level in the initial surgery if it exhibits degenerative disc disease. Some authors suggest supplementing anterior cervical discectomy with fusion for treatment of degenerative disease associated with the high risk of developing ASD at C5-6 and C6-7 (2, 7). Adjacent segment fusion is partly justified by the fact that patients with a multiple-level fusion of the degenerative segments experience a notable decrease in ASD. The incidence of ASD was reduced by using preoperative discography to identify degenerative discs before they are incorporated into the fusion (3). Nevertheless, Clements and O’Leary (1) “advocated not operating on adjacent level of patients, if patients had no clinical symptoms attributable to the radiographic degenerative disc.”
Key words 䡲 Anterior cervical discectomy 䡲 Asymptomatic degenerative discs 䡲 Spinal fusion
Every patient with cervical spondylosis needs to undergo a detailed history and physical examination to identify any signs or symptoms attributable to a degenerative disc. If the signs, symptoms, and clinical examination are consistent with the radiologic findings, anterior cervical discectomy should be performed on all symptomatic segments. In their article in this issue of WORLD NEUROSURGERY, Boakye and Mindea used a decision analysis model to compare single-level and two-level fusions in patients with asymptomatic discs adjacent to a symptomatic disc. The extensive application of probabilities and utilities of alternative outcomes in the decision tree was based on systematic review of the literature and on expert opinion. Their findings indicate that observation was the preferred management for asymptomatic adjacent degenerative disc. Although this conclusion seems reasonable, the needs of each individual patient must be treated separately. For example, in a young patient with significant ASD, including that segment with the initial surgery would seem a reasonable approach. In these patients, the risk of developing symptomatic radiculopathy or myelopathy over the life span is significant enough that early surgical intervention might be beneficial and should be discussed with the patient. Another major consideration for including the asymptomatic adjacent degenerative disc in the initial operation is the patient’s medical condition. If a patient is young or middle-aged and in excellent health, including the asymptomatic adjacent level in the initial operation should be considered. Another factor to be considered is the severity of ASD. If a patient has myelopathy and radiculopathy and one level has severe ASD, the seemingly asymptomatic adjacent level should be included in the initial intervention. Another factor to consider is the curvature of the spine. Is kyphosis or straightening of the spine present at the apparently asymptomatic adjacent level?
Abbreviations and Acronyms ASD: Adjacent segment disease
Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA To whom correspondence should be addressed: Volker K. H. Sonntag, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2012) 78, 3/4:241-242. DOI: 10.1016/j.wneu.2012.02.048
WORLD NEUROSURGERY 78 [3/4]: 241-242, SEPTEMBER/OCTOBER 2012
www.WORLDNEUROSURGERY.org
241
PERSPECTIVES
Finally, whether the adjacent level is hypermobile or subluxation is present at the adjacent level should be considered. These factors should also prompt the surgeon to consider including the adjacent degenerative disc in the initial operation. Strategies have been devised to prevent ASD from becoming symptomatic, such as anterior cervical discectomy without fusion. Fusion rates after anterior cervical discectomy ranged from 72%–100% (5, 6, 8). The development of kyphosis after anterior cervical discectomy ranged from 63%– 83% (5, 6). However, in a large series, Lunsford et al. (4) reported no difference in the development of ASD in patients undergoing anterior cervical discectomy without fusion compared with patients undergoing
REFERENCES 1. Clements DH, O’Leary PF: Anterior cervical discectomy and fusion. Spine (Phila Pa 1976) 15:1023-1025, 1990. 2. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH: Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 81:519-528, 1999. 3. Hubach PC: A prospective study of anterior cervical spondylodesis in intervertebral disc disorders. Eur Spine J 3:209-213, 1994.
242
www.SCIENCEDIRECT.com
anterior cervical discectomy with fusion. An alternative way to prevent ASD is placement of an artificial disc. However, it seems reasonable to keep the segment mobile to prevent progression of ASD in an asymptomatic level. Only long-term follow-up will assess its efficacy at preventing the worsening or development of ASD. Nevertheless, this possibility holds enormous potential for preventing ASD from becoming symptomatic. Based on their decision analysis for managing asymptomatic ASD, Boakye and Mindea concluded that observation is the preferred strategy. Nonetheless, surgeons must consider each individual case before this recommendation is adopted on a global basis.
4. Lunsford LD, Bissonette DJ, Jannetta PJ, Sheptak PE, Zorub DS: Anterior surgery for cervical disc disease. Part 1: treatment of lateral cervical disc herniation in 253 cases. J Neurosurg 53:1-11, 1980. 5. Murphy MG, Gado M: Anterior cervical discectomy without interbody bone graft. J Neurosurg 37:71-74, 1972. 6. Savolainen S, Rinne J, Hernesniemi J: A prospective randomized study of anterior single-level cervical disc operations with long-term follow-up: surgical fusion is unnecessary. Neurosurgery 43:51-55, 1998. 7. Shinomiya K, Okamoto A, Kamikozuru M, Furuya K, Yamaura I: An analysis of failures in primary cervical
anterior spinal cord decompression and fusion. J Spinal Disord 6:277-288, 1993.
8. Wilson DH, Campbell DD: Anterior cervical discectomy without bone graft: report of 71 cases. J Neurosurg 47:551-555, 1977. Citation: World Neurosurg. (2012) 78, 3/4:241-242. DOI: 10.1016/j.wneu.2012.02.048 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2012 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2012.02.048