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  In this Article
 »  Abstract
 »  Indications and ...
 »  Choice of Operat...
 » Anterior Approaches
 »  Anterior Cervica...
 »  Anterior Cervica...
 »  Anterior Cervica...
 »  Autologous Iliac...
 » Fibular Allografts
 » PEEK Cages
 » Titanium Cages
 »  Posterior Approa...
 » Laminectomy
 »  Laminectomy with...
 » Laminoplasty
 » Combined Approaches
 »  Complications of...
 »  Prognosis of Sur...
 » Conclusions
 »  References
 »  Article Figures

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TOPIC OF THE ISSUE: REVIEW ARTICLE
Year : 2012  |  Volume : 60  |  Issue : 2  |  Page : 201-209

Surgical management of cervical spondylotic myelopathy


Department of Neurosurgery, Madurai Medical College; Devadoss Multispeciality Hospitals, Madurai, India

Date of Submission22-Mar-2012
Date of Decision22-Mar-2012
Date of Acceptance26-Mar-2012
Date of Web Publication19-May-2012

Correspondence Address:
N Muthukumar
Muruganagam, 138, Anna Nagar, Madurai - 625 020
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.96402

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 » Abstract 

Cervical spondylotic myelopathy (CSM) is emerging as the most common cause of spinal cord dysfunction in the elderly worldwide. In the past decade, our understanding of the biomechanics of the spine has improved along with advances in spinal instrumentation and this has led to significant changes in the surgical management of CSM. This review will discuss the indications, advantages and limitations of different operative approaches as well as the complications and prognosis of surgery for cervical spondylotic myelopathy. Choice of surgical approach for CSM should be based on the clinical and radiological characteristics of the individual patient and not on the preferences of the surgeon.


Keywords: Anterior cervical discectomy, cervical spondylotic myelopathy, laminectomy, laminoplasty, lateral mass fusion, spinal fusion, surgery


How to cite this article:
Muthukumar N. Surgical management of cervical spondylotic myelopathy. Neurol India 2012;60:201-9

How to cite this URL:
Muthukumar N. Surgical management of cervical spondylotic myelopathy. Neurol India [serial online] 2012 [cited 2020 Jan 19];60:201-9. Available from: http://www.neurologyindia.com/text.asp?2012/60/2/201/96402


Cervical spondylotic myelopathy (CSM) is emerging as the most common cause of spinal cord dysfunction in the elderly worldwide. With the average life expectancy increasing worldwide, it is understandable that in future the number of patients with CSM requiring medical attention will increase significantly. In the past decade, our understanding of the biomechanics of the spine has improved along with advances in spinal instrumentation. This has led to significant changes in the surgical management of CSM. Hence, a review of the current status of the various surgical options available for this disease entity is necessary. This review will discuss the indications, advantages and limitations of the various commonly available surgical techniques for CSM. For brevity's sake, details of surgical techniques will not be discussed.

The goals of surgical treatment of CSM are the following: 1. Improvement or preservation of neurological function, 2. Prevention or correction of spinal deformity, and 3. Maintenance of spinal stability. [1] The aforementioned goals should be accomplished with least morbidity to the patient. Recent studies have shown that there are wide variations in the choice of surgical approach to the degenerative disorder of the cervical spine based on an individual surgeon's preferences. [2] Studies, including the recent AOSpine International multicenter prospective study, have also shown that the majority of the spine surgeons prefer the anterior approach in 51-60% of cases, posterior approach in about 35% and a combined approach in the remaining. [3],[4] This is mainly due to the variations in the clinical and radiological parameters and to some extent due to surgeons' preferences. [3],[5]


 » Indications and Timing of Surgical Intervention Top


At present, there is consensus that a modified Japanese Orthopedic Association score (mJOA) of ≤ 12 is a definite indication for surgery in patients with CSM. [6] For patients who have a mJOA score of >12 on presentation, the decision to proceed with surgery should be based on an individualized basis. The timing of surgery depends upon the patient's clinical presentation. A rapid neurological decline will require a more urgent intervention whereas a stable deficit can be approached in an elective manner. [7] When indicated, surgery should be performed within six months to one year of symptom onset to achieve good results. [8]


 » Choice of Operative Approach Top


The choice of operative procedure should take into consideration the individual patient's clinical and radiological characteristics, age, co-morbidities, lifestyle (smoking etc.), procedure-specific risks and finally, the experience and comfort level of the surgeon with various surgical procedures. Several important questions should be carefully considered while choosing the surgical approach as suggested by Komotar and colleagues. [7] 1. Location of compression: anterior or posterior: Logically, a ventral compressive pathology should be treated by an anterior approach and vice versa, although there might be exceptions to this rule. 2. Single or multilevel compression: Anterior interbody grafting beyond two levels is associated with increased rate of pseudoarthrosis. In such cases, supplemental posterior stabilization might be required or a single-stage posterior approach might be more appropriate. [7] 3. Presence or absence of congenital spinal stenosis, 4. Alignment of the cervical spine: Is the spine lordotic, straight or kyphotic? For example, posterior procedures are primarily indicated for lordotic or possibly, straight spines. Standalone posterior decompressive procedures are contraindicated for fixed kyphotic spines. 5. Presence or absence of instability: Severe subluxation visualized on static images or any increase noted in dynamic images necessitates stabilization and fusion. 6. Patient's lifestyle-related factors: Smoking is a well-known factor associated with nonunion and pseudoarthrosis. This factor should be factored into the equation while choosing the surgical approach for a chronic, heavy smoker. 7. Other factors such as the presence of developmental stenosis, pre-existing neck pain and prior cervical spine surgery, if any, should be considered. [5] For example, postoperative axial pain is a well-known complication of laminoplasty and hence, in patients with significant preoperative neck pain this factor should be taken into consideration before choosing the appropriate approach.

Failure of surgical treatment is often due two factors: either poor patient selection or poor choice of surgical procedure.


 » Anterior Approaches Top


The advantage of an anterior approach is that it addresses the ventral pathology by direct decompression and if grafting is added, immediate stability of the cervical spine is achieved. [9] A variety of surgical approaches are available for anterior decompression of the cervical spinal cord in CSM. In this review, emphasis is placed only on the more commonly used approaches: these include 1. Anterior cervical discectomy alone without fusion, 2. Anterior cervical discectomy with fusion with or without supplemental instrumentation, 3. Anterior cervical corpectomy and fusion with or without instrumentation.


 » Anterior Cervical Discectomy without Fusion Top


The currently accepted indications for anterior cervical discectomy without fusion are: 1. Single-level compression anteriorly, 2. Normal cervical lordosis, 3. No instability seen on dynamic radiographs. Instability is defined as: a) subluxation of more than 3.5 mm on static radiographs, b) more than 11 degrees of angulation between adjacent segments, and c) subluxation of more than 4 mms on dynamic radiographs. [10] Special attention should be paid to the sagittal alignment of the cervical spine, i.e. both overall cervical lordosis as well as segmental lordosis at the affected level. Recent studies have shown that the current trend among spine surgeons for single-level disease is moving towards fusion than discectomy alone even though there is no evidence to substantiate the superiority of fusion in single-level disease. [2] For single level disease, The Joint Guidelines Committee of american association of neurological surgeons/congress of neurological surgeons found that functional outcomes were the same between anterior cervical discectomy alone and anterior cervical discectomy with fusion. [11] The advantages of standalone discectomy are: avoidance of implants reduces the cost of surgery, shorter surgical time, shorter hospital stay and sick leave, avoidance of the donor site morbidity if autologous grafts are used. [12] However, a recent study has shown that even though short-term results of standalone discectomy are equal to discectomy with fusion, in the long term approximately one-third of patients complain of disabling neck pain. [12]


 » Anterior Cervical Discectomy with Fusion Top


The indications for anterior cervical discectomy and fusion are as follows: 1. Two level compression anteriorly, 2. Presence of segmental kyphosis i.e. angulation of more than 11 degrees between adjacent segments, 3. Instability seen in static or dynamic radiographs. When Factors 2 and 3 are present, even patients with single-level disease should undergo fusion. The fusion can be an uninstrumented fusion [Figure 1] or an instrumented one [Figure 2]. The material that is used to replace the disc is most often autograft [Figure 3], less commonly, allograft or spacers made of titanium [Figure 4], polyetheretherketone (PEEK) or carbon. There are specific advantages and disadvantages of using the above mentioned struts or spacers and these would be highlighted later in the discussion.
Figure 1: Uninstrumented fusion. (a) preoperative MRI showing compression at C5-C6 and C6-C7 levels, (b) Postoperative sagittal reconstructed CT showing unistrumented fusion with tricortical grafts at the respective disc spaces (arrows)

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Figure 2: Instrumented fusion. (a) preoperative MRI showing single-level disc protrusion at C5-C6, (b) Postoperative radiograph showing instrumented fusion, (c) Postoperative MRI of the same patient showing adequate decompression and stabilization

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Figure 3: Instrumented fusion with autograft. (a) Immediate postoperative radiograph, (b) Postoperative radiograph at 4 months showing bony fusion

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Figure 4: Instrumented fusion with standalone cage. (a) Preoperative MRI showing single-level disc causing cord compression, (b) Intraoperative photograph with the standalone titanium spacer in situ, (c) Postoperative radiograph with the spacer in situ

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 » Anterior Cervical Corpectomy Top


Anterior cervical corpectomy is indicated for 1. patients with pathology that extends beyond the interspace level (for example, migrated disc fragment behind the vertebral body or an associated ossified posterior longitudinal ligament (OPLL) behind the vertebral body), 2. patients with a narrow spinal canal who cannot be treated by a posterior only procedure because of associated kyphosis or instability, for example, a patient with an irreducible kyphotic deformity for whom an entire body must be resected to restore alignment and lordosis. [11] The advantages of anterior cervical corpectomy for multilevel disease include providing fewer sites at which fusion must occur as well as decreasing the operating time by preparation of one graft and one recipient site rather than multiple grafts and multiple recipient sites. [13] Anterior cervical corpectomy can be followed by an uninstrumented fusion or more commonly, an instrumented fusion. Instrumented fusion for corpectomy is currently gaining popularity in view of the decreased rates of pseudoarthrosis and graft dislodgement. [11] The materials that can be used as struts or spacers include: autologous iliac crest grafts, fibular allografts, PEEK or carbon cages, and titanium cages. There are several advantages and disadvantages of using these different materials.


 » Autologous Iliac Crest Graft Top


Iliac crest graft is the traditional graft used in spine surgery. The advantage is the well-known high rates of fusion. However, the disadvantages include donor site morbidity like pain, hernia, and lateral femoral cutaneous nerve injury. The angulation of the iliac crest might pose problems when more than two levels of corpectomy is done. [14]


 » Fibular Allografts Top


The advantages of fibular allograft include: avoidance of donor site morbidity, unlimited supply, ready availability in different sizes and shapes, it can be used for more than two levels of corpectomy unlike autologous iliac crest grafts. The disadvantages include: fusion rates are inferior to autologous grafts, especially, when used for more than two levels of corpectomy. [14]


 » PEEK Cages Top


The advantages include avoiding donor site morbidity, ready availability in different sizes, radiolucency which enables assessment of fusion postoperatively, modulus of elasticity of this material is almost similar to bone and hence, they have lesser chance of telescoping or sinking into the adjacent vertebral bodies unlike titanium cages.


 » Titanium Cages Top


These cages are available in different sizes; when combined with ventral plate fixation [Figure 5] they provide excellent stability by resisting flexion, extension and lateral bending. [15] However, they also have several disadvantages like: their high modulus of elasticity often results in their migration (telescoping) into the end plates of adjacent vertebral bodies, it is difficult to assess fusion, and, when revision surgery is required, the titanium cages are difficult to revise. [14]
Figure 5: Titanium expandable cage-plate combination construct for stabilization following cervical corpectomy. (a) and (b) Postoperative radiographs showing the expandable cage (single arrow) and the attached plates (double arrowheads) that help secure the cage to the vertebral bodies above and below, (c) Intraoperative photograph showing the expandable cage-plate construct in situ

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Limitations of anterior approaches: Studies have shown that for multilevel compression (≥3 levels), the anterior approach is associated with more complications but with better functional recovery in the short term but in the long term, the results are no different when compared to the posterior approach [9] This is attributed to the late deterioration caused by adjacent segment degenerative changes. [16],[17] Failures after anterior approaches for CSM are mainly due to: 1. Failure to fully appreciate the extent of compression in the rostrocaudal and transverse directions and, 2. Loss of midline orientation while performing the decompression. [13]


 » Posterior Approaches for Cervical Spondylotic Myelopathy Top


Advantages and disadvantages of the posterior approach:

The major advantage of the posterior approach is the familiarity of the surgeon with the procedure. Anterior approaches may be difficult for obese patients or for those with short, thick necks. [7] Certain risks specific to the anterior procedure like recurrent laryngeal nerve palsy, swallowing dysfunction, risk of durotomy and resultant cerebrospinal fluid (CSF) leak when there is associated OPLL are all eliminated. Other advantages include: 1. As these procedures are commonly performed for ³3-level disease, quick decompression of multiple segments can be performed which is important in debilitated patients who cannot tolerate prolonged surgery, 2. Risks of dislodgement of long strut grafts used in anterior approaches are eliminated, 3. Motion-preserving operations like laminoplasty allow decompression without necessitating fusion and its attendant complications like adjacent segment degeneration and, 4. Posterior approaches allow decompression of segments at future risk in one operation without substantially increasing patient morbidity. [18]

The main disadvantage of the posterior approach is that it cannot be done in patients with kyphotic spines as the surgical procedure only indirectly decompresses the cord and the decompression effect is dependent on posterior migration of the cord from the ventral pathology. This posterior migration cannot take place in patients with fixed kyphotic spines and hence, the posterior approach is contraindicated in such patients. Posterior approaches like laminoplasty are associated with C5 root palsies which is a unique complication of laminoplasty. Moreover, posterior approaches can exacerbate pre-existing subclinical subluxations or deformities, if they are not accompanied by fusion. They are also associated with increased postoperative pain than anterior approaches.

Currently, the posterior approaches in common clinical practice are: 1. Laminectomy, 2. laminectomy with lateral mass fusion and, 3. Laminoplasty.


 » Laminectomy Top


Laminectomy was the most commonly used surgical procedure for CSM prior to the introduction of anterior approaches. However, in recent times, the popularity of standalone laminectomy has waned due to the well-recognized complications of the laminectomy and the availability of better alternatives. The complications of standalone laminectomy include: 1. The development of post-laminectomy kyphosis, the incidence of which varies from 11-47%, [18] 2. Development of post-laminectomy membranes, 3. Future posterior fusions are compromised by the dura being exposed over multiple levels and, 4. Even if the patient does not develop neurological deterioration due to post-laminectomy kyphosis, the stretching of the posterior musculo-ligamentous structures due to altered alignment often leads to disabling neck pain. However, laminectomy still has a role in properly selected patients with the following features: patients with preserved cervical lordosis and without radiological instability visualized in dynamic radiographs if they have 1. Cervical canal stenosis, 2. ≥3-level disease, 3. Associated posterior compression due to thickened infolded ligamentum flavum, and 4, in patients with associated multilevel OPLL. While performing standalone laminectomy specific care should be taken not to violate the facet joints to avoid post-laminectomy kyphosis.


 » Laminectomy with Lateral Mass Fusion Top


There are several advantages of combining lateral mass fusion with laminectomy. These include: 1. Fusion prevents the development of post-laminectomy kyphosis, 2. Patients with multilevel disease with associated subclinical instability brought out in dynamic radiographs can be dealt with by this procedure, 3. Fusion decreases the chance of dynamic compression due to repetitive microtrauma that is known to occur in CSM, [11],[19] 4. As laminoplasty is known to cause worsening of axial neck pain, laminectomy with lateral mass fusion may be preferable in patients with multilevel disease with significant neck pain preoperatively, [20] 5. Patients with multilevel disease with neutral cervical alignment or in those with reducible cervical kyphosis, lateral mass fusion is an option as the cervical alignment can be restored prior to securing the instrumentation. [18] In these patients, performing standalone laminectomy or laminoplasty may worsen the cervical alignment. Currently, the commonly accepted indications for laminectomy with lateral mass fusion include: 1. multilevel cervical stenotic myelopathy (≥3-level disease) with preserved cervical lordosis, 2. multilevel cervical stenotic myelopathy (≥3-level disease) with subclinical instability requiring posterior decompression with fusion. This procedure can also be done in selected patients with multilevel disease and neutral cervical alignment or a reducible cervical kyphosis in whom a lordotic alignment can be achieved by appropriate positioning before securing the screw-rod system. [18]

Even though multiple techniques for posterior cervical fusion were available historically including onlay grafts, spinous process wiring, facet wiring, Halifax interlaminar clamps, lateral mass plates and screws, [21] they have been replaced by the currently popular lateral mass fusion using polyaxial screw-rod constructs. The currently available literature points to the good outcomes associated with this procedure. [20],[22] The other option is cervical pedicle screw fixation. [23] However, cervical pedicle screw fixation is not widely used at present, as safe insertion of cervical pedicle screws often requires navigation guidance.

There are four different techniques of placing lateral mass screws: Roy Camille, Magerl, Anderson and An. [7] This author prefers to use the An technique in which the entry point is located 1 mm medial to the midpoint of the lateral mass and the direction of the screw is 30* laterally and 15* rostrally [Figure 6]. The lateral trajectory takes the screw away from the vertebral artery which lies ventral to the lateral mass and the rostral angulation is to avoid the nerve root traversing deep to the superior facet of the caudal spinal segment. [7] In addition, such a trajectory also increases the volume of bony purchase in the lateral mass. Usually, to achieve bicortical purchase 3.5-mm diameter screws with a length of 14 mms are used. This author prefers to insert the lateral mass screws prior to performing laminectomy. After laminectomy, under fluoroscopic guidance a lordotic alignment of the cervical spine is achieved prior to securing the rods [Figure 7].
Figure 6: Lateral mass fusion. (a) Preoperative MRI showing multilevel cervical stenosis with cord compression, (b) Postoperative lateral radiograph showing the lateral mass screw-rod construct, (c) Six months' postoperative MRI scan of the same patient showing good decompression, (d) and (e) Postoperative axial CT scans showing the direction of lateral mass screws and bicortical purchase

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Figure 7: Lateral mass fusion. (a), (b), (c) Sequential intraoperative photographs showing the placement of lateral mass screws prior to laminectomy (a), after laminectomy prior to placement of rods (b), and securing the rods after restoring lordotic alignment (c); (d)and (e) postoperative AP and lateral radiographs after lateral mass screw placement

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 » Laminoplasty Top


Laminoplasty was popularized in the late 1970s by Japanese spine surgeons who recognized the complications of standalone laminectomy. [24] The advantages of laminoplasty include: 1. It is a motion-preserving procedure, 2. The disadvantage of laminectomy, namely, the development of post-laminectomy membrane is avoided, 3. Unlike in laminectomy, because the posterior bony elements are preserved, revision posterior surgery is not compromised by the exposed dura, 4. If necessary, laminoplasty can be combined with fusion, [25] 5. In patients who develop adjacent segment degeneration after multilevel anterior decompression and fusion, laminoplasty is a viable option as the surgical procedure is carried out in virgin surgical territory with the added advantage of not requiring additional fusion and further predisoposition to degeneration at adjacent segments. [26]

Currently the commonly accepted indications for laminoplasty include: Patients with preserved cervical lordosis if they have: 1. multilevel cervical stenotic myelopathy (≥3-level disease), 2. Cervical canal stenosis, 3. Posterior cord compression at multiple levels. The contraindication for laminoplasty is the presence of cervical kyphosis. As postoperative axial neck pain is common in patients who undergo laminoplasty, the decision to perform laminoplasty in a patient with significant preoperative neck pain should be taken cautiously.

Several modifications of cervical laminoplasty have been described. However, they can be basically classified into two groups: open-door laminoplasty and double-door laminoplasty. In open-door laminoplasty, two grooves are created at the lamina-facet junction; the groove retains the inner cortex of the lamina on the hinge side and a through-and-through groove is made on the open side. The lamina is kept open by one of the following methods: autologous grafts, allografts, hydroxyapatite spacers, titanium miniplates or simply by suturing the spinous processes to the facets. This author prefers to use autologous grafts to keep the laminar door open and the grafts are kept at alternate levels. For example, for a four-level laminoplasty of C3-C6, grafts are inserted only at C3 and C5. As the supraspinous and interspinous ligaments are kept intact, the closing force generated by the intact ligaments keeps the laminar door open even at the levels where grafts are not placed [Figure 8] and [Figure 9]. A ledge created in the graft helps secure the opened lamina in position without the need for any fixation using sutures or miniplates. In double-door laminoplasty, two grooves are created, one on either side at the lamina-facet junction. In both the grooves, the inner cortex is kept intact. The laminae are then opened and a graft is kept in between the opened laminae. The grafts can be sutured in place using non-absorbable sutures [Figure 10] and [Figure 11]. Both open-door and double-door laminoplasty give equally good functional outcomes. However, there are certain technical factors that should be taken into consideration for a successful outcome in laminoplasty. These include: 1. The laminar door should be opened for a minimum of 10-12 mms; openings less than this dimension will not lead to adequate space for the cord to shift posteriorly and openings more than 18 mms will lead to increased shift resulting in higher incidence of segmental root palsy,2. An opening of 10-12 mms will increase the anteroposterior diameter of the spinal canal by 4-5 mms and the cross-sectional area by 90-120 mm 2 , 3. A posterior shift of the cord of ≥3 mms is required for good outcomes. [27] A study conducted by this author showed that a graft size of 10-12 mms increased the AP diameter of the canal by 5-6 mms and was associated with good outcome (unpublished data). Moreover, the AP diameter of the canal increased more in open-door laminoplasty than in double-door laminoplasty even though this was not found to be statistically significant (unpublished data). There are certain unique complications of laminoplasty which include: 1. Postoperative axial neck pain, [28] 2. Segmental root palsy with an incidence of approximately 5%, [29] 3. Closing of the laminar door [30] and, 4. Worsening of the cervical alignment.
Figure 8: Open-door laminoplasty. (a) and (b) Postoperative axial CT after open-door laminoplasty in Panel A, the arrow points to the laminar door remaining open even though there is no graft at that level (refer text for details); single arrowhead in B points to the graft in situ, double arrowheads point to the tilted spinous process, single arrow points to the ledge in the graft that secures the graft to the lamina; (c) Sagittal reconstructed CT showing the opened laminae (arrowheads) with increased sagittal diameter of the spinal canal at the operated levels

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Figure 9: Open-door laminoplasty. (a) Preoperative MRI showing multilevel cord compression, (b) Postoperative MRI showing good decompression

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Figure 10: Double-door laminoplasty. (a) and (b) Pre- and postoperative axial CT scans showing the effect of double-door laminoplasty; arrows point to the grooves in the lamina-facet junction, arrowhead points to the graft in situ

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Figure 11: Double-door laminoplasty. (a) Preoperative MRI showing multilevel compression with intramedullary signal changes, (b) Postoperative MRI showing good decompression with reduction of intramedullary signal

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 » Combined Approaches Top


Studies have also shown that the majority of the spine surgeons prefer the anterior approach in 51-60% of cases, posterior approach in about 35% and a combined approach in the remaining. [3],[4] The indications for combined approaches are: when there is both ventral and dorsal compression of the thecal sac [Figure 12] or if a patient with multilevel disease had developed kyphosis. [14] For example, a patient with significant ventral and dorsal osteophytic compression might not have adequate decompression with a single ventral or dorsal surgery. [14] In patients with severe osteoporosis or those with poor bone quality due to renal disease or heavy smokers in whom poor bone fusion is anticipated, if a multilevel corpectomy is necessary, a combined approach should be undertaken. [31] A detailed discussion of whether the anterior or posterior procedure should be done first or whether the patient requires a 540* procedure and whether all the procedures should be done in the same sitting or in separate sittings is beyond the scope of this review.
Figure 12: Combined approach. Postoperative radiograph of a patient with cervical canal stenosis from C3-C6 with focal ventral compression at C4-C5; patient underwent anterior cervical discectomy with fusion at C4-C5 followed by lateral mass screw fixation and laminectomy from C3-C6 in the same sitting (one lower screw is in C5 and another at C6 because of fracture of one lateral mass while placement)

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 » Complications of Surgery for CSM Top


Knowledge of the rate and type of complications that occur after surgery for CSM is necessary for patient counseling and quality improvement. [32] A recent AOSpine North America cervical spondylotic myelopathy study found that the overall perioperative complication rate was 15.6%, the rate of major complications was 7% and the delayed complication rate was 4%. The complication rates of anterior, posterior and combined approaches were 11%, 19% and 37% respectively. [32] Interestingly, anterior fusions and posterior fusions had an almost similar rate of complications irrespective of whether the procedure involved corpectomy or laminoplasty. [32] Older age, longer operative time and combined anterior-posterior approaches were associated with higher complication rates.


 » Prognosis of Surgery for Cervical Spondylotic Myelopathy Top


A recent AOSpine study found that 75% of patients who undergo surgery for CSM have a more than 2-point increase in their mJOA score. [33] The Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons found that surgery for CSM leads to significant improvement that is maintained for a minimum of 5 years to as long as 15 years postoperatively. [34] Another recent study has shown that surgery for CSM is associated with significant functional recovery and such recovery reaches a plateau at six months after surgery. [35] However, approximately, 4% of patients show neurological deterioration after decompressive surgery. [35] The compression ratio assessed by magnetic resonance imaging (MRI) can provide a clue to the prognosis. This ratio is assessed by dividing the smallest antero-posterior diameter of the spinal cord by the broadest transverse diameter of the spinal cord. [36] If the ratio is 0.4, especially, after surgery, the chance of neurological recovery is poor. Conversely, if there is an increase in the compression ratio to >0.4 or the transverse area of the spinal cord increases to more than 40 mm 2 in the postoperative scan, the outcome is likely to be good. [37] The presence and persistence of focal high signal intensity in T2 images and the lack of re-expansion of the cord in the postoperative MRI obtained six months after surgery are associated with poor outcomes. [38] If the postoperative MRI shows good decompression and yet the patient has less than expected outcome, then other causes that might contribute to disability in these patients like lumbar canal stenosis, normal pressure hydrocephalus and neurodegenerative conditions should be sought. [38]


 » Conclusions Top


Significant advances have taken place in the surgical management of CSM. Therefore, it behooves the contemporary spine surgeon to be familiar with the indications, advantages, limitations, complications and prognosis of various operative approaches for CSM. The choice of surgical approach should not be based on the preferences of the surgeon but on the individual patient characteristics. The "science" of spine surgery consists of learning the needed surgical skills. The "art" of spine surgery is choosing the right approach for the right patient.

 
 » References Top

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2.Zareth IN, Hilibrand A, Gustavel M, McLain R, Shaffer W, Myers M, et al. Variations in surgical decision making for degenerative spinal disorders: Part II: Cervical spine. Spine 2005;30:2214-9.  Back to cited text no. 2
    
3.Ghogawala Z, Coumans JV, Benzel EC, Stabile LM, Barker FG II. Ventral versus dorsal decompression for cervical spondylotic myelopathy: Surgeons' assessment of eligibility for randamization in a Proposed Randomized control trial. Results of a survey of the cervical spine research society. Spine 2007;32:429-36.  Back to cited text no. 3
    
4.Fehlings MG, Kopjar B, Bartels R, et al. International variations in the clinical presentation and management of cervical spondylotic myelopathy (CSM). One year outcomes of the AOSpine Multi-center Prospective study. Presented at the Annual Meeting of the American Association of Neurological Surgeons. Denver: Colarado; 2011.  Back to cited text no. 4
    
5.Cunningham MR, Hershman S, Bendo J. Systematic review of cohort studies comparing surgical treatments for cervical spondylotic myelopathy. Spine 2010;35:537-43  Back to cited text no. 5
    
6.Matz PG, Ryken TC, Groff MW, Vresilovic EJ, Anderson PA, Heary RF, et al. Techniques for anterior cervical decompression for radiculopathy. J Neurosurg Spine 2009;11:183-97.  Back to cited text no. 6
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7.Komotar RJ, Mocco J, Kaiser MG. Surgical management of cervical myelopathy: Indications and techniques for laminectomy and fusion. Spine J 2006;6(6 Suppl):252S-67S.  Back to cited text no. 7
    
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9.Liu T, Xu W, Cheng T, Yang HL. Anterior versus posterior surgery for multilevel cervical myelopathy, which one is better? A systematic review. Eur Spine J 2011;20:224-35.  Back to cited text no. 9
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10.Epstein N, Epstein JA. Treatment of cervical myelopathy: Part A: Laminectomy. In: The cervical spine. TCSR Society. Philadelphia: Lippincott Williams and Wilkins; 2005. p. 1043-56.  Back to cited text no. 10
    
11.Matz PG, Pritchard PR, Hadley MN. Anterior cervical approach for treatment of cervical myelopathy. Neurosurgery 2007;60(1 Suppl 1):S64-70.  Back to cited text no. 11
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]

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