Accepted Manuscript Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment. The Evidence and the International Common Practice Fernando Techy, MD Edward C. Benzel, M.D PII:
S1878-8750(13)01384-3
DOI:
10.1016/j.wneu.2013.10.053
Reference:
WNEU 2203
To appear in:
World Neurosurgery
Received Date: 9 October 2013 Accepted Date: 23 October 2013
Please cite this article as: Techy F, Benzel EC, Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment. The Evidence and the International Common Practice, World Neurosurgery (2013), doi: 10.1016/j.wneu.2013.10.053. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Page 1
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Editorial Statement “Perspectives” on the article: “Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment: A Survey of Members from AO Spine International.” By: Tetreault L, Nouri A, Singh A, Fawcett M, Fehlings GM
Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy
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undergoing Surgical Treatment. The Evidence and the International Common Practice.
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Fernando Techy, MD Assistant Professor of Clinical Orthopaedics Division of Spine Surgery University of Illinois at Chicago [email protected]
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Edward C. Benzel, M.D. Chairman, Department of Neurosurgery Neurological Institute Cleveland Clinic 9500 Euclid Ave., S40 Cleveland, OH 44195 T: 216-444-7381 F: 216-445-4537 [email protected]
ACCEPTED MANUSCRIPT Page 2
Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment: A Survey of Members from AO Spine International by Tetreault et al, published in
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this issue of World Neurosurgery, reports the results of a survey performed with the AOSpine community to determine international perceptions regarding key predictors of outcome in patients with cervical spondylotic myelopathy. The authors’ objective was to guide the
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development of clinical prediction models by facilitating the alignment of clinical perceptions with evidence-based reality. Their intent was to to better understand the natural course of
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cervical myelopathy, especially after surgical treatment.
Members of AO Spine international were asked to answer to 11 questions pertaining to surgical outcome prediction factors for cervical myelopathy surgery. Six hundred and eighty nine members of AOSpine International completed the survey, representing a response rate of 11.6%
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(689/5,934).
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In order to facilitate a greater understanding of this subject, we analyze each question individually. We also reviewed the available literature on the specific subject addressed by each
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question.
Question # 1 CLINICAL FACTORS: Rank the following clinical factors from the most (1) to least (8) important in terms of their ability to predict surgical outcome. a)
Age
b)
Baseline Severity Score by the modified Japanese Orthopedic Association myelopathy scale (mJOA).
ACCEPTED MANUSCRIPT Page 3 Gender
d)
Co-morbidities
e)
Duration of symptoms
f)
Signs
g)
Smoking status
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c)
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h) Symptoms
For all continents the survey results showed that ”Baseline severity score” was the most
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important predictor for most surgeons. The “Duration of symptoms” was second in all continents, with the exception of Europe which considered “ Symptons of Myelopathy” to be the second most important predictive factor.
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Two extensive systematic reviews on the subject were recently published. Holly et al.(2009) (10) summarized the findings from 14 studies and concluded that there exists low class III evidence suggesting that age and duration of symptoms carry prognostic value. A more recent review by
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Tetreault et al.(2013) (28) included a larger subset of the literature (91 studies) with more high quality prospective studies using validated outcome measures. The authors determined that
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duration of symptoms and baseline severity score were essential predictors and that age was a potential predictor when exploring only high quality studies (n=16).
Several previous studies have confirmed that both the baseline severity score and duration of symptoms are important predictors of the surgical outcome.(16,19,22,24-26,31,32)
ACCEPTED MANUSCRIPT Page 4 In a recent Level II evidence study (Multicenter Prospective Randomized Controlled Trial) including 278 patients, the authors conclude that preoperative mJOA score (greater severity), smoking, older age, psychological comorbidities, longer duration of symptoms, smaller
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transverse spinal cord area, and presence of impaired gait were all associated with a decreased probability of a successful outcome.(29)
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Question #2 PAGE: What is the threshold age above which there is a negative impact on surgical
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outcome? Options: 30, 40, 50, 60, 65 years, Other (please specify)
There is insufficient literature defining’ old age’ to outline how to separate this continuous variable into specific groups. Several studies(10,28,29) (including systematic reviews)(10,28) do cite age as a prognostic factor after cervical myelopathy surgery, however specific age groups as
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in the question cannot be determined from current literature conclusions.
In this study, most participants chose 65 years of age as their answer (53%). This likely
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represents a ‘ceiling effect’ due to the fact that 65 years was the highest choice – thus, relatively
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invalidating the response to this question.
This threshold (65yo) was used by Nagata et al., Yamazaki et al. and Hirai et al. to define an elderly and younger group from their total sample.(9,21,30) Other studies have arbitrarily used 70(6,13,18) or 80(20) as their cut-off value. The latter studies underscore the notion that using age 65 as the oldest choice created a biased response.
ACCEPTED MANUSCRIPT Page 5 Question # 3: DURATION OF SYMPTOMS: What is the threshold duration of symptoms above which there is a negative impact on surgical outcome? Options: 1-3, 6, 12, 24 months, Other
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(please specify)
The preferred answers in all geographic areas were either 6 or 12 months with approximately 40% of the votes each. 20% of the participants chose 24 months. Only in Latin America there
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was a preference for 12 over 6 months.
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Duration of symptoms seem to clearly influence outcomes after cervical myelopathy surgery.(2,7,10,23,25,28,29) Patients with longer standing symptoms do not do as well from a clinical perspective as those who do not. Most studies focuse on the the 12 month period as the
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clinically relevant threshold.(2,7,23,25)
Question # 4 SMOKING STATUS:
Is current smoking status important in predicting outcome? Is past smoking status important in
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predicting outcome? 71% of the participants believe that current smoking is detrimental to the outcome. 39% responded that previous smoking may be associated with poor surgical results.
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The literature is not as conclusive in regards to smoking as it is in regards to severity and length of symptoms presentation as predictive factors for the outcome of surgical treatment of cervical myelopathy. Kim et al. found that smoking status did not affect outcome in the control group. In diabetic patients, smoking increases the risk of an unfavorable outcome after surgery to treat surgical myelopathy.(15) In the AO prospective multicenter study, Fehlings et al demonstrated a poorer outcome in smokers despite similar fusion rate as non-smokers.(29) Hillibrand has shown
ACCEPTED MANUSCRIPT Page 6 that smokers do not fuse as well as non-smokers when multilevel ventral surgery is used to treat cervical myelopathy.(8)
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Question #5 BASELINE SEVERITY SCORE: What is the threshold baseline mJOA above/ below which there is a negative impact on outcome? Options: 0-18 points.
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Two extensive systematic reviews on the subject comment on this issue. Holly et al.(2009) (10) summarized the findings from 14 studies and concluded that there is low class III evidence
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suggesting that age and duration of symptoms carry prognostic value. A more recent review by Tetreault et al. (2013) (28) included a larger subset of the literature (91 studies) with more high quality prospective studies using validated outcome measures. The authors determined that duration of symptoms and baseline severity score were essential predictors and that age was a
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potential predictor when exploring only high quality studies (n=16).
Several prior studies confirmed that both the baseline severity score and duration of symptoms
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are important predictors of the surgical outcome.(16,19,22,24-26,31,32) Forty-one percent of participants in the AO study presented here chose 12 points as the threshold
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baseline severity score below which there is a negative impact on surgical outcome. The second most frequently selected score was 10 points, which was chosen by 24% of the sample. This score has been previously defined as the cut-off for severe myelopathy by Kadanka et al.(12) and Tetreault et al.(29) Since mJOA score may represent a range of severities and the scale has not been validated, it may be more appropriate to retain this variable as a continuous variable and accept slight variances between surgeon classifications.
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Question # 6 CO-MORBIDITIES: Select the five most important co-morbidities in terms of their
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ability to predict surgical outcome.
The most important predictors ranked by the AO community were diabetes, neurological disease
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including neuromuscular disorders, stroke and paralysis and psychological issues.
Diabetes has been shown to be a predictor by four studies, although two studies indicated that the
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disease is not significantly related to outcome(3,14) whereas two other studies suggested a clear correlation with worse outcome.(4,15) With respect to psychological disorders, Kumar et al. found that patients in the poor outcome group had greater emotional problems than those in the
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good outcome group.(17)
When analyzing the number and presence of other comorbidities, the results are contradicting. Two studies conclude that presence of other comorbidities worsen the outcome for surgical
outcome.(5,11)
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myelopathy treatment(16,21) and other two studies state that such is not related to the
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There exist no studies specifically and solely assessing individual comorbidities, other than those cited above.
Question #7 and #8: SIGNS and SYMTOMS. There is insufficient evidence in the literature to conclude that the presence of a particular sign or symptom is predictive of outcome. There exist multiple studies that analyze literally every sign
ACCEPTED MANUSCRIPT Page 8 and symptom associated with cervical myelopathy. Their conclusions, in general, conflict. There exist studies that both support and that do not support a particular sign or symptom.(28)
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Question #7 SIGNS: Select the two most important signs of CSM in terms of their ability to predict surgical outcome. Options: Corticospinal motor deficits, Atrophy of intrinsic hand muscles, Hyperreflexia, Positive Hoffman sign, Upgoing plantar responses, Broad-based
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unstable gait.
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The three signs that were thought to have the greatest relationship with prognosis in the survey were: 1) atrophy of intrinsic hand muscles, 2) broad based unstable gait and 3) corticospinal distribution motor deficits.
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Question # 8. SYMPTOMS:
Select the three most important symptoms of CSM in terms of their ability to predict surgical
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outcome.
Options: Numb hands, Clumsy hands, Impaired gait, Bilateral arm paresthesiae, L’Hermitte’s
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phenomena, Muscular weakness in legs.
The three most popular symptoms chosen by the participants in the AO study were: 1) impaired gait, 2) clumsy hands and 3) muscle weakness.
Question # 9-11 Magnetic Resonance Imaging for predicting the outcome of Surgery for
ACCEPTED MANUSCRIPT Page 9 Cervical Myelopathy.
9) Does Magnetic Resonance Imaging (MRI) provide prognostic information?
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-86% responded yes.
10) Are spinal cord imaging findings (eg.Signal change) more important than spinal canal
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measurements (eg, cross sectional area) for predicting surgical outcome?
-83% felt that signal change is more important than spinal canal measurements in predicting
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prognosis.
11) Rank the following MRI factors from the most (1) to least (8) important in terms of their ability to predict of surgical outcome. Options: Transverse area
b)
Area of signal intensity on T2
c)
High T2 signal intensity
d)
Height of signal intensity on T2
e)
Low T1 signal intensity
f)
Number of compressed segments
h)
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g)
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a)
High T2/Low T1 Segmentation of T2 signal intensity
It was the international AO respondents general consensus that option “High T2 signal Intensity” was the most important predicting factor on Surgical Outcomes to treat myelopathy.
ACCEPTED MANUSCRIPT Page 10 When analyzing the literature, a recent systematic review(27) concluded that: 1) Based on three studies, the presence of focal high signal intensity on T2 does not correlate with worsening prognosis when conservative treatment is chosen. Level of
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evidence: Low.
2) Based on 17 studies, the presence of isolated focal high signal intensity on T2 is NOT a prognostic factor for the Surgical treatment of Cervical Myelopathy. T2 signal changes
resolve after decompression. Level of evidence is low.
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may represent reversible changes in the spinal cord such as edema or ischemia that may
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3) There exists evidence that the number of levels that demonstrate high T2 signal intensity correlate with surgical prognosis. More than one level of signal change implicate a worse result, based on 5 studies. This respresents a low level of evidence. 4) Even though less prevalent, high T2 signal intensity, associated with low T1signal
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intensity is suggestive of greater chronic irreversible changes (ie, suggestive of necrosis, secondary syrynx, or cavitation – as opposed to edema) and therefore is associated with a worse prognosis after surgery. Based on the 5 reported relevant studies, such is the case,
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but the level of evidence is low.
5) The ratio of T2 to T1 signal change and of T2 normal signal to high signal areas of the
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entire cervical spine also seems to be related to prognosis after surgery. This is based on three studies with a low level of evidence, 6) There is controversy in the literature surrounding the ability of MRI to predict surgical outcome. The relatative importance of spinal canal dimensions versus spinal cord signal change as prognostic factors has not been demonstrated in the aforementioned systematic review. In the systematic review previously referred(27), the authors state that they could
ACCEPTED MANUSCRIPT Page 11 not find any studies suggesting that anatomic factors were of prognostic value and, therefore, suggested that signal changes were more important. Conversely, in a separate study, the authors justify why they included “transverse area” in their prediction model
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based on personal experience and literature support. They cite three studies in where “ measurement of the transverse area for the spinal cord” had direct correlation with
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prognosis.(29)
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Conclusion:
The AO Spine International survey study presented here summarized global perceptions of the major imaging and’ clinical predictors of surgical outcome in patients with cervical spondylotic
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myelopathy. The results from this survey can be used to guide the construction of valid clinical prediction models, especially when no or scarce scientific data is available.
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Care must be taken regarding the incorporation of these ‘collective expert opinions' into prediction models, however. With many of the questions, the majority of answers were without
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literature foundation. In some cases, the opinions were erroneous – as based on the published literature (Questions 6,7,8,11). They might have been based on the individuals’ perceptions based on ‘conventional wisdom’. Or, conversely, they may have been based on perceptions learned from mentors, anedoctal personal experience or from an extrapolation of literature to the clinical arena.
ACCEPTED MANUSCRIPT Page 12 Common sense and experience are critical factors associated with the achievement of good results, especially when there is little or no evidence to support the clinical decision at hand. Nevertheless, as data accumulates, we must compare such with our practice experience and
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carefully scrutinize our clinical decisions. Then we must act accordingly. In the end, a balance between experience and evidence, along with a liberal application of common sense,remain the
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‘best way to practice medicine’.(1)
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Lu J, Wu X, Li Y, Kong X. Surgical results of anterior corpectomy in the aged patients
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Morishita T, Murata M, Nanjo Y, Takahashi T, Tanida A, Tanishima S, Yamane K, Teshima R. Clinical features and surgical outcomes of cervical spondylotic myelopathy in patients aged 80 years or older: a multicenter retrospective study. European Spine Journal. 20(2):240-246, 2001.
Nagata K, Ohashi T, Abe J, Morita M, Inoue A. Cervical myelopathy in elderly patients:
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changes on the surgical outcome of patients with cervical spondylotic myelopathy. Spine J.
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Suzuki A, Misawa H, Simogata M, Tsutsumimoto T, Takaoka K, Nakamura H. Recovery
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cervical spondylotic myelopathy. Spine (Phila Pa 1976). 35(10):E396-E399, 2010.
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ACCEPTED MANUSCRIPT
S1878-8750(13)01384-3
DOI:
10.1016/j.wneu.2013.10.053
Reference:
WNEU 2203
To appear in:
World Neurosurgery
Received Date: 9 October 2013 Accepted Date: 23 October 2013
Please cite this article as: Techy F, Benzel EC, Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment. The Evidence and the International Common Practice, World Neurosurgery (2013), doi: 10.1016/j.wneu.2013.10.053. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Page 1
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Editorial Statement “Perspectives” on the article: “Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment: A Survey of Members from AO Spine International.” By: Tetreault L, Nouri A, Singh A, Fawcett M, Fehlings GM
Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy
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undergoing Surgical Treatment. The Evidence and the International Common Practice.
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Fernando Techy, MD Assistant Professor of Clinical Orthopaedics Division of Spine Surgery University of Illinois at Chicago [email protected]
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Edward C. Benzel, M.D. Chairman, Department of Neurosurgery Neurological Institute Cleveland Clinic 9500 Euclid Ave., S40 Cleveland, OH 44195 T: 216-444-7381 F: 216-445-4537 [email protected]
ACCEPTED MANUSCRIPT Page 2
Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy undergoing Surgical Treatment: A Survey of Members from AO Spine International by Tetreault et al, published in
RI PT
this issue of World Neurosurgery, reports the results of a survey performed with the AOSpine community to determine international perceptions regarding key predictors of outcome in patients with cervical spondylotic myelopathy. The authors’ objective was to guide the
SC
development of clinical prediction models by facilitating the alignment of clinical perceptions with evidence-based reality. Their intent was to to better understand the natural course of
M AN U
cervical myelopathy, especially after surgical treatment.
Members of AO Spine international were asked to answer to 11 questions pertaining to surgical outcome prediction factors for cervical myelopathy surgery. Six hundred and eighty nine members of AOSpine International completed the survey, representing a response rate of 11.6%
TE D
(689/5,934).
EP
In order to facilitate a greater understanding of this subject, we analyze each question individually. We also reviewed the available literature on the specific subject addressed by each
AC C
question.
Question # 1 CLINICAL FACTORS: Rank the following clinical factors from the most (1) to least (8) important in terms of their ability to predict surgical outcome. a)
Age
b)
Baseline Severity Score by the modified Japanese Orthopedic Association myelopathy scale (mJOA).
ACCEPTED MANUSCRIPT Page 3 Gender
d)
Co-morbidities
e)
Duration of symptoms
f)
Signs
g)
Smoking status
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c)
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h) Symptoms
For all continents the survey results showed that ”Baseline severity score” was the most
M AN U
important predictor for most surgeons. The “Duration of symptoms” was second in all continents, with the exception of Europe which considered “ Symptons of Myelopathy” to be the second most important predictive factor.
TE D
Two extensive systematic reviews on the subject were recently published. Holly et al.(2009) (10) summarized the findings from 14 studies and concluded that there exists low class III evidence suggesting that age and duration of symptoms carry prognostic value. A more recent review by
EP
Tetreault et al.(2013) (28) included a larger subset of the literature (91 studies) with more high quality prospective studies using validated outcome measures. The authors determined that
AC C
duration of symptoms and baseline severity score were essential predictors and that age was a potential predictor when exploring only high quality studies (n=16).
Several previous studies have confirmed that both the baseline severity score and duration of symptoms are important predictors of the surgical outcome.(16,19,22,24-26,31,32)
ACCEPTED MANUSCRIPT Page 4 In a recent Level II evidence study (Multicenter Prospective Randomized Controlled Trial) including 278 patients, the authors conclude that preoperative mJOA score (greater severity), smoking, older age, psychological comorbidities, longer duration of symptoms, smaller
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transverse spinal cord area, and presence of impaired gait were all associated with a decreased probability of a successful outcome.(29)
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Question #2 PAGE: What is the threshold age above which there is a negative impact on surgical
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outcome? Options: 30, 40, 50, 60, 65 years, Other (please specify)
There is insufficient literature defining’ old age’ to outline how to separate this continuous variable into specific groups. Several studies(10,28,29) (including systematic reviews)(10,28) do cite age as a prognostic factor after cervical myelopathy surgery, however specific age groups as
TE D
in the question cannot be determined from current literature conclusions.
In this study, most participants chose 65 years of age as their answer (53%). This likely
EP
represents a ‘ceiling effect’ due to the fact that 65 years was the highest choice – thus, relatively
AC C
invalidating the response to this question.
This threshold (65yo) was used by Nagata et al., Yamazaki et al. and Hirai et al. to define an elderly and younger group from their total sample.(9,21,30) Other studies have arbitrarily used 70(6,13,18) or 80(20) as their cut-off value. The latter studies underscore the notion that using age 65 as the oldest choice created a biased response.
ACCEPTED MANUSCRIPT Page 5 Question # 3: DURATION OF SYMPTOMS: What is the threshold duration of symptoms above which there is a negative impact on surgical outcome? Options: 1-3, 6, 12, 24 months, Other
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(please specify)
The preferred answers in all geographic areas were either 6 or 12 months with approximately 40% of the votes each. 20% of the participants chose 24 months. Only in Latin America there
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was a preference for 12 over 6 months.
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Duration of symptoms seem to clearly influence outcomes after cervical myelopathy surgery.(2,7,10,23,25,28,29) Patients with longer standing symptoms do not do as well from a clinical perspective as those who do not. Most studies focuse on the the 12 month period as the
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clinically relevant threshold.(2,7,23,25)
Question # 4 SMOKING STATUS:
Is current smoking status important in predicting outcome? Is past smoking status important in
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predicting outcome? 71% of the participants believe that current smoking is detrimental to the outcome. 39% responded that previous smoking may be associated with poor surgical results.
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The literature is not as conclusive in regards to smoking as it is in regards to severity and length of symptoms presentation as predictive factors for the outcome of surgical treatment of cervical myelopathy. Kim et al. found that smoking status did not affect outcome in the control group. In diabetic patients, smoking increases the risk of an unfavorable outcome after surgery to treat surgical myelopathy.(15) In the AO prospective multicenter study, Fehlings et al demonstrated a poorer outcome in smokers despite similar fusion rate as non-smokers.(29) Hillibrand has shown
ACCEPTED MANUSCRIPT Page 6 that smokers do not fuse as well as non-smokers when multilevel ventral surgery is used to treat cervical myelopathy.(8)
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Question #5 BASELINE SEVERITY SCORE: What is the threshold baseline mJOA above/ below which there is a negative impact on outcome? Options: 0-18 points.
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Two extensive systematic reviews on the subject comment on this issue. Holly et al.(2009) (10) summarized the findings from 14 studies and concluded that there is low class III evidence
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suggesting that age and duration of symptoms carry prognostic value. A more recent review by Tetreault et al. (2013) (28) included a larger subset of the literature (91 studies) with more high quality prospective studies using validated outcome measures. The authors determined that duration of symptoms and baseline severity score were essential predictors and that age was a
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potential predictor when exploring only high quality studies (n=16).
Several prior studies confirmed that both the baseline severity score and duration of symptoms
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are important predictors of the surgical outcome.(16,19,22,24-26,31,32) Forty-one percent of participants in the AO study presented here chose 12 points as the threshold
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baseline severity score below which there is a negative impact on surgical outcome. The second most frequently selected score was 10 points, which was chosen by 24% of the sample. This score has been previously defined as the cut-off for severe myelopathy by Kadanka et al.(12) and Tetreault et al.(29) Since mJOA score may represent a range of severities and the scale has not been validated, it may be more appropriate to retain this variable as a continuous variable and accept slight variances between surgeon classifications.
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Question # 6 CO-MORBIDITIES: Select the five most important co-morbidities in terms of their
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ability to predict surgical outcome.
The most important predictors ranked by the AO community were diabetes, neurological disease
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including neuromuscular disorders, stroke and paralysis and psychological issues.
Diabetes has been shown to be a predictor by four studies, although two studies indicated that the
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disease is not significantly related to outcome(3,14) whereas two other studies suggested a clear correlation with worse outcome.(4,15) With respect to psychological disorders, Kumar et al. found that patients in the poor outcome group had greater emotional problems than those in the
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good outcome group.(17)
When analyzing the number and presence of other comorbidities, the results are contradicting. Two studies conclude that presence of other comorbidities worsen the outcome for surgical
outcome.(5,11)
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myelopathy treatment(16,21) and other two studies state that such is not related to the
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There exist no studies specifically and solely assessing individual comorbidities, other than those cited above.
Question #7 and #8: SIGNS and SYMTOMS. There is insufficient evidence in the literature to conclude that the presence of a particular sign or symptom is predictive of outcome. There exist multiple studies that analyze literally every sign
ACCEPTED MANUSCRIPT Page 8 and symptom associated with cervical myelopathy. Their conclusions, in general, conflict. There exist studies that both support and that do not support a particular sign or symptom.(28)
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Question #7 SIGNS: Select the two most important signs of CSM in terms of their ability to predict surgical outcome. Options: Corticospinal motor deficits, Atrophy of intrinsic hand muscles, Hyperreflexia, Positive Hoffman sign, Upgoing plantar responses, Broad-based
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unstable gait.
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The three signs that were thought to have the greatest relationship with prognosis in the survey were: 1) atrophy of intrinsic hand muscles, 2) broad based unstable gait and 3) corticospinal distribution motor deficits.
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Question # 8. SYMPTOMS:
Select the three most important symptoms of CSM in terms of their ability to predict surgical
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outcome.
Options: Numb hands, Clumsy hands, Impaired gait, Bilateral arm paresthesiae, L’Hermitte’s
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phenomena, Muscular weakness in legs.
The three most popular symptoms chosen by the participants in the AO study were: 1) impaired gait, 2) clumsy hands and 3) muscle weakness.
Question # 9-11 Magnetic Resonance Imaging for predicting the outcome of Surgery for
ACCEPTED MANUSCRIPT Page 9 Cervical Myelopathy.
9) Does Magnetic Resonance Imaging (MRI) provide prognostic information?
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-86% responded yes.
10) Are spinal cord imaging findings (eg.Signal change) more important than spinal canal
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measurements (eg, cross sectional area) for predicting surgical outcome?
-83% felt that signal change is more important than spinal canal measurements in predicting
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prognosis.
11) Rank the following MRI factors from the most (1) to least (8) important in terms of their ability to predict of surgical outcome. Options: Transverse area
b)
Area of signal intensity on T2
c)
High T2 signal intensity
d)
Height of signal intensity on T2
e)
Low T1 signal intensity
f)
Number of compressed segments
h)
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g)
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a)
High T2/Low T1 Segmentation of T2 signal intensity
It was the international AO respondents general consensus that option “High T2 signal Intensity” was the most important predicting factor on Surgical Outcomes to treat myelopathy.
ACCEPTED MANUSCRIPT Page 10 When analyzing the literature, a recent systematic review(27) concluded that: 1) Based on three studies, the presence of focal high signal intensity on T2 does not correlate with worsening prognosis when conservative treatment is chosen. Level of
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evidence: Low.
2) Based on 17 studies, the presence of isolated focal high signal intensity on T2 is NOT a prognostic factor for the Surgical treatment of Cervical Myelopathy. T2 signal changes
resolve after decompression. Level of evidence is low.
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may represent reversible changes in the spinal cord such as edema or ischemia that may
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3) There exists evidence that the number of levels that demonstrate high T2 signal intensity correlate with surgical prognosis. More than one level of signal change implicate a worse result, based on 5 studies. This respresents a low level of evidence. 4) Even though less prevalent, high T2 signal intensity, associated with low T1signal
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intensity is suggestive of greater chronic irreversible changes (ie, suggestive of necrosis, secondary syrynx, or cavitation – as opposed to edema) and therefore is associated with a worse prognosis after surgery. Based on the 5 reported relevant studies, such is the case,
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but the level of evidence is low.
5) The ratio of T2 to T1 signal change and of T2 normal signal to high signal areas of the
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entire cervical spine also seems to be related to prognosis after surgery. This is based on three studies with a low level of evidence, 6) There is controversy in the literature surrounding the ability of MRI to predict surgical outcome. The relatative importance of spinal canal dimensions versus spinal cord signal change as prognostic factors has not been demonstrated in the aforementioned systematic review. In the systematic review previously referred(27), the authors state that they could
ACCEPTED MANUSCRIPT Page 11 not find any studies suggesting that anatomic factors were of prognostic value and, therefore, suggested that signal changes were more important. Conversely, in a separate study, the authors justify why they included “transverse area” in their prediction model
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based on personal experience and literature support. They cite three studies in where “ measurement of the transverse area for the spinal cord” had direct correlation with
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prognosis.(29)
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Conclusion:
The AO Spine International survey study presented here summarized global perceptions of the major imaging and’ clinical predictors of surgical outcome in patients with cervical spondylotic
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myelopathy. The results from this survey can be used to guide the construction of valid clinical prediction models, especially when no or scarce scientific data is available.
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Care must be taken regarding the incorporation of these ‘collective expert opinions' into prediction models, however. With many of the questions, the majority of answers were without
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literature foundation. In some cases, the opinions were erroneous – as based on the published literature (Questions 6,7,8,11). They might have been based on the individuals’ perceptions based on ‘conventional wisdom’. Or, conversely, they may have been based on perceptions learned from mentors, anedoctal personal experience or from an extrapolation of literature to the clinical arena.
ACCEPTED MANUSCRIPT Page 12 Common sense and experience are critical factors associated with the achievement of good results, especially when there is little or no evidence to support the clinical decision at hand. Nevertheless, as data accumulates, we must compare such with our practice experience and
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carefully scrutinize our clinical decisions. Then we must act accordingly. In the end, a balance between experience and evidence, along with a liberal application of common sense,remain the
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‘best way to practice medicine’.(1)
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