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Mielopatia Cervical Assintomática: Operar ou Não Operar?

Carl Lauryssen, MD; Daniel Riew, MD; Jeffrey C. Wang, MD

Resumo

Nesta secção, dois especialistas defendem maneiras distintas de abordar a mielopatia cervical assintomática. A principal argumentação para indicar cirurgia neste caso de acordo com o do Dr. Carl Lauryssen é a progressão inexorável da mielopatia cervical, assim, independentemente da dor a cirurgia estaria indicada para prevenir uma possível sequela neurológica no futuro em uma paciente de 60 anos de idade com boa expectativa de vida. Mas, o Dr Daniel Riew tem uma visão diametralmente oposta. Baseado nas estatísticas dos Estados Unidos,ele calcula que o risco de complicação de uma cirurgia de coluna em uma paciente assintomática é muito maior do que a evolução da história natural. E se a paciente está assintomática, o único tratamento recomendado é a observação. Somente se os fatos mudarem, a conduta devera ser mudada.

FONTE: SPINELINE January/February 2006
Dr. Jefferson Soares Leal


Case Presentation
A 60-year-old woman presents with the primary complaint of right arm pain and the secondary complaint of neck pain. The pain starts in her neck and radiates toward the thumb, index finger and middle finger. The arm pain has been present for approximately three weeks, although she has had a long history of neck pain for several years. She denies any loss of hand coordination or dexterity and denies any problems with her balance  or gait. On neurologic examination, the right triceps muscle is weak at 4/5 and there is a slight decrease in the right triceps reflex. Otherwise, the upper extremity exam is normal including no evidence for a Hoffman’s sign and the lower extremity exam is normal including normal reflexes, no clonus, negative Babinski sign and normal tandem gait. Magnetic resonance imaging (MRI) studies of her cervical spine are shown at right and below. Clinically, her presentation seems most consistent with right C7 radiculopathy, presumably from the severe foraminal stenosis at C6-7. However, the MRI demonstrates severe stenosis affecting the central canal at C5-6, greater to the right. Assuming the radiculopathy will improve with medical rehabilitation and the passage of time, would you recommend surgery for the clinically silent central stenosis and spinal cord

Carl Lauryssen, MD, Responds

In this debate case we are presented with a 60-year-old female with a three-week history of arm pain and a long-standing history of neck pain. We do not know the character or severity of the pain. On review of her MRI studies she has evidence of degenerative disc changes at multiple levels. The mid-sagittal diameter of her spinal canal demonstrates severe stenosis with a canal of less than 10 mm.

With a three-week history of pain, it would be easy to recommend a conservative nonoperative approach. There is a very high probability that the pain will subside. However, understanding the long-term consequences of the anatomy and pathology is vital in educating this patient regarding her long-term prognosis.

So rather than focusing on her pain symptoms, I would recommend looking at each of the facts surrounding this case, in particular, canal and cord pathology. First, a little history.

In 1952, Dr. Russel Brain1 established a syndrome of cervical spondylotic myelopathy outlining both the mechanical and vascular components of this disease. In 1956, Clarke and Robinson2 documented that the natural course of cervical spondylotic myelopathy is dismal with up to 75% of patients showing progressive deterioration.

Several Factors Contribute to Myelopathy

A circumferential compression occurs as a result of spondylosis affecting the posterior longitudinal ligaments, the collapsed and often calcified disc, thickening of the ligamentum flavum and deformation of the uncovertebral joint.

In addition, the co-existence of spondylotic encroachment of the foramen, coupled with motion-induced foraminal narrowing, compromise the radicular artery supply, predisposing the spinal cord to be more sensitive to mechanical deformation.

Certain dynamic factors also play a role. The cord diameter enlarges in extension related to shortening of its length and subsequent enlargement of its cross-sectional area.

The mid-sagittal bony canal diameter from C3 through C7 is approximately 15 to 17 mm. The mid-sagittal spinal cord diameter from C3 to C7 is approximately 8 to 10 mm. The midcoronal spinal cord diameter from C3 to C7 is approximately 10 to 12 mm.

This case demonstrates significant compromise of the spinal canal with compression of the spinal cord and the exiting nerve

Treatment Algorithm

While at Washington University in St. Louis, Dr. Amgad Hanna and I developed a treatment algorithm for cervical spondylosis. These guidelines incorporate four criteria (Table 1):

1. Symptoms. Patients with mild to moderate pain and/or intermittent numbness would be graded mild to moderate and would receive a score of 1. Severe pain, including a burning or dysesthetic type of pain, constant numbness or loss of dexter ity or poor balance resulting in the inability to walk without assistance would be graded as severe and be designated a score of 2.

2. Signs. Mild to moderate signs would include hyperreflexia, Hoffman’s sign, Babinski’s sign and mild weakness (4+, 5-) and would be given a score of 1. Significant weakness graded less than 4+ or spasticity would be considered severe and given a score of 2. In addition, a number of authors including Singh4 and Fessler8 found that the duration of symptoms is an important negative predictor of outcome.

3. Signal change in the spinal cord on the T2 images. If a patient had evidence of signal change on the MRI, this would be considered severe and significant and be given a score of 2. If there was no evidence of spinal cord MRI signal abnormality then no points would be given to this criteria.

Based on current literature, signal change on the MRI indicates severe spinal cord compression.3,4 Also, a number of reports demonstrate that a dysesthetic post-traumatic spinal cord pain syndrome is the most difficult pain syndrome to treat and also the most preventable.

4. Mid-sagittal diameter of the bony spinal canal. Patients with a mid-sagittal diameter measurement from the ventral dura to the dorsal dura of the spinal canal of 10-12 mm would be considered moderate stenosis and allocated a score of 1. Patients with mid-sagittal diameter measurement from the ventral dura to the dorsal dura of the spinal canal of less than 10 mm would be considered severe and allocated a score of 2.

The reason for this is that a number of predictors of myelopathy have been documented in the literature. These include Pallis et al,5 who noted that spondylotic myelopathy occurred in patients with canal diameters averaging 14 mm. Pavlov et al6 confirmed these findings and established a 92% accuracy for diagnosis of canal stenosis when ratios were less than .082. If the average spinal diameter of the cervical spinal cord is 10 mm, we know that the mid-sagittal diameter of the spinal canal plays an important role in the development of myelopathy.7

We recommend nonoperative management for patients who have a score of 1 to 3, surgical intervention for patients that have a score of 5 through 8 and frequent clinical observations every three to six months in patients who have a score of 4. We set out to validate this treatment guideline by randomly selecting 39 cases of cervical spondylotic myelopathy. These cases came from seven different neurosurgeons and excluded patients who had previous surgery or other associated neurologic disorders (parkinsonism, multiple sclerosis, etc).

The results of the study demonstrate that 15 of 39 patients had a score of 1 to 3. Three of these patients that were managed nonoperatively progressed to a higher score and subsequently underwent surgery.

Five of the 39 patients had a score of 4 and of these, one patient on follow-up improved to a score of 3. Three were managed nonoperatively but progressed to a higher grade and underwent surgery. One patient with a score of 4 underwent surgery.

Nineteen of 39 patients scored from 5 to 8: 17 (89%) underwent surgery and two were managed nonoperatively. One patient with a score of 5 was advised to have surgery, but preferred to wait and his symptoms improved. Another patient who also scored a 5 was managed nonoperatively. A month later his symptoms persisted and a CT myelogram was advised, but the patient preferred to wait and his symptoms also improved with nonoperative management.

If we apply these guidelines, with the limited information available, to help decide on the management of the patient described in the case presentation, a number of scenarios or variables can be used.

Looking at the various combinations of her four criteria, at the very best she has a score of 3, if we give her 1 for symptoms, 1 for signs, 0 if we assume she had no signal change on her MRI and 1 if we believe that her mid-sagittal canal diameter was 10 to 12 mm. If we give her a score of 2 for her symptoms, 1 for her signs, 0 for no signal abnormality and a 2 for her severe stenosis, then her score increases to 5. If we assume that her symptoms are severe and give her a score of 2, her signs remain mild to moderate for a score of 1, she has signal change for a score of 2 and her spinal canal mid-sagittal diameter is less than 10 mm, then we would give her another 2 for a total of 7. In these three scenarios, at the very best she could be treated nonoperatively.

If we considered the other two scenarios, she would score either a 5 or 7 and this would constitute a reason for surgery.

Two other additional factors are of significance in this case. The ordinary life annuities and life expectancy tables from the National Underwriter Company demonstrate that a woman who is 60 years of age would be expected to live for another 21.7 years if she were not married9 and if she was married, the 60-year-old woman would be expected to live another 27.9 years.10

When it comes to surgical intervention, an anterior cervical discectomy and fusion (ACDF) is probably the most benign surgery with the best outcomes. The risk of developing a complication in the form of injury to the spinal cord occurs in 0.3% to 3% of patients. Patients who already have myelopathy before their surgery have the highest risk of developing an injury to the spinal cord as a result of surgery. However, the overall risk of performing an ACDF is exceedingly low.

Conclusion and Recommendation

In conclusion, we have a relatively young healthy patient who has severe cord compression. She has a low risk for surgical complications at her age. There is also a 100% guarantee that her pathology will progress and increase the structural compression of her spinal cord with time. We also know that according to the lifetime tables from the National Underwriting Company that she will live to the age of 81.7 years without a companion and with a companion she will live to the age of 87.9. Based on her current health status and life expectancy, it would be reasonable to offer this patient an ACDF, not for her pain, but for the inevitable progression of her cord compression.

Author Disclosure
C Lauryssen: Consultant, Speaker’s Bureau Member and Grant Research
Support: Depuy Spine.

References
1. Brain WR, Northfield D, Wilkinson M. The neurological manifestations
of cervical spondylosis. Brain. 1952;75:187-225.

2. Clarke E, Robinson PK. Cervical myelopathy: a complication of
cervical spondylosis. Brain. 1956;79:483-510.

3. Ebersold MJ, Pare MC, Quast LM. Surgical treatment for cervical
spondylitic myelopathy. J Neurosurg. 1995; 82:745-751.

4. Singh A, Crockard HA, Platts A, Stevens J. Clinical and radiological
correlates of severity and surgery-related outcome in cervical
spondylosis. J Neurosurg. 2001;94(2 Suppl):189-198.

5. Pallis C, Jones AM, Spillane JD. Cervical spondylosis: incidence
and implications. Brain. 1954;77:274-289.

6. Pavlov H. Torg JS. Redefining cervical spinal stenosis using MRI.
Med Sci Sports Exerc. 1993;25(9):1082-1084.

7. Edwards WC, La Rocca H. The developmental segmental sagittal
diameter of the cervical spinal canal in patients with cervical spondylosis.
Spine. 1983; 8:20-27.

8. Fessler RG, Steck JC, Giovanini MA. Anterior cervical coprectomy
for cervical spondylotic myelopathy. Neurosurgery. 1998; 43:257-
267.

9. Ordinary Life Annuities –One Life–Expected Return Multiples.
National Underwriter Co. 2004.

10. Ordinary Joint Life and Last Survivor Annuities – Two Lives
– Expected Return Mulitples. National Underwriter Co. 2004.

K. Daniel Riew, MD, Reponds

To reiterate, this is a case of cervical stenosis in a 60-year-old woman with predominantly right radicular arm pain. She has no signs or symptoms of myelopathy. On the mid-sagittal MRI view, it appears that this is mostly a soft disc herniation, which
is elevating the posterior longitudinal ligament. A CT scan would reveal whether this is spondylosis or predominantly a herniated nucleus pulposus. If it is the latter, as I suspect, then it may resolve over time. Although difficult to determine, there does not appear to be cord signal change. I will argue in favor of initial nonoperative treatment.

What is the rationale for operative treatment of such a patient? I would recommend surgery if the following three assumptions were all valid: (1) paralysis is a devastating problem; (2) this patient’s risk for paralysis is extremely high; and finally, (3) asymptomatic cord compression is a prelude to spinal cord injury.

Let’s examine the validity of these three assumptions. The first assumption is that paralysis is devastating. I agree 100%. There are many patients who say, “I’d rather be dead than be paralyzed.” We all would do whatever we could to avoid seeing any of our patients rendered quadriplegic.

The second assumption is that this patient’s risk for paralysis is extremely high. If her risk is, say, 10%, I too would recommend operative treatment. But I believe that the actual risk is much lower. According to data obtained by the Paralyzed Veteran’s of America and the National Library of Medicine/ National Institutes of Health,1,2 approximately 10,000 Americans are paralyzed each year. The US Census tells us that there are almost 300 million Americans. Therefore, the average American’s risk for paralysis is 10,000 divided by 300 million, or 1 in 30,000 per year.

If we further analyze the statistics, we can get a better understanding of who gets paralyzed. It turns out that only 40% of those paralyzed are over the age of 30 and only 20% are women. Therefore, only 8% (40% of 20%) of paralysis victims are women over 30. That means that in the entire United States, there are about 800 such women (8% of 10,000) paralyzed each year. While 800 is a large number, you have to realize that there are 85 million women over the age of 30 (online census data).3

Therefore, the odds of any one American woman over the age of 30 being paralyzed is 800 divided by 85 million, or about 1 out of 100,000. Such low risk would not justify operative treatment in my opinion. But one could argue, “Our patient is not average; she has a very stenotic canal so her risk is many times an average woman’s risk.”

This brings us to the third assumption: that spinal stenosis is very often a prelude to spinal cord injury. On first glance, a few papers seem to support this premise. Frank Eismont4 published an article a couple decades ago stating that small canals correlated with neurologic injury in cervical fracture dislocations. And Jim Kang,5 when he looked at the data of Henry Bohlman over a number of years, found that patients with permanent cord injury from fracture or dislocation had narrow spinal canal diameters. I agree that if you are involved in trauma AND you have a stenotic canal, that you will fare worse than if you have a normal size canal. But it is wrong to extrapolate from this information that spinal stenosis is a prelude to spinal cord injury, because the necessary caveat is that you have to be involved in trauma. Further, these papers analyze paralyzed patients but give you no information about what the risks are.

To calculate that risk, we need to know the following: the number of people with stenosis that are paralyzed each year and the prevalence of cervical stenosis in the general population. Then the risk is simply determined by the following formula: Paralysis risk of a person with cervical stenosis # of stenotic people who are paralyzed Total # of stenotic people While we don’t know how many of the total number who are paralyzed each year (10,000) are stenotic, it is likely to be far less than all of them. But, taking the worst-case scenario, let’s assume that all 10,000 had stenosis.

Next, we determine the total number of stenotic people. According to the literature, between 7% and 29% of Americans have cervical stenosis.6,7 That means approximately 21–87 million Americans (7% and 29% of 300 million, respectively) have stenosis. Taking the worst case scenario, let’s assume that it’s the lower number: 21 million. Now we have all the information to determine the risk of a person with cervical stenosis becoming paralyzed: Paralysis risk of a person with cervical stenosis 10,000
21,000,000
1
2,100
Therefore, even with this worst case scenario, you have to realize that if you operate on someone like her, you are operating on 2099 patients who are never going to be paralyzed this year, in order to save the one person.

But there are still some who would argue that paralysis is so devastating that even if the odds of paralysis is only one in 2,100, it is worth operating. This might be reasonable, but for the inescapable fact that spine surgery is associated with some

major complications. Even if the complication rate is as low as one out of 1000, it is two times more likely for this patient to have a major complication from surgery than for her to be paralyzed if she opts for nonoperative treatment. This is why I do not recommend surgery.

To put this further into perspective, let’s examine some other statistics. The annual risk of dying for ages 55 to 64 is one out of 100 per year. That’s 21 times the risk of paralysis. If an annualized risk of paralysis is one in 2100, and this 60-year-old lives another 21 years, then her remaining lifetime risk of paralysis is one in 100. Her risk of dying from breast cancer is almost four times greater, at one out of 28. For men, the risk of dying from prostate cancer is three times greater, at one out of 33. It might therefore make more sense for a woman to opt for a prophylactic mastectomy or a man to opt for a prophylactic prostatectomy than for this patient to opt for prophylactic spine surgery for asymptomatic stenosis.

Conclusion and Recommendation

So getting back to our 60-year-old patient, I believe that it would be reasonable to try initial nonoperative treatment of the radicular symptoms and closely monitor the cervical stenosis. Bednarik8 published a study following 66 patients with cord compression on MRIs, without myelopathy. The subjects were 32 to 75, and followed for two to eight years. None had spinal cord injury. But 20% eventually developed myelopathy, for which they were decompressed. I would do similarly: follow her with serial exams and MRIs, and if she develops symptoms or cord signal change, then recommend surgery.

In conclusion, paralysis is devastating. But because it is so devastating, it is easy to make decisions based not on facts, but on fear and irrational emotions. Our patients trust us to set aside such confounding emotions to make rational decisions after weighing all the facts. And the facts are these: First, this woman’s chance of being paralyzed in any given year is less than one out of 2,100. Second, the risk of a major complication from spine surgery is higher than her chance of paralysis. So before you recommend surgery, remember Hippocrates’ admonishment:
Primum non nocere (First, do no harm). Twenty-five hundred years later, the principle still holds true that a physician should not use treatment that has a greater chance of causing harm than the condition left untreated.

Author Disclosure
KD Riew reports that he has no financial relationship that creates, or may be perceived as creating, a conflict related to this article.

References
1. Consortium for Spinal Cord Medicine. Clinical Practice Guidelines:
Neurogenic Bowel Management in Adults with Spinal Cord Injury.
Paralyzed Veterans of America. 1998:8. Available at: www.pva.
org/publications/pdf/BWL.pdf

2. MedlinePlus. Spinal cord trauma. 2004. Available at: http://www.
nlm.nih.gov/medlineplus/ency/article/001066.htm

3. US Census Bureau. Population clocks. Available at: http://www.
census.gov/main/www/popclock.html

4. Eismont FJ, Clifford S, Goldberg M, Green B. Cervical sagittal
spinal canal size in spine injury. Spine. 1984;9:663-666.

5. Kang JD, Figgie MP, Bohlman HH. Sagittal measurements of the
cervical spine in subaxial fractures and dislocations. An analysis of
two hundred and eighty-eight patients with and without neurological
deficits. J Bone Joint Surg Am. 1994;76:1617-1628.

6. Phillips WJ, Strauss AJ, Kattapuram SV. Bilateral hand pain. Del
Med J. 1986;58:559–564.

7. Smith M, Fulcher M, Shanklin J, et al. The prevalence of congenital
cervical spinal stenosis in 262 college and high school football players.
J Ky Med Assoc. 1993;91:273–275.

8. Bednarik J, Kadanka Z, Dusek L, et al. Presymptomatic spondylotic
cervical cord compression. Spine. 2004;29:2260-2269.

 

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