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Benefits and Risks of Decompressive Spinal Surgery

 

 

Benefits and Risks of decompressing spinal cords

Wise Young, Ph.D., M.D.

W. M. Keck Center for Collaborative Neuroscience

Dept. Cell Biology & Neuroscience, Division of Life Sciences

Rutgers State University of New Jersey, Piscataway, NJ 08854

Email:  wisey@pipeline.com, Web: http://sciwire.com

Created: 24 July 2002, Updated 27 July 2002

 

Summary.  Many people with spinal cord injury have compression of their spinal cord.  What are the risks and benefits of decompressing the spinal cord late after injury?  Over the past 30 years, Dr. Henry Bohlman and colleagues at Case Western Reserve University in Cleveland, Ohio decompressed the spinal cord of many patients with spondylosis (arthritic deformity of the spinal column), stenosis (narrowing) of the lower thoracic spinal canal, “incomplete” spinal cord injury, and “complete spinal cord injury.   Their results suggest relatively high benefit-to-risk ratios for anterior decompression of cervical spondylosis, thoracic spinal stenosis, and “incomplete” spinal cord injury.  Over two-thirds of patients with cervical spondylosis showed significant reduction in pain and improved motor function.  Over half of patients with some function below the injury level showed significant improvement after surgical decompression.  Postoperative complications occurred in 5-6% of the cases.  The results in “complete” spinal cord injury were not as good but may still be worthwhile.  Although only one patient showed significant distal improvement, about half of patients with “complete” spinal cord injury had a 1-2 segment improvement with decompression.  The operation was less effective in “complete” patients who were more than 18 months after injury and over 53 years old.  Thus, patients who have some function below the level of injury and have cord compression should be decompressed.  Young patients who are less than 18 months after “complete” spinal cord injury likewise probably should be decompressed as well.  The success of decompressive surgery of course depends on the presence of spinal cord compression.  The beneficial effects of decompressive surgery raises the possibility that some of the claimed beneficial effects of transplant surgeries (macrophage, stem cell, shark embryo, omentum) may result from decompression rather than from the transplants.  However, this is a strong argument for inclusion of decompressive surgery as a control for clinical trials assessing the efficacy of transplant surgery. 

 

Anterior cervical decompression in cervical spondylosis.  Emery, et al. (1998) assessed the risks and benefits of anterior cervical decompression and arthrodesis (bony fusion) in 108 patients who had cervical spondylosis (arthritic deformity of the spine).  Anterior decompression is probably the least invasive of the decompressive surgical methods.  Of 108 patients, 38/108 (35%) who had abnormal gait recovered normal gait, 33 (31%) had improvement in gait, 6 (5%) had no change, four improved and then deteriorated (4%), and one was worse (1%).  Of 87 patients with preoperative deficits, 55 (63%) had complete recovery and 26 (30%) had partial recovery.  In terms of risk, 16 patients had a pseudarthrosis (failure of bony fusion) and required reoperation, mostly in patients who had a previous multilevel disc removal surgery.  Patients who developed pseudoarthroses showed less pain relief.  Complications of surgery were more prevalent in patients who have had preceding operations.  The best predictor of recovery was the presence of pre-operative function.  The more function a person had before the surgery, the greater the recovery.  None of the patients died as a result of the operation.  So, anterior decompression seems to be a reasonably safe and worthwhile surgical treatment of cervical spondylosis.

 

Decompression of lower thoracic spinal stenosis.  Palumbo, et al. (2001) examined 12 patients that had operative decompression of the lower thoracic spine for stenosis and pain.  They followed the recovery of the patients for 2-9 years after surgery.  Eight of the 12 patients had reduction of pain, 8 of 10 with motor deficits had improved motor function, 7 of 11 with locomotor deficits improved but two got worse, and one patient got worse after surgery.  So, thoracic decompression of stenotic spine has a higher risk of about 10% complications but about 80% of the patients got better and only 10% got worse.  The authors concluded that “although satisfactory short-term results can be expected, deterioration of the early outcome because of the potential for recurrent stenosis and deformity/instability at the thoracolumbar junction can sometimes be seen with longer follow-up evaluation periods.” 

 

Anterior decompression of thoracolumbar fractures.  Bohlman, et al. (1994) examined outcomes of anterior decompression of 45 patients with thoracolumbar fractures, at an average of 4.5 years after the spinal cord injury.  The patient population consisted of people had residual spinal cord injury from trauma, infection, or tumor.  Note that 25 of the 45 patients (56%) had incomplete neurological deficits.  Presumably , in the rest of the patients, the chief complaint was pain.  The procedure reduced pain in 41/45 (91%) of the patients and improved function in 21/25 (84%) of patients with neurological deficits.  No patient had an increase in pain or lost neurological function as a result of surgery.  This study suggests that anterior decompression of thoracolumbar fractures is reasonably safe and quite effective procedure.  It reduced pain in over 90% of the patients and improved function in 84% of the patients with minimal complications, justifying their conclusion that “anterior decompression of the thoracolumbar spine for chronic pain is a safe and effective treatment for patients with this uncommon and difficult problem.” 

 

Anterior decompression of cervical fractures in “incomplete” patients.  Bohlman & Anderson (1992) reported long-term follow up of anterior decompression in patients that had incomplete motor quadriplegia.  Of 58 patients that had displaced fragments of bone or disc compressing the cord and decompressed anteriorly at an average of 13 months (1 month to 9 years) after injury, 3 died and the remaining 55 patients were followed up for 6 (2-17) years.  Of the 55 patients, 29 (53%) became functional ambulators.  Six patients who could walk before the surgery showed improved ambulation.  No patient lost function.  Improvement was less in patients who were older and had spondylosis.  So, over half of patients showed remarkable improvement from the decompression and this benefits justify the risks of the procedure.

 

Anterior decompression of cervical fractures in “complete” patients.  Anderson & Bohlman (1992) reported long term follow up of anterior decompression in 51 patients with “complete” spinal cord injury.  The average interval between injury and surgery was 15 months.  Two patients died within 2 months after surgery and two died more than 2 years after operation.  Of the remaining 46 patients were followed for an average of 5 years (2-13 years), 7 (15%) patients showed at least two levels of root improvement and 18 (39%) patients showed 1 level of root improvement.  When they used the Barthel index to measure ability to improve activities of daily living, the index increased from 17 to 33 (out of a maximum total of 100).  They saw functionally important recovery in the spinal cord below the injury site in only one patient.   One patient showed loss of one motor root.  In patients that were more than 18 months after injury, 9 of 11 patients showed poor results.  In 5 patients that were more than 53 years old, the results were also poor.   So, decompression is worthwhile when patients are less than 18 months after injury and less than 53 years old. 

 

What are the risks of decompressive surgery?  Most of the decompressive surgery involve anterior decompression and bony fusion of the spinal column.  The anterior approach to decompression minimizes manipulation of the spinal cord and fuses the spinal column so that the procedure does not destabilize the spinal column, two important sources of complications of decompressive surgery.  But the fusion itself introduces probably the most common problem encountered after decompressive surgery, particularly in patients with cervical spondylosis.  For example, Emery, et al. (1998) reports that 16 of 108 patients with cervical spondylosis that had anterior decompression developed a pseudarthrosis, mostly in patients with multilevel discectomy.   Increasing use of anterior cervical plates that stabilize the spinal column minimizes the consequences of failed bony fusion.  However, surgery itself carries some risk.  Most of the trials had a 5-6% incidence of post-operative mortality or loss of function.  However, such risks depend on the severity of the injury, the presence of spondylosis, previous surgery, and the age of the patient.

 

When is decompressive surgery worthwhile?  These results suggest that it is worthwhile doing decompressive surgery if you are “incomplete” and have a narrow lower thoracic spinal canal, spondylosis, or have disc or bone pressing on your spinal cord.  The surgery may be effective as long as 9 years after injury.  The risk of death from surgery is in the range of 5-6% but over half of the patients recovered functional walking and those who could walk before surgery showed improvements.  The surgery is less effective for older patients with “complete” spinal cord injury.  However, if you are young and less than 18 months after injury, the surgery may be worthwhile as well because over half of the patients showed 1-2 segmental level improvement.  The restoration of even 1-2 segments, particularly in the cervical region, may lead to improved ability to perform activities of daily living.  Anderson & Bohlman (1992) showed that anterior decompression of the cervical spine of people with “complete” spinal cord injury significantly improved their Barthel index. 

 

Balancing benefit and risk.  The benefits of decompressive surgery clearly depend on the presence, severity, and duration of spinal cord compression.  If the spinal cord is not compressed, then there is no point to decompressing the cord.  If the spinal cord had been compressed for many months or even years, the surgery may not be as beneficial.  However, the clinical trials suggest that a majority of patients with compression of the cord by extruded discs, bony fragments, or narrowing of the spinal canal will show significant functional benefit, including reduction or elimination of pain.  The clinical trials did not address other complications of cord compression, such as autonomic dysreflexia and muscle atrophy, but the presence of such problems would be an addition argument for benefits balancing the risks of surgery.

References

 

  Emery SE, Bohlman HH, Bolesta MJ and Jones PK (1998). Anterior cervical decompression and arthrodesis for the treatment of cervical spondylotic myelopathy. Two to seventeen-year follow-up. J Bone Joint Surg Am. 80 (7): 941-51. Summary: We reviewed the cases of 108 patients with cervical spondylotic myelopathy who had been managed with anterior decompression and arthrodesis at our institution. Operative treatment consisted of anterior discectomy, partial corpectomy, or subtotal corpectomy at one level or more, followed by placement of autogenous bone graft from the iliac crest or the fibula. At the latest follow-up examination, thirty-eight of the eighty-two patients who had had a preoperative gait abnormality had a normal gait, thirty-three had an improvement in gait, six had no change, four had improvement and later deterioration, and one had a worse gait abnormality. Of the eighty-seven patients who had had a preoperative motor deficit, fifty-four had complete recovery; twenty-six, partial recovery; six, no change; and one had a worse deficit. The average grade according to the system of Nurick improved from 2.4 preoperatively to 1.2 (range, 0.0 to 5.0) postoperatively. A pseudarthrosis developed in sixteen patients, thirteen of whom had had a multilevel discectomy. Only one of thirty-eight arthrodeses that had been performed with use of a fibular strut graft was followed by a non-union. An unsatisfactory outcome with respect to pain was significantly associated with pseudarthrosis (p < 0.001). The development of complications other than non-union was associated with a history of one previous operative procedure or more (p = 0.005). Recurrent myelopathy was rare, but when it occurred it was associated with a pseudarthrosis or stenosis at a new level. The strongest predictive factor for recovery from myelopathy was the severity of the myelopathy before the operative intervention--that is, better preoperative neurological function was associated with a better neurological outcome. Anterior decompression and arthrodesis with autogenous bone-grafting can be performed safely, and is associated with a high rate of neurological recovery, functional improvement, and pain relief, in patients who have cervical spondylotic myelopathy. Department of Orthopaedic Surgery, University Hospitals Spine Institute, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.

 

  Palumbo MA, Hilibrand AS, Hart RA and Bohlman HH (2001). Surgical treatment of thoracic spinal stenosis: a 2- to 9-year follow-up. Spine. 26 (5): 558-66. Summary: STUDY DESIGN: A retrospective investigation of the results of operative treatment of patients with symptomatic thoracic spinal stenosis. OBJECTIVES: To establish the effectiveness and define the limitations of surgical treatment for stenosis of the thoracic spinal canal. SUMMARY OF BACKGROUND DATA: In contrast to cervical and lumbar stenosis, symptomatic narrowing of the thoracic spinal canal is rarely encountered. Although the treatment of thoracic stenosis has been described in multiple case reports and in several small series with minimal follow-up evaluation, there are few studies of patients treated surgically for this condition with follow-up evaluation beyond 2 years. METHODS: Twelve patients who underwent operative decompression for symptomatic stenosis of the lower thoracic spine were followed up for an average period of 62.4 months. Surgery was performed on the thoracic spine alone in four cases and on the combined thoracolumbar spine in eight. Factors that were investigated included pain severity, lower extremity motor function, ambulatory status, and postoperative complications. RESULTS: The level of pain after surgery was decreased in eight patients and unchanged in four patients. Of the 10 patients with a motor deficit before surgery, eight had improvement of muscle function. Of the 11 patients with a gait disturbance before surgery, ambulatory status was improved in seven, unchanged in two, and worse in two. One patient lost neural function secondary to surgical intervention. There were five cases in which the early result subsequently deteriorated because of recurrent stenosis, spinal deformity/instability, or both. CONCLUSIONS: Thoracic stenosis can occur in isolation or, more commonly, in association with lumbar stenosis. Ideally, operative treatment should address all stenotic segments and directly decompress the primary anatomic abnormalities causing neural element compression. Although satisfactory short-term results can be expected, deterioration of the early outcome because of the potential for recurrent stenosis and deformity/instability at the thoracolumbar junction can sometimes be seen with longer follow-up evaluation periods. University Hospitals Spine Institute, Department of Orthopaedic Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA. MPalMD@AOL.com.

 

  Bohlman HH, Kirkpatrick JS, Delamarter RB and Leventhal M (1994). Anterior decompression for late pain and paralysis after fractures of the thoracolumbar spine. Clin Orthop. (300): 24-9. Summary: Anterior decompression of the thoracic and lumbar spine is indicated for patients with trauma, infection, or tumor that causes compression of the neural tissues, resulting in an incomplete neurologic deficit. The complication of chronic pain, with or without paralysis, that results from fractures with canal compromise has received little attention. This study involved 45 patients who had anterior decompression for chronic pain or paralysis at an average of 4.5 years after having thoracolumbar fractures. Pain was improved in 41 of 45 patients, with complete relief in 30 and partial relief in 11. In 25 patients with neurologic deficit, 21 noted improvement, 14 of which improved one or more grades of the Eismont classification. No patient had an increase in pain or loss of neurologic function. Complications were few. Anterior decompression of the thoracolumbar spine for chronic pain after thoracolumbar fractures is a safe and effective treatment for patients with this uncommon and difficult problem. Reconstructive and Traumatic Spine Surgery Center, University Hospital, Cleveland, Ohio.

  Bohlman HH and Anderson PA (1992). Anterior decompression and arthrodesis of the cervical spine: long-term motor improvement. Part I--Improvement in incomplete traumatic quadriparesis. J Bone Joint Surg Am. 74 (5): 671-82. Summary: Between 1973 and 1983, fifty-eight patients who had an incomplete spinal-cord injury secondary to a fracture or dislocation of the cervical spine were managed by anterior cervical decompression and arthrodesis with iliac bone grafts. In all patients, myelography showed that displaced fragments of bone or disc were compressing the anterior aspect of the spinal cord. Anterior decompression was performed in an attempt to improve function in the upper and lower extremities. The average interval from the injury to the decompression was thirteen months (range, one month to nine years). Two patients died of cardiopulmonary disease within two months after the operation, and one patient died eighteen months after the operation. The remaining fifty-five patients were followed for an average of six years (range, two to seventeen years). Twenty-nine patients became functional ambulators after the operation. An additional six patients who could walk before the operation had improvement in the ability to walk. Noteworthy improvement in motor-root function in the upper extremities was seen in thirty-nine patients. Only nine patients had no signs of improvement of motor function. Improvement was less in the patients in whom operative decompression had been done more than twelve months after the injury. The patients who had an extension injury to a spondylotic spine were older, and fewer of them had improvement. No patient lost neurological function as a result of the operation. Anterior decompression and arthrodesis, even when performed late after the injury, can improve neurological function in both the upper and lower extremities in many patients who have incomplete quadriplegia due to a fracture or dislocation of the cervical spine. Acute Spinal Cord Injury Services, Veterans Administration Medical Center, Cleveland, Ohio.

 

  Anderson PA and Bohlman HH (1992). Anterior decompression and arthrodesis of the cervical spine: long-term motor improvement. Part II--Improvement in complete traumatic quadriplegia. J Bone Joint Surg Am. 74 (5): 683-92. Summary: Fifty-one patients who had complete motor quadriplegia secondary to a fracture or dislocation of the cervical spine were managed by anterior cervical decompression and arthrodesis with iliac bone grafts between 1973 and 1983. In all patients, myelography demonstrated that displaced fragments of bone and disc were compressing the anterior aspect of the spinal cord. Decompression was performed in an attempt to gain further improvement of the motor-roots in the upper extremities and thereby to improve the ability of the patients to care for themselves. The average interval from the injury to the decompression was fifteen months (range, one month to eight years). Two patients died within two months after the operation, one had a respiratory arrest that resulted in brain damage one day after the operation, and two died from cardiovascular disease more than one year after the operation. The remaining forty-six patients were followed for an average of five years (range, two to thirteen years). Neurological improvement of at least two new functional motor-root levels was documented in seven patients and of one level, in eighteen. Increased motor strength by two or three grades was seen in six patients. Noteworthy motor improvement did not occur in the remaining twenty patients. The mean modified Barthel index (used to measure improvement in the ability to perform activities of daily living) increased from 17 to 33 (of a possible 100) points. Functionally important improvement of the caudad part of the cord occurred in only one patient. In one patient, neural injury, with loss of one motor-root level, occurred, with only partial improvement. At the latest follow-up examination, the result was poor in nine of eleven patients who had decompression eighteen months or more after the injury. Only two of these patients had any improvement in the Barthel index, and then of only 5 points each. The result also was poor in the five patients who were more than fifty-three years old; two had no improvement in the Barthel index, one improved by 5 points, and two died. Acute Spinal Cord Injury Services, Veterans Administration Medical Center, Cleveland, Ohio.

 

 



©Wise Young PhD, MD


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