To investigate the clinical characteristics of entrapment cervical myelopathy and the necessity of combined anterior and posterior decompression. Methods From January 2001 to December 2004, 23 cases of entrapment cervical myelopathy were treated with posterior single-opening spinal canal enlargement and selective anterior decompression and internal fixation, including 14 cases of combined developmental spinal stenosis, 6 cases of giant disc herniation, and 3 cases of posterior longitudinal ligament calcification.
The scope of decompression was 3-5 vertebral plates in the posterior single-opening approach; in the anterior approach, simple disc and bone removal or selective subtotal resection and decompression of 1~2 vertebral bodies were performed. All cases were followed up for more than 6 months to 2 years, and postoperative imaging showed that the original fine line or bead-like spinal cord compression was lifted and the physiological arc basically existed, except for 2 cases with obvious preoperative spinal cord signal changes and poor postoperative recovery. Conclusion One-stage sequential and then combined anterior decompression can provide more complete decompression for entrapment cervical myelopathy, which not only reduces the surgical risk and treatment cost, but also fundamentally improves the surgical efficacy and is a feasible surgical approach for the treatment of entrapment cervical myelopathy.
[Keywords] Cervical myelopathy; anterior surgery; vertebroplasty
Clamping Cervical Myelopathy CCM is a spinal cord type of cervical spondylosis in which the anterior and posterior aspects of the cervical medulla are severely compressed, resulting in impaired spinal cord nerve function. Conservative treatment is often ineffective, and surgical intervention is now an effective treatment measure. In clinical practice, we often encounter this type of spinal cord cervical spondylosis in which posterior or anterior decompression surgery alone is performed, but after surgery, the outcome is not improved or the symptoms recur or worsen, and surgery has to be performed again. For the above reasons, our hospital performed one-stage combined anterior and posterior decompression surgery for 23 cases of entrapment cervical myelopathy from January 2001 to December 2004 after reasonable preoperative evaluation, and achieved more satisfactory results, as reported below.
1. Clinical data
1.1 General information
There were 23 cases in this group, 18 males and 5 females. Age 43-68 years, average 56.3 years; disease duration 9 months-7 years, average 1.7 years; among them, 14 cases of combined developmental spinal stenosis, 6 cases of giant disc herniation, 3 cases of posterior longitudinal ligament calcification; according to the Japanese JOA score 2-12 points, average 5.7 points. All cases in this group showed progressive aggravation of cervical medullary damage, 21 cases with positive Hoffman’s sign, 15 cases with positive ankle clonus, 17 cases with hyperactive tendon reflexes, 11 cases with weakened hand grip, 7 cases with unstable gait and cotton tread feeling in the lower limbs, 9 cases with thoracic and abdominal girdle feeling, as well as hypoesthesia or loss of sensation in different parts and degrees, and 4 cases with sphincter dysfunction.
1.2 Imaging examination
X-ray and MRI examinations were performed before surgery, and CT scan was performed at the same time for those who considered serious osteophytes at the posterior edge of the vertebral body or calcification of the posterior longitudinal ligament. x-ray plain film showed that the physiological anterior convexity of the cervical spine was reduced or disappeared, and the intervertebral space of the diseased segment was narrowed and the hook vertebral joint hyperplasia was obvious, often combined with spinal stenosis and calcification of the posterior longitudinal ligament. The spinal cord is compressed by the ligament at the same time, resulting in “thread-like” or “bead-like” changes in the spinal cord, and the spinal cord signal is abnormal in the severely compressed area in most cases, with part of the area accounting for more than 50% of the spinal cord cross-section.
1.3 Surgical method
Preoperative examination, comprehensive assessment and adequate preparation were carried out, and patients who could not tolerate the first-stage surgery temporarily were treated with perioperative treatment or staged surgery. In this group of cases, general anesthesia with tracheal intubation was performed, and posterior single-opening vertebroplasty was performed in the prone position, with a decompression range of 3~5 vertebral plates (for combined giant disc herniation or posterior longitudinal ligament calcification, 3~4 vertebral plates were opened for decompression; for combined developmental spinal stenosis, cervical 3~7 vertebroplasty was routinely performed to prevent the “plaster window” compression phenomenon after decompression). “The cervical collar is protected by turning to supine position, and under the fixation of Caspar cervical spreader, simple disc and bone removal or selective subtotal resection of 1~2 vertebral bodies is performed to decompress the severely compressed segment in front, and then iliac bone or titanium mesh implantation plus plate internal fixation is performed, and negative pressure drainage tube is routinely placed. After three days of postoperative bed rest, semi-recumbent, recumbent and bedside functional exercises were started under the cervical collar. After three months, the cervical collar was removed for protection.
1.4 Results
The operating time of this group of cases ranged from 150 to 270 min, with an average of 187 min; intraoperative bleeding ranged from 110 to 950 ml, with an average of 336 ml; intraoperative and postoperative blood transfusion ranged from 0 to 1000 ml, with an average of 379 ml; postoperative transient nerve root paralysis in one case, hoarseness in two cases, delayed healing of posterior neck wound in two cases, and hyponatremia in one case, all of which were cured after symptomatic treatment. MRI review showed that the spinal cord compression was released relatively completely and the spinal cord bulge became thicker, but limited high signal was still present in the lesion area in 6 cases, especially in 2 cases; X-ray showed bony fusion in the implantation area and portal axis area in 3 months on average, and cervical retrolateral deformity in 5 cases. The postoperative improvement rate was 20% to 87%, with an average of 68.1%, according to the JOA score of 5 to 16, with an average of 12.4. The clinical efficacy was more satisfactory.
2. Discussion
2.1 Clinical characteristics of entrapment cervical myelopathy
Cervical myelopathy is a spinal cord disease in which the cervical spine is damaged due to the excessive narrowing of the disc and ligamentum flavum formed by the protruding disc and the hyperplastic bone flab in front of the cervical lesion gap and the thickened and degenerated ligamentum flavum in the back. Clinically, it is often found to be combined with developmental spinal stenosis. On MRI imaging, the cervical spinal cord is “thread-like” or “bead-like” compressed, and the anterior compression is severe. Most of the cases have high signal abnormalities in the T2-weighted image of the severely compressed area of the spinal cord. Because of the slow and insidious onset, the disease duration is long and the compression is severe, so that the symptoms of spinal cord neurological impairment are very obvious, and the motor and sensory hypofunction exist at the same time, and the cone bundle sign is particularly prominent, and it shows a progressive trend of aggravation, and the conservative symptomatic treatment is often ineffective. The average preoperative JOA score in this group of cases was only 5.7, indicating that the patients’ quality of life and labor ability had been significantly reduced or lost.
2.2 The necessity of combined anterior-posterior surgery for entrapment cervical myelopathy
According to the study of the natural course of cervical spondylosis, 70~80% of cervical spondylosis of spinal cord type has progressive development, and surgical intervention is an important means to restore the function of spinal cord. In the case of entrapment cervical myelopathy, there is severe anterior-posterior compression of the cervical medulla and the disease has a long course, so surgery should be considered as soon as it is diagnosed. Although two cases in this group underwent more thorough spinal decompression, the postoperative outcome was still poor, which may be related to the irreversible recovery of spinal cord nerve function due to edema degeneration after prolonged compression of the cervical medulla.
Posterior cervical canal expansion decompressionplasty is an effective surgical procedure for the treatment of multi-segmental spinal cord cervical spondylosis and developmental spinal stenosis. However, in clinical practice, we often encounter patients with severe anterior and posterior compression of spinal cord type cervical spondylosis who have poor results or aggravation after posterior decompression. In addition to the disease duration, degree of disease and other factors, the key to the postoperative efficacy is that the compression from the front is not really removed or not effectively cushioned indirectly. The decompression principle of posterior cervical canal enlargement and decompression is the “bowstring principle”, that is, the canal enlargement releases the posterior compression of the spinal cord, and the spinal cord moves back to avoid its anterior compression, but the “anchoring effect” of the dentate ligament causes the spinal cord to move back to a limited extent, and the opening of the door of 1 cm However, the “anchoring effect” of the dentate ligament limited the degree of spinal cord posterior displacement, and the width of the 1 cm opening moved the spinal cord posteriorly by 4-6 mm.
For cervical myelopathy with severe anterior and posterior compression, if the anterior cervical decompression is performed, theoretically, direct decompression can be achieved, because the compression from the anterior side is often more obvious than the posterior side, but in practice, the difficulty and risk of surgery are significantly increased. It is often combined with spinal stenosis, and it is clinically believed that cervical spinal stenosis with >40% spinal stenosis in cross-section increases the likelihood of spinal cord injury.
At the same time, in most cases, MRI imaging shows high signal in the spinal cord on T2-weighted images, with part of the area accounting for more than 50% of the spinal cord cross-section, indicating local ischemic edema in the spinal cord, which may be in a high-risk state, so it is highly susceptible to external factors, and a slight over-extension of the position before surgery, slight improper operation or stimulation during surgery may aggravate the condition or even paralysis. At the same time, the posterior cervical canal expansion decompression and shaping provides a certain buffer and space for the anterior surgery. In addition, considering that the anterior decompression and internal fixation of multiple segments may have an impact on the postoperative activity of the cervical spine and the degeneration of the adjacent discs, only the “target” segments with severe anterior compression should be decompressed and fixed after posterior cervical spinal canalplasty, and direct decompression of all the compressed segments with medical source is not necessary. It is not necessary to directly decompress and medically interfere with all the affected segments.
For patients with entrapment cervical myelopathy, a combination of one-stage sequential plication followed by anterior decompression and internal fixation is feasible. From the clinical experience of this group, the postoperative improvement rate of this group is 20%~87%, with an average of 68.1%, and there are no serious complications, which shows the necessity of this operation, which can really achieve the purpose of direct decompression and indirect decompression, and is the complement of both anterior and posterior surgery, which not only reduces the surgical risk and treatment cost, but also fundamentally improves the surgical efficacy, and is a feasible surgical method.
2.3 Precautions for one-stage combined anterior-posterior surgery
Therefore, a comprehensive and systematic examination must be carried out before surgery to provide perioperative treatment and control of the relevant diseases, and a comprehensive assessment of the patient’s cardiopulmonary function and physical ability to tolerate surgery is required. In hospitals with the appropriate conditions, not only spine surgeons skilled in the anterior and posterior approaches, but also experienced anesthesiologists and nurses are required; intraoperative turning and repositioning before the necessary arousal test to understand the functional status of the spinal cord nerves, and preferably somatosensory evoked potential monitoring.
In order to reduce intraoperative bleeding, when lifting the lamina in the posterior “opening”, the epidural vascular plexus adhering to the lamina must be carefully separated to prevent rupture leading to hemorrhage; if a lamina “portal axis” is excessively loose, it should be decisively changed to a full laminectomy to prevent closing or moving the lamina after suturing. In case of excessive loosening of a certain lamina “portal axis”, it should be decisively changed to a full laminectomy to prevent the adverse consequences of closing the door again after suturing or displacement to compress the spinal cord; turning and changing the position under the protection of the cervical collar and anterior surgery should be done under the protection of Caspar cervical spreader fixation in order to prevent excessive loosening of the decompressed segment.
Because of the limited follow-up time of this data set, possible late complications and long-term outcomes remain to be observed in further follow-up.