Clinical data and methods
1.1 General data: 10 males and 6 females in this group of 16 cases; age 55-72 years, average 55.7 years, all had developmental cervical stenosis and ossification of the ligamentum flavum hypertrophicum folds combined with multi-segment or single-segment anterior compression and segmental instability. Eleven of these cases had developmental spinal stenosis and five had degenerative spinal stenosis, mainly hypertrophic folds and ossification of the ligamentum flavum. Six of the cases had cervical segmental instability. There were 14 cases of neck weakness and discomfort, 15 cases of numbness in the extremities, 10 cases of stepping on cotton in the lower extremities, 8 cases of thoracoabdominal girdling, 12 cases of decreased skin pain and temperature sensation, 4 cases of diminished key reflexes in the extremities, and 6 cases of active reflexes.
1.2 Imaging characteristics
The standard lateral cervical spine X-ray showed a sagittal pavlov index <0.75 in 12 cases; the hyperextension-hyperflexion X-ray showed intervertebral loosening or instability in 6 cases; all cases had narrowing of the intervertebral space on the X-ray and protrusion of bone at the posterior edge of the vertebral body, and the characteristic MR changes were small symmetrical bead-like changes of the spinal cord and anterior-posterior compression of the spinal cord.
1.3 Treatment procedure and surgical method
1.3.1 Surgical approach.
The surgery was performed under general anesthesia with tracheal intubation, and the posterior surgery was performed in the prone position. A longitudinal incision was made at the back of the neck, the subcutaneous skin was cut, the paravertebral muscles on both sides were separated, the vertebral plates on both sides were exposed, (the range was more than 1 plate each in the upper and lower part of the lesioned segment), part of the spinous process was removed, and the vertebral plate was connected to the lateral block with a miniature power grinding drill (pneumatic or electric drill) or a sharp biting forceps to cut a groove in the vertebral plate on one side. The bone groove is longitudinal, located at the inner edge of the small articular eminence, the groove is truncated and “V” shaped, preserving the inner lamina (completely disconnected during total laminectomy), cutting off the upper and lower lamina of the open segment and the yellow cut band under the open segment, uncovering the lamina to the strand side, and sewing it to the paravertebral muscle membrane on the strand side with a 10-gauge suture through the spinous process preparation hole, so that the vertebral canal has been enlarged and formed, and the open gap is 1-1.5 Cm. The lamina was completely removed using the uncovering technique during total laminectomy.
If the cervical 2 spinous process and the muscles attached to the lamina are stripped, the cervical 2 spinous process is perforated and the paravertebral muscles are fixed to preserve the posterior cervical muscle tone and prevent cervical retroflexion. A drainage tube was left in place and the incision was closed layer by layer. After posterior surgery, the patient was placed in a supine position, a transverse incision was made at the anterior border of the right sternocleidomastoid muscle, the anterior vertebral body was routinely exposed according to the anterior cervical approach, the anterior vertebral fascia was separated to both sides, and the vertebral space was inserted into the long needle C-arm X-ray machine for fluoroscopic positioning. The anterior border ligaments of the diseased vertebral body are incised and pushed to both sides. The screws of the intervertebral spacer are screwed into the middle of the two adjacent vertebrae to be cut and the intervertebral space is opened. The annulus fibrosus of both or both intervertebral spaces is incised and a spatula is used.
The lesioned nucleus pulposus is partially removed, and the middle of the vertebral body is longitudinally removed with a bite forceps to make a long 14-16 mm wide, bony groove, and the anterior spinal membrane compression, including thin cortical bone, ossified posterior longitudinal zone, and posterior protrusion of bone and degenerated disc tissue at the interspace, is completely removed with a spatula to achieve full decompression of the spinal cord. A bone strip 1-2 mm in length from the skeletal crest and trimmed to 14-16 mm in thickness is implanted in the decompression sulcus. The spacers and screws are loosened and removed. After inspection, the bone block is well positioned and an appropriately sized locking titanium plate is pre-bent and placed in front of the vertebrae, and holes are drilled, tapped, and nailed sequentially in the upper and lower vertebral body near 1/3 of the resected vertebrae.
The hollow screw is then screwed into the locking screw. After flushing the operative field and checking for no active bleeding, the incision is closed layer by layer and drainage strips are left in place.
Postoperative treatment Postoperative treatment was performed by removing the pillow and lying flat, adding a pillow when lying on the side, giving dehydrating agents, hormones, hemostatic drugs and antibiotics, removing the drainage for 48-72h, and taking the cervical collar to the ground after removing the stitches. The cervical collar was fixed for 3 months after surgery. 3 months later, the collar and back muscles were exercised under the protection of the cervical collar.
2.Results
The surgical efficacy was determined by the Japanese Society of Orthopedic Surgery (JoA) standard. 17 points included 4 points for each upper and lower limb motor function, 2 points for each upper and lower limb and somatosensory function, and 3 points for bladder function. The postoperative improvement rate was calculated as follows: 14 patients complained of significant improvement in numbness and pain in the upper extremities of both hands and in the chest and abdomen on the second postoperative day, and all cases were followed up for an average of 15.6 months. 16 patients had a star reduction of axial symptoms in the neck at 3,6 and 24 months after surgery, and 14 patients resumed labor and work capacity. There were no complications such as plate loosening and bone graft prolapse during the follow-up. All of them achieved bony fusion and good cervical curvature at 3 months after surgery.
3. Discussion
The diagnosis of clamped spinal cord type cervical spondylosis has the following three main points: the presence of typical spinal cord compression symptoms, i.e., decreased muscle strength of the limbs, sensory impairment, increased muscle tone, and progressive aggravation, which seriously affects the patient’s normal life; X-ray shows that the absolute value of the sagittal diameter of the spinal canal is <11 mm.
The Pavlov index was <0.75, and MRI showed that the spinal cord was clamped, especially on T2-weighted images, with asymmetric bead-like changes.
3.1 Pathogenesis of clamped spinal cord cervical spondylosis
The following causes were found by hyperflexion and hyperextension radiographs and MRI: cervical degeneration caused by ligamentous ligaments, folds and hypertrophy protruding into the spinal canal, which compressed the spinal cord anteriorly and produced a clamping effect on the spinal cord with the posterior border of the vertebral body; the original developmental cervical spinal canal was narrowed, and then the cervical disc protrusion compressed the spinal cord anteriorly. The cervical spine instability is also an important factor, as the slippage of the upper and lower vertebral bodies can cause the compression of the cervical spinal cord from the upper vertebral plate from the posterior force. In addition to the compression caused by the protruding discs and the formation of the bony mass at the posterior edge of the vertebral body, the inflammatory response from the degenerating and protruding cervical discs also plays a role.
(1) Compression of the nutrient vessels of the spinal cord, which can also cause microcirculatory disorders leading to spinal cord damage.
(ii) Posterior spinal cord compression, which manifests as symptoms of conduction block in the thalamic and lateral tracts of the spinal cord, commonly as sensory disturbances and increased muscle tone. Anterior damage to the spinal cord, manifesting as symptoms of damage to the anterior horn of the spinal cord and the vertebral tracts.
3.2 Choice of surgical approach
Once diagnosed with a clamped spinal cord type cervical spondylosis according to the traditional treatment model, the spinal canal is expanded successively, and if the result is not good, anterior cervical surgery is performed again after 3-6 months. Before the second surgery, the cervical spinal cord is still in a state of compression, and there is a possibility of degeneration and necrosis in the parenchymal part of the spinal cord. The posterior cervical canal enlargement and plasty is performed first, with limited posterior displacement of the spinal cord. Although the anterior compression is relatively relieved, the anterior compression of the spinal cord may still not be completely released. One-stage combined anterior-posterior surgery has the advantages of complete decompression, reconstruction of cervical spine stability, elimination of secondary surgical pain, and economic cost savings.
The posterior cervical decompression allows space for the spinal cord to float backward, relieving the posterior spinal cord compression. At the same time, the single opening of multiple segments in the posterior approach can also – prevent secondary compression of the spinal cord caused by degeneration of adjacent cervical vertebrae due to fusion of anterior cervical segments. With anterior cervical decompression, direct removal of fibrous and bony compressors that compress the spinal cord may improve and enhance the blood supply to the spinal cord after decompression. At the same time, intervertebral bone grafting, fusion and internal fixation with locking plates can better maintain the vertebral body, the height of the intervertebral space and the physiological curvature of the cervical spine, which can enhance the stability of the cervical spine, and the rate of bone grafting and fusion is high, and the one-stage anterior-posterior cervical decompression surgery is more traumatic and risky than the simple anterior or posterior cervical decompression surgery.
When performing phase I anterior-posterior cervical decompression surgery, attention should be paid to: the posterior decompression should be performed first to give the spinal cord a backward cushion space, and then the anterior surgery can reduce the trauma to the cervical medulla; when changing positions during surgery, the patient should be carefully lifted and placed to prevent damage to the cervical medulla, and attention should be paid to the patient’s anesthesia and oxygen administration to prevent accidents at any time; after surgery, the patient should be closely observed for wound hematoma and respiratory tract. The surgeon should master the skills of anterior and posterior cervical spine surgery, and should be calm, careful and dexterous during the operation to minimize the side injuries caused by the operation.
3.3 Advantages and disadvantages of this procedure
Compared with the anterior and posterior surgery performed in separate steps by the anterior or posterior approach, this procedure has the following advantages.
(1) The anterior and posterior surgeries are performed simultaneously, so that the decompression is complete and adequate, and the effect is obvious.
(2) Decompression and internal fixation are performed at the same time to rebuild the stability of the cervical spine, which reduces the patient’s pain and makes it easy for the patient to accept, greatly shortens the treatment period, facilitates early landing and functional exercise during the dry period, helps the spinal cord function recovery, and gains valuable time for the rehabilitation of spinal cord injury.
(3) Shorten the hospitalization time and greatly save the hospitalization cost, avoiding the patient twice hospitalized and twice operated. The disadvantage is that one operation is more traumatic, and the anesthesia time and stay in the operating room is longer, which puts higher requirements on the patient’s tolerance and must strictly control the indications for surgery.
The combined anterior and posterior one-stage surgery can both indirectly decompress the cervical spinal cord by expanding the volume of the cervical spinal canal through the posterior approach and directly remove the fibrous and bony compressive material compressing the spinal cord from the anterior approach, thus achieving good clinical results in improving the function of the cervical medulla. Therefore, the author believes that one-stage anterior and posterior cervical decompression surgery is an effective and feasible surgical method for the treatment of clamped spinal cord cervical spondylosis.