Anterior Cervical Hybrid Decompression and Fusion Surgery to Treat Multilevel Cervical Spondylotic Myelopathy

Summary

This paper describes a hybrid surgical technique that combines anterior cervical discectomy and fusion with anterior cervical corpectomy and fusion to treat patients with multilevel cervical spondylotic myelopathy.

Abstract

Cervical spondylotic myelopathy (CSM) is a common disease resulting from intervertebral disc herniation, ossification of the posterior longitudinal ligament, and other pathological changes that cause spinal cord compression. CSM progresses insidiously with mild upper-limb numbness, which patients tend to ignore. As the condition worsens, the patients may experience a limp, limited fine motor activity, and eventually, a loss of daily activity. Conservative treatments, such as physical therapy and medication, are frequently ineffective for CSM. Once surgery is deemed to be required, decompression surgery is the best option. So far, both anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF) have been commonly used to treat CSM. In addition, a type of hybrid procedure that combines ACDF with ACCF has been used to treat some CSM cases and achieved satisfying results. Thus, this study aims to introduce this hybrid surgical technique and advocate for it based on its patient success.

Introduction

Cervical spondylotic myelopathy (CSM) is a common cause of cervical nerve dysfunction. It is characterized by acquired stenosis of the cervical spinal canal, osteoarthritic degeneration, or spinal column ligamentous aberrations¹. Due to the pathological characteristics of the disease, conservative treatments are ineffective in removing the increasing compression, and prompt surgical intervention is required. In clinical practice, anterior cervical discectomy and fusion (ACDF) surgery is usually the first option for single-level CSM². Despite the variety of procedures available, the best procedure for multilevel cervical spondylotic myelopathy (MCSM) remains debatable.

In MCSM cases, the typical compression of the spinal cord comes from the ventral side, and this compression causes central and peripheral nerve injury symptoms. Cervical surgeries are usually needed to treat MCSM. There are two common surgical approaches: anterior and posterior surgeries. The anterior approach includes ACDF, anterior cervical corpectomy and fusion (ACCF), and anterior cervical hybrid decompression and fusion surgery (ACHDF, the combination of ACDF and ACCF). These anterior surgeries are suitable for MCSM with ventral compression to the spinal cord. The benefits of ACHDF as a hybrid surgical technique include maintaining the anterior and middle columns of the cervical spine while ensuring as much decompression as possible and allowing the surgeons to customize their surgical strategy. In this study, we aim to introduce the ACHDF technique combining ACDF and ACCF for treating MCSM.

Case presentation
A 50-year-old female patient who complained of neck pain for 1.5 years and numbness in her left limbs for 7 months was admitted to the spine surgery department of the Third Hospital of Hebei Medical University. Consent from the patient was obtained to use her medical history in this study. This patient's main symptoms were aggravated by daily activities and relieved by rest and unrelated to temperature changes. The patient had undergone conservative treatments in a local clinic, including transfusion therapy and acupuncture, but without any successful relief of her symptoms. Physical examination revealed decreased strength in the left biceps and triceps (grade 3) and muscle groups of the left lower extremity (grade 4), as well as diminished biceps and triceps tendon reflexes. The Hoffmann's sign and Babinski's sign were both negative.

Diagnosis, assessment, and plan
The patient underwent cervical X-rays, CT scans, MRIs, and laboratory tests in preparation for surgery. The radiological examinations revealed a straightening of the physiological curvature of the cervical spine, herniated intervertebral discs, and spinal cord compression. The patient's visual analog scale (VAS) was 5, and her cervical Japanese Orthopaedic Association Score (JOA) was 7. Cervical spondylotic myelopathy was diagnosed according to the symptoms of decreased muscle strength, decreased tendon reflexes, and limb numbness. As the patient showed no signs of peripheral nerve compression, cervical spondylotic radiculopathy was ruled out. In addition, pain caused by muscle strain and rheumatic diseases was ruled out because there was no obvious correlation between the pain symptoms and temperature changes in the patient^3,4.

As conservative treatment was ineffective, surgical treatment was recommended to the patient. ACHDF surgery was selected to treat the disease because an osteophyte could be observed in the patient's X-ray and CT in segment C6/7 (Figure 1A,B, yellow arrow). Meanwhile, a low-signal shadow protruding posteriorly and pressing on the dural sac could be observed on MRI in C6/7 (Figure 1C, yellow arrow). Sagittal CT imaging revealed osteophytes protruding from the posterior margin of the vertebral body by ~5.7 mm, which compressed the spinal cord not only at the disc levels but also behind the cervical vertebral body in C6 and C7. A herniated disc could be observed in C5/6, while C4/5 suffered a relatively mild disc herniation. In line with the recommendations of the WFNS Spine Committee⁵, C6 corpectomy and C4/5 discectomy were performed to treat the disease. The patient's neck pain and numbness improved after surgery, and although physical examination revealed no significant recovery of muscle strength, the patient reported improvement in her own perception of her muscle strength. There were no major postoperative complications observed.

Protocol

The protocol was approved and followed the guidelines of the Ethics Committee of the Third Hospital of Hebei Medical University. Informed consent was obtained from patients for including them and the data generated as a part of this study.

1. Preoperative preparation

1. Apply the following inclusion criteria.
   1. Ensure that the radiological examination shows three or more diseased levels.
   2. Ensure that the symptoms are caused by pathological changes of the cervical vertebrae with the exclusion of other systemic diseases.
   3. Look for hypertonia, hyperreflexia, positive pathological signs, or symptoms of upper motor neuron injury.
2. Apply the following exclusion criteria.
   1. Exclude those diagnosed with cervical spondylotic radiculopathy.
   2. Exclude patients who have undergone cervical surgery or have a history of cervical injury.
   3. Exclude patients with a cervical tumor or inflammation.
   4. Exclude patients with serious ossification of the posterior longitudinal ligament.
3. After general anesthesia and tracheal intubation are performed, place the patient in the supine position on the operating table.
4. Place a cylindrical pillow on the back of the patient's neck to maintain the cervical spine in a hyperextension position.
5. Disinfect the surgical area with iodine and alcohol, and then lay the sterile sheets over the patient.

2. Lesion exposure

1. Make a right transverse or longitudinal incision (depending on the surgeon's preference) centered on the fusion segments (localization according to body surface markers).
2. Use a scalpel to cut the skin, and use an electrocoagulation electrotome to isolate the subcutaneous tissue and cut through the platysma myoides (cut the omohyoid muscle if the scope of surgery is large and there is no need to suture the muscle).
3. Determine the carotid pulse and carotid sheath location with a finger. Perform blunt dissection of the muscle medial to the carotid sheath up to the prevertebral fascia.
4. Use a periosteal detacher to separate the muscle along the attachment points. Use a goiter retractor to pull the thyroid and tracheoesophageal structures to the patient's left side.
5. Use an electrocoagulation electrotome to cut the prevertebral fascia and expose the vertebral body; then, use a cervical spreader to widen the intervertebral space.

3. Decompression

1. ACDF surgery
   1. Use a scalpel to cut the required amount of the annulus fibrosus. Then, use a curette and a nucleus pulposus clamp to remove the nucleus pulposus until the dura is exposed. Use a laminectomy rongeur to remove the endplates and hyperplastic bone.
   2. Use a nerve dissector to search for potential compression, and use to remove part of the posterior vertebral body edge to make a decompression.
   3. Insert a properly sized interbody fusion cage filled with autologous bone into the intervertebral space.
2. ACCF surgery
   1. Use rongeur forceps to remove the vertebral body located between two diseased discs. Use a curette and a nucleus pulposus clamp to remove the two adjusted discs and endplates, similar to step 3.1.1.
   2. After the dura is exposed, use the nerve dissector to search for potential compression. Use gelatin sponges or fluid gelatin accompanied by brain cotton pieces to stop bleeding.
   3. Insert a properly sized titanium mesh cage filled with autologous bone into the space between the two vertebrae.

4. Titanium plate fixation

1. Choose a titanium plate of an appropriate length to cover the surgical segment. Implant six screws into the vertebrae to fix the titanium plate.

5. Closing the incision

1. Use saline to flush the surgical area, and elicit hemostasis with bipolar electrocoagulation. Fill the void by using gelatin sponges, and insert a drainage tube.
2. Use an interrupted suture to close the superficial fascia and skin (size 2-0 suture material).

NOTE: The suturing method can be chosen according to the operator's preference or patient's request.

6. Postoperative care

1. Measure the blood loss through the drainage bottle each day. When the daily blood loss is less than 50 mL, the drainage tube can be removed.
2. Allow the patient to walk with a separated collar support the day after surgery. Advise the patient to keep wearing the support for 1.5 months.

Results

The CT and MRI scans revealed disc herniation in the cervical segments C3-C7 and ossification in C6-C7 (Figure 1). Although C3-C4 had pathological changes, spinal cord compression was not observed. As a result, C4-C7 was chosen as the surgical segment. The postoperative VAS score decreased from 5 before the operation to 3 at 3 months and 1 at 20 months. The JOA score increased from 7 before the operation to 8 at 3 months and 12 at 20 months. The neck pain only occurred if the patient bowed t...

Discussion

Multilevel cervical spondylotic myelopathy is a disease that affects multiple intervertebral discs. This increases the severity of the disorder, makes it more challenging to obtain a good prognosis, and makes determining the responsible segment more difficult than for single-level CSM. Clinically, the mJOA score is commonly used to grade CSM. An mJOA score ≤ 11 is generally regarded as severe, 12-14 is moderate, and 15-17 is mild; moderate and severe CSM require prompt surgical treatment, while patients graded as m...

Materials

Name	Company	Catalog Number	Comments
Adhesive	Biatain	3420	12.5 x 12.5 cm
Bipolar electrocoagulation tweezers	Juan'en Medical Devices Co.Ltd	BZN-Q-B-S	1.2 x 190 mm
Bone wax	ETHICON	W810T	2.5 g
High frequency active electrodes	ZhongBangTianCheng	GD-BZ	GD-BZ-J1
interbody fusion cage	WEGO	900200013	5 x 16 x 13 mm
Laminectomy rongeur	Qingniu	2051.03	220 x 1.5 x 130°
Laminectomy rongeur	Qingniu	2054.03	220 x 3.0 x 130°
Pituitary rongeur	Qingniu	2028.01	220 x 3.0 mm
Pituitary rongeur	Qingniu	2028.02	220 x 3.0 mm
self-tapping screw	WEGO	700054012	4.0 x 12 mm
spreader	WEGO	818-021	-
Surgical drainage catheter set	BAINUS MEDICAL	SY-Fr16-C	100-400 mL
Surgical film	3L	SP4530	45 x 30 cm
titanium plate	WEGO	700000057	57.5 mm
Titanium cage	WEGO	9051028	10 x 28 mm