Anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord for single-segment cervical spondylotic myelopathy: The technical interpretation and 2 years of clinical follow-up

This is a single-center clinical retrospective study. From Aug. 2015 to Apr. 2017, 32 patients with single-segment CSM underwent spinal cord decompression treatment with the anterior percutaneous full-endoscopic transcorporeal procedure: 18 males and 14 females of 59.25 ± 6.849 years (51~73 years). The disease course was 8.766 ± 4.887 months (3–21 months). The distribution of clinical symptoms along with the type of lesion and their level was shown in Table 1. The magnetic resonance imaging (MRI) and computerized tomography (CT) scans to identify the characteristics and exact location of the lesion. The compression of the spinal cord was mainly attributable to single-segment protruding discs-osteophytes complex [15]. And CT scan was utilized for preoperative measurement of the depth and direction of the tunnel trajectory. Patients were excluded for cervical instability, calcification of the posterior longitudinal ligament, yellow ligaments or simple posterior compression, and compression of the two or more segments spinal cord; Cases of coagulant dysfunction, intervertebral infection, cervical malformation, and anterior cervical surgery history were excluded. The study was performed after obtaining due permission from the local institutional review board as well as informed consent from the patients.

The spinal endoscopy system (SPINENDOS GmbH., Germany) comprised a 30^°-angled scope, a 4.3-mm working channel with a water irrigation system, a 6.9-mm outer sheath, and related surgical instruments, a gimmi-SPINENDOS digital camera system. And a low-temperature radiofrequency system (ArdthroCare Co., California, USA).

The operations were performed by the corresponding author. All patients had gastric tube inserted prior to the surgery and were administered general anesthesia with endotracheal intubation, and the patient was placed in the supine position and kept the neck slightly overstretched. Downward traction was applied to the upper limbs to avoid the blocking of the lower cervical intervertebral space on X-ray. Fifteen milligrams of iodohydride was injected into the gastric tube to show the position of the esophagus under the c-arm perspective and the skin puncture point was marked on the far side of the esophagus. Strict surgical disinfection was performed, and sterile waterproof coating covers were used in the surgical area to avoid flushing the sterile dressing. According to preoperative CT and MRI, the locations of the disc-osteophyte complex were identified (Fig. 1a–d), and the trajectory of the osseous channel was designed (Fig. 2a). The puncture point was located in the lower part of the lower vertebral body under the section of the responsible segment. Using the “two-fingering” technique at the puncture point, the endotracheal sheath of the esophagus and the vascular nerve sheath were pushed aside to touch the front of the vertebral body, and a puncture-safe area was created with the skin pressed to the vertebral body [16, 17]. A puncture needle was inserted between the fingers. The position of the puncture point and the direction of the guide needle in the vertebral body were established according to the C-arm X-ray perspective (Fig. 2c, d). When the guide needle properly inserted the vertebral body fixation, and the expansion sleeve (D = 6.3 mm) was inserted along the guide needle, the tube was slowly rotated and placed in the protective casing (D = 8.5 mm). Under the protection of the trephine casing, according to the target of disc-osteophyte complex, the bone tunnel was gradually established. The bone tunnel continued until the trephine penetrated the posterior margin of the vertebral body in the C-arm monitoring perspective (Fig. 2e–f), and the trephine was properly shaken to remove the vertebral bone. The trephine protective casing was replaced with a work casing (7.6 mm) (Fig. 2g, h). The endoscopic operating system was inserted through the casing, and the endoscopic decompression procedure began. Continuous saline irrigation was used to maintain a clear view during the operation. Various types of medullary forceps were used to remove the protruding disc tissue. A high-speed diamond burr and rongeur were used to clear up the disc-osteophyte complex (Fig. 2i), and epidural capsule decompression and pulsation were acquired (Fig. 2j). Hemorrhaging of the posterior longitudinal ligament or epidural was stopped with radiofrequency hemostasis. When no active bleeding was observed, the work casing was stepped out of to the front of the vertebral body. The work casing was removed, a drainage tube was not required due to no active bleeding, and the incision was sutured and covered with a sterile dressing to complete the procedure. On the first postoperative day, antibiotics, hormones, and mannitol were administered, a neck protection collar was applied, and the patient walked away from the bed. The patients were discharged 2–4 days after surgery, wore the neck collars and oral administration of mecobalamine and B-complex vitamins improve neurological function for 4–6 weeks.

Typical case: Male, 51 years old, neck pain accompanied by numbness, and weakness of limbs, with the left side as the focus, C5~6 disc-osteophyte complex protrudes into the spinal canal, resulting in spinal stenosis and compression of the spinal cord (Figs. 1, 2, 3, 4).

Operative time, surgical complications (spinal cord injury, dural injury, esophageal vascular injury, hematoma, wound infection, etc.), postoperative time of getting out of bed and postoperative hospitalization were recorded. Visual analog scale (VAS) was used to evaluate neck pain and Japanese Orthopaedic Association Score (JOA) to evaluate clinical neurological function. The degree of spinal decompression was objectively assessed by postoperative cervical MRI, and vertebral structure was assessed by CT examination. The HI between the upper and lower endplate center of the operative segment was measured by neutral cervical X-ray. CSA was measured using Harrison’s method [18]: an acute angle formed by the intersection of C2 and C7 posterior vertebral tangent lines. The patients in this study were followed up at the outpatient clinic at 1 week, 6 months, and 24 months after surgery. Methods of follow-up: VAS and JOA scores were performed, and modified MacNab standard was added for the last follow-up to evaluate the excellent-good rate of treatment. X-ray plain film of anterioposterior and lateral of cervical spine was taken to measure the HI of the surgical segment and the CSA. The stability of the operative segments was observed by X-ray plain film of the hyperextension and hyperflexion of the cervical spine.

All patients had mild intraoperative neck edema, and the edema was subsided in 2~4 h after surgery. After the removal of the casing, three cases of bleeding in the cut were observed, and the bleeding was stopped after a few minutes of compression. One patient experienced difficulty breathing due to laryngeal spasms, which was improved after the administration of a pressurized oxygen supply and control the spasms. No dysphagia, hoarseness, spinal cord injury, cerebrospinal fluid leakage, infection, or other intra- or postoperative complications occurred.