Introduction
Spinal stenosis is a pathological condition wherein bony, ligamentous and synovial structures of the spine degenerate and overgrow. As the disease progresses, the neural and vascular anatomy of the spinal canal are compressed [1]. Patients experience debilitating pain and reduced muscle strength in their extremities. Disease progression necessitates surgical intervention to prevent irreversible neurological deterioration [2].
Minimally invasive surgery has become a widespread approach to treating pathologies of the spine. Most techniques rely on the endoscope. The introduction of tubular retractors, however, has increased the popularity of minimally invasive surgery among neurosurgeons who lack endoscopic experience. Tubular retractors with wide diameters such as the EasyGO! system provide narrow but sufficient space for bimanual techniques under an operating microscope [3].
Only one previous study has assessed the outcome of a microscopic anterior cervical approach using tubular retractors [3]. We here present our first experience of using the EasyGO! tubular retractor system for an anterior cervical decompression. To the best of our knowledge, this is the first report of an EasyGO!-assisted microscopic anterior approach to the cervical spine.
Case report
A 68-year-old man presented to our department with a two-year history of neck pain radiating into the left hand, accompanied by numbness and significant strength reduction of the left extremity. Conservative therapy had shown no benefit.
Muscle strength was 2/5 in the left upper extremity, predominantly in the biceps and wrist extensors. He had hypoesthesia in his left radial forearm and hand, predominantly in the thumb and index finger. His epicritic and proprioceptive sensations were altered accordingly. Spurling’s test was positive. Bicipital, tricipital and Tromner reflexes were all preserved. Abdominal cutaneous reflexes were present. Magnetic resonance imaging and computer tomography of the cervical spine revealed degenerative stenosis of the spinal canal, predominantly at the C5–C6 levels.
Microsurgical decompression at the C5 and C6 segments was indicated (Fig. 1). Neuronavigation was used to localise the site for a minimally invasive access. A linear incision from the midline to the middle of the sternocleidomastoid muscle at the level of the cricoid cartilage was made. Dissection was performed along the anterior edge of the sternocleidomastoid muscle. Then, under constant control of the common carotid artery, access to the anterior surface of the spine was gained. The C5 and C6 vertebral bodies were skeletonised. We then inserted an EasyGO! tubular retractor system (Karl Storz, Tuttingen, Germany). The surgeon can choose between retractors of three different diameters: 15 mm, 19 mm, or 23 mm. We had not made use of an endoscope, relying instead on the use of a binocular operating microscope because our experience with endoscopic surgery was very limited. We therefore chose the EasyGO! tubular retractor with the largest diameter, the one which allowed broad visualisation of the surgical field and convenient bimanual manipulation. Using a high-speed drill, one third of the C5 and C6 vertebral bodies was cut along a diagonal path decompressing the anterior surface of the dura mater. The posterior longitudinal ligament was visualised and removed with a Kerrison rongeur. Autologous bone graft obtained during the dissection was used to stabilise the C5 and C6 vertebrae. Haemostasis was achieved with the help of Surgiflo.
The EasyGO!-assisted microsurgical approach was safe and feasible. We did not experience any complications or technical difficulties. Conversion to a conventional open surgical approach was not considered at any time. The operating time was significantly longer than that of our conventional open procedures.
The patient showed a marked improvement after the first postoperative day. He suffered no neurological alteration, and was discharged on postoperative day three in good clinical condition.
Discussion
Minimally invasive techniques have become increasingly popular due to the minimal disruption of the patient’s anatomy. Reduced blood loss and less postoperative pain lead to swifter recovery and discharge. Long-term clinical outcomes may not significantly differ between minimally invasive and open procedures. However, long follow-up data is scarce [4].
Despite the widespread use of endoscopy in spinal surgery, a shallow learning curve must be overcome for safe routine use. Neurosurgeons with little or no experience in endoscopic spinal surgery, such as our group at the time of this report, may thus be hesitant about adopting this technique. The EasyGO! tubular retractor, however, provided a sufficient working canal to perform a bimanual dissection with the help of a binocular microscope [3]. As in any new procedure, operating time was notably longer than that of our open procedures. However, we believe that this increase in operating time may decrease and even become negligible once the learning curve has been overcome. A previous study estimated the number of surgeries necessary to achieve full familiarity with an EasyGO!-assisted microendoscopic procedure as being up to 30 [5].
We further conducted a literature review using the search terms EasyGO and minimally invasive spine surgery to identify all previous articles on the use of the EasyGO! system. We found eight studies, seven of which described the use of EasyGO! for endoscopic interventions (Tab. 1) [5–12]. The remaining study, conducted by Burkhardt et al. in 2017, compared the image quality between endoscopic and microscopic EasyGO!-assisted surgery [10]. They found their high-definition endoscopic camera allowed more reliable identification of anatomical structures than an operating microscope. All studies have reported very good results regardless of endoscopic or microscopic visualisation. Martin-Láez et al. conducted a large comparative trial to assess the outcomes of EasyGO!-assisted endoscopic discectomy vs. a conventional open approach. The EasyGO! group achieved superior results in terms of both average hospital stay (2.4 vs. 3.4 days) and symptom relief (90% vs. 69%) [5].
Previous reports on use of EasyGO! system for minimally invasive spinal surgery |
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Lead author (date of publication) |
Objective |
Study population |
Results |
|
Priola (Mar 2019) |
To assess long-term clinical outcome of EasyGO!-assisted percutaneous interlaminar endoscopic sequestrectomy in lumbar radiculopathy |
5 patients were operated with help of EasyGO! system |
EasyGO!-assisted surgery was well-tolerated; no complications or recurrences noted at 3-year follow-up |
|
Burkhardt (Oct 2019) |
To assess instrument handling and endoscopic image quality in EasyGO!- -assisted spinal decompression |
46 patients (39 x lumbar, 7 x cervical) |
EasyGO! system offered good view of surgical field and allowed bimanual decompression Clinical success noted in 85% of lumbar and 100% of cervical cases according to Odoms criteria |
|
Burkhardt (Jul 2017) |
To assess endoscopic high definition image quality in comparison with conventional microscopic visualisation in EasyGO!-assisted posterior lumbar and cervical procedures |
A junior resident was required to identify anatomical structures in 13 lumbar and three cervical EasyGO!-assisted surgeries using either endoscopic or microscopic visualisation |
66% of structures were identified correctly under endoscopic view, 41% under microscopic view Endoscopic high-definition camera imaging allowed significantly more reliable identification of anatomical structures |
|
Oertel (Jul 2017) |
To describe EasyGO!-assisted endoscopic intralaminar approach for cranially and caudally migrated lumbar disc herniations |
31 patients (26 x caudally, 5 x cranially migrated disc herniations) |
EasyGO!-assisted endoscopic intralaminar approach was safe Clinical success reported in 95% at mean final follow-up (37 months); Oswestry Disability Index 9% |
|
Oertel (Jul 2017) |
To present a series of lumbar synovial cysts treated via EasyGO!-assisted endoscopic approach |
11 patients |
EasyGO!-assisted endoscopic approach allowed safe complete removal while preserving muscle, ligamentous and bony anatomy 82% of patients reported excellent or good clinical outcomes |
|
Burkhardt (Nov 2016) |
To present a series of cervical osseous foraminal stenosis treated via EasyGO!-assisted posterior foraminotomy and to compare outcomes of patients with and without previous surgery |
45 patients (20 without previous surgery, 25 with previous surgery) |
Clinical success rate 95% in patients without previous surgery, 75% in those with previous surgery Reduction in preoperative pain and motor recovery in 100% of patients without previous surgery Reduction in preoperative pain in 92%, and motor recovery in 67% of patients with previous surgery |
|
Oertel (Jul 2016) |
To present a series of cervical osseous foraminal stenosis treated via posterior EasyGO!-assisted endoscopic approach |
43 patients (31 x single-segment, 11 x two-segment, 1 x three-segment decompression) |
EasyGO! system was easy to handle in all procedures 95% improved or had no further pain No dural tear or nerve root injury, but one reoperation due to postoperative haematoma |
|
Martín-Láez (Jun 2012) |
To compare EasyGO!-assisted microendoscopic discectomy to conventional microsurgical discectomy |
37 patients in EasyGO! group vs. 101 patients in conventional group |
Learning curve for EasyGO!-assisted surgery overcome after 30th case Average hospital stay in EasyGO! group 2.4 days vs. 3.4 days in conventional group Symptom relief in 90% of patients in EasyGO! group vs. 69% in conventional group Revision surgery in 0% of patients in EasyGO! group vs. 10% in conventional group |
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Previous reports on use of tubular retractors for anterior cervical spine surgery |
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Lead author (Date of publication) |
Objective |
Study population |
Reported advantages |
Reported disadvantages |
Vergara (Nov 2018) |
To present a series of minimally invasive microscope-assisted anterior cervical discectomy and fusion using Medtronic MetrX tubular retractors |
6 patients (3 x C3–4, 1 x C5–6, 2 x C5–7) |
Minimal tissue disruption Less blood loss Less post-operative pain Shorter hospital stay Better cosmetic result Protection for surrounding structures (carotid, oesophagus, laryngeal nerve) |
Increased operative time Steep learning curve Instrument handling and spatial sense difficult in very narrow space Not recommended for more than two-level surgery |
We then identified previous reports on anterior approaches to the cervical spine using tubular retractors and conventional microscopy. To our surprise, only one recent study, by Vergara et al., matched our search terms. The group described six cases of anterior cervical discectomy and fusion performed with the help of an operating microscope and the MetrX tubular retractor system (Medtronic) [3]. Though percutaneous insertion of serial dilators is a common technique, the group preferred to perform the dissection under direct microscopic view before inserting the tubular retractor. We used a similar strategy to ensure visual control and avoid neurovascular injury. Angling the retractor allows visualisation of the surrounding anatomy without enlarging the exposure. However, we agree with Vergara et al. that this technique is not suitable for surgery on more than two adjacent segments. We decided to use neuronavigation as an additional modality to increase the safety of our procedure.
The EasyGO! system can help microsurgically-trained neurosurgeons to offer the benefits of a minimally invasive approach using standard bimanual microsurgical techniques. Patients may experience better symptom relief with less intraoperative blood loss and soft tissue trauma. Lower rates of reduced muscle strength and less postoperative pain may accelerate patient recovery times and shorten hospital stays. The surgeon can choose between different trocar sizes, the largest of which allows safe bimanual manipulation and the insertion of a high-speed drill. Angling the retractor enables two-segment surgery through the same opening. Similarly, bilateral decompression can be done through a unilateral approach.
Conclusions
We believe that EasyGO! and similar tubular retractors may encourage neurosurgeons with no previous endoscopic experience to use minimally invasive techniques, although a shallow learning curve must be expected. Prospective and comparative studies are needed to demonstrate the potential long-term benefits over conventional microsurgery.
Conflicts of interest: None.
Funding: None.