One Percutaneous Portal Endoscopic Discectomy in the Treatment of Two-Level Lumbar Disc Herniations Patients with Leg Pain and Numbness

Background: Although minimally invasive has been adopted in the treatment of lumbar disc herniation, there were no studies in literature of two-level lumbar disc herniations patients with leg pain and numbness treatment by one portal percutaneous endoscopic procedures. The purpose of this study was to evaluate the ecacy of one percutaneous portal transforaminal endoscopic lumbar discectomy techniques in the treatment of two-level lumbar disc herniations patients with leg pain and numbness. Methods: A total of 98 patients of two-level lumbar disc herniations who had one portal endoscopic surgery were categorized into two groups depending on the level number of endoscopic procedures. There were 51 patients had leg pain and leg numbness (A group), and 47 patients with leg pain (B group). One portal percutaneous endoscopic discectomy procedures were performed and the clinical outcomes were recorded. Results: The entry point of two levels disc herniations is planned by parallel to the plane of the proximal disc level and target to the site of distal disc herniation. The procedures in two levels disc herniations was performed beginning at proximal level in L3/4 with L4/5 herniation and distal level in L4/5 with L5/S1. There were no nerve root injury and dural tear of cerebrospinal uid leakage complications. The postoperative disk and foramen height were no signicant difference compare to preoperative in all patients (P > 0.05), and no signicant difference between two groups (P > 0.05). The pain index and Oswestry Disability Index score were better than preoperational in all patients, and no signicant difference between two groups (P > 0.05). The central disc herniation patients had more leg numbness than lateral disc herniation patients (P < 0.01). For patients with leg pain and leg numbness, the leg numbness release in lateral disc herniation patients were better than central herniation patients, and leg numbness dismissed were 6 months post-operation in lateral herniation patients and 12 months post-operation in central herniation patients Conclusions:


Background
Lumbar disc herniation was common in adult population, and most symptomatic lumbar disc herniations can be successfully treated with conservative therapy. When conservative management fails, discectomy have been shown to result in good outcomes [1][2][3][4][5][6]. With the development of minimally invasive methods in spine surgery, a number of techniques have recently been developed that are applicable in the treatment of lumbar disc herniation [7,8]. The current trend of evolution in lumbar spinal surgery has been toward endoscopic discectomy, which is a minimally invasive treatments aimed at removing nuclear material and decompression the nerve through the devices were inserted into intervertebral discs by percutaneous [9][10][11]6]. Endoscopic lumbar discectomy has become attractive procedures for patients because it not only doesn't damage the spinal structures with less trauma and faster recovery but also safe procedures with local anesthesia [12][13][14][15]. For multilevel disc herniation case with monoradicular symptom, selective endoscopy discectomy that only deals with the responsible level can relieve symptom with minimal injury [12,16,3,10]. However, there are some multilevel disc herniation patients with more than one radicular symptom, and the multiple responsible level was con rmation on clinical symptom and radiological data. Then, percutaneous transforaminal endoscopic lumbar discectomy technique has evolved in treating multilevel disc herniation [17,2,18,19].
Endoscopic discectomy in multilevel lumbar disc herniation has become attractive procedures for patients due to its advantages of less trauma and local anesthesia [12,[20][21][22]15]. Endoscopic discectomy may sometimes be challenging be performed successfully in patients with multilevel disc herniation because of the prolonged operative times and increased manipulation of the neural elements may cause postoperative complications. In one percutaneous portal discectomy treatment two-level disc herniation techniques, the trajectory from the enter point to two target was planned, and the working channel been precisely placed into the spinal canal for discectomy [13,19,23,24]. The most common lower extremity symptoms of multilevel disc herniation is pain, but often accompanied by numbness, tingling, and sometimes a burning sensation. Multilevel lumbar disc herniation patients, pain and numbness of the lower extremities are the most typical symptoms, which disturbed walking ability and limit their activity of daily living. After discectomy and nerve decompression, the tingling and burning sensation often released with the pain. However, the numbness always present and don't disappear with these accompanying symptoms [25][26][27].
With the minimally invasive surgery development, more and more patients take the endoscopic discectomy surgery for its minimally injury and fast recovery. However, the residual leg numbness not relieved by the minimally invasive procedures [28,27]. For multilevel lumbar disc herniation patients, pain and numbness are the most typical symptoms, which disturbed walking ability and limit their activity of daily living. After operation, residual leg numbness following endoscopic lumbar discectomy can lower patient satisfaction, which led to patients usually complain of leg numbness during or just after walking or standing [26,29]. The presence of residual leg numbness symptoms was a problem in clinical practice.
The purpose of this study was to evaluate the clinical outcomes and e cacy of one percutaneous portal transforaminal endoscopic lumbar discectomy in the treatment of two-level lumbar disc herniation with numbness.

Methods
From February 2016 to January 2019, a total of 98 consecutive patients (42 cases were L3/4 with L4/5 level and 56 cases were L4/5 with L5/S1 level) of two-level lumbar disc herniations had endoscopic discectomy because of leg pain with or without leg numbness. The inclusion criteria were two responsible level lumbar disc herniations at L3/4 with L4/5 levels and L4/5 with L5/S1 that was con rmed by two root clinical symptom involved and magnetic resonance imaging (MRI). Exclusion criteria included one responsible level with monoradicular symptom, and pathologic conditions of the lumbar spine (trauma, tumor, or infection). According to the symptoms of leg numbness, ninety eight patients were belong to two groups, 51 patients had leg pain and leg numbness (A group), and 47 patients with leg pain (B group).
All patients had single portal endoscopic discectomy for two-level disc herniation, and 12 patients were lost to follow-up (7 cases in A group and 5 patients in B group). Of the remaining 86 patients available for analysis, 44 patients had leg pain and leg numbness (A group, 20 cases was L3/4 and L4/5 levels and 24 cases was L4/5 and L5/S1 levels, included 23 men and 21 women with an average age of 42.73 ± 6.48 years), and 42 patients with leg pain (B group, 19 cases was L3/4 and L4/5 levels and 23 cases was L4/5 and L5/S1 levels, included 22 men and 20 women with an average age of 43.16 ± 5.39 years). The pain history were 11.75 ± 2.39 months in A group patient, and 11.38 ± 3.47 months in B group (P > 0.05). There was no signi cant difference between two groups in age, and gender distribution (

Surgical procedures
With the patient prone on a radiolucent operating table, the entry point of two levels disc herniations is planned by preoperative imaging according the proximal level, and the route of the working cannulas that from the entry point to the target was planned and marked on the skin (Fig. 1,2). If the iliac crest was higher than L4/5 disc level in L4/5 with L5/S1 patient, the approach line was forming the iliac highest point to the L4/5 level. The procedures in two levels disc herniations was performed beginning at proximal level in L3/4 with L4/5 herniation and distal level in L4/5 with L5/S1. After the rst level herniated disc fragment was removed and nerve decompression was completed, the next levels procedures was performed. The transforaminal endoscopic discectomy was performed as the previous reported [30,31].
Since the surgery is done under local anesthesia, the surgeon has complete communication with the patient in procedures, by checking the movements of the affected limb and patient complaining sudden and severe radicular pain during the procedure. Foraminoplasty was performed when disc herniation at L5/S1 level, which removed small portions of anterolateral bone of facet articulation and its attached ligamentum avum without interrupting the facet joint space, provided enough working space [32,33].
Finally, the endoscope and working cannula are removed from the patient, and the wound is closed with a single skin suture.

Critical of clinical outcomes
Before surgery and at the one-year follow-up, operation times, blood loss, hospital stays, pain (Visual Analog Scale, VAS) and functional disability (Oswestry Disability Index, ODI) were quanti ed in follow-up.
All patients had preoperative and post-operative plain radiographs, computed tomography (CT) scans, and MR images. The focus was to evaluate height of disk space and intervertebral foramen.

Statistical analysis
All measurements were performed by a single observer and are expressed as means ± SD. Using the SPSS 17.0 statistics software, classic t-test and chi-square test were performed. Between-group comparisons should be performed using unpaired t-tests and chi-square tests, while within-group comparisons (preoperative vs. postoperative) should be performed using paired t-tests. The threshold for statistical signi cance used in this study was p < 0.05.

Results
The one percutaneous portal endoscopic discectomy for two-level lumbar disc herniation was performed in all cases. The approach from one entry point to two lumbar disc levels is planned and marked on the skin which parallel to the proximal and trajectory to the distal level. The endoscopic procedures were performed beginning at proximal level in L3/4 with L4/5 herniation and distal level in L4/5 with L5/S1 case. The procedure was performed successfully in all case, and no complication of nerve root injury and dural tear of cerebrospinal uid leakage in this series cases.
In ends 86 cases had follow-up at least one year and 12 cases lost, and the follow-up rate was 86.3% (44/51) in A, and 89.4% (42/47) in B (P > 0.05). The followed time was from 12 to 16 months (average 13 months), and average 13.16 ± 1.57 months on A group, and 13.24 ± 1.73 months on B patients (P > 0.05). There were no patients suffered from any symptoms caused by recurrent herniated discs after 12 months of follow-up.  There was no signi cant difference between two groups on the average change of VAS-pain (P > 0.05).
VAS-pain improved from 7.24 ± 1.25 to 1.12 ± 0.47 in A group patient (P < 0.01), and from 7.75 ± 1.29 to 1.48 ± 0.36 in B groups (P < 0.01). For patients with leg pain and leg numbness, the leg pain discharged postoperatively (P < 0.01), and leg numbness were last three to six months of post-operation. The residual leg numbness patients' data shown in Table 4. The lumbar disc herniation locations were difference between two groups (Table 1), and the central disc herniation patients had more leg numbness than lateral disc herniation patients (P < 0.01). Patients with leg pain and leg numbness pre-operation complain of leg numbness during or just after walking or standing not diminished after surgery. Among these patients, the leg numbness release in lateral disc herniation patients were better than central herniation patients, and leg numbness dismissed were 6 months post-operation in lateral herniation patients and 12 months post-operation in central herniation patients (P < 0.01).

Discussion
Lumbar disc herniation in adults is characterized by the pain of leg with or without leg numbness due to disk degeneration, which involves a multitude of cellular and biochemical changes [34,16,13]. When conservative management fails, discectomy was safe and effective surgery. With the minimally invasive techniques development, endoscopic discectomy was become popular for its advantages of small incision and faster recovery [11,20,24]. When patients with two responsible levels disc herniation need surgery treatment, patients always want the surgery was minimally [19,14,4]. At the present study, the percutaneous transforaminal endoscopic discectomy was performed from one percutaneous portal. The pain index and ODI scores were signi cantly better the preoperative in all patients, and no nerve injury and dural tears complication. The results of this series cases were accordance with the previous reported, which show the percutaneous transforaminal endoscopy discectomy to be safe and its complication rate is low. Then, two-level endoscopic discectomy can be successfully performed by one percutaneous portal.
Percutaneous transforaminal endoscopic lumbar discectomy has proven to be a faster and safe practical approach for treating lumbar disc prolapse [34,35,3,21,22]. Ideally, the most direct and safest approach towards the pathology of two-level herniated fragments should be utilized in one portal transforaminal endoscopic discectomy [13,18,23,1,35,36]. The transforaminal approach was reported to be hard to conduct at the level of L5/S1, because iliac crest may bother the cannula installation through the intervertebral foramen especially for the high iliac cases [37,22,19,10]. From the trajectory of skin entry point approaching the foramen, identi cation of anatomical landmarks will help to follow plan the route and avoid complications of surgery [37,21,14,3]. In this series cases, using the transforaminal routes depending on the characteristics of each level, accuracy of approach has huge bearing on the success of two-level endoscopic discectomy from one portal.
Endoscopic lumbar discectomy has evolved into not only suitable for one level disc herniation, but also to multiple level disc herniation [2,13,18,15]. For patients with leg pain and leg numbness, the leg pain discharged postoperatively, and leg numbness were last three to six months of post-operation. Patients with leg pain and leg numbness pre-operation complain of leg numbness during or just after walking or standing not diminished after surgery. Symptoms of numbness was result in regional nerve and cord ischemia which been compression by pathology tissue [27,38]. Long term of ischemia leads to an imbalance between nerve metabolic demand and oxygen supply and the nerve tissue damage.
In ammatory responses are known as a major component of secondary injury of initial ischemic insult and play an important role in modulating the pathogenesis of leg numbness [26,25]. The leg numbness symptoms were last longer in central disc herniation patients than in paracentral and foraminal disc herniation patients after surgery, which means the in ammatory response from herniated herniate disc fragments compression nerve may be an important factor in affection on it.
Percutaneous one portal endoscopic transforaminal discectomy technique is ideally suited for unilateral disc herniation with leg pain and numbness [23,24,10]. The most direct and safest approach towards the pathology should be utilized in one portal treatment two-level herniation. Although patients with leg pain and leg numbness pre-operation complain of leg numbness during or just after walking or standing not diminished after surgery, the leg numbness dismissed were 6 months post-operation in lateral herniation patients and 12 months post-operation in central herniation patients. Then, percutaneous one portal transforaminal endoscopic lumbar discectomy is the preferred minimally invasive approach in two-level disc herniation case due to less trauma, less blood lost, and short operation time, and faster recover [25].

Conclusions
Although two-level disc herniation present a signi cant challenge for spinal surgeon when adopted single portal techniques of endoscopic discectomy, one percutaneous portal transforaminal endoscopic lumbar discectomy was safe and minimally invasive techniques with faster recovery. For patients with leg pain and leg numbness, the central disc herniation patients had more leg numbness than lateral disc herniation patients, and the leg numbness release in lateral disc herniation patients were better than central herniation patients. Availability of data and materials The datasets are available under reasonable request, please contact Yan.

Competing interests
All authors declare that they have no con ict of interests.

Funding
Not applicable of funding on this work.

Authors' Contributions
DLY participated in the design of the study, performance the surgery, and drafted the manuscript. ZZH helped to draft the manuscript and performed the statistical analysis. ZZ participated in the design of the study and coordination. All authors have read and approved the manuscript.  Male patient of 41 years had two level disc herniations at L4/5 and L5/S1 with leg pain and leg numbness underwent the procedures of one portal endoscopic discectomy. A, L4/5 and L5/S1 disc herniation on MRI; B, procedures rote was marked on the skin; C, image of foraminoplasty was performed at L5/S1 level; D, image of needle was inserted the L4/5 level from transforaminal; E, Single percutaneous portal for two level discectomies was shown after procedures.