Indian Journal of Pain

REVIEW ARTICLE
Year
: 2018  |  Volume : 32  |  Issue : 3  |  Page : 125--131

Full-endoscopic lumbar discectomy for high canal compromised disc at upper lumbar level: A technical review


Manish Raj1, Kailash Kothari2, Anurag Agarwal3, Hyeun Sung Kim4, Pankaj Surange5, Kapil Tyagi6, Prashant Punia7, Palea Ovideu8,  
1 Department of Interventional Spine and Pain, Yatharth Hospital, Noida, Uttar Pradesh, India
2 Department of Interventional Spine and Pain, Pain Clinic of India, Mumbai, Maharashtra, India
3 Department of Anesthesiology and Pain Medicine, Dr. RML Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
4 Department of Neurosurgery, Nanoori Hospital, Seoul, South Korea
5 Department of Interventional Spine and Pain, IPSC, Delhi, India
6 Department of Orthopedic Surgery, Yatharth Hospital, Noida, Uttar Pradesh, India
7 Department of Neurosurgery, Dr. D. Y. Patil Medical College, Pune, Maharashtra, India
8 Department of Interventional Spine, Centrul Provita Hospital, Bucharest, Romania

Correspondence Address:
Dr. Manish Raj
Department of Interventional Spine and Pain Medicine, Yatharth Super-Speciality Hospital, Sector 110, Noida, Uttar Pradesh
India

Abstract

Objective: In this study, we have described the technique to overcome difficulty faced during trans-foraminal endoscopic discectomy for the treatment of lumbar radiculopathy in patients who have herniated discs at the upper lumbar level & thoracolumbar junction. Method: After institutional review board approval, A retrospective analysis of 27 patients operated between March 2013- September 2017, by a single specialist for disc herniation at upper lumbar levels D12-L1, L1-2, L2-3 with or without high canal compromise by outside in technique (using rigid endoscope, sequential reamers) along with detailed description of our technique is the focus of this study. Results: Out of 27 patients there were 11 cases for L1-2 & 16 cases of L2-3 disc herniation respectively. There were 21 cases of broad-based, high canal compromised disc herniation with significant neurological deficit & only 6 cases were of focal herniation type. The average preoperative VAS score of 8.5 (range 6-10) reduced to 4 (range 2-7) immediate postoperatively & it further reduced to 2 (range 0-4) at one month follow up. The average preoperative ODI score of 65 (range 28- 88) reduced to 27 (range 12-40) immediate postoperatively & it further reduced to 10 (range 3- 18) at one month follow up. Post-operative MRI showed that the ruptured disc had been successfully removed. Conclusion: An anatomically modified surgical technique promote a more successful outcome after percutaneous endoscopic discectomy for upper lumbar disc herniation. Foraminotomy is recommended for all intra-canalicular herniation. Transforaminal endoscopic discectomy and foraminotomy can be used as a safe yet minimally invasive technique for the treatment of lumbar radiculopathy in the setting of an upper lumbar disc herniation.



How to cite this article:
Raj M, Kothari K, Agarwal A, Kim HS, Surange P, Tyagi K, Punia P, Ovideu P. Full-endoscopic lumbar discectomy for high canal compromised disc at upper lumbar level: A technical review.Indian J Pain 2018;32:125-131


How to cite this URL:
Raj M, Kothari K, Agarwal A, Kim HS, Surange P, Tyagi K, Punia P, Ovideu P. Full-endoscopic lumbar discectomy for high canal compromised disc at upper lumbar level: A technical review. Indian J Pain [serial online] 2018 [cited 2019 Jan 17 ];32:125-131
Available from: http://www.indianjpain.org/text.asp?2018/32/3/125/249106


Full Text

 Introduction



Since the introduction of the concept of percutaneous posterolateral nucleotomy by Kambin in the year 1973, the technique of percutaneous endoscopic transforaminal lumbar discectomy (PETLD) has evolved over the years and is increasingly becoming a preferred choice of treatment for the management of lumbar disc herniation.[1] PETLD, by virtue of its transforaminal approach, offers several advantages over open methods such as protection of posterior ligamentous and bony structures, lesser postoperative instability, facet arthropathy, and disc space narrowing.[2],[3] Lumbar disc herniation generally was observed at lower lumbar levels of L4– L5 and L5–S1, but it may also occur at upper lumbar levels 1%–2% of total disc herniation, which is more of traumatic in origin than degeneration.[4],[5],[6],[7]

Surgery at upper lumbar levels is complicated by not only the presence of spinal cord but also restricted by the presence of retroperitoneal structures in the trajectory of instrumentation.[8],[9] Protection of vital retroperitoneal structures causes the entry point of the needle to shift more medially to midline, which hampers working with intracanal herniation. In such cases, it is difficult to reach the base of herniation by inside-out transforaminal endoscopic decompression technique or to place working sheath closer to herniation by outside-in transforaminal endoscopic decompression technique. Both the techniques are limited by steep angle and medial entry point, leading to less shallow trajectory near the annulus or anterior epidural space. Difficulty in proper instrument placement causes inadequate fragmentectomy.

We would like to describe a technique where we can reach closer to all types of intracanal herniation, perform adequate herniectomy even for the disc which is obstructing central spinal canal by more than 75%, also known as high canal compromised disc, yet avoid injury to the retroperitoneal structure.

 Materials and Methods



A retrospective analysis of 27 patients which were operated between March 2013 and September 2017, by a single specialist for disc herniation at upper lumbar levels L1– L2 and L2– L3 with or without high canal compromise by outside in technique using rigid endoscope (Richard Wolf, Germany), sequential reamers (Maxmore Spine, Germany) along with a detailed description of our planning and technique is the focus of this study.

Patients were selected as per the following criteria:

Acute low back pain with or without radiation to legsPositive nerve root tension (femoral nerve)Corresponding intracanal focal or broad-based soft disc herniation on computed tomography/magnetic resonance imaging (MRI), causing significant neural compressionLumbar canal stenosis with the only involvement of disc.

Patients were excluded who had:

Extracanal herniationCalcified discPresence of motion segment instabilityInfective pathology in the spine.

Preoperative assessment of all patients was done with visual analog scale (VAS), and functional assessment was done by the Oswestry Disability Index (ODI). Patients were examined for nerve root impingement and neurological deficit. All other causes of pain such as facet arthropathy, vertebral compression fracture, and myofascial spasm were ruled out.

Routine X-ray lumbar spine in anteroposterior (AP) view and MRI were done to assess the nature of pathology, along with anatomical structure in the pathway of trajectory [Figure 1], [Figure 2], [Figure 3]. X-ray lumbar spine was also done in lateral flexion and extension view assessing the foraminal size for entry into the spinal canal. Immediate postoperative MRI was done to ensure adequate disc decompression. VAS, ODI, and neurological examination were repeated immediately in the postoperative period and at follow-ups, at 4 and 6 weeks, and subsequently if required.{Figure 1}{Figure 2}{Figure 3}

 Radio Mapping



Preoperatively, we did radio mapping, which is drawing disc fragments on X-ray antero-posterior/lateral view and instrument projection on axial, coronal, and sagittal MRI. This mapping technique is very helpful since we have the only two-dimensional fluoroscopic image and endoscopic view which is inadequate to show depth and direction of instruments in one plane. It is always better to know trajectory for safety, as a small diversion from the path can lead to the complete change in endoscopic anatomy and also increases the risk profile of procedure such as transient paresthesia, hematoma, retroperitoneal puncture, dural tear and unnecessary facetectomy in some case. For mapping, the following steps are taken.

We need to draw disc fragments from the coronal section of MRI on X-ray of AP view of the spine; this drawing will help to locate the direction and reach of instruments in fluoroscopic view intraoperatively [Figure 4].{Figure 4}

Drawing herniated disc orientation from sagittal section of MRI to lateral X-ray will help us depth assessment and direction of instrumentation. This will restrict any diversion from intended trajectory, and if diversion occurs, we can come back to the preplanned trajectory. Lateral X-ray mapping also helps in assessment of foraminal window, i.e., from the superior articular process to the posterior vertebral line. If the foraminal window is narrow or facet is covering the extruded fragment, extent of foraminotomy can be planned preoperatively with focus on keeping the joint integrity intact for proper sleeve placement and adequate decompression [Figure 5].{Figure 5}

Few additional steps in radio mapping are given.

Close analysis of axial view MRI will help determine safe entry point. We are able to measure exact entry point from the midline, sufficient for decompression of intracanalicular disc, yet causing no injury to retroperitoneal structure such as kidney for upper lumbar herniations.

Structural analysis of the pathway from the entry on the skin to landing point at Kambin's triangle on axial and coronal MRI helps in avoiding injury to dorsal root ganglion. This analysis is more important for lower lumbar level herniation, where dorsal root ganglion is prominent in the foraminal region.

 Surgical Technique



PETLD patients received preoperative intravenous antibiotic injection cephazolin 1–2 g IV 60 min before the procedure, and the following intraoperative protocols were observed:

Positioning and skin markingSkin incision and anesthesiaNeedle insertion and evocative chromodiscographyForaminoplasty with sequential reamersWorking channel insertionDecompressive discectomyRepositioning of the cannula and removal of pathological discConfirmation of the free exiting root or traversing rootHemostasisSkin closure.

All patients were placed in prone position on a radiolucent table. The operative area was cleaned and draped.

Skin marking was done with the preoperative radio-mapping knowledge of the safest lateral starting point. The skin and subcutaneous tissues till facet mass were infiltrated with 2% lignocaine. The whole procedure was performed with conscious sedation using midazolam 1–2 mg and fentanyl 50–200 mcg.

An 18-gauge long spinal needle was introduced under fluoroscopic control up to the lateral border of the facet joint in AP view and checked its position in the lateral fluoroscopic view. The needle was manipulated further to reach the mid-pedicular line in AP view and posterior vertebral line in lateral view. This area corresponds to Kambin's triangle, where exiting and traversing root bifurcates posterior to the annulus.

At this site, a patient received transforaminal lateral recess block with 7 ml 2% lignocaine in 15 ml 0.9% normal saline to block only C- and A-delta fiber, and the procedure was proceeded with continuous feedback from the patient.

Evocative discography was performed with a solution (methylene blue 3 + 3 ml of radiopaque dye [Omnipaque 300] +4 ml of normal saline) after putting needle further inside the disc.

A guidewire 0.8-mm was inserted, and the needle was removed. On guidewire, 4-mm Tom Shidi needle (Maxmore Spine, Germany) was inserted to reach closer to herniation under fluoroscopic control [Figure 6].{Figure 6}

TOM Shidi needle was replaced by a guidewire and through guidewire sequential reaming done with 4-, 6-, 8-, and 9-mm reamer, respectively. Reamers were replaced by dilator and dilator by working sheath.

After fat clearance, annular fenestration done with dissector and thru-cut punch and decompressive discectomy was performed till contralateral medial pedicular line. After initial fenestration, working sheath repositioned posteriorly. Annulectomy was done to reach the base of herniation. The entire procedure was carried out like routine outside in technique of transforaminal endoscopic discectomy with no significant harm to disc architecture.[10]

Disc fragments were removed either in one go or through multiple fragmentectomy.[11],[12] Hemostasis was achieved by the curved radiofrequency probe, which was also used as a probe for the search for hidden fragments. The amount of removed fragment was consistent with the preoperative assessment of MRI, or further search was continued for the remaining fragment. After removal of all fragments, free exiting and traversing root was observed to have a pulsatile dural sleeve. Patients were immediately assessed for postoperative MRI for adequate decompression [Figure 7], [Figure 8], [Figure 9].{Figure 7}{Figure 8}{Figure 9}

 Results



Out of 27 patients, 18 were female and 9 were male with an average age of 41 years (range: 25–63 years). There were 11 cases for L1–L2 and 16 cases of L2–L3 disc herniation, respectively. There were 21 cases of broad-based, high canal compromised disc herniation with significant neurological deficit, and only 6 cases were of focal herniation type.

The average preoperative VAS score of 8.5 (range: 6–10) reduced to 4 (range: 2–7) immediate postoperatively, and it further reduced to 2 (range: 0–4) at 1-month follow-up.

The average preoperative ODI score of 65 (range: 28–88) reduced to 27 (range 12–40) immediate postoperatively, and it further reduced to 10 (range: 3–18) at 1-month follow-up.

Postoperative MRI showed that the ruptured disc had been successfully removed [Figure 7], [Figure 8], [Figure 9].

One patient underwent a repeat PETLD procedure next day, due to inadequate decompression, and one patient had inadequate pain relief despite adequate decompression on MRI and went for transforaminal nerve root steroid injection after 4 weeks, which gave him adequate relief. There were no complications such as hematoma or infection although two patients had transient paresthesia, despite using floating retraction technique which recovered on conservative management by 4–6 weeks.[13] No other surgical procedure required in any other patients [Table 1].{Table 1}

 Discussion



Despite the excellent application of transforaminal endoscopic disc decompression at lower lumbar levels, its application for high canal compromised and migrated discs is not ideal at upper lumbar levels and thoracolumbar junction.[14] This limitation to reach the base of herniation is due to anatomical factors such as proximity of retroperitoneal structures, spinal canal diameter, and the proximity of ribs, short and decreased angle of exiting nerve root when compared with lower lumbar level.[6],[7] Several studies have also demonstrated reduced interpedicular distance at the upper lumbar level (20–22 mm approximately) compared to lower lumbar levels (28–30 mm).[5]

For transforaminal approach targeting at lower lumbar levels, the usual target is the medial pedicle wall on AP fluoroscopy. This targeting would have the endoscope enter the thecal sac at T12–L1. Hence, the needle trajectory is planned to enter the disc space at the mid-pedicle line, to get as close as possible to the herniation impinging the neural structures without directly contacting them at upper lumbar levels.[9]

The most difficult part is the limitation of far-lateral entry point due to the presence of kidney, which forces entry point to be more medial (7–9 mm), and this leads to inappropriate placement of the needle, far from base of herniation. The working sheath was placed at a steeper angle in the sagittal plane and intention of placing sleeve medially leads to anterior placement inside the disc. Placing sleeve for huge high canal compromised cases becomes difficult since adequate decompression cannot be achieved if sleeve placement is not precise.[12] To overcome this problem, we use radio-mapping where trajectory angle is measured medial to the retroperitoneal structure [Figure 10] and [Figure 11].{Figure 10}{Figure 11}

The author would like to show the failure of routine endoscopic approach in a patient, causing the sleeve to move more anterior when the intention was to place it more medial. Post-failure of decompression, the entry point was measured on axial MRI bypassing anterior facet. This bypassing, unlike lower lumbar level, is insufficient to reach the base of herniation [Figure 10]. An optimal trajectory is chosen where the needle can be placed close to herniation. Drawing such trajectory leads to crossing it through the anterior facet [Figure 11]. Hence, we proposed to do foraminotomy before placement of the sleeve for all high canal compromised and migrated disc at upper lumbar levels.[13],[15] This small resection of the superior articular process can easily place the sleeve close to herniation, yet maintaining the structural integrity of the facet joint, hence avoiding any instability in future [Figure 12]. We proceeded with foraminotomy and placed the sleeve in close proximity of the herniated fragment. Following outside in intervertebral approach, adequate decompression achieved.[10] Rest of the procedures were identical to lower lumbar disc endoscopic decompression.{Figure 12}

Limited papers have been published addressing the upper lumbar level disc herniation with percutaneous endoscopic disc decompression.[9],[16],[17]

Telfeian et al. have demonstrated successful use of transforaminal endoscopic discectomy for upper lumbar herniation, where articular resection avoided in compared to open spine surgery and adequate decompression achieved with the use of semi-bendable graspers postforaminoplasty.[9]

Ahn et al. showed that patient selection and an anatomically modified surgical technique promote a more successful outcome after percutaneous endoscopic discectomy for upper lumbar disc herniation.[8]

Some authors have shown the use of interlaminar approach for removal of the extruded fragment by doing partial laminectomy without getting close to the joint for the passage of instruments. This technique seems to be promising for upper lumbar levels, but the use of trephine blindly for laminectomy requires further assessment along with long-term outcome.[17]

Many studies have shown the effectiveness of endoscopic spine surgery treating multiple pathologies in the lumbar spine including lateral, paracentral, central, extruded, and even contralateral herniated discs, as well as lateral recess stenosis and conversion to conventional open spine surgery for upper lumbar level, may well be question of past, just like lower lumbar levels.[8],[10],[14],[15],[18]

 Conclusion



An anatomically modified surgical technique promotes a more successful outcome after percutaneous endoscopic discectomy for upper lumbar disc herniation. Foraminotomy postradio templating is recommended for all intracanalicular herniation. Transforaminal endoscopic discectomy and foraminotomy can be used as a safe yet minimally invasive technique for the treatment of lumbar radiculopathy in the setting of upper lumbar disc herniation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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