Treatment of spine surgeries has evolved from traditional surgeries to open surgeries. Endoscopic spine surgeries (ESS) and endoscope assisted surgeries along with microscopic and tubular surgeries has developed significantly over the last three decades. With improvement in the diagnostic methods it is now possible to find and differentiate the spinal pathologies. ESS was initially limited to the lumbar disc herniations (DH). But, now it can be used for cervical and thoracic DH. Minimized technical problems has been brought by evolutions in endoscopy, better optics, instruments, access, and safety. Similarly acquired knowledge and skills are being extrapolated to advanced indications in different spinal pathologies. Due to the further advantages of ESS within the ambit of minimal invasive spine surgeries, many misnomers are as well getting added. This confuses the new learners and potential patients as well. ESS should be classified for uniformity in reporting and common nomenclature like FESS (Full endoscopic spine surgery) should be used. It specifically refers to surgery through one working channel under irrigation with incorporated optics. This will make easier understanding for novice surgeons and general population. It will lead to standardised reporting of high quality clinical studies, trials, and meta-analysis for the publications. Rising misnomers and complex nomenclature of endoscopy is suggesting along with the exponential publications in last decade that ESS is entering into its golden era. This review is undertaken to throw light on the techniques, advances and literature review of only FESS and clear the misnomers. This review also describes the evolution of different techniques and goals that led to impeccable advances in the field of FESS. Further improvement of technologies and techniques in future will soon establish FESS as the Gold Standard in spine surgery.
Patients have started demanding for the least invasive procedures for all spine surgeries and its equally evident with the training desires of the novice and accomplished spine surgeons. In the last quarter of the 20th century and early 21st century, there has been an evident shift from traditional open to minimal invasive spinal surgical techniques (MIS). Endoscopic Spine surgeries (ESS) are also a spectrum of this MIS [
There are numerous reasons for this development. In general, minimal incision reduces the extent of underlying tissue disruption and blood loss. This leads to cascading events of reduced tissue dissection and trauma leading to negligible disruption of structural and functional ability of spine. This further reduces postoperative pain and incidence of complications. Moreover it increases patient confidence, cosmesis, improved clinical outcomes with quality of life, early ambulation with return to work and reduced length of hospital stay [
Initially, ESS technique was restricted to the lumbar, cervical and thoracic disc herniations (DH). But gradually it has also found use for stenosis and ESS fusion [
These improvements and advances happened on the shoulders of pioneers, and with concurrent improvements in the optics, high resolution camera, light source, cutting instruments, hand instruments, irrigation pump, navigation etc, and with better specific diagnosis and classification of the disorders [
During the initial practice, higher than normal rates of symptomatic recurrences and treatment failures should be anticipated by surgeons when incorporating ESS techniques [
The authors in this review article aim to describe the anatomical corridors, techniques for full ESS approaches to the cervical, thoracic and lumbo-sacral spine. The current full-endoscopic techniques advances to discuss the potential benefits, limitations, and future perspectives. Key relevant literature evidence respective to the techniques are also cited. These were identified from Google Scholar, PubMed and the Cochrane Library with cross-referencing of articles. Emphasis has been placed on literature published in the last ten years.
There are many misnomers or tantamount terms used in ESS. This creates a lot of confusion in the minds of beginner surgeons and patients. But, the most common and minimalistic surgical approach system in ESS is the full-endoscopic spine surgery(FESS). It is defined typically by: use of a working channel endoscope with the working channel, the optics and irrigation ingress/regress channel in the same device; complete uniportal percutaneous approach with a stab skin incision; and works with continuous saline irrigation [
Ahn’s Classification of ESS is a simple explanation of the complex nomenclature of endoscopy [
1. Full-endoscopic discectomy
a. Full-endoscopic cervical discectomy
I. Anterior endoscopic cervical discectomy (AECD)
i) Anterior endoscopic transdiscal cervical discectomy (AETdCD)
ii) Anterior endoscopic transcorporeal cervical discectomy (AETcCD)
II. Posterior endoscopic cervical discectomy (PECD)
b. Full-endoscopic thoracic discectomy
I. Transforaminal endoscopic thoracic discectomy(TETD)
II. Interlaminar endoscopic thoracic discectomy (IETD)
III. Retropleural Endoscopic transthoracic Discectomy (RETTD)
c. Full-endoscopic Lumbar discectomy
I. Transforaminal endoscopic lumbar discectomy (TELD)
i) Unilateral
ii) Bilateral
iii) Contralateral
iV) Bi-segmental
II. Interlaminar endoscopic lumbar discectomy (IELD)
III. Extraforaminal endoscopic lumbar discectomy (EELD)
2. Full-endoscopic foraminotomy
a. Posterior endoscopic cervical foraminotomy (PECF)
b. Transforaminal endoscopic lumbar foraminotomy (TELF)
c. Interlaminar contralateral endoscopic lumbar foraminotomy (ICELF)
3. Full-endoscopic lumbar lateral recess decompression
a. Transforaminal endoscopic lateral recess decompression (TE-LRD)
b. Interlaminar endoscopic lateral recess decompression (IE-LRD)
4. Full-endoscopic laminotomy for bilateral decompression
a. Cervical endoscopic unilateral laminotomy for bilateral decompression (CE-ULBD)
b. Thoracic endoscopic unilateral laminotomy for bilateral decompression (TE-ULBD)
c. Lumbar endoscopic unilateral laminotomy for bilateral decompression (LE-ULBD)
5. Full-endoscopic Ventral Decompression
a. Transforaminal endoscopic Lumbar ventral decompression (TELVD)
b. Transforaminal endoscopic thoracic ventral decompression (TETVD)
6. Full-endoscopic assisted procedures
a. Transforaminal endoscopic lumbar annulopasty (TELA)
b. Trans-sacral Epiduroscopic Lumbar Discectomy (SELD)
c. Retropharyngeal endoscopic cranio-cervical decompression (RECD)
d. Transforaminal Endoscopic Lumbar Interbody Fusion (TELIF)
Other procedures which are still not categorised but described have been discussed individually as reported. Microscopic Or Endoscope Assisted procedures are not incorporated except when FESS was used as the major component of the surgery (Type 6 of the above classification). Generation of endoscopes as evolved are used in all FESS (Rigid-Fibreoptic) and technological gadget enablers (Navigation, Laser, Burr etc) have not been individualised into category to avoid complexity.
In this review TELD is the representative index ESS which is discussed in detail. Other developments, innovations and extended applications of FESS are subsequently discussed separately and succinctly. Each procedure is discussed as a concept, its indication & contraindications, technique, technical points with regard to advanced indications/innovations, advantages disadvantages with limitations, literature review, current standard of care and foreseeing future.
The transforaminal approach refers to a posterolateral approach to the disc or epidural space through the foraminal window [
Indications & contraindications: The classical indication of this technique was soft lumbar disc herniation (LDH) of various types. With the advancement in technology and experience, its practical application has widened, to include migrated, recurrent, foraminal, extraforaminal, and even partially calcified LDH. This technique has been proven to be of significant benefit by many randomized trials, meta-analyses, and systematic reviews [
The landing point of needle insertion in radiographic view is divided into vertical lines at medial, mid and lateral pedicular lines in antero-posterior view and posterior vertebral line in the lateral view. The medial pedicular line and posterior vertebral line are commonly used reference point for most of the TELD. Representative index TELD ‘inside out’ (IO) technique will be elaborated here to discuss the classic original technique [
Surgical technique: An independent anaesthesiologist should always be present during the whole surgical procedure even if it is done under local anaesthesia (LA) and conscious sedation. GA and regional anaesthesia (RA) are also employed by many institutes. The patient is put in protected prone position on a radiolucent table and supplemental oxygen is given. Prone position is preferred by most of the surgeons due to better anatomical orientation. Though lateral position is more comfortable for patient and is also practised by many surgeons. Pre-emptive, intramuscular midazolam (0.05 mg/kg) and diclofenac can be given. Titrated infusion of dexmedetomidine (0.5-1 mcg/kg) &/or fentanyl (1 mcg/kg) of bolus followed by additional doses as needed are used.
A uniportal approach is used. A desired trajectory determination by extending a line from the target point bypassing the ventral facet to skin entry helps in planning of any transforaminal surgery on MRI axial section at upper endplate of lower vertebral level section [
Advances in TELD: There are numerous techniques with subtle modifications employed depending upon the training, type of LDH, level and location. Standard basic techniques of OI or FEE are used.
In case of settled disc space, sequential dilator is more easily positioned to avoid pain [
A FEE approach can be taken nearly at an angle of 0° landing in the epidural space avoiding the piercing of the disc and facet reaming. This is a far lateral approach. This is done for direct removal of the dislocated nucleus piece (extruded or sequestrated low migrated) in central, paracentral or low migrated or foraminal and extraforaminal location [
An endoscopic visualised burred foraminoplasty(BF) or OI approach is taken when there is a technical requirement to reach more dorsal in epidural space [
Special modification of the standard technique are needed to tackle other special situations, extra foraminal LDH and high grade up/down migrated LDH and high iliac crest for L5-S1 level [
In migrated DH the needle entry point and target point should be caudo-cranial for up migrated disc herniation and cranio-caudal for down migrated DH. This is done after the primary “IO” technique. After completion of the sub-annular decompression the endoscope is angulated towards the migrating fragment. The half-and-half transforaminal technique for near migrated DHs, is based on annular release and leveraging of the working sheath [
In L5-S1 LDH, TELD is a demanding procedure due to iliac crest, L5 transverse process, hypertrophic facet joint, smaller foramen and sacral ala. The major landmark in preoperative planning should be the height of the iliac crest with reference to the L5 pedicle [
Calcified disc stenosis is also amenable by TELD [
TELD has been used in spondylodiscitis and postoperative spondylodiscitis effectively the last two decades [
Bipolar cold coagulation/radiofrequency helps in evaporating soft culprits and Ho-YAG laser can ablate hard tissue also and expedite surgery, Endoscopic epidural visualization and using lasers to vaporize the disc fragments was popularised in 1990’s [
The most common pathology of the degenerative stenosis is hypertrophy of the SAP, LF hypertrophy, disc space settling (annulus buckling) with or without LDH, osteophyte formation and associated dynamic or static instability [
The TELD approach seems to give good results for the treatment of LSS also. But, this approach may be less effective for LSS patients who have lumbar instability or require revision surgery in the same segment. The time tested lumbar fusion surgery with decompression has a high fusion rate, but with obvious great damage to the muscles and facet joints in open surgery. Although this collateral damage is less in MIS fusion, but it still exists. With mechanical stress on above or below disc, adjacent segment degeneration may occur [
The transforaminal endoscopic approach can be suitable for the treatment of the lateral recess/foraminal stenosis by resection of the hypertrophied SAP [
Technique: Like for LDH, in the same way needle positioning followed by docking the working cannula is done but usually within the foramen on the facet and not in the intradiscal space. Typically, a foraminoplasty approach is undertaken. This is done under 15-20 ml of more LA agent. The docking is done in the lower foramen at the caudal surface of the SAP and supra-pedicular notch. The tip of the SAP is removed by bone trephines or reamers. It is done blindly under fluoroscopic control with medial pedicle line as the limit and the give away feeling suggests the completeness of bony resection. It though appears risky and doubtful for non-believers and early novice endoscopy surgeons, but there is a soft curtain of capsule and LF still intervening between the advancing sharp reamer and the traversing root. Visualised endoscopic burred foraminoplasty can also be done, which is apparently safe. But with burred foraminoplasty alone, it takes more time and traversing root neuropraxia can occur. Best use is using trephine followed by fine burr usage. After sufficient removal of the bone, the exposed LF and capsule are removed by dissectors, cutters, micro-punches and forceps. For foraminal stenosis the focus is in the cranial foramen and removal of the tip of SAP, capsule and LF. Visualisation of the pulsatile exiting nerve root is the end point of decompression. For the lateral recess stenosis, the caudal foramen is focussed, and additional adjoining pedicle removal is needed many times in addition to SAP, IAP, LF and capsule. Visualisation of the entire pulsatile traversing root on ventral, lateral and dorsal aspect confirms adequacy of decompression. This is lateral and dorsal decompression. For central stenosis ventral decompression by removal of the LDH, buckling annulus (which is usually hardened or calcified) and removal of the superior vertebral end plate spur of the inferior vertebra is done with use of burr, endoscopic osteotomes and curettes. Visualisation of the entire pulsatile traversing root and central dura affirms the adequacy of decompression. For bilateral symptomatic cases further flattening of the endoscope trajectory and ventral decompression of contralateral traversing root and visualisation is to be done.
Successful clinical outcomes with full-endoscopic surgery for the specified indications have been reported for LSS [
The axilla between the traversing and exiting nerve is the location of the missed patho-anatomy in patients with lateral recess stenosis and hides the pain generators. The complete decompression of this “hidden zone” of pathology obviates the symptoms and is another recommendation [
TELIF surgeries when indicated for instability and backache can be executed under local or regional or general anaesthesia. This is done after adequate decompression surgery or solely relies on indirect decompression with restoration of disc height without decompression. Long-term results with fusion surgery are awaited though it looks highly promising in the initial reports [
Complications & limitations: The cost of the instruments and procedure are significant. The radiation exposure associated with TELD is more than other minimally invasive techniques. Although the procedure has good efficacy, complications may occur which are infrequent as well as unique at times. The complications can be classified as per-operative (local and systemic) and delayed (early and late). Injury to exiting nerve root, traversing root or central rootlets, dural tears, vascular injury (major vessels or segmental twig in the foramen), peritoneal content injuries, missed/residual fragments, pedicle/facet injury, instrument related complications, wrong level surgery, seizures, posterior neck pain are per-operative complications that are reported [
The interlaminar (IL) approach or IELD was proposed after TF technique to overcome its apparent limitations and early contraindications. Initially, for the treatment of LDH at the L5-S1 level. This further contributed to expand the indications of ESS, especially in treating spinal stenosis of all regions. The IL approach for lumbar discectomy was being done with the aid of microscope [
Indications & Contraindication: LDH (paracentral or foraminal) from L2-S1 level, calcified LDH, upward or downward migrated LDH, LSS without significant instability, central canal stenosis, LF hypertrophy, lateral recess stenosis, foraminal stenosis, synovial cysts and hypertrophic facet. Except general surgical contraindications, there are none specific to the procedure.
Technique: Local anaesthesia can be used but regional or GA is preferred. It is done with the patient in prone position under radiological control. The image intensifier is set into Fergusson’s view. The interlaminar window is marked in AP view and a skin incision of 5 mm is made in the cranio-caudal middle of the IL window as much medial as possible. A dilator of 6 mm outer diameter (without any needle, as against the initial pioneering technique), is inserted bluntly to the lateral edge of the IL window. Over this, a beveled working sheath of 7 mm outer diameter is inserted by railroading. The bevel opening is directed medially toward the LF. Endoscope assembly is inserted, and the further procedure is performed under vision with constant irrigation. A cutter is used to make lateral incision in the LF, which is enlarged usually around to 5 mm. Epidural space with the neural structures and the epidural fat tissue is exposed. The LF splitting technique may cause transient weakness. Moreover, the blind spot may limit visualization resulting in residual fragments. The beveled working sheath is used as a second instrument and rotated to work like a nerve hook [
Complications and limitations: Surgeons usually attempt more aggressive discectomies to try to reduce the incidence of recurrences. This approach might cause more post-operative accelerated severe degeneration and back pain [
Advances: The mobility of IELD provides broad indications in dealing with all kinds of patho-anatomies and various kinds of stenoses equivalent to or more than MLD. With overhanging lamina, laminotomy to widen the interlaminar window can be done. Different sizes of endoscope to reach far-migrated disc fragments is possible. IELD/IE-LRD/ICELF has focused on degenerative lumbar pathologies. It is continuously evolving and getting standardized. If exiting root is to be decompressed, the ICELF is feasible to perform SAP tip removal and the lateral half of the foraminal LDH or far-lateral LDH removal can be accomplished. Stenoscopic decompression of the central and lateral recess spinal stenosis over the top (over the top decompression) and removal of any type of LDH simultaneously is possible (
Thoracic disc herniation(TDH) is an uncommon entity although frequently disabling when symptomatic. Its treatment has been approached classically by open circumferential approaches [
Trans-facetal pedicle sparing approach & transpedicular approach although sparingly are reported [
Indications and contraindications: The major reported use of FESS in thoracic spine is limited to indications pertaining to soft TDH in paracentral and lateral locations. The sporadic indications have now started to include thoracic spinal stenosis (TSS) due to central LDH, calcified LDH, OLF and ossified posterior longitudinal ligaments (OPLL). It is worthwhile to note that these extended indications once formed contraindications to endoscopy. Generally, patients with profound neurological deficits due to significant myelopathy, history of previous spine surgery and multi-level involvement are few contraindications for this type of surgery [
Techniques with Advantages and Limitations: The techniques of FESS in thoracic spine depends on the pathology type and location. Thus, it depends directly on the type of approach used for accessing the pathology (
Transforaminal endoscopic thoracic discectomy (TETD) was first described by Choi et al. in 2010 for soft paracentral TDH and has been extensively used afterwards by many others [
Interlaminar endoscopic thoracic discectomy (IETD) and Thoracic endoscopic unilateral laminotomy for bilateral decompression (TE-ULBD) [
Retro-pleural Endoscopic transthoracic Discectomy (RETTD) [
FESS literature with respect to lower thoracic spine have progressed to its use in the upper and mid dorsal regions too [
In the RETTD and TETD approaches, performing indirect box-shaped decompression before direct decompression is suggested for medial calcified pathology. In cases of bilateral ventral compressive pathology the resection over to the contralateral side has to be particularly done with care. In these cases the 25° field of view provides false satisfaction of free anterior spinal cord and leading to a tendency of less contralateral decompression. In all techniques, free-floating dura mater in the irrigation fluid was evidence of sufficient decompression. Good visibility and pulsatile cord is enough to judge the decompression endpoint in all the three approaches [
Complications & limitations: The peculiar location of thoracic pathologies in a narrow neuro-foraminal space makes complications an important part of the operative procedures. In a recent review of literature by Gibson et al, Dural tears were reported in 2% patients and transient paraesthesia or neuralgia in 2% patients, Revision surgery was required in 1.5% patients, neurological injury was reported in 0.6% patients and epidural hematoma in 0.6% patients. Complications including vertebral insta bility, cerebrospinal fluid leak, pleural fistula, thoracic viscerainjury and intercostal neuralgia which are common with open surgeries were not reported in any of the papers on FESS approach to the thoracic spine [
Anatomic considerations and less frequent cases a surgeon sees in his lifetime are major limitations for this technique’s evolution.
Full endoscopic procedures have been reported in the cervical spine. Though the procedure is technically difficult but can be acquired by training. The learning curve is steep but the advantages of this procedure with a good outcome approaches to that of FESS surgeries in the other region. There are mainly four categories of FESS procedures that have been classified depending on the approach used and the type of aetiology addressed: anterior endoscopic cervical discectomy (AECD), anterior endoscopic cervical trans-discal decompression(AETdCD), anterior endoscopic cervical trans-corporeal decompression (AETcCD), Posterior endoscopic cervical foraminotomy (PECF), Posterior endoscopic cervical discectomy (PECD) and cervical endoscopic unilateral laminotomy for bilateral decompression (CE-ULBD) [
The choice of the endoscopic approach is determined based on the location of the primary pathology [
Indications & Contraindications: The classical indication for FESS procedures in the cervical spine is focal cervical radiculopathy due to cervical disc herniation (CDH) or foraminal stenosis [
Technique Anterior endoscopic cervical discectomy (AECD): Local or general anaesthesia is used with the patient in supine position. The anterior approach comprises mainly of the transdiscal route and the trans-corporeal route. Right side is usually preferred for central DH and contralateral approach for the paracentral DH which provides a better trajectory. The approach needle is advanced through a safe space created between the carotid sheath and the trachea by two fingers. The carotid artery is pushed laterally and the trachea medially with the help of index and middle finger of the left hand. This provides a safe space for the insertion of the spinal needle and it is targeted towards the disc space or the body depending upon the type of approach used (transdiscal vs transcorporeal). The transdiscal route is often associated with reduction of disc height after surgery, a minimum of 4 mm ventral height of the intervertebral space is a pre-requisite for the transdiscal approach [
In
Technique: Posterior endoscopic cervical discectomy (PECD)/Posterior endoscopic cervical foraminotomy (PECF) [
Technique: Cervical endoscopic unilateral laminotomy for bilateral decompression (CE-ULBD) [
Complications & Limitations: The most commonly reported complications in endoscopic procedures were dural tear (4.65%) transient hypesthesia (3.37-4.65% and transient dysphagia (1.96-3.70%) [
Advances: Although calcified discs are difficult to address under the endoscope, a recent report of posterior transpedicular endoscopic access to calcified focal stenosis has reported good results [
Acute or progressive myelopathy at craniovertebral junction needs odontoidectomy by trans nasal or transoral route, which have been reported by endoscopy also (RECD). But, the chances infection are there. The FESS uniportal retropharyngeal approach is feasible and gives excellent alternative and a feasible good option in retro-dental pannus, infection at Craniovertebral junction or basilar invagination [
SELD allows epiduroscopic access through the sacral hiatus and facilitates visualisation and treatment of a wide variety of epidurally located lesions. Currently it is done with steerable flexible epiduroscopic system. The indications for this procedure have been ever increasing and most authors believe SELD to be an effective alternative for percutaneous epidural neuroplasty(PEN) [
The underlying concept is of decompression via ablation changing protein structure [
Indications & Contraindications: SELD is most commonly used in the treatment of discogenic low back pain and radicular pain attributed to HNP. Central and paracentrally located herniations are classical indications. Similarly presence of discal cysts, HIZ and fibrosis around the nerve fibres are also indications for SELD [
Profound motor weakness, CES, hard disc herniations, lateral and foraminal disc herniations, instability, known haemorrhagic disorders and anatomic abnormalities of the sacral hiatus are known contraindications [
Technique: The procedure is performed in the prone position under local anaesthesia and sedation. It is done under fluoroscopy. A 3-5 mm skin incision is made over the sacral hiatus. A puncture is made in the sacrococcygeal ligament using a trocar. It is advanced to S2-3 level it is followed by a guide wire and a dilator. This is followed by introduction of a video guided catheter (VGC) into the ventral epidural space. It is advanced to targeted disc. Next, an endoscope (1.2 mm) is inserted through one of the two portals in the VGC to visualise the epidural space. The other portal is used to advance a Ho:YAG laser. An epidurography is performed through a side tube of the catheter by injection of contrast and confirming anterior epidural catheter, and also showing outline of LDH or adhesions. A hole is created in the posterior longitudinal ligament (PLL) by laser cauterisation with variable power. Any sequestrated fragments can be removed with a 1 mm forceps. Repeat epidurogram is performed to confirm a free flow of dye. Physiological saline is constantly irrigated.
Complications & Limitations: Some limitations arise due to the technical problems (images acquired during the procedure are of low quality as are the equipments) associated with SELD. Secondly laser induced damage to the posterior annulus may lead to recurrent herniations [
Advances: Recently the indications for SELD have expanded to even discal cysts, treatment of migrated LDH and up to moderate canal stenosis as well [
Given the general notion that minimally invasive surgery would be associated with less muscle injury than open surgery could not been proven [
The rate of common perioperative complications such as hematoma, dorsal dural tear, and surgical site infection are too low. There are unique complications such as a ventral dural tear, injury to the exiting nerve root, instrument breakage, seizures and increased radiation exposure [
The only RCT that compared transforaminal or inter-laminar endoscopy with microdiscectomy and proving better quality outcomes of percutaneous procedure, was doubted for its randomisation, but still was an eye opener [
Another systematic review and meta-analysis noted no significant differences in rates of complication or re-operation between approaches, and was published around the same time [
TELD technique has been authenticated by most of the randomized trials [
High quality reports have now boomed in the last demi-decade [
Choi et al, (2005) in a study of IELD on 67 patients under local anaesthesia succeeded in 65 patients (2 patients had to be converted to open surgery) and further stated that it is a safe alternative approach for LDH and clinical efficacy is comparable with other techniques. The mean LOS was 12 hours. Successful outcome was reported in 90.8% patients, while there were complications (18.5%.) like two cases of dural injury, nine patients suffered from POD, one patient had recurrence(managed with OD), two patients had residual back pain and two had leg pain [
Ruetten et al reported feasibility in 372 patients suffering from LDH managed with IELD. He reported a recurrence rate of 2.4% without tneurological complications. On 331 patients followed for 2 years, 82% reported having no leg pain, and 13% had only occasional pain. All the 29 patients(9%) with poor results had additional back pain. Five of the patients had previously undergone conventional surgery at the same level, the other 24 were found intraoperatively to have only hard tissue and epidural adhesions instead of soft disc prolapse. It was concluded that LDH can be treated effectively with this technique but further technical advancements are required for satisfactory resection of the hard tissues which at that time was not achievable due to the smaller size of the endoscope [
A retrospective study of 479 cases (4 patients lost to follow up, higher segment, extraforaminal or recurrent LDH excluded) with a mean follow-up time of 44.3 months showed favourable outcomes threw great light on the learning and complications associated with the procedure. Twenty-nine (6.0%) complications including 3 cases (0.6%) of incomplete decompression in which the symptoms gradually decreased by conservative methods, 2 cases (0.4%) of nerve root injury which recovered in 1-3 months, 15 cases (3.1%) of paraesthesia, and 9 cases of recurrent herniation (1.9%) were noted. No dural tears were reported. Furthermore, the complication rate for the first 100 cases was 18%. This rate decreased to 2.9% for in the later cases. The complication rate for the L4-5 herniations (8.2%) was greater than that for the L5-S1 herniations (4.5%) [
Further Ruetten et al reported that IELD provided better results than MLD due to better visualization. If any hindrance is encountered switch to standard open procedure. Their results demonstrated that the complication rate of the full-endoscopic group (10.9%) was significantly lower than that of the microsurgical group (19.5%) [
Nerve root injury is still a common complication of FESS [
Most authors have reported good outcomes on their FESS approaches in the thoracic spine. In one of the largest series reported by Bae et al on 92 patients undergoing full endoscopic surgery of the thoracic spine, they reported excellent or good outcomes(Modified Macnab’s criteria) in 90% patients [
Overall, there are no clear standards in the literature as of now with respect to the surgical approach to be chosen. Though certain recommendations have been made, the surgical technique must be determined for every pathology on a case-by-case basis. If equal suitability of the TETD and the RETTD approaches is noted, the TETD approach is to be preferred. The larger, more medial, or more calcified the disc herniation would allow a more likely use transthoracic approach [
In a study of outcomes of discectomy by endoscopic transdiscal vs transcorporeal route, Ren et al have reported no significant difference between both the approaches. The trans-corporeal route offered lower recurrence and rate of disc collapse but the operative time and rate of end plate collapse were higher [
In one of the early series described by Ruetten et al. about the epiduroscopy guided interventions on 93 patients, 45.9% patients reported positive results post procedure [
Ultrasound (US) guided TELD is a new method to reduce the radiation dose during puncture and cannulation, also for radiation safety against cancers and infertility, it is definitely a better tool. This method is the only one that gives the real time guidance while inserting the needle. Thus it avoids the threat of causing injuries. Moreover, the US guidance allows the surgeon to visualize each step, allowing to give exacting control of movement near the foramen and nerve root [
Navigation is another development in spine surgery and FESS (
The techniques and indications of FESS has evolved. The scientific evidence has moved away from inferiority to non-inferiority when comparing results with conventional techniques. Its superiority in all aspects would soon get established and is likely to be the future of spine surgery with further innovations in technology and learnings.
Dr. A Krishnan is an editorial board member of the journal but was not involved in the peer reviewer selection, evaluation, or decision process of this article. There are no other potential conflicts of interest relevant to this article to declare.
The typical transforaminal ‘inside out’ approach leads the endoscope to posterior one third of the disc. Ⓐ : Central disc or osteophytes from ventral aspect, SAP and ligamentum flavum hypertrophy contributing to lateral and central stenosis. A transforaminal endoscope lands lateral to the pathology and going inside addresses only ventral pathology partially. Ⓑ : Foraminoplasty and joy-sticking of the endoscope allows medialization, dorsalization and horizontalization. Three necessary steps for dealing with epidural compression (soft or hard) ventrally and lateral recess decompression.
Oblique pediculectomy position of endoscope for high migrated LDH.
C arm images showing a foraminoplasty approach for Very high migrated Disc L45. Steerable grasper position in epidural space in antero-posterior Ⓐ : & lateral Ⓑ : view.
Hook can be used to swipe the floor. This helps to check the smooth floor of the endoscopic approach after decompression.
Ⓐ, Ⓑ, Ⓒ: Conus syndrome in a 19 year boy, non-walker paraparetic with bladder affection. CT Scan axial section, MRI T2 Sagittal and MR meyelogram showing calcified disc complex with severe compression. Ⓓ: Post-operative MRI showing complete decompression. Ⓔ: Bilateral biportal transforaminal approach taken under Local anaesthesia. Ⓕ: Intra-operative endoscopic view with decompressed cord and opposite working cannula(*)
The various components of stenosis Ⓐ can be addressed here by transforaminal approach Ⓑ. Ventral Caudal(end plate spur), Ventral Disc and annulus and postero-superior corner and end plate of caudal vertebra contributing to central stenosis. Dorsal superior pediculo-facet junction, facet overhang and ligamentum flavum contributing to the lateral recess stenosis. Ligamentum flavum, tip of superior articular processes and Ventral cranial (end plate spur) contributing to foramina stenosis.
In stable listhesis showing components of stenosis Ⓐ. Removal of the supero-posterior corner of inferior vertebra with annulus when combined by FESS foraminoplasty with removal of ligamentum flavum and facet overhang adequately does the decompression work, especially in elderly Ⓑ.
In interlaminar decompression, pedicle to pedicle decompression possible on the ipsilateral and contralateral side.
Interlaminar Decompression: Ⓐ: Central/ or unilateral Laminotomy, Ⓑ: Contralateral decompression, Ⓒ: Contralateral Foraminotomy. Smaller endoscope preferred Ⓓ: Ipsilateral ventral decompression. It is to be noted that the ventral decompression is done with retraction of the root from shoulder or axilla. Smaller endoscope preferred.
CT scan cut at thoracic disc level showing different approaches of FESS. TF approach needs partly removal of facet, pedicle and rib head. RETTD approach needs removal of head of rib articulating with two vertebra and then removal of ventral compression.
The left 30 degree Oblique view of the thoracic vertebrae. The green dot is the target entry point of the needle. Removal of part of facet and/or pedicle is needed for medialising the endoscope and coming near the medial and ventral area to cord (Blue Rail). The end-plate spur, annulus, disc fragment and calcifications can be removed. The noteworthy point is that the posterior surface of lumbar vertebral body is nearly straight but the thoracic vertebrae is concave and the cord is hugging and slightly encased into the vertebral body. It helps remove compressions without being horizontal in many cases.
Transthoracic retro-pleural FESS. The approach does not open the pleural cavity and after resecting the head of the articulating rib, all ventral stenotic calcification can be excised without cord manipulation till the contralateral aspect.
Posterior FESS Foraminotomy and discectomy are for pathology lateral to meylon only. Whereas anterior FESS can approach all pathology medial and lateral to melon. Dotted blue lines showing the extent of myelon. Area in red ventral to the myelon can be accessed by anterior route (Brown arrow). Area in red dorsal to the myelon can be accessed by posterior route (orange arrow). Area in green can be accessed by both anterior and posterior routes (brown and orange arrow).
Ⓐ, Ⓑ: The author AK Navigating with Medtronic-O-Arm low dose CT acquisition. Navigated projected images (Black Arrow) helps decide the trajectory, length and hinderance if any (facet, transverse process or iliac crest specially in L5S1 level Ⓒ: Digital Reference Frame Stick to skin(Arrow), with markings done supra iliac in this index case.
History
Year | Pioneers | Invention |
---|---|---|
1909 | Krause & Oppenheim [ |
First lumbar discectomy |
1911 | Goldthwaite & Middleton [ |
Described nucleus pulposus as the reason of the low back pain |
1931 | Burman [ |
Introduced the concept of Epiduroscopy |
1931 | Leu [ |
Reported the use of peridural intraductal endoscopies via the sacral approach technique |
1934 | Mixter & Barr [ |
They actually published the first series of successful disc operations in 1934. Their technique however was a complete laminectomy and some of the disc herniations were removed through a trans-dural approach |
1939 | Love [ |
Inter-laminar approach which became standard procedure for many years |
1973 | Parviz Kambin [ |
Transforaminal access |
1977 | Yasargil & Caspar [ |
Microsurgical-Interlaminar approach |
1978 | Tax williams [ |
First surgeon to implement the microsurgical-interlaminar approach in the United States |
1983 | Forst & Hausmann [ |
Introduces a modified endoscopic camera through the working cannula through which they were able to examine the intervertebral disc. |
1989 | Schreiber & Suezawa [ |
Began to perform nucleotomy under continuous endoscopic visualization, and reported successful outcomes in 72.5% of patients who had a herniated lumbar disc |
1997 | Yeung [ |
Yeung endoscopic spine system-Inside Out Approach |
1998 | Thomas Hoogland [ |
Hoogland endoscopic system-Outside In approach |
1999 | Foley & Smith [ |
Reported their experience of micro-endoscopic discectomy for far-lateral disc herniation in 11 consecutive patients using a tubular retractor and disposable endoscope. |
2002 | Fessler & Khoo [ |
Applied these micro-endoscopic techniques to cervical foraminotomy in cadaveric specimens and subsequently in clinical settings in 2002. |
2003 | S.Ruetten [ |
Described the use of epiduroscopy guided interventions in patients of chronic back leg pain syndromes in 2003 |
2005 | Schubert & T.Hoogland [ |
Described a “foraminoplasty” technique in which the working angle through the Kambin’s triangle is expanded by removing the ventral portion of the superior articular process with reamers. |
2005 | G.Choi [ |
Percutaneous Interlaminar technique as alternative to transforaminal technique for better access. |
2007 | S.Ruetten [ |
Reported successful endoscopic decompression of foraminal pathology |
2001-2021 | S.Gore [ |
All of them are contributors to develop advance techniques and make Spine Endoscopy popular in their respective region. |