Minimizing the amount of tissue injury, trauma and post-operative pain are important to optimize any patient’s recovery from back surgery. Over the years, we have seen great strides in spine surgery technology, equipment, instrumentation, and procedures. Endoscopic Spine Surgery (ESS) is currently the foremost example of how far we’ve come in the surgical treatment of our patients.
What Is Endoscopic Spine Surgery?
By definition, ESS is a surgical procedure using micro-sized incisions (less than 1-inch) and small tubular systems in combination with an endoscope to visualize the surgical field.
Endoscopic spine surgery is an advanced, state-of-the-art form of minimally invasive spine surgery designed to provide the patient a quicker recovery time and less recurring pain than traditional spine surgery methods. ESS also can help preserve normal range of spine mobility post-operatively. In some cases, the ESS procedure can be performed using regional anesthesia instead of general anesthesia, decreasing overall medical risks in patients who are older and/or have co-existing medical disorders that may increase surgical risk.
Rationale for spinal endoscopy and the role of anatomic perspective during surgery
The vast majority of spinal procedures being performed throughout the world currently rely on direct visualization aided by magnification, either through eyewear (eg, loupes with a headlamp) or the use of an operating microscope. A frequent goal of most spine procedures for degenerative pathologies involves addressing and relieving extrinsic neural compression.
As the tools and techniques to perform these procedures have evolved, surgeons have been able to perform these procedures with more limited operative exposures.
Furthermore, as the working area of access to the spinal canal decreases, direct external visualization begins to create substantial limitations, and moving the point of anatomic perspective into the body of the patient, and closer to the surgical site, dramatically increases the area and quality of visualization. This improvement in anatomic perspective during surgery minimizes surgical dissection, and may allow for reduced requirements for inpatient care, lower surgical expenditures, and expedited recovery.
Spinal endoscopic surgery
With improvements in the optics, high resolution camera, light source, high speed burr, irrigation pump etc, minimally invasive spine surgeries can be performed with various endoscopic techniques for lumbar, cervical and thoracic regions. Advantages of endoscopic spine surgeries are less tissue dissection and muscle trauma, reduced blood loss, less damage to the epidural blood supply and consequent epidural fibrosis and scarring, reduced hospital stay, early functional recovery and improvement in the quality of life & better cosmesis. With precise indication, proper diagnosis and good training, the endoscopic spine surgery can give equally good result as open spine surgery.
Initially, endoscopic technique was restricted to the lumbar, cervical and thoracic disc herniations but gradually it can also be used for spinal canal stenosis and endoscopic assisted fusion surgeries.
Endoscopic spine surgery can play important role in the treatment of adolescent disc herniations especially for the persons who engage in the competitive sports and the athletes where less tissue trauma, cosmesis and early functional recovery is desirable.
What are the advantages?
- Utilizes an HD camera coupled to an endoscope which provides the spine surgeon a superior view to that of traditional surgical techniques
- Less than a 1/2 inch incision minimizes potential skin scarring
- No muscle or tissue tearing thus less scar tissue and preserve spinal mobility
- Conscious sedation reduces the risk associated with general anesthesia
- Less post-operative pain and need for narcotic medicines
- Less recovery time needed
- Return to work sooner – as early as one week.
Types of endoscopic techniques
There are 2 main types-Uniportal and Biportal
Uniportal Endoscopy
Typically involves a single working channel, which houses the endoscope and one surgical instrument. The working channel only allows for the utilization of one instrument at a time. The operator can change the instrument, for example switching from a bone removal device to a cautery device, but the size of the working channel does not allow for the concurrent use of two instruments. Additionally, the small working channel dictates that the camera used for visualization and the tool being used can only be moved in concert, with some modifications allowing for limited independent motion of the distal working end of the instrument.
Because the working channel is relatively small and does not itself create a potential space around the surgical field, these techniques require an aqueous environment to create space around the surgical field in between tissue planes. The advantage of full endoscopy is that it creates the least amount of collateral tissue damage. Disadvantages stem primarily from the single working channel that precludes multiple concurrent instrument use and independence between the camera and instrument movements.
Biportal Endoscopy
Biportal endoscopy, as the name indicates, utilizes two working channels, one for the endoscope and another for instruments, much akin to arthroscopy techniques used in knee or shoulder surgery.The main advantages of this approach are the independence of scope and instrument control, as well as greater degree of freedom for positioning of the instruments. This technique may also have increased affinity for those surgeons who are making a switch from open/ microscopic techniques to endoscopic techniques..
Let’s look at some of the endoscopic techniques according to in various regions of the spine
Endoscopic surgery in lumbar spine
In endoscopic lumbar spine surgery two approaches are most popular, Transforaminal and Interlaminar endoscopy.
Transforaminal Endoscopic Lumbar Discectomy-TELD
In the TELD, discectomy and decompression is performed through intervertebral foramen between exiting and traversing root so before going in depth of TELD we need to know anatomy of intervertebral foramen (IVF). IVF is bounded by two mobile joints, zygapophyseal joints posteriorly and intervertebral disc anteriorly, because of mobility of two joints dimension of IVF change dynamically with movement of spine and with age related degeneration. Roof and floor are formed by inferior and superior notch of respective vertebral pedicles, medial wall by thecal sac and lateral wall by a facial sheath and overlying psoas muscle.
Crux of TELD is precise insertion of needle into the disc through safe triangle of Kambin’s which lies between the exiting and the traversing root.
Boundaries of the Kambin’s triangle are anterior or hypotenuse line: exiting nerve root; base or inferior boundary: superior endplate of inferior vertebra; and roof or medial border: thecal sac and traversing nerve root curtailed by the facet.
There are mainly 2 types in TELD
inside out and outside in.
Inside-out TELD
Surgical technique
In the inside-out technique, the cannula is first to inserted into the disc just underneath the herniated nucleus pulposus (HNP) and discectomy carried out first. Once the disc is debulked and discectomy is done then the cannula is slowly withdrawn to see the neural structures. Exiting nerve root injury (ENRI) is a specific troublesome complication of the transforaminal approach and hence careful study of the MRI is necessary before this technique.
Outside-in TELD: foraminoplastic TELD
Surgical technique
In the outside-in technique, the cannula is placed on the disc surface and just outside of the intervertebral foramen. The first step in the outside-in technique would be enlargement of the foramen for safer insertion of the cannula into the spinal canal and foraminotomy . This technique uses a high-speed drill for this purpose.
The two types of TELD is usually done under local anesthesia. The procedure only requires an 8-mm skin incision and is thus the least invasive disc surgery. Done under local anesthesia, this technique would be of benefit for elderly patients in aging communities.
Interlaminar approach.
Interlaminar (posterior) approach for the lumbar/thoracic spine
This technique is usually done under GA. is characterized by a percutaneous posterior or interlaminar approach to the epidural space or disc pathology. The interlaminar approach is familiar to general spine surgeons, because it is similar to that of open microscopic lumbar/thoracic decompression. The decompression processes are also similar to those of open microscopic decompression.
The technique initially was used for l5/s1 discectomy. They found that the interlaminar space of the L5–S1 level is usually large enough to pass the endoscopy and working cannula. This technique uses a posterior interlaminar approach with the small working cannula in the epidural or intradiscal space, while preserving paraspinal musculatures and lamina. It can also be applicable to the other levels by using endoscopic punches or drills to enlarge the interlaminar space for introduction of the working cannula and instruments.
A standard spine surgeon can be more familiar with the interlaminar approach than the transforaminal approach. In fact, the presence of the innocent exiting nerve root during the transforaminal approach can be stressful for the endoscopic spine surgeons. This technique has evolved and eventually become the interlaminar endoscopic lumbar decompression technique for lumbar stenosis.
The next stage in the evolution of interlaminar approach was laminotomy/ laminectomy and discectomy. It eventually evolved to single sided approach with bilateral decompression for all levels of lumbar spine and thoracic spine.
The patient is placed in a prone position under general or epidural anesthesia. The initial target point is the lateral edge of the interlaminar window. After serial dilation, the final working cannula was placed on the lamina surface. Endoscopic laminotomy was performed from the medial border of the superior facet using the endoscopic burr and bunches. Decompression can proceed including cranial and caudal laminotomy, medial facetectomy, and removal of the ligamentum flavum. In the case of bilateral decompression, further decompression of the contralateral side is needed after ipsilateral decompression.
The endoscope and the working cannula were directed toward the contralateral side, dorsal to the dural sac. At this point, it is better to leave the ligamentum flavum intact to protect the dural sac during the contralateral laminotomy. The undercutting technique over the ligamentum flavum should be performed until the medial aspect of the contralateral facet can be reached. The remaining ligamentum flavum is then completely removed using the endoscopic punches and other supplementary instruments. All surgical fields are manipulated under endoscopic visual control and constant saline irrigation. Now even lumbar interbody fusion is possible using this technique by introducing cages thru endoscopic technique between the vertebral body.
Cervical endoscopic procedures.
Percutaneous endoscopic posterior cervical foraminotomy
Open posterior cervical foraminotomy is frequently used by surgeons when the primary focus of pathology leading to cervicalgia is foraminal stenosis in the presence or absence of an associated disc protrusion. Open surgery however requires detachment of the paraspinal muscles, and this may be associated with post-operative neck pain and spinal instability. To minimize muscle damage clearly, a minimally invasive approach is attractive. Endoscopic technique allows this in ultra-minimally invasive way.
Through a stab incision with anteroposterior spinal imaging, a 2-mm diameter dilator tube is placed directly onto the medial margin of the facet joint at the affected intervertebral level. Progressive dilators are then inserted to allow placement of a 7.5-mm working cannula for a 6.3-mm endoscope. A diamond endoscopic burr may then be used to remove the medial margin of the facet and expose the underlying nerve root.
Endoscopic surgery is also used in anterior cervical approaches and posterior decompression.
The evolution of minimally invasive or endoscopic surgery is the main focus for current spine surgeons. The patients’ need for early recovery and return to a healthy lifestyle while maintaining a high quality of life will make the endoscopic surgery the mainstream of spine medicine.
Furthermore, the increasing number of elderly patients will increase the demand for percutaneous endoscopic procedures with a minimal incision under local anesthesia. Regarding the current technological status, most lumbar herniated disc diseases and a considerable portion of spinal stenosis cases can be treated with endoscopic techniques. In the future, the definitive indications for endoscopic surgery will broaden rapidly. Eventually, most degenerative spine diseases will be treated with endoscopic surgery under local anesthesia in the near future and might even become the standard of care for spine surgery.
See you soon with some more spine tips in My Spine World. Remember, we got your back !