Monoportal endoscopy, also known as full-endoscopic surgery, is a surgical technique that can be used to treat certain pathologies of the spine, with the advantage of being minimally invasive surgery that causes as little injury as possible to the surrounding tissues.
Two of the most common causes of spinal nerve compression are osteoarthritis (which can lead to spinal or foraminal stenosis), and herniated discs. No matter which surgical technique is used, the goal is always to release the affected nerve or nerves by removing the cause of compression. Monoportal endoscopy allows the surgeon to access the area to be treated through one very small incision, less than a centimeter in size.
How is endoscopic spine surgery different from traditional surgery?
Monoportal endoscopy is performed using an endoscope -- a device incorporating a camera, light source, irrigation system, and tube for instruments to pass through, which can be inserted through a single incision less than a centimeter in size. This is sufficient to allow the surgeon to access and treat a specific pathology, such as a herniated disc, while protecting the surrounding spine structures as much as possible.
Traditional spine surgery usually requires a larger incision and wider opening of the back, which exposes structures such as muscles, bones, ligaments, and connective tissues. Although the surgeon tries to minimize injury to these tissues, with the traditional approach there may be some degree of undesired impact on the supporting structures.
As medical technologies have advanced, smaller incisions are used in more cases. With the lighting and magnification provided by a neurosurgical microscope, for example, it is possible to perform surgery through an incision only a few centimeters long, reducing exposure of the anatomy.
Biportal endoscopy is another minimally invasive surgical technique. This technique uses two incisions, each less than a centimeter in size: one for the camera and lighting and one for the instruments. The goal is to minimize any injury to surrounding tissues and limit the formation of scar tissue.
Step by step, how herniated disc surgery is performed using monoportal endoscopy
This procedure can be performed with various approaches, two of the most common being the interlaminar approach and the transforaminal approach. The approach used will depend on the location of the hernia, the level of the affected vertebra, and the individual patient's anatomy, among other factors.
1. Interlaminar approach
First, the exact point for the incision, slightly to one side of the midline of the back, is marked with the aid of radioscopy (an imaging technique that allows the area to be seen during the procedure). The surgeon makes an incision of about 7 mm, and inserts dilators to gradually create a path for the endoscope to pass through by separating the muscle fibers rather than cutting them.
Then, a beveled working cannula is inserted under radioscopic guidance, and the endoscope is introduced through the cannula. The goal is to reach the yellow ligament, a structure which connects the laminae of two adjacent vertebrae. This ligament is then carefully dissected, and in some cases, small cuts with microsurgical scissors may be needed, so that the tip of the working cannula can enter the spinal canal.
The endoscope allows detailed visualization of the nerve structures, including the dural sac and nerve roots. The cannula is placed next to the nerve root and rotated to protect the root and expose the hernia. Then the hernia is opened with a dissector and the necessary tissue fragments are removed using microsurgical forceps. Once the lesion has been treated, the cannula is returned to its initial position and the surgeon checks to confirm that the compression has been resolved. Finally, the instruments are removed, a single suture is made under the skin, and the wound is covered with a dressing.
2. Transforaminal approach
In contrast to the interlaminar approach, in the transforaminal approach, the small incision will be located farther from the midline of the back: between 8 to 12 cm to one side, depending on the vertebral level of the lesion and the patient's anatomy. An incision of approximately 7 mm is made and a needle is inserted, monitored by radioscopy as it is directed to the neural foramen, the opening through which the nerve roots exit the spine.
Then the needle is replaced by a metal guide. Accurate placement of the guide is essential in order to access the hernia and avoid injuring the nerve root emerging from that area. Next, dilators, the working cannula, and the endoscope are inserted. On rare occasions, it is necessary to use manual or motorized drills to expose the disc space.
Once the hernia is located, it is released with dissectors and removed with microsurgical forceps. Lastly, the surgeon uses a 30º endoscopic camera to confirm that the nerve roots have been released. This approach takes advantage of a natural access route through the neural foramen, in an effort to avoid manipulation of important vertebral structures outside the area to be treated.
Is endoscopic spine surgery an option for all patients?
Advances in medical technology and techniques have made endoscopic spine surgery a possibility for an increasing number of patients. However, like any surgical technique, it is not suitable for every case. Patient selection depends on many factors: the decision must be made together with the surgeon and taking into account the characteristics of the pathology and the anatomy of the patient.
Thanks to continuing developments in endoscopy, in selected cases it can now be used for some pathologies where previously it was contraindicated, such as certain calcified or migrated hernias.
How much time does an endoscopic spine operation take?
How long the surgery takes depends on the complexity of each case. Generally speaking, many operations can be performed in less than an hour. However, the time needed for the operation must always be determined by the medical team and depending on the nature of the pathology.
How is recovery after endoscopic spine surgery?
Because muscle tissues are separated and dilated rather than cut, some patients may be up and walking around just a few hours after surgery. In many cases, the patient is discharged from the hospital within 24 hours. Physical therapy can begin soon after, subject to the advice of the medical team, and the patient can usually return to work within a few weeks. The recovery timeline may vary depending on the procedure, the patient’s clinical situation, and the type of work they do.
The small size of the incision and constant irrigation used in endoscopic spine surgery help reduce certain risks, such as infection. However, every surgery has some risk, and the surgeon must make sure the patient is informed of the benefits, limitations, and possible complications in each case.
Is monoportal endoscopy right for me?
The appropriate technique for each case depends on the diagnosis, the location of the nerve compression, the patient’s anatomy, and other clinical factors. With an individualized patient evaluation, a spine specialist can study the available options and decide if monoportal endoscopy is an appropriate choice.
Doctor Gregory Zegarek
Neurosurgeon
Categories: Spine treatments, Surgery, Techniques