Minimally Invasive Techniques for Lumbar Disc Herniations

By Alexander Berg

Minimally invasive surgical techniques for spinal surgery are on the rise. The endoscope, a tool used to observe and operate internally has been increasingly featured in many minimally invasive techniques, and the market for endoscopy is projected to grow to a 44 billion threshold by 2025. Other minimally invasive techniques, like microdiscectomies and other microscopic surgeries, are becoming prominent as surgeons wish to do less damage to their patients’ tissues. With the number of elderly in the United States growing, the number of spine issues have proportionally gone up (Freburger et al., 2009). More spine problems mean more surgeries, and as many patients want surgery to relieve their back pain, the desire for less-invasive techniques also rises.

One of the most common spine issues in America is a herniated lumbar disc. When a lumbar disc is herniated, the nucleus pulposus (inner part of the disc) and/or the annulus fibrosus (tough outer shell) are displaced beyond the usual intervertebral disc space (Jordan et al., 2009). Lumbar disc herniations typically occur for people in the age range of 30-50 years old, with males being more commonly affected (Jordan et al., 2009). Typically found at L4-5 or L5-S1, a disc herniation is usually caused by a person's aging. As we age, the water content in our spine decreases and thus the flexibility of our spine also decreases, meaning spinal discs can tear or rupturing under minor stress. (Deyo, Loeser, & Bigos, 1990). 

There are many different approaches to treat a lumbar disc herniation. Only 5-10% of lumbar disc herniations require surgical intervention, as the symptoms can usually be resolved with conservative therapy (Deyo, Loeser, & Bigos, 1990). However, if the pain becomes too extreme or therapy fails to relieve symptoms, many opt for surgery. Many different surgical approaches can be taken to relieve a patient of their pain. Traditionally, a lumbar disc herniation is treated via laminectomy, which involves removing a portion of or the entire lamina to enlarge the spinal canal to ease the pressure on nerves, along with the removal of herniated tissue (discectomy). While the procedure is fairly safe, there is the possibility of damage to spinal structures or epidural scarring (Shen et al., 2011). In addition, when undergoing a traditional laminectomy, it is sometimes required to remove the entire corresponding lamina to gain access to the herniated disc (Jha et al., 2015). This can then increase the instability of the vertebrae, which negatively affects the patient's health as they can be in constant pain (Jha et al., 2015). Thus, a laminectomy is sometimes combined with a spinal fusion, but that procedure lengthens recovery time (Jha et al., 2015). Another decompression procedure, the foraminotomy, involves the enlargement of certain nerve passages in the spine. This procedure can cause issues similar to other open surgeries, such as large amounts of blood loss, but is increasingly being done in minimally invasive forms (Clark, Abdullal, Steinmetz, Benzel,  & Mroz, 2011).

Compared to a typical open surgery, minimally invasive surgery promises patients less pain, and perhaps even more importantly, a shorter recovery time. These types of surgery also guarantee less cosmetic damage to the outer epidermal layer compared to traditional surgery, which leaves behind a large scar for the rest of the patient's life. Minimally invasive surgery also promises reduced blood loss (Vaishnav, Othman, Virk,  Gang & Qureshi, 2019). Lastly, as the postoperative pain is not as extreme as a traditional open surgery, fewer pain medications can usually be prescribed, reducing a patient's chance of possibly becoming addicted to the medication (Spoor & Oner, 2013).

There are multiple techniques for treating lumbar disc hernias with minimally invasive surgeries, with the more common microdiscectomy having been around for decades now. The newer technique, endoscopic lumbar disc surgery, has become more popular with surgeons. In 1999 the Yeung endoscopic spine system was pioneered by Anthony Yeung to conduct minimally invasive spine surgery (Kim et al., 2019). From there, the technology has only been improving. An endoscope is a tool that can be inserted into the body to internally visualize it. In addition, surgical endoscopes have a working channel from where the surgeon can operate. In an endoscopic lumbar disc herniation surgery, the endoscope is used to visualize the herniated mass, which then can be removed piece by piece through the working channel (Jha et al., 2015). One major benefit to the endoscopic procedure is that it can be done under local anesthesia. This allows the patient to be awake during the procedure, allowing the operating team to communicate with the patient during the surgery (Jha et al., 2015). Endoscopic lumbar disc herniation surgery has been found to be associated with fewer problems intraoperatively and postoperatively compared to a typical laminectomy (Jha et al., 2015). With this type of minimally invasive surgery, tissue damage is minimized and the patient can undergo rehabilitation sooner, which greatly increases patient satisfaction (Jha et al., 2015).

The lumbar microdiscectomy, a microscopic surgery, is another minimally invasive technique to treat lumbar disc herniations. The microdiscectomy procedure was developed as an advancement of the traditional discectomy. Popularized at the end of the 1970s, the surgeon uses a lighted microscope to see the affected area. The surgeon creates a small incision, moving muscle tissue and nerve roots out of the way, through which they can remove the herniated tissue with minimal damage to surrounding tissue. Similar to endoscopic surgery, the microdiscectomy demonstrates limited blood loss, shorter surgical duration, and faster postoperative recovery when compared to more invasive surgical options (Dalbayrak, Yaman, Yilmaz, & Ozer, 2013).

A case study by Dohrnmann and Mansour in 2015 further analyzed the effectiveness of these three types of surgeries, laminectomies, endoscopic discectomies, and microdiscectomies. An analysis of 39,000 patients who underwent surgery for lumbar disc herniations found similar levels of success for the three types of surgery. Success of the surgery was determined by the patients themselves. For patients who underwent endoscopic discectomy surgeries for lumbar disc herniations, their surgery was found to be successful 79.5% of the time. Patients who underwent microdiscectomy had a success rate of 84%. And finally, patients who had a traditional laminectomy had a success rate of 78.4%. The success rates of these operations are all within the same range, with the minimally invasive techniques being slightly more successful (Dohrmann & Mansour, 2015). However, it is important to note that the minimally invasive techniques also benefit the patient much more than a traditional open technique as both tissue damage and recovery time are reduced, indicating few downsides for opting for the minimally invasive technique, as long as it is an option for surgery.

While the microdiscectomy and the endoscopic discectomy are both different surgeries, they share many of the same qualities. Both surgeries have a similar functional recovery time and rate of complication (Zhang et al., 2018). In addition, the leg pain common after a lumbar discectomy had the same rate of occurrence in both types of surgery (Zhang et al., 2018). The only major difference between both surgeries (disregarding procedure) is that patients who underwent endoscopic discectomy stayed less time at the hospital compared to those who underwent microdiscectomy (Zhang et al., 2018). One possible flaw in endoscopic spine surgery is its steep learning curve. While many surgeons actually appreciate this, it means that when surgeons first start using the endoscope for surgery, there will be more complications such as dural tears, nerve or vessel injury, and infection (Moon & Manoharen, 2018). Proposed solutions to this flaw involves training surgeons with cadavers and using virtual reality (Moon & Manoharen, 2018).

While lumbar disc herniations are increasingly being treated through minimally invasive techniques, there are many other types of spinal surgeries where minimally invasive techniques have not yet been developed or are not yet widely used. Lumbar fusions, a common procedure in which a patient's spine is fused to prevent back pain are traditionally done as an open surgery. Relatively recently however, lumbar fusions using an endoscope have been done using a method known as endoscopic lumbar interbody fusion. In this procedure, a “cage” is inserted in order to fuse the spine. While lumbar fusions with an endoscope have been done, they have been associated with a low fusion rate, and the overall results have been lacking compared to a traditional fusion (Kim et al., 2019). This has not stopped development of minimally invasive techniques, and it is surmised that with the rate of current development and interest, minimally invasive procedures will be an option for all forms of spinal surgery, promising patients less pain and a greater quality of life.

References

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