Description
Percutaneous treatment of cervical and lumbar disc herniations involves a variety of chemical, thermal, or mechanical ablative devices. These devices are administered inside the nucleus pulposus, with the purpose to ablate the protruding intervertebral discs.
Percutaneous endoscopic discectomy. Percutaneous endoscopic transforaminal discectomy is the least invasive method for treating lumbar disc prolapse. This technique decompresses the lumbar disc space by mechanically removing the nucleus pulposus. The advantages of percutaneous endoscopic discectomy are early mobilization and early return to work (61). Percutaneous transforaminal endoscopic discectomy is associated with less blood loss, faster rehabilitation, and less tissue scarring than conventional open microdiscectomy. Percutaneous transforaminal endoscopic surgery allows patients to return home only 2 hours after surgery (19). Percutaneous endoscopic lumbar foraminoplasty is used to enlarge the narrow intervertebral foramen (48). Biportal percutaneous transforaminal endoscopic discectomy is a better technique than the uniportal endoscopic minimally invasive microsurgery in patients with foraminal, lumbar canal stenosis, and paracentral disc herniations (20). A meta-analysis observed similar functional outcomes from percutaneous endoscopic lumbar discectomy or open lumbar microdiscectomy for lumbar disc herniations (47). The advantage percutaneous endoscopic lumbar discectomy group had was less operation time and less hospital stay. CT-navigated percutaneous endoscopic technique is better in patients with lumbar disc herniation. This technique is particularly useful in patients with high-grade disk migration. This technique is also associated with better functional recovery than conventional fluoroscopic guidance (34). A network metaanalysis of 50 randomized controlled trials compared seven surgical interventions for lumbar disc herniation. Microendoscopic discectomy and percutaneous endoscopic lumbar discectomy showed the best outcomes in visual analog scale scores and Oswestry disability index scores, outperforming standard open discectomy, which had the worst Oswestry disability index score. Microendoscopic discectomy also had advantages in reducing blood loss and reoperation rates. Tubular discectomy resulted in the fewest complications. Despite variability in follow-up data, minimally invasive surgeries like microendoscopic discectomy and percutaneous endoscopic lumbar discectomy offer effective and safer alternatives to standard open discectomy (44).
A retrospective study of 98 patients with lumbar disc herniation treated with percutaneous endoscopic lumbar discectomy combined with platelet-rich plasma hydrogel injection or percutaneous endoscopic lumbar discectomy alone showed promising results (60). The treatment group had significantly better outcomes in terms of lower visual analog scale scores for back pain, improved Japanese Orthopaedic Association scores, lower Oswestry disability index, and better disc height and Pfirrmann grades over an 18-month follow-up. No severe adverse events were reported, and the recurrence of lumbar disc herniation was lower in the treatment group.
Deep learning–derived 3D reconstruction of lumbosacral structures (nerves, bones, and disc) by thin-layer computed tomography is a technique that has proved valuable in predicting surgical difficulties before a procedure is performed (15). Robot-assisted systems for performing transforaminal percutaneous endoscopic lumbar surgeries are being developed, and these systems will make percutaneous spinal procedures more accurate and efficient. The robot-assisted system will reduce the risk of injury to vital blood vessels and nerves. The robot-assisted system consists of three components: a planning system, a navigation system, and a foraminoplasty system (16).
Percutaneous endoscopic cervical discectomy is an effective technique that can decompress the compressed nerve root and dural sac effectively. Percutaneous endoscopic cervical discectomy can resolve the patient's symptoms without the need for intervertebral body fusion. Selective decompression under vision with minimal surgery-related trauma is achieved. This procedure can be performed via anterior and posterior approaches, depending on site of disc protrusion (45).
A meta-analysis examined risk factors for recurrent lumbar disc herniation following percutaneous endoscopic lumbar discectomy. Analyzing 58 studies with a mean follow-up of 38.8 months, the review identified nine key risk factors. High-quality evidence linked diabetes, protrusion-type lumbar disc herniation, and less-experienced surgeons to increased recurrent lumbar disc herniation rates. Medium-quality evidence suggested advanced age, Modic changes, smoking, lack of college education, obesity, and inappropriate manual labor are also significantly correlated with postoperative recurrent lumbar disc herniation (35).
Choice of anesthesia. A systematic review compared local and general anesthesia in percutaneous interlaminar endoscopic discectomy, examining six articles with 549 participants. Findings suggest that patients under local anesthesia had shorter hospital stays and lower costs, with no significant difference in complications, operation time, or patient satisfaction compared to general anesthesia. Local anesthesia was found to be an effective pain relief method during percutaneous interlaminar endoscopic discectomy, ensuring operational safety without increased postoperative complications (25).
A double-blind, randomized, placebo-controlled trial explored the effectiveness and safety of using 100 µg intrathecal morphine with low-dose spinal ropivacaine in percutaneous endoscopic lumbar discectomy. Ninety patients were randomized into two groups, one receiving intrathecal morphine (n=45) and a control group (n=45). Results showed that the intrathecal morphine group had significantly lower intraoperative pain scores and a higher satisfaction score, with fewer requiring rescue analgesia. However, intrathecal morphine use led to increased pruritus and one case of respiratory depression (58).
Radiofrequency thermocoagulation. Radiofrequency thermocoagulation is also a minimally invasive, target-selective technique where thermal energy is created to ablate pain-producing nerves. Ablation sites are usually negotiated under computed tomographic guidance (59). For cervical levels, a dedicated 19-gauge electrode with a looped tip is used (08). This electrode creates small spherical voids in the annulus when the electrode is rotated on its axis. The electrode is advanced to the mid part of the disc but never beyond the mid-third or posterior-third junction to avoid damage to the spinal cord or the nerve roots. Sedation is minimized to allow complete neurologic monitoring of the patient during the whole procedure.
Percutaneous cervical nucleoplasty is a minimally invasive procedure used to perform disc decompression in cases of pain caused by cervical disc herniation. Nucleoplasty reduces pain and improves patients' functional mobility (14). In percutaneous cervical nucleoplasty, a portion of the nucleus tissue is ablated using the “coblation technique,” which involves soft tissue dissolution with the help of bipolar radio frequency energy. A case-control study compared percutaneous cervical nucleoplasty with conservative treatment in patients with symptomatic contained cervical herniated intervertebral discs. The study found that the percutaneous cervical nucleoplasty group showed significantly improved pain levels and functional outcomes after 1 month, which lasted through the 6-month follow-up period, compared to the conservative treatment group. Although disc height decreased after percutaneous cervical nucleoplasty treatment, this did not correlate with the substantial improvement in pain. The study concluded that percutaneous cervical nucleoplasty seems a better option than conservative treatment (09).
Percutaneous lumbar laser discectomy. Percutaneous lumbar laser discectomy is a minimally invasive procedure indicated in the treatment of disc herniation with back pain. After puncturing the disc with an 18-gauge needle, the tip of the laser fiber is positioned at the posterior annulus/nucleus junction. Then, short pulses of 1 second with a power of 15 W are applied, separated by free intervals of 5 to 10 seconds to achieve vaporization (08). If back pain occurs during the intervention, it may be due to the heating of the adjacent vertebral endplates or hyperpressure within the disc from trapped gas; in such cases, the position of the fiber should be checked, and the interval between the pulses increased. For complex L5–S1 approaches, a 17-gauge introducer needle may be very stiff and difficult to bend; in this situation, the flexible laser fiber introduced coaxially through a bended 18-gauge spinal needle is more easily positioned into the disc (08).
Ozone nucleolysis. Ozone nucleolysis is a minimally invasive technique meant for treating lumbar disc herniations. Intradiscal ozone administration is an effective and cost-effective technique for treating discogenic back pain (04; 46). A mixture of ozone and oxygen (O3-O2) is used for the ozone nucleolysis. Ozone nucleolysis leads to reduced herniated disc volume; subsequently, it alleviates pain because of nerve root compression and venous stasis. The reaction of active oxygen with hydroxyl-radical with carbohydrates and amino acids produces dehydration of nucleus pulposus. The combined percutaneous microdiscectomy and ozone injection has shown better results than ozone injection alone in cervical disc hernia (56). A prospective study comprising 246 consecutive patients with cervical disc herniation treated with intradiscal injection of ozone-oxygen mixture (ozone disc nucleolysis) had excellent improvement in 138 (56%), good recovery in 50 (20%), and fair recovery in 22 (9%), with overall success rate of approximately 85% (22). In patients with lumbar disc herniation treated with ozone disc nucleolysis, previous infection with COVID-19 adversely impacted the recovery. Past COVID-19 infection has led to a longer recovery time (53).
Percutaneous chemonucleolysis using ethanol gel. A radiopaque gelified ethanol is viscous material in comparison to absolute alcohol. This technique involves chemonucleolysis in patients with lumbar disc herniation. Gelified ethanol (eg, DiscoGel ®) is injected intradiscally by percutaneous route. Gelified ethanol produces destruction of nucleus pulposus and dehydration of the protruding disc and reduces volume of disc herniation.
Percutaneous image-guided intradiscal injection of gelified ethanol has been found satisfactory in the management of both lumbar and cervical discs. In a questionnaire-based survey of 83 participants, only 5% remained unsatisfied (31).
Percutaneous intervertebral disc coagulation therapy. Percutaneous plasma disc coagulation therapy uses a laser source called a plasma light that applies radiofrequency energy directly to the middle of the disc. Laser rays generated by plasma light remain concentrated at the end of dome-shaped fibers and do not travel linearly. Percutaneous plasma disc coagulation technique provides sufficient energy to the disc area without damaging surrounding soft tissues. No damage is done to surrounding neural tissues as well. Percutaneous plasma disc coagulation technique leads to disc coagulation, evaporation, and, ultimately, decompression. Percutaneous intervertebral disc coagulation therapy is used for the treatment of lumbar and cervical disc hernias resistant to medical therapy (62).
Lumbar microdiscectomy. Lumbar microdiscectomy is the most commonly performed minimally invasive spinal surgical procedure. During microdiscectomy surgery, protruding portions of the herniated disc are dissected out to relieve pressure on compressed nerves. During the procedure, a 1-inch incision in the skin over the affected area of the spine is made. Hospital stay is usually not more than 24 hours and restricted physical activities for a few days thereafter (13; 55).
The procedure should be performed in the prone position. For cervical levels, the disc puncture is performed under fluoroscopic guidance with an anterolateral approach (08). Cushions are positioned under the upper thoracic spine to hyperextend the neck and open up the anterior aspect of the cervical discs. The operator presses against the spine, moving the carotid artery and the jugular vein laterally. Then, the disc is punctured directly between the two fingers. The needle passes between the esophagus medially and the major cervical vessels laterally.
For lumbar levels, the disc puncture is performed under fluoroscopic guidance with a posterolateral approach (08). To open up the posterior aspect of the disc space, pillows are positioned under the abdomen to extend the lumbar spine in a semiflexed position. The disc puncture is performed in the axis of the x-ray beam (lateral-oblique projection), just lateral to the articular process. The needle must systematically slip along the articular process to avoid the nerve root in its extraforaminal course. Prominent iliac wings may block L5-S1direct puncture; therefore, a bended needle may be required. After puncturing the disc, the needle positioning is confirmed with anteroposterior and lateral fluoroscopic projections. A prospective randomized controlled study compared percutaneous transforaminal endoscopic discectomy with microendoscopic discectomy. After 2 years of follow-up, the authors concluded that percutaneous transforaminal endoscopic discectomy did not have better outcome, as well as it did not appear to be safer as compared to microendoscopic discectomy (11).
Operative procedures. Postoperative instructions following radiofrequency nucleoplasty are very similar to laser nucleotomy. For cervical decompression, a surgical collar is prescribed for the first week, and neck rotation or bending is limited. For 2 weeks after intervention, sitting, bending, and stooping are restricted. Athletic activities should be halted for a minimum of 6 weeks. Follow-up relies mainly on clinical symptoms. The main goal is to decrease pressure in the herniated disc by removing the nucleus pulposus through thermal energy (laser) or radiofrequency.
For lumbar levels, a dedicated 17-gauge introducer needle is inserted into the disc via a conventional posterolateral approach and placed at the posterior annulus/nucleus junction (08). The radiofrequency electrode is inserted coaxially. Its curved tip allows the creation of different channels within the nucleus when the axis of the electrode is rotated. Six to 10 channels are created depending on the desired amount of tissue reduction. The gas produced by nucleus disintegration escapes through the introducer needle. Particular caution should be taken to keep the electrode parallel to the adjacent vertebral endplates to avoid touching them during the procedure. The ablation procedure usually takes less than 2 minutes once the electrode is in position.
High-frequency spinal cord stimulation. High-frequency spinal cord stimulation is an invasive procedure that is used to relieve pain in patients with failed back surgery. Spinal cord stimulation is performed by an implanted stimulation device connected to electrodes placed near the spinal cord. A 10-kilohertz high-frequency spinal cord stimulation is superior in relieving pain in comparison to conventional low-frequency (50 hertz) spinal cord stimulation (39).
Indications
The main indication of percutaneous disc decompression is a failure of conservative therapies like image-guided steroid injection to control radicular pain due to disc herniation. CT or MRI should demonstrate a contained disc herniation that clinically correlates with radicular pain. Conservative treatment should be attempted for at least 6 weeks, including image-guided selective steroid injection.
A worldwide survey regarding current practice patterns of surgeons about surgical and nonsurgical management of lumbar disc herniation shows that international practice patterns for lumbar disc herniation surgery are diverse. There is a discrepancy between preferred surgical techniques, the attitudes of surgeons worldwide, and the evidence (18).
Contraindications
Extruded disc herniations or free discal fragments benefit from open surgery rather than percutaneous nucleotomy. This is based on the concept that the intervertebral disc is a closed hydraulic system; therefore, only contained herniations can be expected to respond to a reduction of intradiscal pressure. Other contraindications include nerve paralysis, hemorrhagic diathesis, spinal stenosis or instability, greater than 50% of disc collapse, and infection. Patients with severe neurologic symptoms, such as cauda equina syndrome or paraplegia, may benefit from open surgery (51). Previous surgery at the same level is considered a relative contraindication. Due to the lack of safety data, pregnancy is considered a contraindication as well.
Results
Disc decompression is confirmed by radicular pain relief. CT or MRI control is only indicated if a complication is suspected. The shrinkage of the herniation is generally moderate and only visible after several months. A decrease in pain and improvement of quality of life has been reported in 70% to 89% of cases for both radiofrequency nucleoplasty and percutaneous laser disc decompression (05; 21). Pain improves rapidly and stabilizes after 6 weeks. The success rate is similar for lumbar and cervical levels if used for precise indications.
The overall results of radiofrequency nucleoplasty and laser decompression are very similar (23). With nucleoplasty, the disc decompression is much faster (less than 2 minutes once the electrode is in the disc), and the risk of thermal damage to the adjacent vertebral endplates is reduced as lower temperature is utilized. One drawback of radiofrequency nucleoplasty is the cost of the electrode, which is significantly higher than the cost of the laser fiber.
Adverse effects
The overall rate of complication is low: 0.6% to 1% for cervical levels and 0.4% to 0.5% for lumbar levels (26). The major complication is infectious spondylodiscitis, which is rare. Thermal injury to the adjacent vertebral endplates leading to aseptic spondylitis with severe back pain has been reported. If back pain occurs during vaporization, the position of the optical fiber should be checked as well as the laser energy delivered (08).
Mayer and collaborators reported in a retrospective analysis of 658 patients treated at nine different centers with percutaneous laser disc decompression 1.1% and 1.5% intraoperative and postoperative complication rates, respectively (51). Four patients had radicular deficits; L5 nerve root injury was seen in three patients, vascular injuries in two, sigmoid artery injury in one, anomalous iliolumbar artery injury in one, and transverse process injury in one.
The overall prognosis of low-back pain due to herniated discs is good. The evidence of percutaneous laser disc decompression is moderate for short-term and limited for long-term relief (06). Reintervention rates are reported to be between 5% and 25% (36; 03). The evidence for radiofrequency nucleoplasty is limited for short- and long-term relief (06).
Special considerations
Low-back pain is common during pregnancy; it has been reported in as many as 90% of pregnant women (17; 40; 01). However, the incidence of symptomatic lumbar disc displacement is extremely rare, occurring in approximately 1/10,000 pregnancies (32). The incidence of lumbar disc herniation may not increase by pregnancy. However, the prevalence of lumbar disc herniation during pregnancy has increased because the mean age of women becoming pregnant is higher (07).
Surgical indications of lumbar disc herniation in pregnant women are not different from the general population. If neurologic symptoms are minimal and stable, surgical treatment can be postponed until after delivery. Absolute surgical indications are cauda equina syndrome or progressive motor weakness and represent fewer than 2% of lumbar disc herniations (40). In such cases, emergent surgery can be safely performed at any stage of pregnancy (30). Classic surgical methods include laminectomy and discectomy under microscopy. Han and collaborators described the surgical management of five pregnant women with herniated lumbar discs (24). All women underwent partial hemilaminectomy and successfully completed their pregnancies. There are no reports in the literature about the use of percutaneous laser disc decompression or radiofrequency nucleotomy in pregnant women, and the safety of these procedures in this population is uncertain. Moreover, pregnancy is a contraindication for steroid neural blockade and other therapeutic interventional techniques such as neuroablation, intradiscal therapies, percutaneous disc decompression, and vertebral augmentation (06).
