Lumbar disc herniation (LDH) is the most common cause of low back pain, the most studied subject in spinal disorders, and the most frequently encountered clinical problem in pain medicine. Since the first description of LDH by Mixter and Barr in 1934, clinical knowledge of LDH has been accumulated for 70 years, and a wealth of experience in diagnosis and treatment has been accumulated.
Especially in the last 20 years, the development of neurobiology, spinal surgery, imaging, pain and material science, the application of endoscopic techniques and minimally invasive interventions have given us more options to diagnose and treat LDH. At the same time, it also brings us a lot of confusion, such as how to evaluate the traditional treatment? How to objectively view and apply new technologies? How do clinicians choose treatment methods? How to improve the effectiveness of treatment to meet the needs of patients is still a challenge that the medical community must face. At present, we must understand the diagnosis and treatment status of lumbar disc herniation in an objective and scientific manner in an effort to improve the diagnosis and treatment of LDH.
I. Lumbar disc degeneration is the basic pathogenesis of LDH
The lumbar intervertebral disc is one of the earliest organs in the human body to degenerate, starting at about 20 years of age, and is an irreversible degenerative change process that occurs under the influence of multiple factors. The degenerated disc has a reduced ability to resist pressure due to the degradation of proteoglycans in the nucleus pulposus and a reduction in polymerized water; the collagen composition changes make it less able to buffer pressure and resist tension, and the combined effect of the two decreases the mechanical function of the disc to absorb load and disperse stress.
Based on the degeneration of the biochemical composition of the disc, the loss or weakening of biomechanical function leads to a series of changes in the annulus fibrosus, such as fissures, ruptures and even ruptures, which eventually leads to protrusion of the nucleus pulposus, compression and stimulation of the spinal cord and nerve roots, resulting in symptoms and signs of lumbar pain. The International Society for the Study of the Lumbar Spine (ISSLS) and the American Academy of Orthopaedic Surgery (AAOS) classify LDH as degenerative, bulging, herniated (under the posterior longitudinal ligament), prolapsed (behind the posterior longitudinal ligament) and free. The degenerative type is an early change and is generally not confused with the herniated type. The more problematic type is the meaning and treatment of bulging and bulging. Bulging disc is a degenerative disc with a reduced height and a symmetrical peripheral annulus fibrosus that exceeds the normal physiological limits of the vertebral endplate edge, with the disc bulging backwards in the MRI sagittal plane, showing 1.6 to 2.3 mm beyond the periphery of the vertebral body in CT and MRI cross-section.
Due to low back pain in the majority of middle-aged people, the disc has been degenerated, and therefore often reported as “disc bulge” in the imaging, such as this imaging report, not combined with the patient’s symptoms, signs and neurological localization, and perform chemical lysis of the nucleus pulposus, discotomy or electrothermal discoplasty, that can Theoretically, a bulging disc can be misunderstood. Theoretically, disc bulge is a physiological degenerative process, and in the absence of other pathological factors, most bulges do not produce symptoms. Most patients with LDH can recover by non-surgical treatment.
II. Pathological typing of LDH
There are many methods of LDH typing, and pathological typing is an important guide for judging prognosis and choosing treatment methods.
1, bulging type (bulging): physiological degeneration, the fiber ring is relaxed but intact, the nucleus pulposus is crinkled, as shown by the fiber ring uniformly beyond the edge of the vertebral body end plate. Generally no clinical symptoms, sometimes due to narrowing of the intervertebral space, vertebral joint instability, secondary changes in the joint protrusion, recurrent back pain, rarely radicular symptoms. If combined with developmental spinal stenosis, the spinal canal stenosis is manifested and spinal decompression should be performed.
2, protrusion: protrusion is the protrusion of the nucleus pulposus into the annulus fibrosus but the outer layer of the annulus fibrosus is intact, manifesting as a limited protrusion of the intervertebral disc into the spinal canal, which can be asymptomatic, and some patients show typical neurogenic symptoms and signs. This type can be relieved by conservative methods such as traction, bed rest and lesion injection, but the recurrence rate is high due to the poor healing ability of the ruptured annulus fibrosus.
3, extrusion type (extrusion): complete rupture of the fiber ring, posterior longitudinal ligament, the nucleus pulposus protrudes into the spinal canal, there are obvious symptoms and signs, extrusion is difficult to self-heal, conservative treatment effect is relatively poor, most need minimally invasive intervention or surgery.
4, free type (seqestration): the herniated nucleus pulposus is not connected with the corresponding intervertebral disc, and can be free into the upper or lower segments of the spinal canal, intervertebral foramen, etc. Its clinical manifestations are persistent neurogenic symptoms or spinal stenosis symptoms, and a few can appear cauda equina syndrome, this type often requires surgery.
3. Distinction between LDH and discogenic pain
Lower back pain caused by intervertebral disc lesions can be broadly divided into two categories according to their pathogenesis: discogenic and spinal cord or nerve-derived. The difference lies in whether the pain is confined to the lower back or involves radiating pain to the lower extremities, with the latter indicating nerve root damage, mostly due to disc herniation. Discogenic pain is defined as degeneration of the fibrous annulus forming an internal fissure without superficial rupture, without signs and symptoms of nerve root damage, and is dominated by chronic lumbosacral pain that is aggravated by sitting. The diagnosis depends on MRI showing degenerative manifestations of the intervertebral disc, and T2-weighted images showing a high-signal area posterior to the disc, suggesting a fissure behind the fibrous ring, as the fissure contains fluid from the disc and a local inflammatory response.
Discography induces corresponding pain and reveals a disc fissure extending into the outer 1/3 of the annulus fibrosus, usually a marginal tear connected to the nucleus pulposus. At the same time, other adjacent discs may be free of degeneration, and discography without replication of pain is diagnosed as discogenic pain when combined with clinical symptoms and signs.
After the diagnosis of this disease, non-surgical treatment is mainly applied, and in recent years, intradiscal electrothermal therapy and ozone nucleolysis therapy are mostly used, the former including radiofrequency intradiscal electrothermal IDET (intradiscal electrothermal IDET) or intradiscal electrothermal fibrous annuloplasty (intradiscal electrothermal IDETA). The puncture catheter of IDETA can be circumferentially curved to reach the posterior annulus fibrosus rupture along the annulus fibrosus tissue and gradually heated to cause collagen fibers to contract, degenerate, polymerize, and destroy local nerve endings. These new treatment methods have been developed rapidly recently, but the long-term efficacy remains to be observed.
IV. Selection and evaluation of LDH treatment methods
(i) Conservative treatment
It is the basic treatment method for LDH. Most patients with LDH can be relieved or cured by conservative therapy, which aims to accelerate the decompression of inflammatory edema in the herniated part of the lumbar disc and the irritated nerve roots, thus reducing or relieving the irritation and compression of the nerve roots.
1.Conservative therapy is mainly suitable for: ① young people with first attack or short duration of disease; ② people whose symptoms can be relieved by themselves after rest; ③ people without spinal stenosis on X-ray examination.
2.Specific methods include absolute bed rest, continuous traction, physiotherapy, massage, massage, oral anti-inflammatory and pain-relieving drugs, focal injection therapy, etc. The role of focal injection therapy is to reduce the inflammatory response of the nerve root, with an efficiency of 76% for the herniated type and only 26% for the bulging type. Generally, regular conservative treatment for 6-8 weeks has no effect on the consideration of other methods, and it is currently believed that the efficacy of surgery within 2 months of onset is significantly better than that of late surgery.
(II) Minimally invasive interventional techniques
1.Intervertebral disc chemolysis (chemonucleolysis)
Chemical lysis of the intervertebral disc is the application of collagenase hydrolysis, resulting in the degradation of the nucleus pulposus or herniated material, and achieving the treatment purpose by relieving the irritation and compression of the nerve root. This technique is mainly used for herniated and prolapsed LDH, and a large number of basic and clinical studies have shown that disc chemolysis is an alternative treatment method. The current problem in China is that the indications for this treatment should be clarified and the technical operation should be strictly regulated. Due to the lack of formal training of some operators and irregular treatment, various complications and accidents have occurred. Therefore, it is necessary to discuss the safety and operation specification of collagenase chemolysis. According to the author’s several years of clinical experience and related research, I have learned that the safety of collagenase chemolysis depends on the following factors.
① Correct selection of indications and contraindications; strict operation according to the specifications;
(3) Awareness of the risk of inadvertent introduction of collagenase into the subarachnoid space and preventive measures.
(1) Indications.
① Chronic LDH with clear clinical diagnosis and ineffective conservative treatment;
② Acute and subacute LDH;
③Protruding and dermoid LDH;
(iv) LDH with central calcification of the protrusion and no surrounding calcification;
⑤ Combined mild bony spinal stenosis without nerve entrapment and cauda equina syndrome.
(2) Contraindications.
① Combined bony spinal stenosis with nerve entrapment and cauda equina syndrome;
② Severe bilateral stenosis of the lateral saphenous fossa or ipsilateral stenosis of the lesion;
(iii) Severe calcification of the protrusion; (iv) Significant apprehension in patients with a history of severe drug allergy;
⑤ Patients with severe metabolic diseases such as liver cirrhosis, active tuberculosis, and severe diabetes mellitus;
(6) Pregnant women and children under 14 years of age.
(3) Recognize the risk of inadvertent introduction of collagenase into the subarachnoid space and preventive measures.
①Animal experiments showed that the injection of collagenase into the subarachnoid space of rats led to spinal cord hemorrhage and necrosis, and all experimental rats developed hind limb paralysis. It is suggested that collagenase accidentally injected into the subarachnoid space can cause spinal cord injury.
The incidence of delayed spinal anesthesia was 1.22%.
③ collagenase chemical lysis when the local anesthetic test dose observation time should be extended to 20 minutes, 20 minutes after no signs of spinal anesthesia before the injection of collagenase, this method is called delayed spinal anesthesia test. The promotion of this method by clinical observation of large samples is an effective measure to prevent the inadvertent introduction of collagenase into the subarachnoid space.
2.percutaneous lumbar discectomy (PLD)
The mechanism of PLD is to reduce the disc pressure by removing the disc tissue, thus diminishing or eliminating the tension mechanism of nerve root damage. Clinical reports of randomized controlled studies have an excellent rate of less than 70%, with only 10-15% of indications. Patients requiring surgery are suitable for this technique, but the operation is blind and the postoperative recurrence rate is high. The efficacy and reliability are inferior to those of chemical lysis and endoscopic disc removal, and this technique is not used alone.
3.percutaneous laser disc decompression (PLDD)
Choy et al. reported an excellent rate of 78%, but most authors subsequently reported a significantly lower efficacy than chemical lysis. This procedure is also a non-direct vision minimally invasive procedure, and its safety, efficacy and cost-effectiveness ratio need to be further observed.
4. Endoscopic discectomy (microendoscopic discectomy, MED)
(1) The endoscope is divided into three types according to the access.
(1) Posterior-lateral transvertebral foramen approach discectomy.
(2) Anterior laparoscopy.
(3) Posterior discoscopy: i.e., standard interlaminar disc approach.
(2) MED is suitable for single-segment paracentral herniation and prolapse, and allows simultaneous decompression of the spinal canal such as lateral fossa enlargement. Due to good monitoring of the imaging system, it avoids blindness, precise localization, appropriate amount of resection and effective decompression, little trauma, quick recovery, good spinal stability, and high recent excellent rate. However, due to the limitation of exposure, high technical requirements, difficulty, difficulty in complete surgery, and long-term efficacy to be further observed.
(III) Selection of surgical methods
1. Indications for surgery Those who are diagnosed with LDH by symptoms, signs, imaging and neurological localization, who have not been relieved by regular conservative treatment for 6 to 8 weeks, who have sensory-motor dysfunction, cauda equina syndrome, intolerable pain or recurrent attacks affecting work and life.
2. Contraindications to surgery Patients with severe cardiopulmonary, hepatic and renal diseases, infectious lesions, severe neurasthenia and psychiatric disorders.
3.Selective surgical methods
(1) Open decompression surgery: low back pain with unilateral lower limb pain and accumulation of one gap.
(2) Hemilaminectomy: patients with low back pain accompanied by unilateral limb pain, accumulating two interstitial spaces or those with original diagnosis of protrusion of a certain interstitial space and intraoperative discovery of pathological changes in that interstitial space insufficient to explain preoperative symptoms and the need to explore the adjacent interstitial space.
(3) Total laminectomy.
(i) Giant central lumbar disc herniation with symptoms of acute cauda equina injury.
(2) For recurrence after nucleus pulposus removal that is ineffective with conservative treatment and requires a second operation.
③For those with extreme lateral type or combined spinal stenosis. Partial resection of the articular process or resection of the articular process to achieve complete decompression of the spinal canal and nerve root canal is the fundamental guarantee of satisfactory results. The clinical data and a large number of cases have an excellent rate of 80-90%, and the excellent rate is still 75-80% 15 years after surgery.
4.Efficacy evaluation
A small number of people still have residual low back pain and worsening symptoms after LDH treatment with the standard procedure. These manifestations are often attributed to pathological changes such as narrowing of the intervertebral space after discectomy, secondary lumbar instability, and spinal stenosis. The pain of many such patients has been resolved by methods such as segmental fusion, including posterior intertransverse fusion; intervertebral fusion and the intervertebral fusion device technique (BAK, Cage) developed in the 1990s, and it is now generally accepted that the fusion rate is positively correlated with the clinical satisfaction rate. It has also been observed through a group of patients combined with internal fixation followed by posterior posterolateral fusion that despite a fusion rate of 89%, the clinical satisfaction rate was only 60%. Therefore, some authors believe that a solid fusion does not necessarily predict a satisfactory clinical outcome and that there may be other reasons for residual symptoms after conventional disc surgery.
(iv) Reconstruction techniques
Accelerated disc degeneration in adjacent segments after lumbar fusion and the formation of pseudoarthrosis in fused segments leading to intractable postoperative low back pain have raised concerns. Allogeneic disc transplantation, artificial disc replacement, attempts of artificial nucleus pulposus technology aiming to reconstruct the physiological function of the disc and experimental studies of gene therapy for delaying and reversing disc degeneration are new topics in the treatment of disc diseases.
1.Allogeneic disc transplantation
At present, it is difficult to be used clinically due to the problems of early degeneration and displacement. Artificial nucleus pulposus prosthesis replacement is suitable for a small number of patients with LDH and discogenic lower back pain with intact annulus fibrosus and intervertebral space height ≥5mm, and the clinical effect is symptom relief and satisfactory restoration of intervertebral space height. Its shortcomings are prosthesis displacement and postoperative lumbar and leg pain residual, materials and processes to be further studied.
2. Artificial total intervertebral disc replacement
The indications that can be considered at present are mainly discogenic pain, post-lumbar discectomy failure syndrome, while LDH in general should be considered as a contraindication because most LDH has good long-term results by conventional decompression and/or fusion. The choice of indication for any technique is the primary issue, because if there are very few cases with this technique or if there are other simpler, safer, and more effective methods available, then the widespread use of this technique is questionable. Until the material problem is solved, no artificial disc design and technology can replace conventional decompression fusion, and blind clinical application can be too costly for patients.
3, gene therapy Some people hope that gene therapy strategies to achieve the purpose of delaying or reversing disc degeneration, growth factors and disc degeneration, regeneration of the relationship between one of the hot spots, animal testing through transgenic methods to regulate the expression of a certain growth factor to promote the regeneration of the intervertebral disc extracellular matrix has shown initial results, I believe that in the future there is hope to apply to humans, to delay the purpose of disc degeneration.
In conclusion, it is the inescapable responsibility of our clinicians to explore, innovate and experiment with therapeutic methods, and it is correct to require any innovation to be less costly, safer and more effective than existing methods. At present, in addition to conventional open surgery, minimally invasive interventional techniques have been an important means of treating LDH, especially for those with more severe symptoms, with better results than conservative treatment. For spine surgery how to prevent postoperative failure syndrome (FBSS) has always been a challenge to the operator, practice has proved that strict mastery of surgical indications and careful performance of the first surgery is the key to prevent postoperative FBSS, because the second surgery can only improve in 50% of cases, while 20% worsen. Therefore, correct diagnosis and reasonable treatment of LDH is the key to achieve satisfactory results.