Degenerative lumbar spinal stenosis (DLSS) is an age-related disease and one of the common diseases of chronic back and leg pain in the elderly. With the increase of aging population and the increase of average life expectancy in China, the incidence of DLSS in the elderly is increasing, which seriously affects their daily activities and even loss of self-care ability. At the same time, most elderly patients are accompanied by medical disorders, so the treatment of DLSS in the elderly has special characteristics. The treatment of DLSS in the elderly and related issues are now discussed.
1.Pathological mechanism of DLSS
With increasing age, degenerative changes occur in the lumbar spine. The basis of the degeneration is the degeneration of the intervertebral disc, the loss of water in the nucleus pulposus, the rupture of the fibrous ring and the degeneration of the cartilage plate, which reduces the pressure in the nucleus pulposus, decreases the bearing capacity of the lumbar intervertebral disc, increases the stress around the vertebral body, causes the formation of vertebral lip-like hyperplasia and leads to the narrowing of the spinal canal and the nerve root canal; the degeneration of the intervertebral disc also causes the narrowing of the intervertebral space, the reduction of the intervertebral foramen and the shortening of the spinal canal, which further reduces the volume of the spinal canal The compensatory reaction of segmental instability and the increase of stress in the small joint capsule lead to hyperplasia and coalescence of the small joints and vertebral plates, and the ligamentum flavum is also hyperplastic and thickened, and some of them even calcify and ossify and protrude into the spinal canal, causing lumbar spinal stenosis. The narrowed spinal canal eventually leads to compression of the cauda equina or the corresponding nerve root, which then produces more obvious clinical manifestations, such as lower back pain, lower limb sensorimotor impairment and characteristic neurogenic intermittent claudication (NIC).
2.Characteristics of DLSS in the elderly
The main symptoms and signs of DLSS are low back pain, restricted movement, discomfort in standing position, painful numbness of lower limbs, NIC, muscle atrophy, weakened muscle strength of lower limbs, and weakened or disappeared Achilles and knee tendon reflexes.
As far as it is concerned, elderly patients have the following characteristics.
(1) Slow onset, long duration, sometimes mild and sometimes severe, many lesion segments, and complex symptoms and signs.
(2) Recurrent intermittent attacks. The typical manifestation of spinal stenosis is that some patients have difficulty walking a hundred meters on foot and can continue to walk after sitting or squatting down to rest.
(3) Many patients have a combination of chronic respiratory disease, cardiovascular disease, diabetes mellitus and different degrees of osteoporosis, which increases the risk and complications of surgery to some extent.
(4) The narrowed spinal canal can cause severe compression of nerve roots, nerve root adhesions and fixation, degeneration and atrophy.
(5) Most of them are accompanied by disc herniation, degenerative vertebral slippage, degenerative lumbar lordosis, lordosis or segmental instability, etc.
3.Conservative treatment
Patients with the first onset of the disease are routinely treated conservatively. The methods mainly include anti-inflammatory and analgesic, nerve nutrition, physical therapy, exercise, massage, acupuncture, lumbosacral brace, traction, epidural injection of drugs, etc. According to the 2007 Evidence-Based Guidelines for Degenerative Lumbar Spinal Stenosis published by the North American Spine Surgery Society, multiple imaging-assisted epidural injections have long-term efficacy in DLSS, but there is no or insufficient evidence of long-term efficacy in other non-surgical treatments. For mild patients, non-surgical treatment can achieve longer-term efficiency; however, for patients with moderate to severe disease, surgical treatment is more effective than non-surgical treatment.
4.Surgical treatment
For patients whose conservative treatment is ineffective, surgical treatment is one of the effective methods. With the development of imaging and internal fixation technology, the surgical treatment of DLSS has also made significant progress. The surgical plan for DLSS in the elderly should be determined based on multiple factors such as the specific condition, age, and general condition of the patient.
Among the surgical approaches currently performed, they can be broadly categorized into three major groups.
(1) Fusion internal fixation.
Decompression fusion internal fixation is a commonly used surgical method in the past. This procedure has the advantages of complete decompression and restoration and maintenance of spinal stability, but also has the disadvantages of high trauma, complicated surgery, and high complications. However, fusion internal fixation is necessary in some cases with combined segmental instability, degenerative spinal slippage, scoliosis, and where decompression can destabilize the spine. Posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), posterior lateral lumbar fusion (PLF), and extreme lateral interbody fusion (XLIF) are the most commonly used fusion methods. Regardless of the fusion method, precise surgical manipulation, an ideal bone graft bed, and an adequate amount of bone graft are important. Adequate decompression is the key to successful surgical treatment of DLSS. Patients will have a good outcome as long as bony fusion can be obtained after surgery. The extent of fusion should be limited to the vertebral body of the responsible segment, with short segmental fusion whenever possible. Do not fuse across the lesion, as extensive fusion may accelerate degeneration of the adjacent active lumbar segment and produce adjacent spondylolisthesis (ASD).
(2) Non-fusion internal fixation.
Numerous follow-up studies have shown that fusion internal fixation is of increasing concern because of the complications associated with internal fixation fracture, sagittal imbalance, pseudoarthrosis, bone graft failure, and degeneration of adjacent segments, in addition to partial loss of lumbar spine motion. With the development of nonfusion techniques, certain degenerative lumbar spinal stenosis is surgically decompressed and then fixed in a nonfusion manner accordingly. Some of the commonly used non-fusion techniques are the posterior interspinous dynamic internal fixation system and the posterior transforaminal dynamic fixation system (Dynesys system).
In recent years, dynamic stabilization techniques to protect lumbar spine motion have matured, and the use of Coflex, Wallis, Aperius, and interspinous dynamic assisted motion (DIAM) systems as posterior interspinous stabilization devices in degenerative lumbar spine diseases has been gradually developed. Biomechanical studies have shown that interspinous dynamic stabilization devices significantly reduce disc pressures and synovial loads, prevent further narrowing of the spinal canal and nerve root canal, and are effective in the short term. However, the use of interspinous dynamic stabilization devices has been associated with loss of intervertebral space height, spine fracture, and displacement of the prosthesis in the long term, which requires attention. The preferred indication for these interspinous dynamic stabilization devices should be a single-segment DLSS, and patients with too many segments or a combination of severe osteoporosis, lumbar segmental instability, or slippage should be contraindications to this technique.
The Dynesys Posterior Dynamic Stabilization System is a new non-fusion technique for the posterior spine. structure, providing dynamic stability. Because the mobility of the operated segment is preserved, the mobility of the upper and lower adjacent segments is not significantly altered before and after surgery, theoretically preventing degeneration due to excessive stress on the adjacent segments. Follow-up studies have found that the Dynesys System is effective in relieving clinical symptoms in patients with DLSS with or without lumbar spondylolisthesis, while reducing surgical and adjacent segmental degeneration.
(3) Minimally invasive techniques
Traditional open surgery decompresses too much and destroys the stability of the spine. Extensive soft tissue muscle stripping can cause muscle fibrosis and loss of innervation, resulting in muscle atrophy and low back pain and long recovery time. For some elderly patients with limited and well-defined spinal stenosis, especially those who are too frail to undergo open surgery, minimally invasive surgery is a more reasonable option. Although the efficacy of some patients is not as good as that of open surgery in terms of significance and durability, it has relieved the pain of these special elderly patients to a certain extent. The literature reports that decompression of both the operated side and the contralateral nerve tissue can be performed through a posterior median incision with satisfactory results by microscopic or minimally invasive endoscopic techniques. Single-segment mild to moderate patients are treated well with the minimally invasive technique, but multi-segment severe patients have poor results. Therefore, it is recommended that this technique be limited to single-segment DLSS.
5. Perioperative management
Elderly patients are often combined with medical diseases, so they should pay great attention to comprehensive and meticulous medical history, careful physical examination and improvement of auxiliary examinations, and if necessary, special examinations such as targeted dynamic electrocardiogram, cardiopulmonary function, cardiac ultrasound and cerebral angiography should be given. Pre-operatively, we should combine the internal medicine department for joint diagnosis and treatment, coordinate multidisciplinary consultation, actively and reasonably treat the accompanying diseases, make the patient’s systemic condition stable to reach the expected index, control blood pressure and blood sugar in a reasonable range, and achieve the requirements of satisfactory nutritional status and stable cardiopulmonary function. Postoperative analgesia, routine use of antimicrobial agents for 2 days, and if necessary, use of small doses of hormones. Whether to use anticoagulants after surgery is still controversial, but recently, more scholars advocate postoperative anticoagulation. According to the Guidelines for the Prevention of Major Orthopedic Venous Thromboembolism in China, anticoagulation can be considered for older patients (age >60 years) for 12-24 hours after surgery. The postoperative period should also be more closely monitored and treated for pre-existing or secondary comorbidities, and attention should be paid to the prevention of acute postoperative bone loss in elderly patients and the treatment of pre-existing osteoporosis to reduce the negative impact on the internal implant.
6.Surgical efficacy
The surgical efficacy of DLSS will be affected by the prolongation of the disease course, the increase of age and the aggravation of compression. As elderly people mostly have combined osteoporosis and lumbar strain, the symptomatic relief of back pain after surgery is not ideal and patients should be informed. Longer bed rest can also affect cardiopulmonary function, so early intervention should be made in elderly patients and the conservative time should not be too long.
In conclusion, elderly patients with DLSS are often combined with medical diseases and have their own special characteristics in treatment. For mild patients, conservative treatment has certain efficacy; however, for moderate and severe patients surgical treatment plays a more effective role and conservative treatment should not be too long. Among the current surgical treatment options, limited decompression is increasingly accepted by patients and spine surgeons because of its less invasive nature, preservation of spinal stability, and reduced perioperative morbidity and mortality. Of course, comprehensive assessment of the general condition of elderly patients, strict control of the indications for surgery, selection of a reasonable surgical plan, and individualized treatment are the keys to successful treatment of DLSS in the elderly.