Symptomatology, diagnostics, therapies

Lumbar back pain is one of the most common complaints in the population. Lumbar spinal stenosis is a common cause of lumbar back pain. An overview.

Lumbar back pain is one of the most common complaints in the population and occurs in adults with a prevalence of 30-70% depending on age. They are the main cause of incapacity for work and the need for medical rehabilitation. Musculoskeletal disorders are among the most costly diseases in industrialized countries and are the second leading cause of premature retirement after psychiatric disorders. Whereas in non-specific back pain, which is by far the most common type (80-90%), there is no correlation between the complaints, the clinical findings and the imaging diagnosis, in specific back pain a compression of neural structures, an inflammation of joints or an instability of the spine with corresponding symptoms can be detected. These can be lumbar disc herniations, spinal stenosis, spondylolisthesis, vertebral body fractures, vertebral body metastases, spondylarthritides or spondylodiscitides, etc [1].

Definition

Lumbar spinal stenosis is a common cause of lumbar back pain with radiation to the legs, occurring predominantly in older age. The prevalence of degenerative spine disease is nearly 100% in patients over 60 years of age.

Radiologically, lumbar canal stenosis is defined as circumscribed osteoligamentous narrowing of the spinal canal to an anterior-posterior diameter of 10-14 mm in relative and less than 10 mm in absolute spinal stenosis on axial computed tomography. According to radiological criteria, more than 20% of all patients over 60 years of age have spinal stenosis.

Pathogenesis

The cause is progressive segmental degenerative changes of the spine with degeneration and height reduction of the intervertebral discs with protrusion of the dorsal ligamentous structures into the spinal canal, increasing arthrosis of the facet joints and thickening of the ligamenta flava, leading to progressive narrowing of the spinal canal and neuroforamina. Secondary degenerative instability with deformity of the spine and rotational sliding (spondylolisthesis) may occur. Hyperlordosis during standing and walking leads to an increase in constriction with mechanical constriction of the nerve roots and vascular compression, so that the vascular supply to the spinal nerves is impaired. Whether this is due to arterial underperfusion or venous congestion is not clear pathophysiologically.

Clinical symptoms

Patients with lumbar canal stenosis suffer from load-dependent back pain with pseudoradicular or radicular radiation to the legs. This is referred to as spinal claudication. The legs are described as heavy, powerless or tired. Secondary neurological deficits or bladder disorders may occur. The bent-forward gait as a compensatory mechanism is typical. Riding a bicycle and leaning on a shopping cart alleviate the discomfort, as this achieves kyphosis of the lumbar spine.

Differential diagnoses

Spinal stenosis may occur simultaneously with other pathologies of the lumbar spine. In addition to other disorders of the lumbar spine such as lumbar disc herniation, spondylolisthesis, spinal fractures, spinal inflammation and tumors, facet or sacroiliac joint arthrosis, differential diagnoses include the following conditions in descending frequency: Peripheral arterial occlusive disease, Cox/gonarthrosis, cervical or thoracic stenosis with myelopathy, neuropathies, somatization disorders, osteoporotic sintering fractures, tendopathies, abdominal aortic aneurysm, Leriche syndrome, chronic inflammatory CNS diseases and neurological systemic diseases, thromboses, etc.

Diagnostics

The basis for the diagnosis of spinal stenosis is a detailed history with recording of general symptoms of the disease, a detailed description of pain, neurological deficits and other limitations of function. Relevant points from the history and physical and neurologic examination are summarized in Table 1. On the one hand, the physical examination is symptom-related; on the other hand, differential diagnoses must be excluded by means of a comprehensive clinical and neurological examination. Back pain can be an expression or accompanying symptom of a serious disease (“red flag”), which must be ruled out by further diagnostics. In patients with chronic back pain (over twelve weeks), additional psychosocial risk factors, so-called “yellow flags”, must be recorded.

The imaging modality of choice is lumbar magnetic resonance imaging (MRI). As a rule, T1- and T2-weighted sequences are performed sagittally and axially (Fig. 1) . Contrast medium administration is only necessary for the detection of tumors or infections. Native X-rays of the lumbar spine and lumbar computed tomography provide information on the bony conditions or the extent of osteoporosis or allow the detection of fractures, tumors or scoliosis. If segmental instability is suspected, spinal images are performed. Functional imaging of the lumbar spine and lumbar myelography are becoming less important. Electrophysiologic studies play a role only in ruling out possible differential diagnoses.

Therapy

The decision on therapy is based exclusively on the patient’s complaints, not on the radiological image. The extent of radiological changes does not necessarily correlate with the patient’s symptoms. Although there are few data on the spontaneous course of spinal stenosis, it can be assumed that the symptoms remain stable or may regress in the medium term. However, there is evidence that patients with higher-grade spinal stenosis are at higher risk of becoming symptomatic and progressive.

Conservative therapy

It is essential to inform the patient in detail about the disease, its natural course and how it can be influenced by therapies. This includes advice on behavior in everyday life, at work and during sports. Conservative therapy includes the use of NSAIDs (ibuprofen, diclofenac, naproxen) or weak opioids. There is little evidence for the use of acetaminophen and none for muscle relaxants and steroids. Analgesics should be used for as short a time as possible. Patients should maintain normal activity levels to the extent possible. Bed rest is not indicated, nor is intensive exercise therapy. Physiotherapeutic treatment with de-lordotic exercises, medical training therapy to stabilize the abdominal and back muscles, manual therapy measures and relaxation procedures are perceived by patients as alleviating their symptoms. However, the effectiveness  of these methods is not proven. Therapy is symptomatic, not causal, and does not prevent progression of spinal degeneration.

Peridural injections of local anesthetics and/or cortisone into the spinal canal, infiltration of the facet joints, or periradicular therapy of the spinal nerves may have short- and medium-term analgesic and activity-enhancing effects without clear evidence. Combined injection of a local anesthetic with a glucocorticoid does not provide any additional benefit in the short or long term compared with local anesthesia alone [2].

Surgical therapy

Machado et al. have analyzed in detail in a large Cochrane analysis the place of surgical treatment in comparison between surgical techniques, to conservative procedures, to implantation of interspinous spreaders and to spondylodesis [3]. Surgical decompression, regardless of the surgical method chosen, provides an advantage over conservative therapy in terms of pain control, functionality, and patient satisfaction for the first four  to six years. The convalescence time  is usually shorter in operated patients than in conservatively treated patients [4]. Advanced age is not per se a contraindication to surgery: even those over 80 years of age benefit significantly from decompression of lumbar stenosis [5].

There is a clear indication for surgery in the presence of neurological deficits, uncontrolled pain, or a severe limitation of the patient’s quality of life and functionality. Surgical treatment of lumbar stenosis should lead to decompression of the dural tube and nerve roots and in this way to symptom relief. A variety of different surgical techniques are used (Table 2) .

The trend is toward minimally invasive decompression techniques using small unilateral approaches with undercutting to the other side to relieve spinal canal pressure, as these are as effective as larger approaches (Fig. 2) . A similar extent of bony decompression of the spinal canal can be achieved via all approaches [6]. Because laminectomies lead to a loss of dorsal traction tethering and in this way potentially lead to iatrogenic instability and have a higher risk of causing epidural hematomas, the other posterior decompression techniques appear to be superior [7]. The complication rate for spinal canal decompression is approximately 18%. At 9%, dura injury is the most common complication. Regardless of surgical technique, the reoperation rate within ten years is 18%. Half of reoperations are due to recurrent stenosis or spondylolisthesis, approximately 25% are due to complications, and 16% are due to new spinal pathology. 42% of reoperations are performed within the first two years, and a total of 84% of procedures are performed within eight years of the initial procedure [8]. Even in the presence of multisegmental stenosis, operating on the main level seems to be sufficient for significant improvement of symptoms and functionality in many cases [9].

Interspinous spreaders have been used more frequently in the last decade to reduce intradiscal pressure and widen the spinal canal and neuroforamina by distraction.  Neither implantation of an interspinous spreader alone nor implantation as part of decompression surgery provides any benefit and is even associated with an increased risk of complications and recurrent surgery [4].

In patients with mono- or bisegmental lumbar stenosis with or without degenerative spondylolisthesis, decompression with fusion does not result in a better outcome than decompression alone at two and five years, so the indication for spondylodesis should be reserved. Additional spondylodesis results in increased hospitalization and operative time, increased blood loss, and increased costs [10]. The indication for spondylodesis should only be given if there is evidence of symptomatic scoliosis, rotational instability with rotational sliding or sagittal misalignment, or if there are symptoms caused by increasing instability of the spine during the course of the disease. Which spondylosis technique to use,  has yet to be tested in clinical trials.

Conclusion

The indication for treatment of spinal stenosis is based exclusively on the patient’s symptoms. Although there is little evidence for conservative therapy, it can provide relief and stabilization of symptoms in many cases. In symptomatic stenosis, surgical therapy is superior to conservative therapy, although there is no evidence for the superiority of any specific surgical technique. Implantation of interspinous spreaders or spondylodesis is not indicated for most degenerative lumbar stenosis.

Take-Home Messages

• The diagnosis of spinal stenosis is not made exclusively radiologically, but clinically after exclusion of numerous differential diagnoses.
• Treatment of spinal stenosis is primarily conservative, as little is known about the spontaneous course of the disease, although there is little evidence for the efficacy of all conservative therapeutic approaches.
• Surgical therapy is superior to conservative therapy because it leads more quickly to a reduction in pain and an increase in the patient’s functionality and quality of life.
• The indication for surgery is symptom-based and should be made early in cases of neurological deficits and significant patient impairment.
• Implantation of interspinous spreaders and spondylodesis do not benefit patients with monosegmental or bisegmental stenosis with or without instability compared with decompression alone.

Literature:

1. National Health Care Guideline Non-specific Low Back Pain. 2nd edition, version 1, 2017, AWMF registry no. nvl-007.
2. Friedly JL, et al: Long term effects of repeated injections of local anesthetic with or without corticosteroid for lumbar spinal stenosis: a randomized trial. Arch Phys Med Rehabil 2017; doi 10.1016/j.apmr.2017.02.029
3. Machado GC, et al: Surgical options for lumbar spinal stenosis (review). Cochrane Database of Systematic Reviews 2016; Issue 11, Art. No. CD012421
4. Lurie JD, et al: Long-term outcomes of lumbar spinal stenosis: eight-year results of the spine patient outcomes research trial (SPORT). Spine 2015, 40(2): 63-76.
5. Antoniadis A, et al: Decompression surgery for lumbar spinal canal stenosis in octogenarians; a single center experience of 121 consecutive patients. Br J Neurosurg 2017; Vol. 1, doi 10.1080/02688697.2016.1233316.
6. Leonardi MA, et al: Extent of decompression and incidence of postoperative epidural hematoma among different techniques of spinal decompression in degenerative lumbar stenosis. J Spinal Disord Tech 2013; 26(8): 407-414.
7. Overdevest GM, et al: Effectiveness of posterior decompression techniques compare with conventional laminectomy for lumbar stenosis. Cochrane Database of Systematic Reviews 2015, Issue 3 Art. No.: CD010036.
8. Gerling MC, et al: Risk factors for reoperation in patients treated with surgically for lumbar stenosis: a subanalysis of the 8 year data from the SPORT trial. Spine 2016; 41(10): 901-909.
9. Ulrich NH, et al: The influence of single-level versus multilevel decompression on the outcome in multisegmental lumbar spinal stenosis: analysis of the lumbar spinal outcome study (LSOS) data. Clin Spine Surg 2017, doi 10.1097/BSD.00000000000469.
10. Försth P, et al: A randomized controlled trial of fusion surgery for lumbar spinal stenosis. N Engl J Med 2016: 374: 1413-1423.

InFo NEUROLOGY & PSYCHIATRY 2017; 15(3): 10-13.