Degenerative Lumbar Spinal Stenosis in Older People
Current Treatment Options
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Background: Degenerative lumbar spinal stenosis is increasingly being diagnosed in persons over age 65. In 2011, 55 793 older people with this condition were treated as inpatients in German hospitals. Among physicians, there is much uncertainty about the appropriate treatment strategy.
Method: Selective literature review
Results: Lumbar spinal stenosis in older people is characterized by spinal claudication and neurological deficits. A precise clinical history and physical examination and ancillary radiological studies are the necessary prerequisites for treatment. Magnetic resonance imaging is the radiological study of choice. Conservative treatment consists of physiotherapy, drugs, and local injections; various surgical treatments can be considered, depending on the severity of the problem. The main purpose of surgery is to decompress the spinal canal. If the lumbar spine is demonstrably unstable, an instrumented fusion should be performed in addition. There is, however, only moderately good evidence supporting the superiority of surgery over conservative treatment. In a prospective study, the complication rate of purely decompressive surgery was found to be 18%. The utility of the current operative techniques cannot be definitively assessed, because they are applied to a wide variety of patients in different stages of the disease and at different degrees of severity, and the reported results are thus not comparable from one trial to another.
Conclusion: No evidence-based recommendation on the diagnosis and treatment of lumbar spinal stenosis in older people can be formulated at present because of the lack of pertinent randomized trials.
Because of the aging of the population, neurosurgeons, orthopedists, trauma surgeons, and spine surgeons are now increasingly confronted with a very wide variety of degenerative changes of the lumbar spine. The treatment of symptomatic lumbar spinal stenosis is surely among the major clinical challenges of this kind. As the available scientific evidence on the diagnosis and treatment of this entity is not very reliable (1, 2), there is no currently valid overall assessment of treatment strategies for older patients (i.e., persons over age 65).
Not only do older people make up a higher percentage of the population than before; there has also been a disproportionate rise in the frequency of lumbar spinal surgery in this age group (3) (Figure 1). The precise nature of this rise is hard to determine, however, because of the broad range of spinal procedures that are performed, with widely varying degrees of complexity. In 2005, lumbar spinal stenosis (ICD-10 code M48.06) was given as the main admitting diagnosis of 28 001 hospitalized patients over age 65 in Germany. By 2011, this figure had more than doubled, to 55 793 (3).
Osteoporosis and other typical spinal problems of advanced age, multiple comorbidities, and the lessened physical performance that goes along with age are now accompanied, at least as far as our experience suggests, by markedly heightened expectations on the part of our older patients. Thus, the value of different treatment strategies needs to be rationally assessed. In this article, we ask what the existing scientific evidence tells us about the current methods of diagnosis and treatment of symptomatic lumbar spinal stenosis in older people. Possible treatment strategies are indicated.
The goal of this article is to acquaint readers with
- the specific therapeutic situation of spinal stenosis in older people,
- the pathophysiology, clinical manifestations, and clinical course of the condition,
- conservative treatment options, and
- the different operations that can be performed for this disease and the risks associated with each.
This article is based on a comprehensive, selective literature search in the main medical databases (Medline, Ovid, Cochrane Library, Web of Sciences), with particular attention to clinical trials, randomized controlled trials, reviews, and meta-analyses and to the search terms “lumbar spinal stenosis,” “lumbar degenerative spine disease,” “lumbar degenerative spondylolisthesis,” and “spinal spondylosis.”
Definition and pathogenesis
Even the definition of “lumbar spinal stenosis” is problematic. The term, standing alone, is a morphological description of imaging findings (anteroposterior [AP] diameter by computed tomography [CT] of less than 10 mm); it has no pathological significance in itself. Degenerative changes of the lumbar spine that are visible on magnetic resonance imaging (MRI) become more common with age and are present in nearly 100% of persons over age 60 (4). By radiological criteria alone, 21% of all persons over age 60 have lumbar spinal stenosis (5). The main radiological criteria for spinal stenosis are bony narrowing, obliteration of epidural fat, and deformities of the spine in the sagittal and frontal imaging planes.
The main cause of lumbar spinal stenosis is progressive segmental degeneration. From a patho-anatomical and pathophysiological point of view, disc degeneration is presumed to lead to loss of segmental height, with disc protrusion and ensuing narrowing of the spinal canal. The loss of segmental height also narrows the neural foramina and causes increasing protrusion of the dorsal ligamentous structures into the spinal canal. The altered biomechanical situation promotes progressive arthrosis of the intervertebral joints. Reactive hypertrophy of the ligamenta flava additionally narrows the spinal canal and the lateral recesses, so that, in the end, the spinal canal is hemmed in on all sides. Progressive changes of these kinds can bring about a secondary degenerative instability with the development of a pseudo-spondylolisthesis, i.e. a chronic degenerative slippage of the vertebral bodies, which narrows the spinal canal still further. Disc degeneration also promotes the formation of secondary curvatures in the frontal plane, leading to (for example) rotational slippage or a multisegmental deformity. A role for vascular factors in the pathophysiological process has been proposed, but not yet proved (6).
Lumbar spinal stenosis typically manifests itself clinically in spinal claudication, a symptom complex including exercise-related pain in the back and sometimes radicular, but more often pseudoradicular radiation of pain into the lower limbs. As the condition progresses, neurological deficits can arise in the lower limbs, including autonomic disturbances. The symptoms are typically worst when the patient walks in a body posture with marked lumbar lordosis, e.g., when the patient walks downhill; conversely, they are less severe when the lumbar spine is kyphotic, e.g., when the patient walks uphill or rides a bicycle. A further typical feature is that the older person stoops forward while walking. This can be thought of as a compensatory measure for the narrowing of the spinal canal (7).
Particularly in older people, the clinical picture may be blurred by accompanying illnesses. For example, it has been reported that 26% of elderly patients with lumbar spinal stenosis also have peripheral arterial occlusive disease (PAOD) (8), and a comparable percentage suffers from coxarthrosis (9). Meanwhile, a study from the Far East suggests that 100% of over 70-year-old patients with lumbar stenosis have either osteoporosis or osteopenia, although this finding clearly cannot be directly applied to the Central European population without further study (10). Potential differential diagnoses are listed in Box 1, the more common ones in boldface type. Patients (particularly older ones) often present with mixed clinical pictures that complicate diagnostic assessment and treatment planning.
Precise history-taking from patients with degenerative spinal diseases is very important, never more so than in the older patient. A sensible treatment can only be proposed when the clinical situation and the imaging findings are jointly considered. Specific history-taking should include the catalogue of questions and investigations that is given in Box 2.
The comprehensive physical examination should include a symptom-directed examination, a general physical examination (pedal pulses, pain on hip rotation, and further tests), and a thorough neurological examination. The possibility of accompanying systemic diseases of the nervous system—including old or recent stroke—should be considered and actively sought. Particularly when advanced degenerative changes are found in the lumbar spine, clinically relevant cervical spinal stenosis must be ruled out, as this can cause overlapping symptoms.
Especially in surgical candidates, a psychological evaluation is indicated as well. A psychopathological component may turn out to be an (accessory) cause of the patient’s symptoms.
Imaging studies are indispensable for diagnostic evaluation and treatment planning in symptomatic patients. There are many morphometric methods for the description of the spinal canal. Such terms as absolute and relative spinal stenosis are defined by purely radiological criteria and lack any clinical correlation in themselves. They thus convey no more than auxiliary information to be considered in treatment planning.
Lumbar MRI is the standard procedure for the demonstration of stenosis and cauda equina compression. As reported in the literature, its sensitivity is 87% to 96% and its specificity is 68% to 75% (11). As a rule, T1- and T2-weighted images should be obtained in both the sagittal and the transverse planes. It is now possible for MRI to be performed with the patient standing upright; this type of study will be increasingly useful in the future, as it enables visualization of the patho-anatomical changes that come about under axial loading.
Plain films of the lumbar spine can yield clues to the origin of exertional back pain and demonstrate degenerative changes. They should be obtained with the patient standing upright, because the pathological changes in the frontal and sagittal views are visible only under axial loading. When these changes are found, views of the entire spinal column in the standing position must be obtained in order to detect any instability due to the abnormal static conditions. In recent years, the role of functional x-ray studies has declined. Conventional films often reveal plentiful evidence of osteoporotic changes that need further work-up.
Lumbar CT may be useful for the assessment of bone condition and potential osteoporosis with a view toward the planning of surgery. If the use of implants is under consideration and osteoporosis is suspected, then either dual x-ray absorptiometry (DEXA) or a quantitative CT (qCT) should be performed. On the other hand, lumbar myelography with post-myelographic CT should now only be performed in exceptional cases. The main indications for this invasive study are the presence of metal implants in the lumbar spine that would make MRI uninterpretable because of artefacts, the need for dynamic assessment, and any residual diagnostic uncertainty after the relevant non-invasive tests have been performed.
Electrophysiological studies are mainly useful in that they can reveal potential differential diagnoses, e.g., spinal cord lesions or systemic disorders of the nervous system, but they may also help identify the segment that requires treatment when the patient presents with diffuse, multisegmental symptoms. The performance and interpretation of such studies are often complicated by coexisting non-pathological changes of advanced age, such as loss of the somatosensory evoked potential (SEP) of the tibial nerve, and/or by common age-related pathological conditions, such as diabetes mellitus and polyneuropathy affecting the tibial nerve.
Further diagnostic evaluation
Further ancillary testing may be needed to rule in or out the various differential diagnoses mentioned above. When PAOD is suspected, the test that is generally performed is Doppler-assisted measurement of the ankle-brachial index (ABI). Degenerative or traumatic diseases of the hips and pelvis need further radiological evaluation. Laboratory tests can help rule out inflammatory etiologies and can also provide evidence of an acute or chronic metabolic disturbance as the cause of symptoms: In particular, a complete blood count, C-reactive protein concentration, renal function tests, blood glucose concentration, and HbA1c level should be obtained. Suspected polyneuropathy can be confirmed by electrophysiological testing, as mentioned above, and a diagnostic lumbar puncture should be performed if there is suspicion of a chronic inflammatory disease of the nervous system, such as borreliosis or multiple sclerosis.
It can be stated as a rule that only symptomatic patients should be treated. A “pathological” radiological finding is not, in itself, an indication for treatment. The treatment options range from analgesic medication as needed all the way to extensive dorsoventral surgery. The scientifically valid studies that have been performed in this area to date are few, and none of them had a clear age limit or age restriction. Direct comparisons of conservative and surgical treatment are further complicated by the fact that patients with mild stenoses generally undergo the former, while those with severe stenoses generally undergo the latter. Chou et al., in a review of this topic, concluded that moderately good evidence indicates the superiority of surgical over conservative treatment in the first two years. The available evidence is hard to assess, however, because the six randomized trials whose findings were presented involved different surgical methods (laminectomy vs. interspinous spacers) and variable follow-up intervals (12).
Atlas et al. (13) prospectively followed patients for eight to ten years and found better results in the first four years in the patients who had undergone surgery. At the end of the follow-up period, however, the two groups no longer differed with respect to low back pain or overall satisfaction, while all patients had a marked reduction of the leg-pain component. It must be noted, however, that 37% of the patients who were initially treated conservatively went on to have surgery. Radicular symptoms were improved in 67% of the patients who had surgery and in 41% of those treated conservatively. Chang et al. (14), too, found that surgery yielded better results than conservative treatment after ten years of follow-up. Analogously to the observations of Atlas et al. (13), the two groups did not differ significantly at five or ten years with respect to spinal symptoms or overall satisfaction, but the surgical patients had greater improvements in functional status and leg pain.
A functionally limiting neurological deficit (paresis) is a clear-cut surgical indication. The indication is urgent if the deficit is acute and severe, particularly if there is a disturbance of bladder and/or bowel function.
Our search revealed no valid evidence regarding potential surgical indications for patients without any neurological deficit. The individual decisions that are made in such cases are based mainly on the patient’s degree of suffering and impairment of quality of life. The surgical indication is hard to confirm objectively, though the maximal distance the patient can walk without pain is a potential measure of the patient’s impairment.
Given the high frequency of degenerative changes in imaging studies of the lumbar spine, surgery should only be performed if the clinical manifestations are clearly correlated with the radiological findings.
The potential predictors of a favorable outcome are foraminal stenosis, predominant leg pain, and neurological deficits.
Interestingly, it has been clearly demonstrated that non-smokers benefit more from surgery than smokers do; thus, smoking cessation is recommended before surgery. Persons who have had symptoms for less than a year also seem to have a better outcome (15).
Conservative treatment is mainly aimed at alleviating the major clinical manifestation of degenerative instability and may, in fact, bring some patients long-lasting relief. There has been criticism of the long-term use of non-steroidal anti-inflammatory drugs and muscle relaxants, the use of steroids and antidepressants, and the use of long-acting opioids (16, 17). The main pillars of conservative treatment, above all in older people, are intensive physiotherapy with muscle-relaxing techniques in the acute phase, and strengthening of the back muscles in the later course to preserve function and mobility. Local injections (facet infiltrations, epidural injections of local anesthetic and/or steroids) may be helpful in individual cases but are not supported by any hard scientific evidence, even though multiple randomized trials have been performed (18, 19). The available data are insufficient to document the efficacy of treatment with remedial gymnastics, back immobilization, posture training, or orthoses (16, 17).
The goal of surgery is to decompress the nerve roots, dura mater, and vessels without impairing segmental stability. It must first be determined whether the patient is suffering from spinal stenosis alone or from segmental instability in addition. Possible decompressive techniques include laminectomy, hemilaminectomy, uni- or bilateral hemilaminotomy, foraminotomy, and fenestration with undercutting decompression (Figures 2 and 3). Laminectomy involves removal of the dorsal “tension boom” and is thus considered to promote instability, while hemilaminectomy permits better stability with preservation of the dorsal tension boom as well as all of the contralateral ligamentous structures. In hemilaminotomy, portions of two neighboring hemilaminae are removed on one side or both; in bilateral hemilaminotomy, the midline structures are preserved (20). Hardly any scientific evidence supports the use of any particular type of surgery over any other, but there has been one randomized trial showing laminotomy to be superior to laminectomy (21).
The complication rate after surgical treatment of spinal stenosis is considerable. In a prospective study published in 2010, 101 patients over the age of 70 who underwent purely decompressive procedures had an 18% complication rate. The most common complication was a dural injury without further clinical consequences (9%). Two patients had deep wound infections, and three died of concomitant, unrelated illnesses 26 days, 9 months, and 11 months after surgery (22).
Inadequate decompression may leave a significant degree of recurrent stenosis. Jansson et al. (23) documented a reoperation rate of 11% over ten years of follow-up.
Surgical technique—instrumentation in addition to decompression
A meta-analysis revealed that there is good evidence favoring the addition of a fusion to a decompressive operation for spinal stenosis if spondylolisthesis is also present (24). Schulte et al. (25) chose to perform a non-instrumented fusion for multimorbid patients but expressly noted that they recommend instrumentation in cases of multisegmental decompression. A Cochrane report dated 2005 (26) documented a better fusion rate for instrumented than for non-instrumented fusion, which, however, was associated with an only slightly better clinical outcome. Van Tulder et al. (27) found no evidence for the superiority of instrumentation over posterolateral fusion alone with respect to the end result of treatment.
Indications for interspinous spacers and dynamic stabilization—Conventional fusion techniques are intended to immobilize one or more motion segments. In recent years, however, alternative methods have been devised, arising from the conviction that it is only non-physiological motion, not normal motion, that gives these patients pain (28). Implants such as the “dynamic” fixator and the interspinous spacer are intended to stabilize the segment only partially without eliminating functional movement (29, 30). They are said to lower intradiscal pressure, lessen mechanical stress on the intervertebral joints, and widen the spinal neural foramina and spinal canal by distracting the vertebral bodies. Zucherman et al. found in a randomized trial (31) that patients treated with an interspinous spacer experienced a 45% reduction of symptoms at two years, compared to 7% in a group treated non-operatively. Grob et al. (32), Sapkas et al. (33), and Schnake et al. (34) carried out retrospective follow-up studies and concluded that dynamic instrumentation yields results comparable to, but no better than, those of fusion surgery.
Indications for fusion—Documented lumbar spinal instability is a universally accepted indication for fusion. This indication is present in cases with symptomatic lumbar scoliosis, rotational instability with slippage, demonstrable sagittal deformities such as lordosis-associated facet joint degeneration with corresponding symptoms, or severe lumbosacral kyphosis and demonstrated spondylolisthesis with intense low back pain (Figures 4–7).
The differential indications for various types of surgery for spinal stenosis can be roughly delineated as follows. The indication depends on the degree of instability of the segment that is to be decompressed, as well as on the severity of preoperative low back pain. The surgical techniques that can be used range from non-instrumented posterolateral fusion to dorsoventral instrumented fusion. Instrumented fusion is considered a modern technique; it can be performed as an anterior, posterior, or transforaminal lumbar intercorporeal fusion (ALIF, PLIF, or TLIF), or else dorsoventrally. Any of these methods can directly decompress the spinal canal through distraction of the affected segment. The neural elements can also be further decompressed by application of the surgical techniques discussed in the preceding paragraphs. In multisegmental fusion surgery, particularly when multisegmental stenosis or rotational instability is present, an excellent decompression can be obtained with laminectomies at the vertebral levels that are to be fused, without any compromise of spinal stability.
Moreover, spondylodesis is clearly indicated if decompressive surgery alone would exacerbate instability, or if the patient’s symptoms are mainly instability-related (35). In one of the few randomized trials that have been performed in this field, Weinstein et al. (36) found that patients with degenerative spondylolisthesis obtain better pain relief and functional improvement from surgery than from conservative treatment. Fusion surgery increases the mechanical stress on the motion segments adjacent to the fusion, accelerating their degeneration (37). Min et al. (38) emphasize the lack of correlation between the radiological and clinical outcomes. More studies will be needed to determine whether percutaneous TLIF and PLIF (so-called PTLIF and PPLIF) (39) actually improve the outcome still further, as reported by Gepstein et al. (40).
Although the number of persons over age 65 with lumbar spinal stenosis is rising, there is still no evidence-based treatment approach that takes the specific problems of older patients into account. In our view, the wholesale application to older patients of treatment strategies that are suitable for younger ones is problematic. Moreover, the decision to treat surgically or conservatively should be made individually in each case.
Although the evidence base on conservative treatment is sparse for want of clinical trials, all cases of spinal stenosis are treated conservatively at first, except those with high-grade instability. In particular, conservative treatment is best for patients with accompanying illnesses that heighten the risks of surgery and anesthesia.
The purpose of surgery for symptomatic lumbar spinal stenosis is to decompress the spinal canal. In choosing the appropriate treatment, the surgeon must take account of the diminished physical and mental performance of older people, the poorer condition of their muscles, and the physiological aging of their spines. The surgeon must not aim for a cosmetic radiological result that restores the spinal anatomy of a 30-year-old. Rather, the best form of treatment is an age-adapted one that maximally preserves the independence of the older patient after surgery. (This may not be the case, for example, after extensive, multisegmental fusions.) Further studies are needed, particularly in patients of advanced age.
Conflict of interest statement
The authors state that they have no conflicts of interest.
Manuscript submitted on 18 February 2013, revised version accepted
17 July 2013.
Translated from the original German by Ethan Taub, M.D.
PD Dr. med. Christian Ewald
Klinik und Poliklinik für Neurochirurgie
Erlanger Allee 101
07747 Jena, Germany
Prof. Dr. med. Kalff, PD Dr. med. habil. Ewald, Dr. med. Waschke
Department of Spine Surgery and Neurosurgery, Pediatric, Oncologic and Orthopaedic Surgery, Lubinus Clinicum, Kiel: Dr. med. Gobisch, Prof. Dr. med. Hopf
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