What is Chronic Back Pain
Chronic back pain, often with associated leg pain, is the most common medical complaint in developed countries ( Bigos et al 1994 ). Headache is its only peer ( Lawrence 1977 ). Costs associated with back pain are enormous ( Kelsey 1982 ). While it is doubtful that any of the cost estimates currently available are entirely accurate, they all emphasize that direct and indirect costs of this disabling complaint are huge ( Frymoyer & Cats-Baril 1991 ). A complaint of back pain is the most common reason for early social security disability in the USA. The disability issues are so important that several countries and many organizations have convened to examine the problem ( Damkot et al 1984 , Anderson 1996 , Riihimaki 1985 ). Back pain is one of the most common reasons why patients see physicians, one of the most common reasons for secondary referral, and both operative and non-operative treatment of back pain ranks high in terms of total expenditures of healthcare dollars in the USA (Moeri et al 1899, Bush et al 1992 , Davis 1994 ).
In spite of the obvious importance of back pain as a complaint, the problem is poorly understood and few treatments have been validated ( Bigos et al 1994 ). One of the major issues is the lack of an appropriate classification system. Back pain is simply a complaint which originates in a large heterogeneous spectrum of diseases. Another major issue is that the actual pathophysiological causes of complaints are unknown ( Kuslich et al 1991 ). Even when the complaints can be associated with definable diseases, what is causing the back pain is unclear ( Boden et al 1990a , Jonsson & Stromqvist 1993 ). There is reasonable evidence that overt instability causes pain and elimination of that instability will reduce pain ( Cholewicki & McGill 1996 ). The strongest evidence is that root compression is associated with pain and neurological deficit ( Saal & Saal 1989 , Saal et al 1990 , Weber 1994 ). Decompression is a satisfactory treatment for a majority of patients ( Bohannon & Gajdosik 1987 ). However, these two conditions are relatively rare in the spectrum of patients with back and/or leg pain complaints, and for the majority the association of complaints with demonstrated structural abnormalities is tenuous at best ( Saal & Saal 1989 , Weber 1994 ).
It is not surprising that therapies are problematical in a condition without known causes of pain ( Bell & Rothman 1984 , Basmajian 1989 ). Much research will be required to examine the unanswered questions in low back pain in a rational way. Until there is a better scientific basis for understanding back pain and its treatment, we must use what is known to decide upon the best current therapy for these patients. All too often speciality bias is substituted for rational treatment.
In order to reach supportable decisions concerning the evaluation and treatment of these patients, the physician involved in their care must have an organized classification framework in which to work ( Box 23.1 ). Knowing what the various diagnostic tests available can be expected to demonstrate is important. A rigorous evaluation of claims of therapeutic efficacy for all modalities of treatment is required. It is also important to have an equally rigorous understanding of outcomes measurement to assess these claims ( Wiesel et al 1980 ).
Box 23-1. Temporal classification of low back pain with or without sciatica
Self-limited; duration is hours to days; comes to medical attention when episodic
Self limited, but protracted; duration is days to weeks; often seen by physicians; treatment is symptomatic; most recover spontaneously; evaluation and treatment required for severe symptoms
Lasts more than 3–6 months; does not relent with time; high correlation with spondylotic disease; no psychological co-morbidities; surgical intervention occurs mostly in this group
Chronic (pain syndrome)
Lasts more than 6 months; worsens with time; associated with major co-morbidities, especially psychological. Multidisciplinary therapy is commonly required
The goal of this chapter is to provide the framework for the evaluation, diagnosis, treatment, choice and assessment of treatment outcome for patients complaining of chronic low back pain with or without sciatica.
CLASSIFICATION OF THE COMPLAINT OF LOW BACK PAIN
The most practical classification yet devised describes low back pain in terms of temporal characteristics. While incomplete, this classification is useful because so much of low back pain is still idiopathic ( Bigos et al 1994 ). Transient low back pain typically lasts for a very short period of time and does not come to medical attention, except by history later. Treatment is usually symptomatic and instituted by the patient. The causes are virtually never known and the problem does not have great significance for practice or disability.
Acute low back pain is generally defined as pain which lasts from a few days to a few months. Back pain with or without leg radiation is common. Experience and some evidence says that the majority of these problems are self limited and resolve spontaneously. Standard treatments have little influence upon the natural history. Typical treatment algorithims include short periods of bedrest, adequate analgesia, local physical measures and watchful waiting. Some patients, particularly those with acute disc herniation, have intractable pain which cannot be allowed to resolve spontaneously because of its severity. Rarely, a significant neurological deficit may accompany pain. Both situations usually lead to prompt surgical intervention ( Bigos et al 1994 ).
PERSISTENT LOW BACK PAIN
Most commonly it is assumed that pain which persists for 6 months progressively leads to the chronic state, defined by preoccupation with pain, depression, anxiety and disability. In the recent past, a large group of patients has been identified in whom pain persists for more than 6 months without any concomitants of the chronic pain syndrome. Ninety-five per cent of patients seen demonstrated complaints of pain and dysfunction which reduced, but did not seriously affect, all activities otherwise. Psychological testing in these patients revealed patterns similar to those expected in any ill normal population. There was a 5% incidence of psychological dysfunction in the overall group. We have termed this constellation the persistent pain syndrome to differentiate it from the implications of the word chronic in the pain field. The majority of these patients suffered from spondylotic disease. There was no significant worsening or improvement with longitudinal evaluation and these patients did not respond to typical modalities of therapy employed for them.
THE CHRONIC PAIN SYNDROME
For the past 20 years, there has been general agreement about the symptoms and signs which define a group of patients who chronically complain of pain ( Waddell et al 1980 ). Virtually irrespective of the cause of the pain, these patients present with similar complaints and findings. They are preoccupied with pain and pain is the cause of their impairment. A very high percentage are depressed and anxious. There is an unusually high incidence of psychiatric diagnoses among them. An even larger number have features consistent with personality disorder. Drug misuse is common, although addictive behaviour is relatively rare. These patients use medical resources heavily and are consistently disabled from pain. Specialized treatment facilities have been developed throughout the world to deal with them. Patients with low back pain and leg pain complaints who fall into this category do not seem to have different anatomical diagnoses than those patients in the persistent pain syndrome who do not exhibit the co-morbidities of the chronic pain patient.
EVALUATION OF BACK AND LEG PAIN
The evaluation should begin with a careful history which describes the pain severity, location and influences ( Deyo et al 1992 ). Back pain only is unlikely to be associated with root compression ( Hakelius & Hindmarsh 1972a ). When only radicular pain is present, instability will not be a problem. Physical examination is unlikely to be diagnostic but will assess neurological and musculoskeletal abnormalities. Posture and range of motion are helpful ( Heliovaara 1987 ). Routine neurological examination is needed as a baseline at least. Vascular examination is important ( Hurme et al 1983 ).
During these examinations, listen for the danger signals such as night pain (intraspinal tumour), constant pain (cancer or infection), systemic symptoms (cancer or infection) and symptoms of other organ or systemic disease.
Also, observe the patient’s behaviour during the examination. Is there much pain behaviour? Are actions consistent with complaints? Is motor examination reliable ( Hurme et al 1987 , McCombe et al 1989 )?
Unlike the acute pain problems, imaging is important in the chronic patients. Plain films with flexion/extension are important. Magnetic resonance imaging (MRI) is best for most screening. Computed tomography (CT) can be used if bony pathology is suspected: with 2–3D reconstructions fixator artefacts can be reduced. CT myelogram is needed rarely, most commonly in patients with previous surgery ( Hakelius & Hindmarsh 1972b , Wiesel et al 1984 , Boden et al 1990b , Deyo et al 1994 ).
There is no need for psychological testing unless symptoms suggestive of psychiatric disturbance are present. If concerned, carry out a thorough evaluation of the DSM-designated factors rather than relying on screening tests ( Waddell et al 1980 ).
CAUSES OF CHRONIC BACK AND LEG PAIN ( BOX 23.2 )
Another way to categorize patients with chronic back and leg pain is to list the causes. The prevalence is hard to determine for any of these conditions because reported series are always biased by referral patterns and adequate population studies have not been done. However, most experts agree that the preponderance of these patients have spondylotic disease which is at least associated with the pain problem, if not proven to be causative yet ( Spangfort 1972 , Weber 1983 , Waddell 1987a ).
Box 23-2. Causes of chronic back and leg pain
Bony tumour or spinal cord tumour / Lumbar metastases
Lumbar spinal infection / Retroperitoneal inflammation
Renal disease / Aortic aneurysm
Endometriosis / Abdominal or pelvic cancer
Secondary to compression fracture / Osseous pain (?)
Rheumatoid arthritis / Ankylosis spondylitis
Psoriatic arthritis / Acromegalic spondylitis
Myofascial-pain syndrome / Associated with HIV/AIDS
Depression / Somatiform disorder
Schizophrenia / Personality disorder
State-anxiety / Early dementia
Pyriformis syndrome / Pudenal syndrome
Meralgia paraesthetica /
Transverse facets / Spondylolysis
Myelomeningocele – forme frustes / Sacral cysts – usually with Marfan’s
syndrome or Ehlers–Danlos syndrome
Tumour (chordoma) / Fracture (osteoporosis)
Sacroiliac joint disease
BACK AND LEG PAIN AS A MANIFESTATION OF UNEXPECTED OR INTERCURRENT DISEASE
In our own series of patients, an unexpected systemic disease was found in only 3% of patients. All had symptoms or signs which suggested something other than common spondylotic disease. Osseous metastases are the most common. Retroperitoneal inflammatory processes, sometimes associated with chronic gastrointestinal disease, pancreatitis, chronic and acute renal disease all may cause back pain rarely. The clues that these do not represent spondylotic disease are usually obvious, although differentiation may occasionally be obscure. The pain from any of these processes is usually local. Leg radiation may occur secondary to lumbosacral plexus involvement, but is rarely typically sciatic. These pains are constant, tend not to be exacerbated by activity or relieved by rest, and are often associated with other signs or symptoms of systemic disease. Leg pain is non-radicular, as are the physical findings associated with infiltration of the plexus. Signs and symptoms which suggest intercurrent disease are intractable pain, unremitting pain, neurological deficit suggestive of lumbosacral plexus involvement, a history of cancer or inflammatory disease, a history of any disease likely to be complicated by infection and a history of significant trauma.
Evaluation of patients with any of these should include plain spine films and MRI for diagnosis. Treatment will depend upon the cause of the presenting symptoms.
There is still an argument about whether osteoporosis alone can cause back pain ( Bigos et al 1994 ). Many experts in spinal pain believe it can. However, the most common cause of intractable pain with osteoporosis is compression fracture. Pain with compression fracture is local and extremely severe. If the collapse is great enough, then individual nerve root compression signs and symptoms may occur. However, typically the pain does not radiate, it is focal in the back, and can be localized with great accuracy over the collapsed segment. Those at risk include postmenopausal women, and anyone with other disorders of calcium and oestrogen metabolism, heavy smokers, prolonged steroid users and any patient with prolonged immunosuppression. The diagnosis is made by plain X-ray. Treatment usually consists of rest, external support, limitation of activity and time with therapy for the underlying problem. The pain often persists for 6 months or more following compression fracture.
Recently, vertebroplasty has been introduced ( Fig. 23.1 ). In this procedure, the acutely compressed segment is visualized with fluoroscopy. A needle is placed through the pedicle into the vertebral body and methyl methacrylate is injected to reinforce the collapse. Pain relief is usually immediate and may be very gratifying. The procedure is much more effective when applied early, rather than in the chronic phase of pain.
The most common inflammatory condition to be associated with chronic back pain is rheumatoid arthritis ( Lawrence 1977 ). Back pain is usually not an early characteristic of the disease, so the diagnosis is known when back pain occurs. If systemic manifestations are not prominent, it can be difficult to be certain about the diagnosis on clinical grounds. Plain films, CT, and MRI all suggest inflammatory spondylotic disease. The diagnosis is confirmed by serological testing. Treatment consists of three phases. The first is treatment of the underlying disease. The second is an exercise programme for lifelong maintenance of axial muscle strength. The third is surgical therapy for spinal instability or root compression syndromes. The majority of rheumatoid spinal problems requiring surgery are cervical, but spinal stenosis in the lumbar region does occur. The syndrome is typical neurogenic claudication. Surgery requires decompression and frequently fusion.
The second common problem is ankylosing spondylitis ( Lawrence 1977 ). This is a disease of males predominantly. Symptoms usually begin with back pain early in life and a progressive history of constant back pain is typical. Radicular or cord compression symptoms are uncommon. The diagnosis is made by the typical ‘bamboo spine’ appearance on plain X-ray or MRI. Treatment is typically symptomatic. As spontaneous fusion progresses up the spine, pain relents in the lumbar region, only to reappear at higher levels progressively.
Psoriatic arthritis is a rare similar disease ( Lawrence 1977 ). The problem is more facet arthropathy with synovial proliferation ( Liu et al 1990 , Xu et al 1990 ). Thus in psoriatic arthritis, root compression syndromes are common and spinal stenosis is typical. Back pain alone is best treated symptomatically. Surgical decompression and occasional stabilization is required for root compression syndromes.
Acromegalic spondylitis is common in untreated patients. Fortunately, with the quality of therapy now available for these pituitary tumours, this problem has become very rare. The syndrome is similar to ankylosing spondylitis, with progressive pain usually beginning in the lumbar region and which ceases with spontaneous fusion. Treatment is symptomatic.
Figure 23-1 Vertebroplasty. A The thoracic compression fracture with a transpedicular needle in the vertebro body. B The injection of methacrylate into the body as seen under fluoroscopy. C The finished product after bilateral transpedicular injection. The body is now filled with methacrylate and strength is restored. Pain relief was immediate.