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Low back pain (LBP) is defined as pain occurring at any point from the iliac crest to the coccyx. The vast majority of LBP resolves within a few weeks of onset (80 per cent) but some LBP will persist and become chronic LBP. It is an extremely common condition affecting 80 per cent of the population at some point throughout their lives. LBP is the leading cause of job-related disability (making up one-third of Irish people receiving disability allowance) and causes many missed days from work.
LBP can be classified as: acute, sub-acute or chronic, degenerative or non-degenerative.
Acute LBP last six weeks or less, sub-acute lasts six to 12 weeks and chronic LBP is diagnosed if LBP persists for >12 weeks.
Regarding degenerative LBP, a further sub-classification exists: uncomplicated and complicated.
Uncomplicated: facet joint pain, sacroiliac joint pain, coccygodynia, discogenic pain, and failed back surgery syndrome.
Complicated: degenerative lumbar scoliosis, degenerative spondylolisthesis, and acquired canal stenosis.
Non-degenerative: spondylolysis, scoliosis, tumours, fractures, non-degenerative spondylolisthesis, osteoporotic vertebral collapse, spondylodisciitis, sacroilitis,rheumatoid arthritis/ spondylitis, snfkyphosis.
Risk factors for LBP
Occupational factors: jobs requiring repetitive heavy lifting, use of jackhammers or machine tools, and operation of motor vehicles.
Patient factors: obesity, substance abuse history, lower socio-economic group, poor physical fitness, unemployment, associated morbidities (anxiety, depression, other chronic pain states), and smokers.
Risk factors for chronicity: Radicular leg pain, a positive straight leg test (pain at <60 degrees), reduced elasticity/flexibility of the back, poor coping strategies, high levels of distress, depression, somatisation, and lower activity level.
History and examination
A good history and examination is imperative to establish the presence of any ‘red flag’ signs and symptoms. These red flags can establish if malignancy, fractures or infection are a possible cause of the back pain. Focused history should include the nature of onset, duration, location, radiation, associated neurological symptoms (particularly bowel and bladder dysfunction) and exacerbating and relieving factors. A past medical history of malignancy, immunosuppression and IV drug abuse is important to note.
A full neurological exam to include gait assessment, posture, range of movement, tenderness on palpation and a straight leg raise/Lasègue test is important. A global inspection of the patient’s gait and posture at rest reveals signs of asymmetry (including pelvic tilts and obliquities) and the degree of spinal curvature. Major lumbar scoliosis, kyphosis, and excess lordosis can usually be assessed with inspection and palpation except in the very obese. Soft tissue palpation is important to evaluate paraspinous muscle tone, the localisation of trigger points, and the presence of masses such as lipomas. Pain on palpation over the iliac crest can indicate cluneal nerve entrapment. A ‘slump test’ can be performed also by asking the patient to sit on the edge of the bed, flex neck and attempt to dorsiflex the knee- a positive test is worsening of painful symptoms suggestive of lumbar disc herniation.
Regarding lumbar facet degenerative disease, pain on flexion suggests a possible disc lesion, whereas pain on extension can indicate a facet arthropathy or myofascial pain generator (trigger point). Multiple provocative tests have been described for the lumbar region. The majority of tests are directed toward pathology in the disc and nerve roots, facet joints, sacroiliac joint, hip, and piriformis muscle. The most frequently performed test for nerve root irritation is the straight leg raise.
Facet arthropathy can be diagnosed by eliciting pain with facet loading maneouvers (lateral flexion, lateral rotation, and extension). Sacroiliac joint pathology can be examined for by performing the FABER test, Gaenslen’s test, Yeoman’s test or the posterior shear test. However, the tests are 85 per cent sensitive and 79 per cent specific. If a patient exhibits at least three positive tests, sacroiliac joint dysfunction may be considered.
Imaging is deemed unnecessary in acute back pain unless infection, fractures or malignancy are suspected. If acute pain becomes chronic pain, imaging remains unnecessary unless the chronic LBP continues to worsen or fails to improve despite appropriate therapy. Interventional pain management techniques can still be performed without pre-procedure imaging. A common question surrounds the need for imaging in the case of sciatica. Once again, the sciatica should settle down with conservative management and imaging will not be needed, even if referred to a pain medicine specialist as the management plan will not be altered. The only indications for imaging are pain unresponsive to treatment and if management will be changed based on imaging findings. Also, if surgery is a possibility, a spinal surgeon will need MRI images to help make an appropriate decision and to plan surgery.
Advice and information needs to be tailored to the needs and capabilities of the patient, to help them self-manage their low back pain. They should be advised to keep moving and exercising. Bed rest is to be strongly discouraged at all steps of the treatment pathway as well as encouragement to continue with normal activities.
A group exercise programme (biomechanical, aerobic, mind–body or a combination of approaches) for patients with a specific episode or flare-up of low back pain with or without sciatica would be ideal. Some preventative physiotherapy-based exercise programmes are being established around the country which take people’s specific needs, preferences and capabilities into account when choosing the type of exercise such as pilates, yoga, and cycling.
Orthotics are not recommended as the lower back muscles will become deconditioned. Lumbar supports, belts or corsets for managing low back pain should not be endorsed. Also, foot orthotics solely for managing low back pain should not be encouraged.
Manual therapies in the form of soft tissue techniques such as massage can be advocated for managing low back pain with or without sciatica, but ideally as part of a treatment package including exercise.
Acupuncture does not offer any benefit in low back pain management.
Electrotherapies such as TENS and PENS can provide short-term relief but offer no long-term improvement.
Cognitive, affective, and social factors have long been recognised as influencing the experience of pain. Unfortunately, access to psychologists in this country is severely limited. Their role in the management of chronic LBP cannot be overestimated. Psychological therapies consist of operant conditioning and positive behavioural techniques. Targets for psychological treatment include reducing pain and pain-related disability; treating comorbid mood disturbances, particularly depression; increasing perceptions of control and self-efficacy; increasing healthy behaviours, such as appropriate medication use, exercise/activation, sleep habits; and addressing pain-related psychosocial factors, such as the impact of pain on family functioning and work life.
Some hospitals run a Pain Management Programme that combines a physical and psychological programme. This incorporates a cognitive behavioural approach (preferably in a group context that takes into account a person’s specific needs and capabilities). These groups are mostly for patients with musculoskeletal pain (as compared to neuropathic pain).
To measure the efficacy of analgesic therapy, we use the ‘numbers needed to treat’ statistic. The number needed to treat (NNT) is number of patients who need a specific treatment to prevent one additional bad outcome. In the case of analgesia, we consider the avoided additional bad outcome to be 50 per cent or more improvement in pain for four to six hours after administration of the analgesic in patients with moderate to severe pain.
Paracetamol alone is not effective for chronic LBP. However, it is more effective if given in conjunction with other analgesics. The NNT for paracetamol and codeine combinations (1,000mg/60mg) is 2.3 to three. Topical non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed. The NNT for these creams range from 3.9 for acute pain to 3.1 for chronic pain. The side-effects with these creams are minimal as systemic absorption is so low secondary to their high lipophilicity. Local skin reactions occur around 3 per cent of the time. The NNT for oral NSAIDs for managing low back pain, (acute > chronic) is 2.3 (diclofenac 50mg twice a day). However, the side-effect profile (gastrointestinal, liver and cardio-renal toxicity, and the person’s risk factors, including age and use of anticoagulation) of NSAIDs make them unattractive for long-term use. They are ideally used for a short, defined period of time to manage acute flare-ups.
When prescribing oral NSAIDs for low back pain, prescription for gastro protection must be considered. Consideration of weak opioids (with or without paracetamol) for managing acute low back pain should only occur if an NSAID is contraindicated, not tolerated or has been ineffective. The NNT for 100mg tramadol is 4.8. This improves to 2.4 for 150mg tramadol but the CNS side-effects are very common and unpleasant at this dose.
Regarding stronger opioids, the epidemic of opioid misuse and abuse in the USA has prompted the Surgeon General to commence a campaign called ‘Turn the Tide Rx’. This was instigated by the magnitude and trajectory of the opioid epidemic sweeping across the country. It is likely the situation is similar in Ireland, but there are no figures to confirm this.
Regarding neuropathic medications, their role in low back pain that is not of neuropathic origin is uncertain. Ideally, these neuropathic medications should only be offered if there is a radicular component to their LBP. Advice is similar for TCAs, SSRIs or SNRIs, however, if the patient has a mood disorder there may be some benefit.
Epidural (caudal or lumbar) injections of local anaesthetic and steroid should be considered in patients with acute and chronic, severe sciatica or other radiculopathy. Pain relief provided should last three to four months. The injection may then need repeating, however three to four injections per year would be the maximum.
The main source of pain in facet arthropathy is thought to come from structures supplied by the medial branch nerve. The options for facet arthropathy are as follows; an intraarticular corticosteroid injection called a medial branch block (MBB). Typically, this is performed as a diagnostic block. A short-term (days -weeks) but positive response to this block suggests a good response to pulsed radiofrequency lesioning (PRF).
Radiofrequency (RF) denervation, lesioning is then performed after the PRF lesioning and ideally will give up to one year of good pain relief (>30 per cent improvement in Numerical pain rating scale). Finally, surgical referral may be required if pain continues or if the pathology worsens.
Intraarticular or extraarticular corticosteroid injection has produced varying results with insufficient studies. Anecdotally, some patients report good relief from these injections. Radiofrequency lesioning has also very limited evidence for efficacy. Variability in results has been attributed to individual nerve patterns, improper pre-procedure diagnosis and selection of patients.
Failed back surgery syndrome is defined as one or more lumbosacral operations, with no reduction in pain or a comparable level of pain returned in one year. It occurs in 40 per cent of surgical patients. Causes include a recurrent disc herniation, intro nerve damage, canal stenosis, postoperative infection, epidural fibrosis or adhesive arachnoiditis.
If the pain is disabling and does not respond to initial measures, neuromodulation treatment may be an option. Neuromodulation consists of one or more leads with small electrical contacts placed near the nerves (such as the epidural or more nearer to peripheral nerves beyond the spine along the lower back). If pain is reduced during the trial, a small battery, similar to the device used to power a heart pacemaker, is implanted to provide ongoing stimulation. Insertion of a spinal cord stimulator is usually a two-step procedure requiring two separate operations.