Diagnosing a case of fibromyalgia

No cause for fibromyalgia has been found, however, there are contributing factors, says Dr Raj Thakkar

Fibromyalgia is a functional disorder that can lead to significant disability for the patient and considerable difficulty for their family. It falls in the spectrum of disorders that encompasses chronic fatigue syndromes.

The medical profession has often dismissed the condition, particularly because inflammatory markers in fibromyalgia patients are normal.

Over the past few decades, however, objective evidence has emerged that abnormal processes may be at work.

Evidence for fibromyalgia
Studies have shown that levels of the neurotransmitter substance P, which is involved in the transmission of pain impulses from peripheral receptors to the central nervous system, are three times higher in patients with fibromyalgia than unaffected controls. The concentration of nerve growth factor is also increased four-fold in fibromyalgia patients.

These features act together with central sensitisation through increased glutamate activation of NMDA receptors to increase the patient’s perception of pain.

Changes in their hypothalamic-pituitary-adrenal axis have also been documented as well as mitochondrial abnormalities and poor blood supply in the absence of inflammation.

Around 90 per cent of patients with fibromyalgia are women and it presents most often in those aged 50 to 70 years. Studies have suggested 1–2 per cent of the population is affected, and that less than 10 per cent of patients recover over a five-year period.

The cause of fibromyalgia has not been established, but a number of factors may contribute, including bereavement, anxiety and serotonin deficiency. There is little evidence to suggest a viral aetiology. It is not clear whether the affective symptoms seen in patients with the condition are causal, consequential or associative.

Clinical features
Fibromyalgia is characterised by pain, sleep disturbance and fatigue. Anxiety and depression are also common.

Other features include occipital and frontal headaches, urgency and frequency of micturition, dysmenorrhoea, irritable bowel symptoms, paraesthesia and restless legs, which affects up to a fifth of sufferers.

Some patients feel as if their hands and feet are swollen although there is no objective swelling. According to US guidelines, the symptoms must last for at least three months before a diagnosis of fibromyalgia can be made.

The pain of fibromyalgia, which may be triggered by stress, cold or physical activity, tends to be concentrated around the neck and back, although it may also present as generalised pain.

Multiple hyperalgesic sites are sometimes the only abnormality found on clinical examination. The distribution of these sites is symmetrical and includes the C4–6 and L4–S1 interspinous ligaments, the posterior base of the skull, the trapezius at the mid-point superior aspect, the supraspinatous tendon, the pectoralis major at its insertion, the lateral epicondyle of the elbow, the upper outer quadrant of the buttock, the greater trochanter and the medial fat pad of the knee.

While these sites may be tender in healthy people, patients with fibromyalgia will wince. At least 11 of the 18 sites must be painful to meet the criteria, with non-tender sites used as controls. However, in clinical practice, hyperalgesic points are not necessarily sensitive or specific.

Sleep disturbance leads to patients feeling fatigued throughout the day and waking feeling unrefreshed.

EEG studies have shown that fibromyalgia patients have reduced non-REM sleep, interrupted by alpha waves.

Interestingly, normal subjects who have been deprived of non-REM sleep develop fibromyalgic-type symptoms including hyperalgesic sites.

Clinical examination will produce results incongruent with the degree of disability reported by these patients, and this is itself a clue pointing to a diagnosis of fibromyalgia.

Often, sufferers may not be able to do more than wash and dress themselves. But there will be no evidence of inflammatory processes such as synovitis or deformity. If, rather than typical hyperalgesic sites, the patient claims to be painful at all sites, in the absence of other diseases, psychiatric illness may be considered.

Differential diagnoses should include systemic lupus erythematosis, Sjögren’s syndrome, myositis, polymyalgia rheumatica, malignancy, hypothyroidism, osteomalacia and Paget’s disease. Investigations should be used to exclude these conditions.

The management of fibromyalgia is multifactorial. Patient education is important and the condition should be explained to the family or carers.

Explaining the poor non-REM-sleep model can help patients to understand the condition more readily. Exploring anxiety-invoking events and managing them through counselling techniques may be highly beneficial to patients.

Pain from fibromyalgia may respond to standard and combination analgesics including paracetamol and tramadol. Some trials have shown amitriptyline can modulate pain and restore normal sleep at 25–75mg for up to six weeks. Dosulepin can also be used. Cyclobenzaprine, a tricyclic agent that does not have anti-depressant properties but relaxes muscles, is also effective. Reviews have suggested fluoxetine can be also be used.

Treating any underlying depression is important. Some research has suggested that for every four patients given antidepressants, there will be one success, although the patient’s hyperalgesic points do not necessarily improve. Hypnotics are not routinely used.

Graded aerobic exercise may also be beneficial. It helps restore sleep without medication. The patient needs to be motivated and encouraged to break through the pain barrier. While the role of acupuncture and other complementary techniques is not clear, they may help to relieve stress and restore a normal sleep pattern.  

Dr Thakkar is a GP in Wooburn Green, Buckinghamshire

International fibromyalgia day is set for 12 May. For more information see: www.fibromyalgia- associationuk.org

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