n. a method for acquiring images during specific parts of a fast-moving cycle. Cardiac gating and respiratory gating are used to avoid the movement artifact produced during the cardiac cycle and respiratory movement, respectively. Therefore the area imaged, for example during the R wave on an *electrocardiogram, appears static. The imaging is usually correlated with a physiological measure, such as an ECG trace. Gating is used in CT, MRI, and nuclear medicine.
Symptoms These vary, with pain and fatigue generally prominent, sometimes causing considerable disability. Patients can usually dress and wash independently but cannot cope with a job or household activities. Pain is mainly axial, but may affect any region. ANALGESICS, NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) and local physical treatments are generally ine?ective.
Patients often have a poor sleep pattern, waking exhausted. Unexplained headache, urinary frequency and abdominal symptoms are common, but no cause has been found. Patients generally score highly on measures of anxiety and DEPRESSION. Fibromyalgia is not an ideal description; idiopathic di?use-pain syndrome and non-restorative sleep disorder are increasingly preferred terms.
Clinical ?ndings are generally unremarkable; most important is the presence of multiple hyperalgesic tender sites (e.g. low cervical spine, low lumbar spine, suboccipital muscle, mid upper trapezius, tennis-elbow sites, upper outer quadrants of buttocks, medial fat pad of knees). In ?bromyalgia, hyperalgesia (excessive discomfort) is widespread and symmetrical, but absent at sites normally non-tender. Claims by patients to be tender all over are more likely to be due to fabrication or psychiatric disturbance. OSTEOARTHRITIS and periarticular syndrome are much more common and should be excluded, together with other conditions, such as hypothyroidism (see THYROID GLAND, DISEASES OF), SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) and in?ammatory myopathy (see MUSCLES, DISORDERS OF), which may present with similar symptoms.
Cause There is no investigational evidence of in?ammatory, metabolic or structural abnormality, and the problem seems functional rather than pathological. SEROTONIN de?ciency has a signi?cant role in ?bromyalgia syndrome.
Management Controlled trials have con?rmed the usefulness of low-dose AMITRIPTYLINE or DOTHIEPIN together with a graded exercise programme to increase aerobic ?tness. How this works is still unclear; its e?cacy may be due to its normalising effects on the sleep centre or ‘pain gating’ (reduction of pain sensation) at the spinal-cord level. Prognosis is often poor. Nevertheless, suitable advice and training can help most patients to learn to cope better with their condition and avoid unnecessary investigations and drug treatments.... fibromyalgia syndrome
(multiple-gated acquisition scan) a technique used in *nuclear medicine for studying the left-ventricular function and wall motion of the heart. The patient’s red cells are labelled with radioactive technetium-99m. A gamma camera, connected to an ECG, collects information over a prolonged period for each phase of heart movement (ECG gating) to form an image of the blood pool within the heart at specific points in the cardiac cycle. Tomographic reconstructions can be made to give cross-sectional images of the heart in different phases of the cardiac cycle, using reconstruction *algorithms comparable to CT scanning (see SPECT scanning).... muga scan
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