Fibromyalgia Syndrome

Introduction

Fibromyalgia syndrome (FMS) is a complex disorder characterised by chronic widespread pain and fatigue, sleep disturbances, cognitive dysfunction, stiffness and depressive episodes¹. The condition may coexist with chronic fatigue syndrome, irritable bowel syndrome, irritable bladder syndrome and temporomandibular disorder.

The aetiopathogenesis of fibromyalgia remains undetermined. The condition is not associated with any structural, inflammatory, metabolic or endocrine abnormalities. There is an abnormal central processing of pain causing an increased response to different noxious stimuli. It may develop from the abnormalities in the central system affecting afferent processing of peripheral stimuli, and from impaired endogenous pain inhibiting systems. There appears to be an impaired endogenous analgesic system that fails to ameliorate pain. There is a reduced threshold to pain perception and tolerance at different points throughout the body. The condition appears to have a genetic basis². The condition presents with generalized tenderness. The condition is noted in middle aged individuals, and majority of patients are females³.

FMS presents with widespread pain, often focusing on the neck and back, arms and legs on either side, lasting more than 3 months. It affects the daily activities. The patients complain of difficulty in walking, and difficulty in climbing stains⁴. They are unable to undertake house-hold activities or gardening. The pain is characteristically unresponsive to usual analgesics and non-steroidal anti-inflammatory drugs and physiotherapy. They complain of daytime fatigue especially in the morning. Pain and fatigue often make them disabled and they are unable to carry out their work.  There can be early morning stiffness, numbness and tingling sensation of the fingers and swelling of hands and fingers. They complain of broken, non-restorative sleep. Severe pain affects their emotional health presenting with depression, anxiety, anger, frustration, fear, irritability, and mood disturbances. The condition affects their social functioning and sexual activities⁵. They exhibit poor concentration and marked disability.

Examination reveals hyperalgesia at tender points (TPs) on application of pressure by the thumb on 18 locations of the body bilaterally such as insertion of suboccipital muscle, intertransverse spaces at the level of C5-7, midpoint of the upper border of trapezius, origin of supraspinatus above the scapula spine near the medial border, upper surface of second costochondral junction, lateral epicondyle, anterior fold of gluteal muscle in the upper outer quadrant of the buttocks, posterior to greater trochanter and medial fat pad of the knee joint⁶. Normally the thumb pressure at each site elicits an uncomfortable feeling, but it causes severe pain in patients with fibromyalgia and they exhibit a winced withdrawal response. Though the patients complain ‘pain all over the body’, there is no evidence of synovitis or signs of inflammation over the muscles. There is no neurological deficit.

In the recent years the use of tender points is not stressed and the presence of widespread pain along with fatigue, sleep disturbances, cognitive dysfunctions are taken into account to diagnose the condition. Recently Wolfe and colleagues have formulated new criteria for the diagnosis and to establish the symptom severity on the basis of location of tender points at 19 locations of the body such as either side of jaw, chest, abdomen, both arm and forearm, both thigh and leg, bilateral shoulder, and hip, neck, upper and lower back, and presence of non-refreshed sleep (non-restorative sleep), fatigue, cognitive difficulties and other somatic symptoms⁷.

While tending for tender points, it is desirable to test at negative control sites. Pressure has to be applied over forehead, distal radius and ulna, proximal fibular head. Patients with psychological disturbances or malingering, exhibit hyperalgesia wherever pressure is applied.

The patients may exhibit sexual dysfunction such as decreased sexual desire and arousal, decreased experience of orgasm and increased pain with intercourse⁷. These manifestations should not have developed from the medication used.

There are no laboratory tests to confirm the diagnosis of FMS. Investigations are undertaken to rule out other conditions such as rheumatoid arthritis, osteoarthritis, hypothyroidism, hyperparathyroidism or lupus. Delta waves are noted in deep stages of non-rapid eye movement sleep. In fibromyalgia associated with sleep abnormality exhibit reduced delta sleep. The patients demonstrate an exaggerated skin flare response to topically applied capsaicin⁸. Frequently the patients exhibit occurrence of dermatographism. They show an exacerbated pain sensation to non-noxious stimuli. Abnormal pain processing is associated with increased cerebrospinal fluid levels of substance P and reduction of 5-hydroxytryptamine (HT) or serotonin⁹.

The treatment is designed on individual patient basis. Both pharmacologic and nonpharmacologic therapies are used in the control of pain and improvement of sleep. The patient, spouse, or family has to be educated about the condition. It has to be stressed that the chronic pain has no underlying inflammation, damage or disease.

Pharmacologic therapy:

Analgesics (paracetamol, acetaminophen), non-steroidal anti-inflammatory drugs may help when there is low grade pain. Antidepressants such as tricyclic antidepressants, monoamine oxidase inhibitors, and selective serotonin reuptake inhibitors or serotonin noradrenaline reuptake inhibitors are used to reduce pain sensation, relieve depression, fatigue and sleep disturbances¹⁰. Careful monitoring of the patient is necessary as there is likelihood of cardiovascular side effects.

Amitriptyline is a tricyclic antidepressant tertiary amine. It is administered in a low dose (10-75 mg at night daily). Nortriptyline is a secondary amine and the active metabolite of amitriptyline. These agents may be combined with fluoxetine. Citalopram and its S-isomer escitalopram are serotonin selective reuptake inhibitors. Sertraline and fluoxetine exhibit blocking effect on dopamine reuptake. Duloxetine and ventafaxine are serotonin norepnephrine re-upatake inhibitors.

Non-pharmacologic therapy:

The patients are advocated graded increase in aerobic exercise. It will help in improving general wellbeing and sleep quality. They should be encouraged to undertake relaxation techniques.