Last updated: November 25, 2014

Synonyms: Fibrositis, myofascial pain syndrome, neurasthenic pain syndrome.

ICD-9 Codes: 729.1.

ICD-10: M79.7

Definition: Fibromyalgia is a very common cause of musculoskeletal pain.  Widespread soft tissue pains, fatigue, and poor sleep are highly characteristic.

Etiology: The cause is unknown. Numerous studies have speculated on contributory role(s) for trauma, stress, depression, poor cardiovascular fitness, abnormalities of thalamic pain processing, and loss of non–rapid eye movement (stage IV) sleep.

Pathogenesis: Although most of the pain arises from nociceptors in muscle, numerous muscle studies (e.g., histopathology, electromyography (EMG), exercise testing, nuclear magnetic resonance spectroscopy) have failed to identify consistent abnormalities. Central mechanisms may underlie these heightened pain responses. Sleep electroencephalographic studies have documented alpha wave intrusion during delta (stage IV) sleep and a reduction in rapid eye movement sleep. Recent studies using single-photon emission computed tomography demonstrate lower cerebral blood flow in the thalamus and caudate nucleus of patients with fibromyalgia than in normal controls. Such studies suggest that central mechanisms may play a key role.

Demographics: Fibromyalgia is estimated to affect >5 million Americans. Population studies suggest that the prevalence of widespread pain ranges from 10% to 23% and increases with age. Most reported series show that >80% of patients with fibromyalgia are female. Although the average age at presentation is between 30 and 50 years, fibromyalgia has been uncommonly described in children and is probably underreported in the elderly. Racial and ethnic variances have not been described. Fibromyalgia often accompanies other chronic painful rheumatic disorders, where it is referred to as secondary fibromyalgia. Twenty to 30% of patients with RA and SLE and as many as 50% of patients with Sjögren’s syndrome have secondary fibromyalgia.

Cardinal Findings:  Patients may present with focal, widespread or migratory musculoskeletal pain, but on further examination, fibromyalgia patients exhibit widespread pain affecting the upper and lower torso and both sides of the body. Asymmetric or focal areas of soft tissue pain and spasm may be referred to as myofascial pain syndrome. Patients typically complain of axial pain affecting the neck, interscapular area, and low back. Others may initially present with focal joint pains (e.g., shoulder, elbow, hip), only to demonstrate other evidence of widespread pain on examination. In addition to arthralgias and myalgias, patients complain of prominent fatigue, malaise, subjective weakness, daylong stiffness or gel phenomenon and activity-induced articular pains are common. Articular symptoms often wax and wane and may be related to exacerbating factors. Many patients complain of joint swelling, although objective evidence of effusion or synovial proliferation is lacking.  Although patients often report weakness or neuropathic symptoms, clinical evidence of weakness, myopathy and neuropathy should be absent.

Sleep disturbance occurs in the vast majority of patients, with difficulty falling asleep, staying asleep, frequent awakening, restlessness, early morning awakening and complaints of non-restorative sleep. Most patients admit to only sleeping for short intervals throughout the night and feeling worse or tired on awakening. This results in the loss of the normal progression of sleep stages, and it is thought that loss of slow or delta wave (stage IV) sleep is especially disturbed. Obese males (more so than females) with fibromyalgia should be evaluated for an underlying sleep apnea syndrome.

Tender trigger points, some of which may not be apparent to the patient, are required for the diagnosis. Trigger points are defined as a focal painful response elicited by 4 kg of digital pressure (enough to blanch a thumbnail) over specific locations (Figure). The physical examination should test all 18 trigger points.

Patients with fibromyalgia are often plagued by associated disorders that include migraine headache, irritable bowel syndrome, premenstrual syndrome, chronic fatigue syndrome, depression, allergic rhinitis, multiple drug allergies, or temporomandibular joint pain.

Numerous psychiatric disorders have been associated with fibromyalgia, yet less than 20% of patients exhibit major depression. Anxiety, panic attacks, and inadequate coping mechanisms have all been found in a minority of patients.

Uncommon Findings: Atypical chest pains (often with chest wall tenderness), Raynaud phenomenon, restless leg syndrome, numbness, memory loss, and cognitive dysfunction have been reported. The latter are more likely the result of poor sleep than sleep medications.

Diagnostic Tests: Extensive laboratory testing is rarely indicated, and wide batteries of rheumatic screening tests should be avoided. Although there are patients with secondary fibromyalgia, the diagnosis of fibromyalgia should not prompt additional testing to identify an associated or underlying disorder. Use of the ANA or thyroid function tests should be predicated on symptoms that suggest SLE or hypothyroidism, respectively.

Imaging: MRI and CT scans are normal and should not be performed unless otherwise indicated.

Keys to Diagnosis: Several clues should strongly suggest the diagnosis of fibromyalgia. Most common is the presentation of a patient who claims wide-spread and impressive musculoskeletal symptoms whose history is not sustantiated by physical findings or abnormalities (e.g., no joint swelling). This should prompt a search for soft tissue trigger points and supportive features such as a sleep disturbance. Many of these patients have evidence of somatic pain and spastic disorders such as irritable bowel syndrome, prementrual pain syndrome, and migraine headaches.  Patients who present with musculoskeletal symptoms and a history of psychiatric disorders (e.g., depression) should be evaluated for fibromyalgia.


Fibromyalgia tender points

Figure. Fibromyalgia tender points

Diagnostic Criteria:  Previous diagnostic criteria required “widespread pain” and at least 11 out of 18 tender trigger points.  In 2010 the ACR revised the definition of fibromyalgia using the symptom severity (SS) scale and the widespread pain index (WPI).   FM is therefor defined as a WPI >7 AND a SS >5  or a WPI of 3–6 AND SS >9.  These criteria are intended for use in clinical trials but may also be instructive in establishing a diagnosis of fibromyalgia.  Nevertheless, in daily practice, it is not necessary that >11 trigger points be present or that these calculations for the SS and WPI be met. The diagnosis should be considered for someone with multiple tender trigger points, evidence of widespread pain, and asleep disturbance. 

Table. 2010 American College of Rheumatology Diagnostic Criteria for Fibromyalgia and the Measurement of Symptom Severity
A patient satisfies diagnostic criteria for fibromyalgia if the following 3 conditions are met:
1) Widespread pain index (WPI) 7 and symptom severity (SS) scale score 5 or WPI 3–6 and SS scale score 9.
2) Symptoms have been present at a similar level for at least 3 months.
3) The patient does not have a disorder that would otherwise explain the pain.Ascertainment
1) WPI: note the number areas in which the patient has had pain over the last week. In how many areas has the patient had
pain? Score will be between 0 and 19.
Shoulder girdle,        left Hip (buttock, trochanter),         left Jaw,        left Upper back
Shoulder girdle,        right Hip (buttock, trochanter),       right Jaw,      right Lower back
Upper arm,              left Upper leg,                               left Chest Neck
Upper arm, right       Upper leg,                                    right Abdomen
Lower arm, left         Lower leg, left
Lower arm, right       Lower leg, right
2) SS scale score:
– Fatigue
– Waking unrefreshed
– Cognitive symptoms
For the each of the 3 symptoms above, indicate the level of severity over the past week using the following scale:
0  no problem
1  slight or mild problems, generally mild or intermittent
2  moderate, considerable problems, often present and/or at a moderate level
3  severe: pervasive, continuous, life-disturbing problems
Considering somatic symptoms in general, indicate whether the patient has:*
0  no symptoms
1  few symptoms
2  a moderate number of symptoms
3  a great deal of symptoms
The SS scale score is the sum of the severity of the 3 symptoms (fatigue, waking unrefreshed, cognitive symptoms) plus the
extent (severity) of somatic symptoms in general. The final score is between 0 and 12..
* Somatic symptoms that might be considered: muscle pain, irritable bowel syndrome, fatigue/tiredness, thinking or remembering problem, muscle weakness, headache, pain/cramps in the abdomen, numbness/tingling, dizziness, insomnia, depression, constipation, pain in the upper abdomen, nausea, nervousness, chest pain, blurred vision, fever, diarrhea, dry mouth, itching, wheezing, Raynaud’s phenomenon, hives/welts, ringing in ears, vomiting, heartburn, oral ulcers, loss of/change in taste, seizures, dry eyes, shortness of breath, loss of appetite, rash, sun sensitivity, hearing difficulties, easy bruising, hair loss, frequent urination, painful urination, and bladder spasms.

Differential Diagnosis: Many rheumatic disorders manifest prominent soft tissue pain during the onset period or during disease flares. Disorders that may masquerade as fibromyalgia include hypothyroidism, psychogenic rheumatism, hypochondriasis, somatoform pain disorder, chronic fatigue syndrome, drug-induced myopathy, hypermobility syndrome, polymyalgia rheumatica, or the onset/flare of a connective tissue disease (e.g., SLE, polymyositis (PM), vasculitis, SpA).

Therapy: Patients with fibromyalgia differ from each other in the scope and severity of symptoms. Treatment approaches should be tailored to the individual patient and are best coordinated by a single physician who knows the patient well. Single agent or solitary measures are seldom effective. Successful management relies on the combined use of pharmacologic agents, physical modalities, and psychological measures to ensure an effective, multifaceted approach.

—Pharmacologic agents: It is highly improbable that a single drug will alleviate the patient’s pain. Hence, pharmacologic pain relief is but one component of a comprehensive treatment plan. The four goals of therapy are to improve pain, optimize restorative sleep, promote stretching exercise, and, if present, treat and manage anxiety or depression. Pain relief can be achieved using drugs that target pain, muscle tension, or abnormal patterns of sleep. Analgesic medications may be used to decrease pain and lessen the recurrence of pain. Commonly used agents include acetaminophen (2–4 g/day), NSAIDs, or nonnarcotic analgesics, such as tramadol (50–100 mg b.i.d.) when NSAIDs cannot be used. The clinician should avoid the temptation to escalate NSAID use (with resultant GI risks) or to resort to chronic narcotic analgesic use to control recalcitrant pain.  Sleep habits should be reviewed with every patient and patients should be counseled on proper sleep hygeine (i.e, “The bed is for sleep only! Do not read or watch television in bed. The bed should be free of of books, magazines, food, children, pets, snoring spouses, remote controls, computers, and cellular phones”). Tricyclic antidepressants, pregabalin, duloxetine and milnacipran  are useful analgesic adjuncts and should also be considered as first-line therapy to manage pain. Sleep inducing agents can be used to help sustain sleep ore normalize sleep patterns while providing muscle relaxing and analgesic effects including the use of bedtime trazodone (50–150 mg) or amitriptyline (10–75 mg) or cyclobenzaprine (5-10 mg).  Doses of these agents may be escalated to optimize nighttime sleep without causing attendant daytime drowsiness. Trazodone may be less sedating than amitriptyline.  Other sleep aids may be used in patients who have difficulty falling asleep, including the use of bedtime zolpidem (5–10 mg), zaleplon (5–20 mg) or benzodiazepines such as temazepam and clonazepam.  Clinicians should activity seek out problems such as obstructive sleep apnea or restless leg syndrome (RLS) and refer such patients for a sleep medicine evaluation.  Effective therapies for RLS include ropinerole, pramipexole or hydrocodone – usually give 2-3 hours before bedtime.  The use of newer antidepressant agents, such as duloxetine and milnacipran  may improve useful for both pain and depression, but have not been shown to be superior to sertraline, fluoxetine, citalopram or venlafaxine with regard to adjunctive pain control. However, there is less experience with these drugs in fibromyalgia than with the tricyclic antidepressants, and their expense is generally greater. Pregabalin (during the day) and gabapentin (often at bedtime because of its mild-moderate sedative effects) are often used to manage pain and lessen neuropathic symtpoms. Pain can be reduced further through appropriate stretching and exercise and with control of depression or anxiety.
—Physical modalities: Supervised therapy or instructional exercise programs are important in the overall therapeutic plan in fibromyalgia. Aqua therapy (preferably in a heated pool) may allow patients with pain or weakness to exercise with less discomfort. Exercises that emphasize stretching, such as yoga, pilates or Tai Chi may be useful and should be done at least initially under supervision. Aerobic conditioning is less well tolerated initially but should be encouraged after pain, sleep and stretching programs have yielded substantial clinical improvements.
—Psychologic approaches: Many patients with fibromyalgia exhibit symptoms of psychological distress, including anxiety and depression. A minority will have symptoms that will require psychiatric evaluation and treatment. Others may benefit from cognitive-behavioral therapy. Such a program can include training in relaxation and coping skills as well as guidance in reinforcing positive behaviors.

Monitoring: The frequency of monitoring is determined by the medications used and response to therapy. At each follow-up visit, the clinician should assess the magnitude of the patient’s pain, the quality and quantity of sleep, limitations on activities of daily living, the number of tender trigger points, and the impact of outside stressors or new sources of pain on current status.

Prognosis: Longitudinal studies suggest that the duration of disease is often many years and that only a minority of patients (10%–20%) improve over time and the number of patients requesting disability benefits is increasing. Fibromyalgia is a significant cause of long-term disability and, given the high prevalence of this condition and relatively young age of most patients, the economic and social impact of this disorder is profound. In many, disability can be avoided by vocational counseling, modification of work schedule and activities, and avoidance of exacerbating factors (e.g., trauma, stress, poor sleep, depression, arthritis).

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