Five Differential Diagnoses to Fibromyalgia Syndrome
Diagnosing Fibromyalgia Syndrome can be a complicated and protracted process. Tests that have shown abnormalities related to the condition in research are often not clinically available. A diagnosing physician has to rely on patient history, exclusion of differential diagnoses and the tender point examination to check for the widespread hyperalgesia characteristic of Fibromyalgia Syndrome.
There are a huge number of potential diferential diagnoses to Fibromyalgia Syndrome. Mis-diagnoses either way do occur and often patients need to re-assessed at a later stage.
Here are five differential diagnoses to Fibromyalgia Syndrome that may not have been fully investigated:
1. Sero-negative Systemic Lupus Erythematosus (SLE or Lupus) or other inflammatory conditions
Lupus patients can have a wide variety of symptoms and severity of symptoms, and may present with similar symptoms to Fibromyalgia Syndrome. No single test establishes the diagnosis of systemic lupus - 11 diagnostic criteria were established by the American Rheumatism Association, with 4 out of 11 strongly suggesting a diagnosis of SLE.
A positive antinuclear antibody test is only one of the possible criteria, with blood tests totalling 3 of the 11 possible criteria. Some patients suspected of having SLE may never develop enough criteria for a definite diagnosis and other patients accumulate enough criteria only after months or years of observation. Patients with SLE also often go on to develop Fibromyalgia Syndrome. It is therefore very important to consider more than just blood test results when considering whether a patient has Fibromyalgia Syndrome, an inflammatory connective tissue disorder or both conditions and to revisit the possibility in light of new or worsening symptoms.
Fibromyalgia Syndrome is not associated with elevated levels of ANA, RF, ESR or CRP. Nor is it commonly associated with significant swelling of joints. However, it is not uncommon for these findings to be dismissed if a diagnosis of Fibromyalgia Syndrome has already been made. A patient responding especially well to NSAIDs or steroids is another sign of an underlying inflammatory condition and should be fully investigated.
2. Myofascial Pain Syndrome
Myofascial Pain Syndrome is a relatively newly understood diagnosis, with much of the seminal work into this condition having been done by the American physicians Travell & Simons in the second half of the 20th century. Little training is given on the diagnosis and treatment of this condition, despite myofascial pain problems being widespread amongst the general population. With Fibromyalgia Syndrome, the situation is particularly complicated as patients with Fibromyalgia Syndrome often also have comorbid Myofascial Pain Syndrome. However, Myofascial Pain Syndrome requires a different treatment approach to Fibromyalgia Syndrome and can occur without Fibromyalgia Syndrome.
Signs that a patient may have Myofascial Pain Syndrome, whether or not they also have Fibromyalgia Syndrome, include: tight, "knotty" or hard muscles, which can easily be assessed through physical examination; referred pain or other symptoms, such as headaches, from areas of restrictions - this can manifest as neuropathic-type pain, recurrent or intractable headaches or migraine and even nausea; unusually fast build-up of lactic acid in the muscles upon slight exertion - often a particular problem in the legs; and restricted movement or stiffness, particularly after inactivity.
Some physiotherapists and a few consultants have done some post-graduate training in the diagnosis and treatment of Myofascial Pain. Treatment options include injections (often lidocaine, but saline & botox have also been used), muscle relaxants and physiotherapy, especially to help correct underlying postural problems and to peform direct trigger point release. However, the most effective treatment is often a course of myofascial release therapy and this is usually only available from private, specially trained massage therapists.
For more information, see the articles Tender points Trigger points and Pressure points and The Tender Point Test for healthcare professionals.
3. Vitamin D deficiency
Vitamin D deficiency is common in the UK and much of the Western World. As well as causing osteomalacia, vitamin D deficiency can cause symptoms of fatigue, muscle aches & pain, muscle weakness and bone pain. These symptoms can be mistaken for those of Fibromyalgia Syndrome, so vitamin D deficiency needs to be considered both as a possible differential diagnosis to Fibromyalgia Syndrome and as a comorbid condition that can seem to worsen the symptoms of Fibromyalgia Syndrome. Pregnant or breastfeeding women, and children, need extra vitamin D as it required for growth, so particular care should be taken to check for vitamin D deficiency in Fibromyalgia Syndrome patients who become pregnant, as they may not recognise the symptoms as being something other than their Fibromyalgia Syndrome.
Vitamin D deficiency can be checked for in a simple blood test and basic supplementation can help many patients, although some may require high doses by injection. One factor to consider, especially when supplementing vitamin D in patients with Fibromyalgia Syndrome or Irritable Bowel Syndrome, is that many of the more easily available supplements come as chewable tablets containing artifical sweeteners, which can cause diarrhoea & nausea in some patients, reducing both patient compliance and the absorption of the supplements.
For more information on vitamin D deficiency, see the patient.co.uk website here.
4. Magnesium deficiency
Magnesium is needed in the body for the correct function of the muscles and nervous system. Although a true, severe magnesium deficiency is rare, a relatively minor deficiency could impact on someone with Fibromyalgia Syndrome. Early symptoms of magnesium deficiency can include fatigue, muscle cramps & twitching, insomnia and cognitive dysfunction. Later symptoms may include continued muscle contraction, numbness, tingling and hallucinations.
Patients with Fibromyalgia Syndrome may struggle to eat a balanced diet if they are severely affected and aren't getting the help they need at home. They may also have problems with malabsorption through Irritable Bowel Syndrome or food intolerances causing chronic diarrhoea. This can lead to magnesium deficiency.
Diagnosing magnesium deficiency is complicated by the fact that serum magnesium levels may not accurately reflect intracellular levels. The simplest way to check for it in patient s with Fibromyalgia Syndrome who may have only a slight deficiency is to start the patient on a supplement of magnesium of 3 months and see if they improve and then see if they notice an increase in symptoms on stopping the supplement. As magnesium acts as a lazative if not absorbed, it is important that the patient realises that diarhhoea will mean the supplement is not being absorbed. Clinicians and patients report anecdotally that magnesium malate or chelated magnesium may be more readily absorbed than other varieties.
For more information, see this MedlinePlus article on Magnesium.
5. Lyme Disease
Lyme disease is a bacterial illness transmitted by ticks. It is rarely checked for in Europe - awareness of the condition is much higher in the USA, where an outbreak in children in 1975 kickstarted a lot of research.
Lyme disease is classically associated with a tick bite causing an expanding reddish rash, with accompanying flu-like symptoms. However, many people bitten by ticks do not notice the bite and more than 1-in-4 patients never get a rash, so relying on this symptom progression may mean Lyme Disease is missed. In the later stages, when Lyme Disease can become chronic, it can causes joint pain, peripheral neuropathy, fatigue and cognitive difficulties - symptoms which may be confused with Fibromyalgia Syndrome.
Generally, Lyme blood testing is helpful in a patient who has symptoms compatible with Lyme disease who has a history of a tick bite at least a month prior, or who has unexplained disorders of the heart, joints, or nervous system that are characteristic of Lyme disease, particularly if they are at high risk of having been bitten by a tick (e.g. lived/worked in the countryside or owned dogs or horses).
For more in-depth information see this Medicinenet article on Lyme Disease.