Chapter 120 Chiari Malformation, Chronic Fatigue Syndrome, and Fibromyalgia
A Paradigm for Care
The Chiari malformation (CM) usually is a congenital hindbrain disorder that can be acquired in rare cases. In 1891 Hans Chiari, a pathologist, was the first to describe the deformity and group it into different categories based on the severity of tonsillar and cerebellar descent below the foramen magnum.1
The incidence of Chiari malformation in a study of 22,000 brain MRIs was reported to be 1 in 1280 individuals.2 This study probably underestimates the true incidence of Chiari malformation in asymptomatic individuals and in the general population. There is a higher preponderance of Chiari malformation I in females than in males, by a ratio of 3:2.2
There seems to be some evidence of genetic transmission in a subset of patients with Chiari malformation with syringomyelia.2–4 The extent of cerebellar herniation does not necessarily correlate with subjective complaints, physical findings, and neurologic findings.4
Syringomyelia occurs when cerebrospinal fluid (CSF) forms a cavity within the spinal cord. Chiari malformation is the leading cause of pathologic syrinx formation. It is thought that the displaced cerebellar tonsil acts as a plug that obstructs CSF flow and may act as a miniature piston (i.e., the “piston theory”) to drive CSF inside the spinal cord.5 A syrinx cavity also can develop in other cases of CSF flow obstruction, such as spinal cord tumors, infection, or trauma. The incidence of syringomyelia in Chiari malformation I is estimated to be 50% to 75%.6
What Is Fibromyalgia Syndrome or Chronic Fatigue Syndrome?
Fibromyalgia syndrome is characterized by chronic widespread pain and multiple tender joints.7,8 Most patients have coexisting fatigue, sleep disturbance, paresthesias, and morning stiffness.8 More than 80% of patients with fibromyalgia syndrome have chronic fatigue syndrome. There are more clinical similarities than differences between the two entities. The patient is diagnosed with fibromyalgia syndrome if the predominant complaint is pain or chronic fatigue syndrome if the predominant complaint is fatigue. The prevalence of fibromyalgia is reported to be 2.1% to 5.7% in the general population and may be as high as 10% to 20% in some settings.9–11
In one study, fibromyalgia syndrome was found to be 13 times more common in patients following cervical spine injury as opposed to patients with lower extremity injury.12 It also is reported that 30% to 56% of patients with fibromyalgia syndrome have coexisting mental disorders, anxiety, or depression.13,14 Fibromyalgia can be diagnosed concomitantly in 34% of patients with chronic inflammatory arthritis (i.e., rheumatoid arthritis, systemic lupus erythematosus), and in 28% of patients with chronic spinal pain syndromes.7
Fibromyalgia syndrome currently is thought to be a disorder of pain regulation or “central sensitization.”15 There seems to be significant overlap in symptoms of various chronic disorders, such as irritable bowel syndrome, chronic migraines, chronic fatigue syndrome, and posttraumatic stress disorders. Patients with fibromyalgia have lower pain and heat thresholds and have higher catastrophizing and somatization behaviors in response to painful stimuli.16 Substance P, a peptide associated with chronic pain, is elevated in the CSF of patients with fibromyalgia syndrome.17 There seems to be a genetic predisposition as well: first-degree relatives of patients with fibromyalgia have higher rates of developing fibromyalgia syndrome. There is an increased co-aggregation of fibromyalgia syndrome with major mood disorders in families.18
Controversial Link between Fibromyalgia or Chronic Fatigue Syndrome and Chiari Malformation: Does It Really Exist?
In 1999, an article in The Wall Street Journal and an ABC 20/20 television program featuring prominent neurosurgeons suggested surgical management for patients with fibromyalgia syndrome or chronic fatigue syndrome with Chiari malformation or cervical stenosis.8
In 2001, in an abstract presented at the Congress of Neurological Surgeons in San Diego, Heffez reported on 64 patients with a diagnosis of fibromyalgia syndrome with signs and symptoms consistent with cervical myelopathy from either Chiari malformation or cervical stenosis who underwent surgery.19 There was no randomization in assigning patients. At 6 months, statistically significant improvement was reported as compared with a nonsurgical control group in terms of pain, grip strength, and balance impairment. Headache also improved in 90% of patients in the surgical group compared with 45% in the nonsurgical group. Non–statistically significant improvement also was seen in the surgical group in terms of fatigue, depression, insomnia, and paresthesias.
A link between fibromyalgia syndrome and Chiari malformation has been suggested, with the recommendation that patients with fibromyalgia should be aggressively worked up for possible neurologic disorders such as Chiari malformation or cervical stenosis.19,20 Based on the available literature, however, there is no evidence of a direct link between fibromyalgia syndrome/chronic fatigue with Chiari malformation with or without syringomyelia.21 It is plausible to suggest that patients who have long-standing neurologic disorders (e.g., cervical myelopathy, Chiari malformation, cervical stenosis) can develop secondary fibromyalgia. This is consistent with the concept of chronic central sensitization states. Compared with the prevalence of fibromyalgia syndrome, which is 5% to 20% in the general population), the 0.77% incidence of radiographic Chiari malformation in 22,591 brain/cervical MRI scans reviewed is relatively small.2 It could be by chance alone that they are linked. The nonstatistical improvement in fibromyalgia somatic complaints in the operated group could be explained by reduction in stress and the feeling that something “substantial” had been done. It is unclear whether these somatic symptoms referred to fibromyalgia improved permanently or if there was symptom recurrence over time, because no long-term follow-up was done.
An MRI study of consecutive patients diagnosed with fibromyalgia syndrome at two tertiary centers showed no increase in the prevalence of Chiari malformation/cervical stenosis in this group over that of the “normal” control group. In fact, 11 of 15 patients (73%) in the control group, compared with 8 of 26 patients (31%) in the fibromyalgia group, showed evidence of some degree of tonsillar herniation.22
How Is Fibromyalgia Diagnosed?
Diagnostic Criteria for Fibromyalgia
In 2010, the American College of Rheumatology created simpler, clinically friendly criteria for diagnosing fibromyalgia syndrome.23 These were designed not to replace the 1990 criteria but to provide clinically more relevant alternative criteria to diagnose fibromyalgia with similar diagnostic sensitivity and specificity. The most important change was to do away with tender point palpations and to include a widespread pain index score. The coexisting somatic symptoms that are so common in patients with fibromyalgia syndrome were highlighted.
