The current criteria for the diagnosis of chronic fatigue syndrome are the presence of persistent and disabling fatigue for at least 6 months, coupled with an arbitrary number (6 or 8) of persistent or recurrent somatic and neuropsychologic symptoms including low-grade fever, cervical or axillary lymphadenopathy, myalgias, migrating arthralgias, sore throat, forgetfulness, headaches, difficulties in concentration and thinking, irritability, and sleep disturbances (Holmes et al). A number of such patients in our experience have complained of paresthesias in the feet or hands. On close questioning, many of these sensations prove to be odd, particularly numbness in the bones or muscles or fluctuating patches of numbness or paresthesia on the chest, face, or nose. Unusual descriptions may be given if the patient is allowed adequate time to describe the symptoms. A few have reported blurred or “close to” double vision; in neither case are there physical findings to corroborate the sensory experiences. With regard to headache, it is worth consulting the section in Chap. 9 regarding “recent onset daily headache,” an unusual entity in which severe bilateral headache without distinguishing features arises very rapidly, sometimes after a viral illness, is unremitting for months or longer and resistant to treatment.
There is a common association with the similarly obscure entity of fibromyalgia, consisting of neck, shoulder, and paraspinal pain and point tenderness, as described in Chaps. 10 and 45. Despite these complaints, the patient may look surprisingly well and the neurologic examination is normal. The term for this same chronic fatigue entity, myalgic encephalomyelitis, is preferred in Great Britain and captures the association between the two syndromes.
In a large group of patients who were studied 6 months after viral infections, Cope and colleagues found that none of the features of the original illness was predictive of the development of chronic fatigue; however, a previous history of fatigue or psychiatric problems, and an indefinite diagnosis were often associated with persistent disability. In one study of more than 1,000 patients who were observed for 6 months following an infective illness, the chronic fatigue syndrome was no more frequent than in the general population (Wessely et al). One thing is clear to the authors: that applying the label of chronic fatigue syndrome in susceptible individuals tends to perpetuate this state.
Complaints of muscle weakness are also frequent among such patients, but Lloyd and coworkers, who studied their neuromuscular performance and compared them with control subjects, found no difference in maximal isometric strength or endurance in repetitive submaximal exercise and no change in intramuscular acidosis, serum creatine kinase (CK) levels, or depletion of energy substrates. These individuals share with depressed patients a subnormal response to cortical magnetic motor stimulation after exercise (Samii et al), which can be said to match their symptoms of reduced endurance but otherwise is difficult to interpret. In a small number of affected persons, a chronic but usually mild hypotension, elicited with tilt-table testing and reversed by mineralocorticoids, has been proposed as a cause of chronic fatigue (Rowe et al). Electromyography and nerve conduction studies are typically normal, as is the spinal fluid, but the electroencephalogram (EEG) may be mildly and nonspecifically slowed. Batteries of psychologic tests have disclosed variable impairments of cognitive function, misinterpreted by advocates of the “organic” nature of the syndrome as proof of some type of encephalopathy. Similarly, sensory complaints such as paresthesias and numbness are common, sometimes in one region of the body but little objective evidence of a neuropathy or myelopathy can be found.