The largest study yet of chronic fatigue syndrome has found evidence of inflammation in the brains of patients, the first documentation of a neurological abnormality connected with the mysterious ailment.
But the findings detected on magnetic resonance imaging scans were not specific enough for such scans to be used as a diagnostic test for the syndrome, the authors reported recently in the Annals of Internal Medicine.
“The HHV-6 findings could reflect an immune system abnormality that caused the virus to reawaken after being dormant for many years.”
The study also found evidence that a common virus was active in most patients. But the authors said the evidence did not establish the virus, herpes virus 6, or HHV-6, as the cause of the syndrome.
Rather, one of the authors of the study, Dr. Anthony L. Komaroff of the Brigham and Women’s Hospital in Boston, said the authors suspected that the syndrome in some unknown way led to an abnormality of the immune system, which in turn reactivated a virus that had long been dormant in the body. Earlier studies showed that HHV-6 infects virtually everybody in the first years of life.
The study is the latest of a recent series showing immunologic and hormonal differences between those with the syndrome and healthy people. The studies have strengthened the belief among a growing number of scientists that the syndrome is distinct from depression and other psychological disorders.
The new report was produced by researchers from eight medical centers who studied 259 patients who developed the ailment from 1984 to 1986. Of the 259, 183 were involved in an outbreak detected near Lake Tahoe, Calif. The remaining 76 in the study had similar symptoms.
The outbreak rekindled interest in an ailment that has gone by various names for more than a century. Among such names are postviral fatigue syndrome; Icelandic disease; neurasthenia; chronic mononucleosis, and even “yuppie flu.”
Chronic fatigue syndrome often begins abruptly with flu-like symptoms that are followed by months or years of sometimes disabling lethargy and impaired cognition. Tens of thousands of Americans suffer symptoms of the syndrome, but precise numbers are unknown since no diagnostic test exists.
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Brain Swelling Is Seen
Imaging scans showed pinpoint areas of swelling or loss of part of the sheath that surrounds nerve cells in the central nervous system in 113 of 144 patients, or 78 percent. The abnormal areas were detected on repeat imaging scans and in some cases even after symptoms had eased.
The abnormalities were scattered throughout the brain. But in some patients, the doctors found a relationship between the area affected and a patient’s symptoms. For instance, seven patients with vision problems had abnormalities in the occipit, or vision center of the brain.
But the scan findings were not unique for the chronic fatigue syndrome patients; similar conditions were detected in 10 of 47, or 25 percent of the healthy control group. Perhaps, Dr. Komaroff said, many people experience unrecognized mild inflammation some time in their life that leaves a little scar in the brain.
Two radiologists examined the scans independently and agreed with the findings in 96 percent of the cases.
Doctors have not studied brain tissue of patients with the syndrome, and thus the researchers cannot be certain about the meaning of the findings, Dr. Komaroff said.
Because similar imaging scans of patients with depression have not been done, Dr. Komaroff said, “It is conceivable but doubtful that what we are measuring is a biological manifestation of depression that no one has ever found before.”
But Dr. Komaroff said his team has begun such studies. “If you found that patients with depression have brain inflammation and viral reactivation and immunologic changes, what would it say about our concept of what depression is?” he asked.
Scientistist sought a viral cause of the syndrome because many cases in the Lake Tahoe outbreak occurred among relatives and co-workers, suggesting transmission of an infectious agent by casual contact. A few had transient encephalitis, or inflammation of the brain, that was characterized by confusion, partial paralysis and seizures.
The scientists found evidence that HHV-6 was reproducing in white cells in 79 of 113 patients and in 8 of 40 controls.
The HHV-6 findings could reflect an immune system abnormality that caused the virus to reawaken after being dormant for years. But the virus did not produce the symptoms that made patients feel sick.
Dr. Komaroff, however, also said the findings could mean that once HHV-6 was awakened it contributed to the chronic suffering of the patients. But, he added, it was extremely unlikely that chronic fatigue syndrome resulted from a reinfection with HHV-6.