Other Theories Patients with CFS sometimes complain that they feel so weak that it seems as if their muscles are no longer working properly. It has been proposed that a defect in skeletal muscle could be the cause of the fatigue. However, physical, chemical, and metabolic studies have not found any consistent pattern of abnormalities in the muscles of these patients. Chronic hyperventilation may cause an imbalance in oxygen and carbon dioxide, which can produce chest pain, faintness, numbness in the fingers and toes, and motor impairment. In one study, although a significant number of CFS patients experienced hyperventilation, there were no differences in CFS symptoms between patients with hyperventilation and patients who did not experience it.
Hyperventilation is very unlikely to be a cause of many instances of chronic fatigue.
Causes of Chronic Fatigue-Like Symptoms after the Gulf War Gulf War veterans have been intensively studied because of a high percentage reporting CFS symptoms. Women veterans had three times the risk as men. Because such symptoms have occurred in other veteran groups, some experts suspect that post-traumatic stress syndrome may be responsible for the symptoms in some cases. After finding that stress weakens the blood-brain barrier, some experts believe that, in extremely stressful situations such as the Gulf War, this weakened barrier may allow agents, such as small viruses, to pass into the brain causing damage and triggering CFS symptoms. Whether uncovering the causes of the syndrome in Gulf War soldiers can be applied to civilian cases of CFS, however, is not known.