This syndrome is seen most often in young adults. There isa prolonged period of lethargy, often with muscle pains andfatiguability, usually after an episode reminiscent of a viralillness but sometimes in the absence of an evident acuteillness. The problem causes great distress to patient and relativesbecause an explanation is lacking and there is prolongedinability to work or play at expected levels, oftencoupled with an unreasonable need for sleep. Doctors arefrustrated by their inability to establish a positive diagnosisor to give any specific treatment, and the patient oftenturns to alternative medicine.
Aetiology The syndrome is heterogeneous and no single explanationwill fit all patients. The term 'myalgic encephalomyelitis'is misleading as there is no evidence of encephalomyelitisand myalgia may not be present. A number of infectionshave been associated with this syndrome and they are notall viral. Infectious mononucleosis is the best known andstudied, but CMV infection and toxoplasmosis have beensuspected, and it is likely that many other organisms can actas triggers in susceptible individuals. Enteroviruses, particularlyof the Coxsackie group, have also been suspected butevidence is inconclusive. Often the only evidence for infectionat the onset is a history of febrile illness, perhaps withpharyngitis or lymphadenopathy, and a full blood countmay have revealed some atypical mononuclear cells.The relationship of postviral syndrome to depressionis complex. There is no doubt that some patients developthe symptoms and signs of depression and benefit fromantidepressant treatment. More commonly the patientbecomes depressed as a result of the illness but lacks manyof the features of primary depression. In this situation antidepressanttherapy is unlikely to be beneficial.
Clinical features The central symptoms are profound lethargy and easyfatiguability. Often these are accompanied by muscularpains, headaches and symptoms suggestive of fever, such assweating. This is usually mild, and when the temperature isrecorded it is normal or only minimally elevated in theevenings. Exertion exacerbates tiredness, and the patientoften goes to bed early and wakes late still feeling tired.ManagementPatients benefit greatly from having their illness taken seriously,and if a precipitating infection can be positively identifiedthis also helps. Sometimes the greatest problem isanxiety about the outcome or about whether there is anunderlying disease that has not been diagnosed, so reassuranceis important. When patients have restricted theiractivity it is worth trying to rehabilitate them by a programmeof daily exercise, starting with something lightsuch as walking or swimming, and gradually increasing itin a documented way. The patient is assured that exerciseis not harmful and advised to sleep as required.Most patients recover spontaneously within weeks ratherthan months, but a few continue to suffer for over a year.
