Introduction
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the
causative virus of coronavirus disease (COVID-19), which was discovered
in China in December 2019 (1). To date, there is no end in sight to the
disease. The recognized acute phase symptoms of COVID-19 are fever,
dyspnea, cough, dysgeusia, and anosmia. Recent attention has focused on
COVID-19 sequelae called “long COVID” or post-COVID-19 syndrome (2).
After recovery from COVID-19, approximately 50% of patients reportedly
experience sleep disturbance and chronic fatigue (3), and approximately
25% meet the diagnostic criteria for myalgic encephalomyelitis/chronic
fatigue syndrome (ME/CFS) (4). ME/CFS causes various symptoms such as
morbid fatigue, pain, and mental disorders that worsen after exertion;
however, its pathogenesis and treatment remain unclear (5). Thus, as
many as 80% of patients struggle to receive a diagnosis of ME/CFS, and,
in some cases, are forced to consult several specialists and medical
facilities for a diagnosis (6).
Currently, there are no blood tests or imaging studies that provide a
definitive diagnosis of ME/CFS, although such procedures may serve to
rule out alternative competing diagnoses. However, of the clinical
symptoms and laboratory tests commonly regarded as suggestive of ME/CFS,
two are especially noteworthy and therefore, warrant additional
attention: post-exertional malaise (PEM) (7) and serum acylcarnitine
level (8). In this report, we present a review of the literature
concerning these two features and describe the case of a patient for
whom we were able to correctly diagnose ME/CFS based on accurate
history-taking and clinical examination.