These include:

Epidemic neuromyasthenia was a term used for outbreaks with symptoms resembling poliomyelitis. Iceland disease and Akureyri disease were synonymous terms used for an outbreak of fatigue symptoms in Iceland. Low natural killer syndrome, a term used mainly in Japan, reflected research showing diminished in vitro activity of natural killer cells isolated from patients. Neurasthenia has been proposed as an historical diagnosis that occupied a similar medical and cultural space to CFS. Royal Free disease was named after the historically significant outbreak in 1955 at the Royal Free Hospital used as an informal synonym for "benign myalgic encephalomyelitis". Tapanui flu was a term commonly used in New Zealand, deriving from the name of a town, Tapanui, where numerous people had the syndrome. Society and culture
Naming
Many names have been proposed for the illness. Currently, the most commonly used are "chronic fatigue syndrome", "myalgic encephalomyelitis", and the umbrella term "ME/CFS". Reaching consensus on a name is challenging because the cause and pathology remain unknown. : 29–30 The term "chronic fatigue syndrome" has been criticized by some patients as being both stigmatizing and trivializing, and which in turn prevents the illness from being seen as a serious health problem that deserves appropriate research.
Chronic progressive external ophthalmoplegia (CPEO) is a type of eye disorder characterized by slowly progressive inability to move the eyes and eyebrows. It is often the only feature of mitochondrial disease, in which case the term CPEO may be given as the diagnosis. In other people suffering from mitochondrial disease, CPEO occurs as part of a syndrome involving more than one part of the body, such as Kearns–Sayre syndrome. Occasionally CPEO may be caused by conditions other than mitochondrial diseases. Signs and symptoms
CPEO is a rare disease that may affect those of all ages, but typically manifests in the young adult years. CPEO is the most common manifestation of mitochondrial myopathy, occurring in an estimated two-thirds of all cases of mitochondrial myopathy. Patients typically present with ptosis (drooping eyelids). Other diseases like Graves disease, myasthenia gravis and glioma that may cause an external ophthalmoplegia must be ruled out. CPEO itself
CPEO is a slowly progressing disease. It may begin at any age and progresses over a period of 5–15 years. The first presenting symptom of ptosis is often unnoticed by the patient until the lids droop to the point of producing a visual field defect. Often, patients will tilt the head backwards to adjust for the slowly progressing ptosis of the lids. In addition, as the ptosis becomes complete, the patients will use the frontalis (forehead) muscle to help elevate the lids.