The condition was explained as being a result of exhaustion of the central nervous system's energy reserves, which Beard attributed to modern civilization. Physicians in the Beard school of thought associated<unk>  with the stresses of urbanization and with stress suffered as a result of the increasingly competitive business environment. Typically, it was associated with upper class people and with professionals working in sedentary occupations, but really can apply to anyone who lives within the monetary system. Freud included a variety of physical symptoms into this category, including fatigue, dyspepsia with flatulence, and indications of intra-cranial pressure and spinal irritation. In common with some other people of the time, he believed this condition to be due to "non-completed coitus" or the non-completion of the higher cultural correlate thereof, or to "infrequency of emissions" or the infrequent practice of the higher cultural correlate thereof. Later, Freud formulated that in cases of coitus interruptus as well as in cases of masturbation, there was "an insufficient libidinal discharge" that had a poisoning effect on the organism, in other words,<unk>  was the result of (auto)intoxication. Eventually he separated it from anxiety neurosis, though he believed that a combination of the two conditions existed in many cases. In 19th-century Britain and, by extension, across the British Empire,<unk>  was also used to describe mental exhaustion or fatigue in “brain workers” or in the context of “overstudy”. This use was often synonymous with the term “brain fag”.
Neurasthenia
Tropical ataxic neuropathy
Lambert–Eaton myasthenic syndrome
Multiple system atrophy
Congenital myasthenic syndrome
Metabolic myopathy
Autophagic vacuolar myopathy
Polyneuropathy