53 London Lancet, vol i. p. 113.
In default, then, of positive information upon this point, conclusions must be drawn from a study of the symptoms, the course, and the behavior of these diseases under treatment. An affection of such protean aspect is not likely to have one settled pathological condition underlying it.
Many affections considered hitherto purely functional have under our more advanced knowledge been found to have as a basis a positive organic change.
On the subject of fatigue, Poore54 concisely states that the symptoms “are referable to the muscles, but we must always bear in mind that muscles and motor-nerve are one and indivisible, and that recent experiments have given great probability to the idea that every muscle is connected with a definite spot in the brain; when, therefore, we speak of a sense of fatigue, we must necessarily be in doubt, notwithstanding the fact that the symptoms are referred to the muscles, whether brain, nerve, or muscle, one or all of them, be really at fault.”
54 “On Fatigue,” London Lancet, vol. i., 1875, p. 163.
There is a certain limit to which exercise of a given group of muscles may be carried without producing fatigue and local congestion, or perhaps even inflammatory results; this varies greatly in different individuals, but if it is continually and uninterruptedly overstepped, and insufficient time given for rest and recuperation, the centres in the spinal cord which regulate the action of the various muscles implicated become overstimulated, and the result is an undue amount of nervous energy induced by the peripheral excitation, or there is a distortion of the central impulses in passing through these centres: a perturbation of the co-ordinating power ensues and inco-ordination is the result. Under rest and appropriate treatment these symptoms may pass away, but if the part is continuously used it is highly probable that nutritive changes will be produced in that part of the spinal cord from which the nerves supplying the overtaxed muscles proceed.
In some cases of hemiplegia there is produced during gaping and sneezing an automatic movement of the paralyzed arm; this was noticed as early as 1834 by Marshall Hall,55 and in 1872, Onimus56 noticed that movements of the hand and fingers of the non-paralyzed arm produced similar movements in the paralyzed side.
55 Quoted by Charcot, Diseases of Spinal Cord, transl. by Comyges, Cincinnati, 1881, p. 110.
56 Ibid.
Erb57 states that these movements in certain spinal troubles are partly owing to the establishment of conditions of irritation in the neighborhood of the lesion.