Sensation is not, as a rule, affected in lead paralysis. Pains in the paralyzed muscles, in neighboring muscular masses, and in the structures about the joints often precede the attack of paralysis. Anæsthesia of the skin is rare. When present, it is usually of slight degree, and corresponds to the region of the paralysis. Deep anæsthesia has also been observed.
Atrophy of the paralyzed muscles is constant and rapid. It frequently reaches a high degree, causing characteristic deformities, which are rendered more marked by the fact that the adjacent non-paralyzed muscles preserve to a great extent their original state of nutrition. As the neuro-muscular lesion progresses other deformities arise, in consequence of derangements of the balance of force between opposing muscles and from other causes. Among these deformities are partial or complete dislocations of the more movable joints, as the shoulder and phalanges, with the formation of tumors, which, when they occupy the dorsum of the hand, might be carelessly mistaken for the nodosities of gout. It is to be noted that the latter are occasionally present as complications.
There is rapid diminution, and finally complete loss, of the reaction to the faradic current. With the galvanic current the reaction of degeneration is usually well marked. The reaction of degeneration may be demonstrated in the extensors of the limbs in lead-poisoning before wrist-drop has occurred.
The course of lead palsy is very variable. In a few cases it is progressive. When local emaciation or atrophy arrives at the last degree of marasmus, the skin seems glued to the bones, to such an extent are the paralyzed parts wasted; the muscles especially are so thinned that the contour of the bones is easily distinguished. If the paralysis attack the whole of the limb, then this organ, abandoned to its own weight, stretches the ligaments and permits the head of the bone to leave its cavity. In other rare instances the paralysis remains stationary for long periods of time, only to grow worse after each new attack of lead disease. Much more frequently lead paralysis disappears spontaneously or under treatment in the course of some days or weeks. The convalescence is gradual, and usually rapid, when the gravity of the lesion is considered; occasionally it is complete in the lapse of a few days.
The prognosis depends upon the degree of lead cachexia present, the possibility of withdrawing the patient from the exposure, and finally upon the degree and extent of the paralysis and of the atrophy. It is rendered unfavorable by the necessity of the prolonged exposure of the patient to lead, by a high degree of disturbance of the general nutrition of the patient; and by the fact of his having presented for a considerable period the evidences of lead disease, with occasional attacks of colic or arthralgia; by the complete loss of power and electrical reactions in the affected muscles; and, finally, by absolute wasting of the muscular masses. The prognosis is less favorable in relapses than in the primary attack.
Progressive muscular atrophy has been frequently observed in patients suffering from lead disease (Naunyn).
5. The Encephalopathy; Encephalopathia Saturnina.—This term was suggested by Tanquerel to designate collectively the various morbid cerebral phenomena produced by chronic lead-poisoning. It embraces, therefore, those affections due to the action of lead upon the central nervous system, and occasionally described as lead insanity, delirium, convulsions, epilepsy, coma, etc. It is, of all the disorders produced by lead, the most rare. Tanquerel met with seventy cases only. It occurs only in those individuals who are exposed to large quantities of lead, and in such a manner as to favor the absorption of the metal and its compounds by the digestive and respiratory tract. Hence house-painters and the workers in lead-factories supply the greater number of cases. The time of exposure elapsing before the manifestations of the special morbid action of the poison upon the nervous system show themselves varies from a few days to many years. In a large proportion of the cases the time has been less than one year.
Women are much less liable than men—a fact clearly due to the nature of their occupations even when involving exposure to lead.
The majority of the cases have occurred between the ages of twenty and fifty. Alcoholic habits, insufficient and unwholesome diet, privations, exposure, and an irregular life especially predispose those working in lead to the affection. Lead encephalopathy has developed with nearly equal frequency in warm and in cold weather. Relapses are frequent.