Among the prodromes are headache, vertigo, agitated and interrupted sleep marred by distressing dreams, and troublesome insomnia; derangements of the special senses, dimness of vision, alterations of the pupils, tinnitus aurium; dysphagia and a sense of constriction of the pharynx have also preceded the attack of cerebral disorder. It is usually preceded likewise, and often by a considerable lapse of time, by the other lead affections above described—namely, colic, arthralgia, and palsy. Psychical derangements—stupor, apathy, or excitement—also precede the attack. In a small number of cases lead encephalopathy has occurred abruptly without prodromes.
The symptomatology is exceedingly variable and irregular. Three forms, the delirious, the comatose, and the convulsive, have been described. These conditions may succeed each other in the same attack. The delirium is variable in kind. It is apt to be at first tranquil; after some time it becomes paroxysmal and furious. It is broken by intervals of somnolence. At length true sleep supervenes, and the patient awakes restored almost completely to his reason.
Coma may develop suddenly, even instantaneously. In a very few cases the comatose form has developed itself alone during the course of chronic lead-poisoning. As a rule, however, it is preceded by delirium or convulsions.
The convulsive form is the most common. The convulsions may be partial, involving the face or the one side of it, a single limb, or one side of the body. They may be general, without loss of consciousness. These incomplete attacks are apt to be followed, after a period of dulness or unconsciousness, by acute eclampsia. Epileptiform attacks may now follow each other in rapid succession, ending in more or less profound coma. The attacks are sometimes separated by intervals of uneasiness, restlessness, or delirium. These attacks continue several days. If they are very violent and frequent death may rapidly supervene. In favorable cases consciousness is gradually restored, or the patient may awaken suddenly from his drowsiness after some hours or a day.
These attacks are not preceded by an aura.
Amaurosis is among the more important of the symptoms produced by the action of lead upon the nervous system. It is usually accompanied by dilatation of the pupils. The amaurosis gradually disappears as the other symptoms subside, and with the improvement in sight the pupils contract. Recovery is frequently complete. Occasionally vision does not return with the improved general condition. Norris13 saw, in two cases of lead-poisoning due to the use of white lead as a cosmetic, marked choking of the discs in connection with severe cerebral symptoms. The terminal condition, when recovery does not take place, is that of nerve-atrophy.
13 See this System of Medicine, Vol. IV.
Albuminuria is common in this as in other lead affections. It may be of moderate amount and due to the rapid breaking-down of the blood-corpuscles which marks the exacerbation of the general condition. Albuminuria may be a direct consequence of the eclampsia. Finally, it may be due to coexisting nephritis.
The prognosis is in a high degree unfavorable.
MORBID ANATOMY AND PATHOLOGY.—There are no well-characterized anatomical lesions in chronic lead-poisoning. Lead has been found in almost every organ and tissue in the body. It exists in combination with the albumen of the tissues. The changes in the nervous system that have thus far been described are neither constant nor characteristic. The same is true of the lesions of the intestines. The paralyzed muscles are found to have undergone atrophy, with loss of the striæ and increase of connective tissue. The nerve-trunks are also the seat of atrophic degeneration.