This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Ordinary medicinal doses do not usually produce definite effects on the nerves or muscles, but in acute poisoning from large quantities, besides the pain and cramp already mentioned, general prostration is a marked symptom. There may be also giddiness or stupor, numbness or paralysis, and, in fatal cases, convulsion. In the subacute cases at Stourbridge, the nervo-muscular symptoms were cramp and rigidity of muscles, numbness, and partial palsy of lower extremities, and collapse: the mental faculties were unimpaired.
But it is in chronic plumbism that affections of the nerves and muscles become marked and significant, various forms of paralysis almost always appearing. The most common is a paralysis of the extensors and supinators of the forearm, leading to a condition known as "wrist drop," from the peculiar manner in which the hand hangs down when the limb is extended. This occurs more often on the right side than the left - the fingers and wrists are flexed and the hand prone, the elbow stands out from the side, and the forearm bends on the arm - wasting of the affected muscles quickly follows, and especially of the small muscles of the thumb.
A special plastic or fungoid form of synovitis in the sheath of the extensor tendons has been described (Gubler: British Medical Journal, ii., 1878).
Sometimes other muscles are affected - thus, strabismus has been noted from paralysis of ocular recti, and aphonia from laryngeal palsy. Occasionally hemiplegia occurs, more rarely still paraplegia, and in advanced cases the extensors, at least of the lower limbs, are more or less affected. Death has resulted from paralysis of respiratory muscles. Of the special senses, sight is the most often affected, amblyopia occurring, or amaurosis from anaesthesia of optic nerve; in such cases the pupil is dilated. It is not uncommon for the hearing to suffer, and common sensibility is often altered. There is usually partial anaesthesia, though sometimes, as in the Claremont cases, excessive hyperaesthesia is developed.
During an attack of lead colic the intellect is, as a rule, clear, but in continued cases the moral courage and the spirits give way, and sometimes in the course of the illness distinct delirium occurs, generally of the form "delirium of dread," not unlike delirium tremens. The patient is extremely fearful of being alone, especially at night, and has visions of black and creeping things. Three remarkable illustrations occurring in women-workers at a lead-factory are furnished from the London Hospital (Medical Times, i., 1869). Other cerebral symptoms, such as headache, delirium, epileptiform convulsions, and coma, have been recorded; insomnia is usual.