Although the prodromal stages of malaise, lassitude, loss of appetite, nausea, etc., generally precede both the acute and the chronic forms, colic often commences suddenly. Men may be examined in the factory in the morning, when the ordinary routine examination has elicited no symptoms, and yet cases of acute colic have occurred later in the same day in the very men examined.
The chief points associated with lead colic are—
1. The intermittent character.
2. The relation of the colic mainly to the lower part of the abdomen.
3. The slowing of the pulse.
4. The relief afforded by firm pressure on the abdomen.
To which may be added the action of amyl nitrite and other drugs of a similar physiological action.
Headache.
—Persistent headache is another of the symptoms associated with lead poisoning, but it is not common as an early symptom. The headache complained of by painters is probably not due to lead poisoning, but, as has been suggested, to turpentine. The headache of lead poisoning is invariably a later symptom, and frequently follows an attack of colic a week or more after the abdominal pain has ceased. The position of the headache varies; it may be of the vertex type, almost entirely confined to the vertex and occipital regions. On the other hand, it is frequently irregular, and neuralgic in type; but in this type, frontal and temporal, more particularly temporal, the patient describes the pain as if a blunt instrument were being pushed through his head from both temporal regions at the same time. Earache, or pain in the region of the petrous portion of the temporal bone, may at times suggest ear disease, but this situation is not so common as suboccipital or temporal pain.
The headache in these situations is no doubt associated with the meningeal artery in the temporal region, and with the sinuses in the occipital region. The headache, not unlike the colic, undergoes remissions and exacerbations. With the exacerbations vertigo is common, and on more than one occasion in our experience a person suffering from persistent lead headache and vertigo has been arrested as suspect of alcoholism. Headache and vertigo without either colic or paresis is by no means uncommon, and may be associated with pains in the arms and legs. These pains are generally referred to by the patient as rheumatic, and it is a little interesting to call to mind the number of instances in which rheumatic symptoms are returned as associated with lead poisoning in the statistics given on [p. 48]. It is probable that these pains are neither muscular nor purely nervous in origin, but are primarily due to small lesions of the bloodvessels, as described in the chapter on Pathology, occurring in various parts of the body, and thereby setting up localized irritation, too minute to form an area which can be discovered by palpation, but sufficiently pronounced to produce irritation and reflex pain, in some respects similar to “bends” in compressed air disease. This special type of rheumatic pain differs, of course, from the lumbago associated with constipation.