Tremor.
—Tremor may be observed in a large number of cases of lead poisoning, and is invariably associated with paralysis, although the symptom of tremor by no means always progresses to definite palsy. Two types of tremor are described—fine and coarse—and Gübler further describes a type of tremor which is both rhythmic and intermittent. The tremor is usually distinctly increased on attempting to grasp or point the hand (intention tremor), but it is difficult to separate tremor from alcoholic tremor, and, further, it must not be forgotten that persons engaged in arduous work may show a certain amount of tremor due to muscular fatigue. Persistent tremor, however, is a symptom that is always to be noted and carefully watched.
Of the types of paralysis, the antibrachial is the most common, and, secondly, probably the brachial. The least common is the peroneal. The table on [p. 54] shows the distribution of cases of paralysis, so far as they can be made out from reports received since 1904.
Closely associated with paralysis are affections involving the brain. Tanquerel, in his classical description of affections of the brain associated with lead poisoning, gives the following classification:
- 1. Delirium.
- 2. Lead mania.
- 3. Psychic depression.
- 4. Coma.
- 5. Convulsions, saturnine eclampsia, or epilepsy.
There is probably a very considerable relationship between insanity and lead poisoning, as pointed out by Robert Jones[17], the resident physician and Superintendent of Claybury Asylum.
Rayner[18] remarked that the compulsorily careful habits of life of painters and lead-workers ought to protect them against vicious habits, and should protect them against a too free indulgence in the use of alcohol! Our own experience is that paralysis, and particularly affections of the brain, occur in the majority of cases in persons who are addicted to alcohol, and the experiments quoted in the chapter on Pathology on the influence of alcohol in the production of encephalitis in animals is strong presumptive evidence that alcohol is one of the chief predisposing causes in the determination of saturnine encephalopathy.
Encephalitis is given as a cause of death in the report already referred to in 14·3 per cent. of 264 fatal cases. Amongst this number encephalopathy accounted for 14·3 per cent., cerebral hæmorrhage 9·8 per cent., and paralysis 9·2 per cent. Now, all these are cases in which cerebral lesions may be confidently stated to have existed, which brings the total to 34·4 per cent. of deaths at least due to brain involvement. We have already referred to the high incidence of paralysis amongst file-cutters—40 per cent. as against 21·1 per cent. for all industrial forms of poisoning.
When encephalitis occurs, it is usually an acute symptom, and often develops before paralysis is set up, but as a rule is preceded by a period of persistent headache, such headache being invariably temporal or occipital.
Robert Jones, in his paper, states that of the 133 cases who, from the nature of their work (painters, plumbers, etc.), were liable to lead impregnation, 19 had signs of poisoning upon admission, whilst 22 had a distinct history of lead poisoning at some time or other. He gives the following analysis of the mental condition: