Motor neurone disease and exposure to lead
Disease of the lower motor neurone is a recognized hazard of lead toxicity, but the importance of contact with lead in the causation of motor neurone disease has not previously been ascertained. In 74 cases of motor neurone disease, 15% had a history of extensive exposure to lead, compared with 5·4% of a control group. The five year survival rate of these patients was 54%, compared with 16% in the remainder. The more benign course of the disease in some of these cases may be due to treatment with chelating agents. A history of either disease of the axial skeleton or previous fracture was obtained in 25% of patients compared with 9·4% of controls. There may be a relationship between skeletal demineralization and the development of motor neurone disease. The lead content of iliac crest bone biopsy specimens in 25 patients with motor neurone disease was no greater than that of a control group, but this does not exclude the possibility that lead liberated from bone might affect the motor neurone.