Metals in spinal cord tissue of patients dying of motor neuron disease.

To evaluate the role of toxic metals in causing motor neuron disease (MND), we used a photon-excited, energy-dispersive x-ray analytical system to measure the metal content of spinal ventral horn tissue. Specimens were taken from the cervical and lumbar enlargements of 7 patients who died of MND and the results compared with those found in 12 control patients. Anterior horn lead levels were elevated in MND patients compared to controls (mean, 40.7 micrograms/gm versus 14.6 micrograms/gm; p less than 0.05) and lead levels correlated with the duration of illness (r = +0.84, p less than 0.05). Only 2 MND patients had detectable manganese levels (72.3 and 132.2 micrograms/gm) whereas 1 control had detectable manganese (14.3 micrograms/gm). One MND patient had 244 micrograms/gm selenium, but 3 controls had levels of 180, 58, and 62. Patients with the histories of greatest environmental exposure to metals during life exhibited the highest tissue levels of metals after death; despite chelation therapy for about a year, high lead levels remained in their tissue.