NEUROTOXICITY ASSESSMENT IN ACUTE LEAD POISONING

Objective: We present 3 cases of acute, occupational poisonings in workers exposed to lead during cutting and smelting discarded automobile storage batteries in a 'backyard' plant. Neuropsychological, neurological, examinations as well as EEG, CT scan and MRI were performed to assess the CNS lead neurotoxicity. Case Series: In the last days of October 2000, 3 patients were admitted to the Department of Clinical Toxicology with signs and symptoms of acute lead poisoning. Case 1: In a 36-year-old man, exposed to lead for 5 months, clinical examination revealed a severe encephalopathy (coma, brain edema, seizures), moderate anemia and slight liver dysfunction. Lead concentration in blood was 3100 [micro]g/L, excretion with urine 17.6 mg/24h, delta aminolevulinic acid (ALA) in urine-21.0 mg/L. CT scan performed in the first day confirmed diffuse cerebral edema. Chelating therapy with BAL and Ca[Na.sub.2]DTA was started immediately together with symptomatic and supportive treatment. MRI performed two weeks later revealed cortical and subcortical atrophy of the brain. In neuropsychological examination massive disorders of memory, thought processes, attention and learning ability were stated. In EEG epileptiform waves were observed. The last neurological examination showed proximal paresis in the upper extremities. Case 2: A 34-year-old man was exposed to lead for 5 weeks. At admission generalized weakness, dizziness, headache, abdominal pain and vomiting were observed. Laboratory findings revealed anemia and increased activity of the liver enzymes. Lead blood concentration was 1200 [micro]g/L, lead urinary excretion-16.8 mg/24h, ALA in urine-52 mg/L. Neuropsychological examination showed disorders in non-verbal functions. The CT scan and MRI of the brain showed slight cortical and subcortical atrophy. EEG was normal. Neurological examination revealed tremor of upper extremities and nystagmus. Chelating therapy with BAL and Ca[Na.sub.2]DTA was started. Case 3: A 21-year-old man was exposed to lead for 1 week. He presented only abdominal pain and weakness. Blood lead concentration was 1200 [micro]g/L, lead urinary excretion-3.8 mg/24h, ALA in urine-55.1 mg/L. Laboratory results: insignificant anemia and increased activity of the liver enzymes were observed. Moderate impairment of memory was stated in neuropsychological tests. CT scan, MRI and EEG did not reveal significant changes. Neurological examination: nystagmus and dysesthesia were observed. The treatment was started with DMPS and then continuing with Ca[Na.sub.2]DTA. Peripheral nervous system evaluation will be performed and further dynamic investigations are planed. Conclusion: In all patients exposed to lead by inhalation at the workplace, the blood lead concentration was in the range that causes severe neurotoxicity. The severity of the CNS manifestations was related to the blood lead concentration and the time of exposure. Groszek B, Pach J, Hydzik P, Szczepanska L. Department of Clinical Toxicology College of Medicine, Jagiellonian University, Krakow, Poland