Clinical Spectrum of Accidental Hemlock Poisoning: Neurotoxic Manifestations, Rhabdomyolysis and Acute Tubular Necrosis

Abstract

In the past, hemlock poisoning was only known for its neurotoxic effects; quite recently non-neurological features, consisting of rhabdomyolysis and acute renal failure, have been also described. Here we report our experience with these clinical findings, which we frequently observe in accidental hemlock poisoning. Between 1972 and 1990 we studied 18 patients: 17 of them were poisoned by conline (an alkaloid of Conium maculatim) in Apulia (Italy), and one by cicutoxin (the active principle of water hemlock) in New Mexico (USA). In the non-rapidly-fatal cases we tested myoglobinuria, serum muscle enzymes, and renal function. In the patients with acute renal failure we performed microscopical examination of kidney specimens; immunohistochemistry was carried out to identify myoglobin and actin in tubules. Coniine was detected in urine, serum, or tissues. Neurological features were present in all of our cases: coniine had a curare-like effect on the neuromuscular junction, whereas cicutoxin was convulsant on the central nervous system. In addition rhabdomyolysis was noted in the 17 subjects poisoned by coniine. Acute renal failure was observed in five patients; it was confirmed by histological evidence of tubular necrosis with intratubular deposition of myoglobin and actin released by rhabdomyolysis. Our cases seem to be the first with histopathologically proven acute tubular necrosis in coniine intoxication. In conclusion, in hemlock poisoning neurotoxic manifestations may be accompanied by rhabdomyolysis and acute tubular necrosis; increased awareness of these clinical features is recommended in order to improve the diagnostic and therapeutic procedure.