Analysis of a distinct speech disorder seen in chronic manganese toxicity following Ephedrone abuse

Abstract Introduction In the last fifteen years a new cause of chronic manganese toxicity has been recognized. It follows recreational intravenous injections of Ephedrone, synthesized from a cold remedies contained pseudoephedrine. Potassium permanganate is used as an oxidant. It presents with severe parkinsonism-dystonia and a characteristic dysarthria. Objectives We performed a focus perceptual study of dysarthria in Ephedrone induced parkinsonism and compared the findings with the speech disorders seen in Parkinson's disease (PD) and Progressive Supranuclear Palsy (PSP). Methods A digital voice recording, perceptual speech analysis (Darley, 1975) [18], serial neurological assessment and Brain Magnetic Resonance (MR) imaging were performed at the Lviv regional Clinical Hospital. The results were analysed at the Institute of Neurology in London. Results Dysarthria developed after 8.5±3.2months of daily intravenous Ephedrone abuse and was an initial symptom in a third of cases. It was characterised by a robotic-flat prosody, whispering or continuous phonation, an inability to regulate pitch and volume, frozen lip articulation, a variable degree of dystonic tightness, difficulties in speech initiation and palladia, There was no nasality and swallowing was normal. In some patients speech deteriorated even after the discontinuation of Ephedrone. MR imaging, performed soon after drug cessation showed T1 signal hyperintesity in striatum and pallidum, especially in the Globus Pallidum interna. Conclusion Ephedrone induced chronic manganese toxicity can lead to a mixed hypokinetic-dystonic dysarthria with a distinct dystonic pattern. Perceptual speech analysis can be a helpful ancillary investigation in the differential diagnosis of parkinsonism, and may permit the recognition of chronic manganese toxicity.