Cervical MRI of subacute myelo-optico-neuropathy

Abstract

Study design:Case study.Objectives:Subacute myelo-optico-neuropathy (SMON) is a severe neuro-degenerative disorder caused by poisoning due to over-dose and prolonged oral administration of clioquinol; this disorder was more frequent during 1957-1970. It is characterized by axonal degeneration and gliosis in the cervical gracile fasciculus. Recently, copper-deficient myelo-neuropathies presenting similar symptoms (that is, painful dysesthesia/paresthesia in the lower limbs, ataxia, spastic paraplegia, autonomic disorders and visual impairment) were reported. Magnetic resonance imaging (MRI) of these patients detected T2-weighted hyperintensities in the cervical spinal cord. An unbalanced zinc-copper metabolism was suggested as one of the candidate pathogenesis of clioquinol toxicity because of its metal-chelating ability. The aim of this study was to present MRI findings of old SMON patients and to compare them with those of current copper-deficient myelo-neuropathies.Setting:Japan.Methods:We conducted and analyzed cervical and brain MRIs of seven old SMON patients who contracted the disorder during the 1960s. Serum iron, magnesium, copper, zinc and ceruloplasmin levels were also measured.Results:Cervical T2-weighted MRIs showed mild volume loss and faint hyperintensities in the dorsal columns, which might reflect residual gliosis. Brain fast fluid-attenuated inversion-recovery images and tractography were normal. Current levels of serum copper and zinc were within almost normal ranges.Conclusion:Although fainter, the abnormal T2 MRI signals we observed were similar to and occurred in the same locations as those reported in copper-deficient myelo-neuropathy patients. We suggest that these findings are useful to study the mechanism of clioquinol toxicity before using it to treat neurodegenerative diseases such as Alzheimer's disease. © 2011 International Spinal Cord Society All rights reserved.