Slow periodic myoclonus is a well-recognized phenotype of fulminant subacute sclerosing panencephalitis (video 1).1 This distinctive phenotype has not been previously recognized in another rapidly progressive disorder, fulminant Wilson disease. We documented slow periodic myoclonus in a 34-year-old Peruvian man who developed paranoid schizophrenia and, 6 months later, levodopa-unresponsive parkinsonism and falls, progressing into akinetic mutism (video 2). Prior to death, the diagnosis of Wilson disease was supported by ocular and neuroimaging features (figure), low ceruloplasmin (5.3 U/L), high urinary copper, and diffuse hepatopathy on echography. Slow periodic flexor myoclonus reflects cortical excitability and bears a poor prognosis.2 The EEG correlates are generalized, high-amplitude, quasiperiodic complexes.
Video 1
Periodic myoclonus in subacute sclerosing panencephalitis. Patient with visual loss due to chorioretinitis, evolving into a dementia syndrome with slow periodic myoclonus, synchronous in flexor muscles, classical of subacute sclerosing panencephalitis.Download Supplementary Video 1 via http://dx.doi.org/10.1212/008206_Video_1
Video 2
Periodic myoclonus in fulminant Wilson disease. Akinetic mutism with proximal slow periodic myoclonus, synchronous in flexor muscles of both arms and legs.Download Supplementary Video 2 via http://dx.doi.org/10.1212/008206_Video_2
(A) Head CT shows hypodense putamen and hyperdense medial thalami. (B) Eyes with Kayser-Fleischer rings. Brown rings encircle the iris, due to corneal copper deposition. (C–E) Axial fluid-attenuated inversion recovery brain MRI demonstrates heterogeneous hyperintense signal in the ganglia (C), pons (D, “face of the panda cub”), and midbrain (E, “face of the giant panda”).
Author contributions
R.M. Meza drafted the manuscript and created the videotape. H. Schulz, J. Correa, and M. Rojas evaluated the patient with Wilson disease and participated in the review of the manuscript. V. Lal evaluated the patient with subacute sclerosing panencephalitis and participated in the review of the manuscript. A.J. Espay provided critical review of the cases and participated in the review of the manuscript.
Study funding
No targeted funding reported.
Disclosure
R.M. Meza, H. Schulz, J. Correa, M. Rojas, and V. Lal report no disclosures. A.J. Espay has received grant support from the NIH, Great Lakes Neurotechnologies, and the Michael J Fox Foundation; personal compensation as a consultant/scientific advisory board member for AbbVie, TEVA, Impax, Acadia, Acorda, Cynapsus/Sunovion, Lundbeck, and USWorldMeds; publishing royalties from Lippincott Williams & Wilkins, Cambridge University Press, and Springer; and honoraria from AbbVie, UCB, USWorldMeds, Lundbeck, Acadia, the American Academy of Neurology, and the Movement Disorders Society. Go to Neurology.org/N for full disclosures.
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Teaching slides links.lww.com/WNL/A965
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