Background: Myoclonus and encephalopathy are unusual in patients with Parkinson’s disease (PD).

Case report: We describe the case of a 59-year-old male with PD who developed myoclonus and encephalopathy. Underlying hypothyroidism was revealed after admission and treated with levothyroxine. Myoclonus and encephalopathy were completely resolved following thyroid hormone replacement.

Discussion: Hypothyroidism can cause reversible myoclonus and encephalopathy along with unusual aggravation of parkinsonism symptoms in patients with PD

Ehm, Gwanhee

Jeon, Beomseok

Kim, Han-Joon

Tremor and Other Hyperkinetic Movements

Columbia University Academic Commons

Case ReportsHypothyroidism-induced Reversible Encephalopathy as a Cause of Aggravationof Parkinsonism and Myoclonus in Parkinson’s DiseaseGwanhee Ehm1, Han-Joon Kim2,3,4& Beomseok Jeon2,3,4*1 Department of Neurology, National Medical Center, Seoul, Korea, 2 Department of Neurology, College of Medicine, Seoul National University, Seoul, Korea,3 Movement Disorder Center, Seoul National University Hospital, Seoul, Korea, 4 Parkinson Study Group, Neuroscience Research Institute,College of Medicine, Seoul National University, Seoul, KoreaAbstractBackground: Myoclonus and encephalopathy are unusual in patients with Parkinson’s disease (PD).Case report: We describe the case of a 59-year-old male with PD who developed myoclonus and encephalopathy. Underlying hypothyroidism was revealed afteradmission and treated with levothyroxine. Myoclonus and encephalopathy were completely resolved following thyroid hormone replacement.Discussion: Hypothyroidism can cause reversible myoclonus and encephalopathy along with unusual aggravation of parkinsonism symptoms in patients with PD.Keywords: Parkinson’s disease, hypothyroidism, myoclonus, encephalopathyCitation: Ehm G, Kim HJ, Jeon B. Hypothyroidism-induced reversible encephalopathy as a cause of aggravation of parkinsonism and myoclonus in Parkinson’sdisease. Tremor Other Hyperkinet Mov. 2017; 7. doi: 10.7916/D8BP0F9F* To whom correspondence should be addressed. E-mail: brain@snu.ac.krEditor: Elan D. Louis, Yale University, USAReceived: August 16, 2017 Accepted: September 28, 2017 Published: October 19, 2017Copyright: ’ 2017 Ehm et al. This is an open-access article distributed under the terms of the Creative Commons Attribution–Noncommercial–No Derivatives License, which permitsthe user to copy, distribute, and transmit the work provided that the original authors and source are credited; that no commercial use is made of the work; and that the work is not alteredor transformed.Funding: None.Financial Disclosures: None.Conflicts of interest: The authors report no conflict of interest.Ethics Statement: This study was reviewed by the authors’ institutional ethics committee and was considered exempted from further review.IntroductionMyoclonus is an unusual phenomenon in patients with Parkinson’sdisease (PD), especially non-demented patients. The development ofmyoclonus in the course of PD may herald alternative diagnoses suchas corticobasal syndrome.1 However, since myoclonus may be due toother medical conditions, a diagnosis other than neurodegenerativedisease should be considered. Herein, we describe a patient with PD whohad hypothyroidism presenting as abrupt development of myoclonus.Case reportA 59-year-old male patient previously diagnosed with PD at age 48was admitted for encephalopathy, severe exacerbation of parkinson-ism, and myoclonus. He had been treated with levodopa and had anexcellent response for the first 5 or 6 years of the disease. He under-went bilateral subthalamic nucleus deep brain stimulation surgery(DBS) at age 54 years because of severe dyskinesia and motorfluctuation despite meticulous medication adjustment. Following DBS,his parkinsonism was alleviated, and he could engage in socially active work.One month before admission, he had a delusion that a spy waswatching him and visual hallucinations developed. His caregiverreported that the patient slept for almost 20 hours a day. His articu-lation deteriorated to the point where his family could hardly under-stand his words. He became unable to walk without assistance. Hiscaregiver continued to regularly administer the antiparkinsonian drugsto prevent further symptom aggravation. Although the patient con-tinued taking his usual PD medication, his condition worsened. Onadmission, generalized bradykinesia and rigidity were severely aggra-vated. Remarkably, myoclonus was present in all four extremities. Themyoclonus appeared while maintaining posture and during action andwas more prominent in both distal upper extremities, involving theshoulders. The mainly positive myoclonus was not stimulus sensitive.Electrophysiologic studies were not conducted. The results of thyroidfunction testing included in the routine admission blood work-uprevealed an undetectable free thyroxine level and an elevated thyroid-stimulating hormone level of 200.6 mIU/mL (normal: 0.4-4.1 mIU/mL).Further investigation into the patient’s medical history revealedFreely available onlineTremor and Other Hyperkinetic Movementshttp://www.tremorjournal.orgThe Center for Digital Research and ScholarshipColumbia University Libraries/Information Services1that he underwent total thyroidectomy for papillary thyroid cancer atage 56 and had been treated with levothyroxine at another hospital.However, he had accidentally stopped taking levothyroxine for about2 months before the current admission. Based on his medical history andlaboratory test results, levothyroxine therapy was restarted immediately.After supplementation, his parkinsonism, psychosis, sleep-related prob-lems, emotional lability, and myoclonus markedly improved. By hospitalday 10, his general condition stabilized to his previous disease status.DiscussionOur patient showed rapid deterioration of psychotic, emotional,sleep-related, and motor symptoms over a few weeks, which isuncommon and may not be explained by exacerbation of PD itself.Myoclonus is also unusual in patients with PD. The prompt anddramatic improvement following levothyroxine administration furthersuggests hypothyroidism as the cause of this patient’s rapid, globaldeterioration.There is limited information on patients with aggravated parkinson-ism due to hypothyroidism2,3 or hyperthyroidism.4,5 The accompaniedencephalopathy and myoclonus, which were reversed by levothyroxinetherapy, have not yet been reported in patients with PD and hypo-thyroidism. This lack of literature may be partly due to a low level ofsuspicion because the symptoms aggravated by hypothyroidism can bemasked by and misconstrued as deterioration of PD itself.Based on this didactic case and as pointed out by other authors,2–4thyroid function assessment should not be overlooked in patients withPD who experience rapid aggravation of parkinsonism, encephalo-pathy, and myoclonus. Since hypothyroidism can be managed withappropriate medication, it should be included in the list of differentialdiagnoses of unusual aggravation of parkinsonism and symptoms thatare not typical for PD, especially when the patient has underlyingthyroid disease.References1. Caviness JN. Myoclonus. Parkinsonism Relat Disord. 2007;13:S375–84.2. Garcia-Moreno JM, Chacon-Pena J. Hypothyroidism and Parkinson’sdisease and the issue of diagnostic confusion. Mov Disord. 2003;18(9):1058–9.doi: 10.1002/mds.104753. Munhoz RP, Teive HA, Troiano AR, Hauck PR, Herdoiza Leiva MH,Graff H, et al. Parkinson’s disease and thyroid dysfunction. Parkinsonism RelatDisord. 2004;10(6):381–3., doi: 10.1016/j.parkreldis.2004.03.0084. Kim HT, Edwards MJ, Lakshmi Narsimhan R, Bhatia KP. Hyper-thyroidism exaggerating parkinsonian tremor: a clinical lesson. Parkinsonism RelatDisord. 2005;11(5):331–2. doi: 10.1016/j.parkreldis.2005.01.0095. Prakash KM, Kek PC. Hyperthyroidism ‘‘masked’’ the levodopa responsein newly diagnosed Parkinson’s disease patients. Parkinsonism Relat Disord. 2010;16(10):691–2.Ehm G, Kim HJ, Jeon B Myoclonus Due to Hypothyroidism in PDTremor and Other Hyperkinetic Movementshttp://www.tremorjournal.orgThe Center for Digital Research and ScholarshipColumbia University Libraries/Information Services2

Hypothyroidism-induced Reversible Encephalopathy as a Cause of Aggravation of Parkinsonism and Myoclonus in Parkinson’s Disease

Background: Myoclonus and encephalopathy are unusual in patients with Parkinson’s disease (PD).



Case report: We describe the case of a 59-year-old male with PD who developed myoclonus and encephalopathy. Underlying hypothyroidism was revealed after admission and treated with levothyroxine. Myoclonus and encephalopathy were completely resolved following thyroid hormone replacement.



Discussion: Hypothyroidism can cause reversible myoclonus and encephalopathy along with unusual aggravation of parkinsonism symptoms in patients with PD

Hypothyroidism-induced Reversible Encephalopathy as a Cause of Aggravation of Parkinsonism and Myoclonus in Parkinson’s Disease

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