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Spasms and Myoclonus in a Young Woman With Hashimoto Thyroiditis

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

A 39-year-old woman presented to the emergency department with a 3-week history of worsening spasms in her axial and lower limb muscles and new-onset urinary retention. Sudden episodes of painful involuntary spasms first appeared in her abdominal muscles 2 weeks after a cold. Soon after, spasms spread to all of her axial muscles and both lower limbs. These paroxysmal episodes lasted a few seconds, occurred up to 20 times a day, and were exacerbated by external stimuli. There was no impairment of consciousness during the attacks. A review of her previous records revealed a diagnosis of Hashimoto thyroiditis 1 month earlier. She had no history of tobacco, alcohol, or drug use.

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D. Progressive encephalomyelitis with rigidity and myoclonus (PERM)

The patient’s severe clinical features included rigidity and painful spasms as well as persistent myoclonus that was associated with typical EMG features. These findings are highly suggestive of PERM. The diagnosis was further supported by positive serum testing results for anti–glutamic acid decarboxylase (GAD65) antibodies (>29.43 mg/dL; normal: <0.15 mg/dL; to convert to micromoles per liter, multiply by 67.967). Testing results for anti–glycine receptor (GlyR) and antiamphiphysin antibodies were negative.

First described by Whiteley et al,1 PERM represents a more severe clinical spectrum of stiff person spectrum disorder.2 In this patient, PERM can be distinguished from classic stiff person syndrome by prominent brainstem features, including myoclonus, oculomotor disorder, and a disturbance of respiratory rhythm. Her diffuse neurological symptoms, including encephalopathy (altered mental status), autonomic dysfunction (tachycardia and hyperhidrosis), and spinal cord involvement (urinary retention), also fit within the spectrum of PERM.

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Article Information

Corresponding Author: Sheng Chen, MD, PhD, Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China (mztcs@163.com).

Published Online: March 9, 2020. doi:10.1001/jamaneurol.2020.0175

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient for granting permission to publish this information. We also thank Robert L. Macdnoald, MD, PhD, Vanderbilt University, for comments on the manuscript. He was not compensated for his contributions.

References
1.
Whiteley  AM , Swash  M , Urich  H .  Progressive encephalomyelitis with rigidity.   Brain. 1976;99(1):27-42. doi:10.1093/brain/99.1.27PubMedGoogle ScholarCrossref
2.
Martinez-Hernandez  E , Ariño  H , McKeon  A ,  et al.  Clinical and immunologic investigations in patients with stiff-person spectrum disorder.   JAMA Neurol. 2016;73(6):714-720. doi:10.1001/jamaneurol.2016.0133PubMedGoogle ScholarCrossref
3.
Wiels  WA , Du Four  S , Seynaeve  L ,  et al.  Early-onset Creutzfeldt-Jakob disease mimicking immune-mediated encephalitis.   Front Neurol. 2018;9:242. doi:10.3389/fneur.2018.00242PubMedGoogle ScholarCrossref
4.
Sarva  H , Deik  A , Ullah  A , Severt  WL .  Clinical spectrum of stiff person syndrome: a review of recent reports.   Tremor Other Hyperkinet Mov (N Y). 2016;6:340.PubMedGoogle Scholar
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El-Abassi  R , Soliman  MY , Villemarette-Pittman  N , England  JD .  SPS: understanding the complexity.   J Neurol Sci. 2019;404:137-149. doi:10.1016/j.jns.2019.06.021PubMedGoogle ScholarCrossref
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Meinck  HM , Thompson  PD .  Stiff man syndrome and related conditions.   Mov Disord. 2002;17(5):853-866. doi:10.1002/mds.10279PubMedGoogle ScholarCrossref
7.
Ariño  H , Höftberger  R , Gresa-Arribas  N ,  et al.  Paraneoplastic neurological syndromes and glutamic acid decarboxylase antibodies.   JAMA Neurol. 2015;72(8):874-881. doi:10.1001/jamaneurol.2015.0749PubMedGoogle ScholarCrossref
8.
McKeon  A , Tracy  JA .  GAD65 neurological autoimmunity.   Muscle Nerve. 2017;56(1):15-27. doi:10.1002/mus.25565PubMedGoogle ScholarCrossref
9.
Crisp  SJ , Dixon  CL , Jacobson  L ,  et al.  Glycine receptor autoantibodies disrupt inhibitory neurotransmission.   Brain. 2019;142(11):3398-3410. doi:10.1093/brain/awz297PubMedGoogle ScholarCrossref
10.
Werner  C , Pauli  M , Doose  S ,  et al.  Human autoantibodies to amphiphysin induce defective presynaptic vesicle dynamics and composition.   Brain. 2016;139(pt 2):365-379. doi:10.1093/brain/awv324PubMedGoogle ScholarCrossref
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