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Letter to the editor
Olfactory and Gustatory Function in Early-stage Parkinson’s Disease: Implication for Cognitive Association
Jeongjae Lee, Young Eun Kim, Joong Seob Lee, Suk Yun Kang, Min Seung Kim, In Hee Kwak, Jaeseol Park, Jung Yeon Nam, Hyeo-il Ma
Received November 20, 2023  Accepted June 27, 2024  Published online June 27, 2024  
DOI:    [Accepted]
  • 285 View
  • 11 Download
Original Articles
Fatigue in PD is due to decreased efficiency of the frontal network: quantitative EEG analysis
Min Seung Kim, SangUk Park, Ukeob Park, Seung Wan Kang, Suk Yun Kang
Received February 17, 2024  Accepted June 5, 2024  Published online June 10, 2024  
DOI:    [Accepted]
  • 436 View
  • 28 Download
AbstractAbstract PDF
Fatigue is a common, debilitating non-motor symptom of Parkinson’s disease (PD), but its mechanism is poorly understood. We aimed to determine whether electroencephalography (EEG) could measure fatigue objectively and to expound on the pathophysiology of fatigue in PD.
We studied 32 de novo PD patients who underwent electroencephalography (EEG). We compared brain activity between 19 PD patients without fatigue and 13 PD patients with fatigue via EEG power spectrum and graph including global efficiency (GE), characteristic path length (CPL), clustering coefficient (CCO), small worldness (SW), local efficiency (LE), degree centrality (DC), closeness centrality (CCE), and betweenness centrality (BC).
No significant differences in absolute and relative powers were seen between PD without and with fatigue (all ps > 0.02, Bonferroni-corrected). In network analysis, the brain network efficiency differed by frequency band. Generally, the brain network in the frontal area for theta and delta bands showed greater efficiency, and in the temporal area, the alpha1 band was less efficient in PD without fatigue (p= 0.0000, p = 0.0011, ps ≤ 0.0007, respectively, Bonferroni-corrected).
Our study suggests that PD patients with fatigue have less efficient networks in the frontal area compared with networks of those with PD without fatigue. These findings may explain why fatigue is common in PD, a frontostriatal disorder. Increased efficiency in the temporal area in PD with fatigue is assumed to be compensation. Brain network analysis using graph theory is more valuable than power spectrum analysis in revealing the brain mechanism related to fatigue.
Comparative Olfactory Profiles in Parkinson’s Disease and Drug-Induced Parkinsonism
In Hee Kwak, Young Eun Kim, Suk Yun Kang, Joong Seob Lee, Jeongjae Lee, Min Seung Kim, Dong A Yea, Hyeo-il Ma
J Mov Disord. 2024;17(1):64-70.   Published online October 6, 2023
  • 1,609 View
  • 213 Download
AbstractAbstract PDFSupplementary Material
Drug-induced parkinsonism (DIP) is a frequently encountered diagnostic possibility when considering Parkinson’s disease (PD). While olfactory dysfunction is a common clinical feature in PD, the comparison of olfactory function between the two conditions remains insufficient. This study aimed to compare olfactory function, including threshold, discrimination, and identification (TDI) profiles, between PD and DIP.
Consecutive patients with drug-naïve PD (n = 78) or DIP (n = 31) confirmed through dopamine transporter imaging were enrolled in this study. The YSK olfactory function (YOF) test, composed of TDI domains culturally familiar odorants to Koreans, was administered to all patients.
In the study population, patients with DIP were significantly older than patients with PD. Over 70% of patients in each group had hyposmia or anosmia, and there was no significant difference in the occurrence of olfactory dysfunction between the two groups. In addition, there were no differences in the total YOF score and threshold score between the two groups. Meanwhile, the PD group had a significantly lower discrimination and identification score than the DIP group after adjusting for age, sex, the existence of diabetes, disease duration, and cognitive function.
This study demonstrated that detailed olfactory profiles are different in PD and DIP, even though olfactory dysfunction can be observed in both conditions.
Letter to the editor
Factors associated with anticholinergic-induced oral-buccal-lingual dyskinesia in Parkinson’s disease
Joonyoung Ha, Suk Yun Kang, Kyoungwon Baik, Young H. Sohn, Phil Hyu Lee, Min Seok Baek, Jin Yong Hong
J Mov Disord. 2024;17(1):109-111.   Published online September 22, 2023
  • 1,014 View
  • 77 Download
PDFSupplementary Material
Brief communication
Effectiveness of Exercise on the Sequence Effect in Parkinson’s Disease
Suk Yun Kang, Young Ho Sohn
J Mov Disord. 2020;13(3):213-217.   Published online August 31, 2020
  • 5,352 View
  • 144 Download
  • 2 Web of Science
  • 2 Crossref
AbstractAbstract PDFSupplementary Material
To determine the benefits of motor training on the sequence effect (SE), an essential component of bradykinesia in Parkinson’s disease (PD).
Seven patients with de novo PD participated in this study. The patients performed regular pentagon drawing tests and exercises during four visits. The first two visits occurred before the start of medication, and the last two visits occurred at least six months after the start of medication. We assessed the severity of bradykinesia and SE at each visit and compared the results before and after exercise in both the de novo and treatment conditions.
In the de novo condition, the severity of bradykinesia significantly improved after motor training (p = 0.018), but it did not resolve and only showed a trend of improvement after treatment (p = 0.068). The severity of the SE decreased significantly in the drug-naïve condition (p = 0.028) but not after medication (p = 0.273).
Our study suggests that regular motor training may be beneficial for the SE in PD.


Citations to this article as recorded by  
  • Exploring the Complex Phenotypes of Impaired Finger Dexterity in Mild-to-moderate Stage Parkinson’s Disease: A Time-Series Analysis
    Pattamon Panyakaew, Kotchakorn Duangjino, Apiwoot Kerddonfag, Teerit Ploensin, Krerk Piromsopa, Chanon Kongkamol, Roongroj Bhidayasiri
    Journal of Parkinson's Disease.2023; 13(6): 975.     CrossRef
  • The Effects of Intensive Neurorehabilitation on Sequence Effect in Parkinson's Disease Patients With and Without Freezing of Gait
    Alessia Putortì, Michele Corrado, Micol Avenali, Daniele Martinelli, Marta Allena, Silvano Cristina, Valentina Grillo, Luca Martinis, Stefano Tamburin, Mariano Serrao, Antonio Pisani, Cristina Tassorelli, Roberto De Icco
    Frontiers in Neurology.2021;[Epub]     CrossRef
Original Articles
Sleepiness and Depression in Parkinson’s Disease Patients Treated with Ropinirole and Levodopa
Suk Yun Kang, Ho-Sung Ryu, Mun-Kyung Sunwoo, Sang-Jin Kim, Jong-Sam Baik, Mee-Young Park, Hyung-Eun Park, Joong-Seok Kim, Kyum-Yil Kwon, Seong-Beom Koh, Young-Eun Kim, Mi-Kyong Lee, Jong-Min Kim, Sun Ju Chung, Young-Ho Sohn
J Mov Disord. 2017;10(3):123-129.   Published online September 22, 2017
  • 9,438 View
  • 193 Download
  • 12 Web of Science
  • 10 Crossref
AbstractAbstract PDF
We aimed to investigate the effect of ropinirole on excessive daytime sleepiness (EDS) and depression in Parkinson’s disease (PD) with a large population.
We conducted a cross-sectional observational study at nine hospitals in Korea between April 24, 2013, and April 22, 2015. We analyzed the demographic and clinical features, other medical history, history of antiparkinsonian medication within 6 months, Hoehn and Yahr stage (HY stage), Unified Parkinson’s Disease Rating Scale (UPDRS) part II and III, Epworth Sleepiness Scale (ESS), and 30-item Geriatric Depression Scale (GDS-30).
Four-hundred-thirteen patients with PD (mean age: 65.2 ± 9.0 years; men: 227 patients) were analyzed. Multivariate logistic regression analysis showed that age at examination, UPDRS II, and GDS-30 were independent risk factors for EDS and that sex, UPDRS II, and ESS were independent risk factors for depression.
Our large group study did not find any significant associations of ropinirole with EDS and depression in Korean PD patients.


Citations to this article as recorded by  
  • Associations between non-motor symptoms and patient characteristics in Parkinson’s disease: a multicenter cross-sectional study
    Remi Morimoto, Mutsumi Iijima, Yasuyuki Okuma, Keisuke Suzuki, Fumihito Yoshii, Shigeru Nogawa, Takashi Osada, Kazuo Kitagawa
    Frontiers in Aging Neuroscience.2023;[Epub]     CrossRef
  • Excessive Daytime Sleepiness in Parkinson’s Disease
    Hanshu Liu, Jingwen Li, Xinyi Wang, Jinsha Huang, Tao Wang, Zhicheng Lin, Nian Xiong
    Nature and Science of Sleep.2022; Volume 14: 1589.     CrossRef
  • Excessive daytime sleepiness in Parkinson's disease: A systematic review and meta-analysis
    Fei Feng, YingYing Cai, YanBing Hou, Ruwei Ou, Zheng Jiang, HuiFang Shang
    Parkinsonism & Related Disorders.2021; 85: 133.     CrossRef
  • Sleep Disorders and Cognitive Dysfunctions in Parkinson’s Disease: A Meta-Analytic Study
    Gianpaolo Maggi, Luigi Trojano, Paolo Barone, Gabriella Santangelo
    Neuropsychology Review.2021; 31(4): 643.     CrossRef
  • Longitudinal risk factors for developing depressive symptoms in Parkinson's disease
    Tarek Antar, Huw R. Morris, Faraz Faghri, Hampton L. Leonard, Mike A. Nalls, Andrew B. Singleton, Hirotaka Iwaki
    Journal of the Neurological Sciences.2021; 429: 117615.     CrossRef
  • The effect and safety of ropinirole in the treatment of Parkinson disease
    Jiali Zhu, Min Chen
    Medicine.2021; 100(46): e27653.     CrossRef
  • Pramipexole regulates depression-like behavior via dopamine D3 receptor in a mouse model of Parkinson’s disease
    Shi-Zhuang Wei, Xiao-Yu Yao, Chen-Tao Wang, An-Qi Dong, Dan Li, Yu-Ting Zhang, Chao Ren, Jin-Bao Zhang, Cheng-Jie Mao, Fen Wang, Chun-Feng Liu
    Brain Research Bulletin.2021; 177: 363.     CrossRef
  • A selective D2 dopamine receptor agonist alleviates depression through up-regulation of tyrosine hydroxylase and increased neurogenesis in hippocampus of the prenatally stressed rats
    Mahino Fatima, Mir Hilal Ahmad, Saurabh Srivastav, Moshahid Alam Rizvi, A.C. Mondal
    Neurochemistry International.2020; 136: 104730.     CrossRef
  • ‘Dopamine agonist Phobia’ in Parkinson’s disease: when does it matter? Implications for non-motor symptoms and personalized medicine
    Silvia Rota, Iro Boura, Lucia Batzu, Nataliya Titova, Peter Jenner, Cristian Falup-Pecurariu, K Ray Chaudhuri
    Expert Review of Neurotherapeutics.2020; 20(9): 953.     CrossRef
  • An Investigation on the Clinical Features and Neurochemical Changes in Parkinson's Disease With Depression
    Teng-Hong Lian, Peng Guo, Li-Jun Zuo, Yang Hu, Shu-Yang Yu, Li Liu, Zhao Jin, Qiu-Jin Yu, Rui-Dan Wang, Li-Xia Li, Ying-Shan Piao, Wei Zhang
    Frontiers in Psychiatry.2019;[Epub]     CrossRef
N30 Somatosensory Evoked Potential Is Negatively Correlated with Motor Function in Parkinson’s Disease
Suk Yun Kang, Hyeo-Il Ma
J Mov Disord. 2016;9(1):35-39.   Published online January 25, 2016
  • 25,528 View
  • 87 Download
  • 6 Web of Science
  • 3 Crossref
AbstractAbstract PDF
aaThe aim of this study was to investigate frontal N30 status in Parkinson’s disease (PD) and to examine the correlation between the amplitude of frontal N30 and the severity of motor deficits.
aaThe frontal N30 was compared between 17 PD patients and 18 healthy volunteers. Correlations between the amplitude of frontal N30 and the Unified Parkinson’s Disease Rating Scale (UPDRS) motor score of the more severely affected side was examined.
aaThe mean latency of the N30 was not significantly different between patients and healthy volunteers (p = 0.981), but the mean amplitude was lower in PD patients (p < 0.025). There was a significant negative correlation between the amplitude of N30 and the UPDRS motor score (r = -0.715, p = 0.013).
The frontal N30 status indicates the motor severity of PD. It can be a useful biomarker reflecting dopaminergic deficits and an objective measurement for monitoring the clinical severity of PD.


Citations to this article as recorded by  
  • A Comparison of Sensorimotor Integration and Motor Fitness Components between Collegiate Athletes with and without Long COVID: A Cross-Sectional Study with Pair-Matched Controls
    Ibrahim M. Moustafa, Amal Ahbouch, Raheesa P. Kader, Tamer Mohamed Shousha, Abdulla Alrahoomi
    Journal of Clinical Medicine.2024; 13(9): 2469.     CrossRef
  • Clinical factors affecting evoked magnetic fields in patients with Parkinson's disease
    Ryoji Naganuma, Ichiro Yabe, Megumi Takeuchi, Kirari Morishita, Shingo Nakane, Ryoken Takase, Ikuko Takahashi-Iwata, Masaaki Matsushima, Mika Otsuki, Hideaki Shiraishi, Hidenao Sasaki, Wing-ho Yung
    PLOS ONE.2020; 15(9): e0232808.     CrossRef
  • Short-Term Effects of Thoracic Spine Manipulation on the Biomechanical Organisation of Gait Initiation: A Randomized Pilot Study
    Sébastien Ditcharles, Eric Yiou, Arnaud Delafontaine, Alain Hamaoui
    Frontiers in Human Neuroscience.2017;[Epub]     CrossRef
The Sequence Effect in De Novo Parkinson’s Disease
Suk Yun Kang, Toshiaki Wasaka, Ejaz A. Shamim, Sungyoung Auh, Yoshino Ueki, Nguyet Dang, Mark Hallett
J Mov Disord. 2011;4(1):38-40.
  • 13,234 View
  • 57 Download
  • 12 Crossref
AbstractAbstract PDF
Background and Purpose

The sequence effect (SE) in Parkinson’s disease (PD) denotes progressive slowness in speed or progressive decrease in amplitude of repetitive movements. It is a well-known feature of bradykinesia and is considered unique in PD. Until now, it was well-documented in advanced PD, but not in drug-naïve PD. The aim of this study is to know whether the SE can also be measured in drug-naïve PD.


We measured the SE with a computer-based, modified Purdue pegboard in 4 drug-naïve PD patients, which matched our previous study with advanced PD patients.


We observed progressive slowness during movement, that is, SE. Statistical analysis showed a strong statistical trend toward the SE with the right hand, but no significance with the left hand. There was no statistical significance of SE with either the more or less affected hands.


These results indicate that the SE can be identified in drug-naïve PD, as well as in advanced PD, with objective measurements and support the idea that the SE is a feature in PD observed during the early stage of the disease without medication.


Citations to this article as recorded by  
  • Bradykinesia in Neurodegenerative Disorders: A Blinded Video Analysis of Pathology‐Proven Cases
    Luca Marsili, Kevin R. Duque, Nathan Gregor, Elhusseini Abdelghany, Jesus Abanto, Andrew P. Duker, Matthew C. Hagen, Alberto J. Espay, Matteo Bologna
    Movement Disorders.2023; 38(3): 496.     CrossRef
  • The Sequence Effect Worsens Over Time in Parkinson’s Disease and Responds to Open and Closed-Loop Subthalamic Nucleus Deep Brain Stimulation
    Yasmine M. Kehnemouyi, Matthew N. Petrucci, Kevin B. Wilkins, Jillian A. Melbourne, Helen M. Bronte-Stewart
    Journal of Parkinson's Disease.2023; 13(4): 537.     CrossRef
  • Neurofeedback-guided kinesthetic motor imagery training in Parkinson’s disease: Randomized trial
    Sule Tinaz, Serageldin Kamel, Sai S. Aravala, Mohamed Elfil, Ahmed Bayoumi, Amar Patel, Dustin Scheinost, Rajita Sinha, Michelle Hampson
    NeuroImage: Clinical.2022; 34: 102980.     CrossRef
  • The Pathophysiological Correlates of Parkinson's Disease Clinical Subtypes
    Daniele Belvisi, Andrea Fabbrini, Maria Ilenia De Bartolo, Matteo Costanzo, Nicoletta Manzo, Giovanni Fabbrini, Giovanni Defazio, Antonella Conte, Alfredo Berardelli
    Movement Disorders.2021; 36(2): 370.     CrossRef
  • The Effects of Intensive Neurorehabilitation on Sequence Effect in Parkinson's Disease Patients With and Without Freezing of Gait
    Alessia Putortì, Michele Corrado, Micol Avenali, Daniele Martinelli, Marta Allena, Silvano Cristina, Valentina Grillo, Luca Martinis, Stefano Tamburin, Mariano Serrao, Antonio Pisani, Cristina Tassorelli, Roberto De Icco
    Frontiers in Neurology.2021;[Epub]     CrossRef
  • Evolving concepts on bradykinesia
    Matteo Bologna, Giulia Paparella, Alfonso Fasano, Mark Hallett, Alfredo Berardelli
    Brain.2020; 143(3): 727.     CrossRef
  • Effectiveness of Exercise on the Sequence Effect in Parkinson’s Disease
    Suk Yun Kang, Young Ho Sohn
    Journal of Movement Disorders.2020; 13(3): 213.     CrossRef
  • Neurophysiological correlates of bradykinesia in Parkinson’s disease
    Matteo Bologna, Andrea Guerra, Giulia Paparella, Laura Giordo, Danilo Alunni Fegatelli, Anna Rita Vestri, John C Rothwell, Alfredo Berardelli
    Brain.2018; 141(8): 2432.     CrossRef
  • Insula as the Interface Between Body Awareness and Movement: A Neurofeedback-Guided Kinesthetic Motor Imagery Study in Parkinson’s Disease
    Sule Tinaz, Kiran Para, Ana Vives-Rodriguez, Valeria Martinez-Kaigi, Keerthana Nalamada, Mine Sezgin, Dustin Scheinost, Michelle Hampson, Elan D. Louis, R. Todd Constable
    Frontiers in Human Neuroscience.2018;[Epub]     CrossRef
  • Sequence Effect in Parkinson’s Disease Is Related to Motor Energetic Cost
    Sule Tinaz, Ajay S. Pillai, Mark Hallett
    Frontiers in Neurology.2016;[Epub]     CrossRef
  • Bradykinesia in early and advanced Parkinson's disease
    Matteo Bologna, Giorgio Leodori, Paola Stirpe, Giulia Paparella, Donato Colella, Daniele Belvisi, Alfonso Fasano, Giovanni Fabbrini, Alfredo Berardelli
    Journal of the Neurological Sciences.2016; 369: 286.     CrossRef
  • Neural correlates of progressive reduction of bradykinesia in de novo Parkinson's disease
    Eeksung Lee, Ji Eun Lee, Kwangsun Yoo, Jin Yong Hong, Jungsu Oh, Mun Kyung Sunwoo, Jae Seung Kim, Yong Jeong, Phil Hyu Lee, Young Ho Sohn, Suk Yun Kang
    Parkinsonism & Related Disorders.2014;[Epub]     CrossRef
Case Report
Restlessness with Manic Episodes due to Right Parietal Infarction
Suk Yun Kang, Jong Won Paik, Young Ho Sohn
J Mov Disord. 2010;3(1):22-24.
  • 15,378 View
  • 94 Download
  • 4 Crossref
AbstractAbstract PDF

Mood disorders following acute stroke are relatively common. However, restlessness with manic episodes has rarely been reported. Lesions responsible for post-stroke mania can be located in the thalamus, caudate nucleus, and temporal and frontal lobes. We present a patient who exhibited restlessness with manic episodes after an acute infarction in the right parietal lobe, and summarize the case reports involving post-stroke mania. The right parietal stroke causing mania in our case is a novel observation that may help us to understand the mechanisms underlying restlessness with mania following acute stroke.


Citations to this article as recorded by  
  • Restlessness with manic episodes induced by right-sided multiple strokes after COVID-19 infection: A case report
    Takahiko Nagamine
    Brain Circulation.2023; 9(2): 112.     CrossRef
  • Poststroke Mania During the COVID-19 Pandemic
    Takahiko Nagamine
    Journal of Nervous & Mental Disease.2023; 211(12): 979.     CrossRef
  • Management of psychiatric disorders in patients with stroke and traumatic brain injury
    Gautam Saha, Kaustav Chakraborty, Amrit Pattojoshi
    Indian Journal of Psychiatry.2022; 64(8): 344.     CrossRef
  • Post stroke delirium
    M. A. Savina
    Zhurnal nevrologii i psikhiatrii im. S.S. Korsakova.2014; 114(12. Vyp. 2): 19.     CrossRef
Original Article
Unilateral Standing Leg Tremor as the Initial Manifestation of Parkinson Disease
Suk Yun Kang, Sook-Keun Song, Jin-Soo Kim, Young Ho Sohn
J Mov Disord. 2009;2(1):29-32.
  • 12,130 View
  • 95 Download
  • 3 Crossref
AbstractAbstract PDF

The aim of this study was to analyze the different forms of leg tremors exhibited while standing in patients with Parkinson disease (PD), and to determine if the type of leg tremor exhibited is indicative of prognosis or treatment response in PD patients.


We studied the clinical characteristics of five PD patients (all women; mean age, 59 years, range, 53–64 years) with unilateral standing leg tremor as the initial manifestation of PD, including their electrophysiological findings and the results of long-term follow-up.


For each patient, parkinsonism either existed at the time of onset of the initial symptoms or developed later. Patient responses to drugs were generally good, but one patient showed a poor response to drugs, even though she had only a low frequency leg tremor. For two patients whom we could observe during the 10-year follow-up period, neither the leg tremor nor parkinsonism was aggravated.


There are two forms of unilateral standing leg tremor in PD. One form is high frequency, similar to the primary orthostatic tremor. The other is low frequency and similar to the parkinsonian resting tremor. Based on these observations, it appears that progression might be slow if PD patients have standing leg tremor as the initial manifestation.


Citations to this article as recorded by  
  • Orthostatic tremor as initial presentation of Parkinson’s disease
    Y R Chiew
    QJM: An International Journal of Medicine.2023; 116(7): 549.     CrossRef
  • The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
    Stefania Sozzi, Shashank Ghai, Marco Schieppati
    Brain Sciences.2023; 13(7): 978.     CrossRef
  • An unusual initial presentation of Parkinson’s disease: unilateral standing leg tremor
    Jasem Yousef Al-Hashel, Walaa Ahmed Kamel, Philippe Damier, Ahmad Jasem Abdulsalam
    Acta Neurologica Belgica.2020; 120(2): 415.     CrossRef

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