1Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
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Mallory L. Hacker
2Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
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Maxim Turchan
2Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
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Thomas L. Davis
2Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
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David Charles
2Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
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Disclaimer
1Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
2Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
Edited by: Maria Fiorella Contarino, Leiden University Medical Center, Netherlands
Reviewed by: Rick Helmich, Radboud University Nijmegen Medical Centre, Netherlands; Alessandro Tessitore, Università degli Studi della Campania “Luigi Vanvitelli” Caserta, Italy
*Correspondence: David Charles ude.tlibrednav@selrahc.divad
This article was submitted to Movement Disorders, a section of the journal Frontiers in Neurology
Received 2017 Dec 11; Accepted 2018 Jul 11.
Copyright © 2018 Heusinkveld, Hacker, Turchan, Davis and Charles.
This is an open-access article distributed under the terms of the Creative Commons Attribution License [CC BY]. The use, distribution or reproduction in other forums is permitted, provided the original author[s] and the copyright owner[s] are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Abstract
Tremor is one of the most visible features of Parkinson's disease [PD], and the majority of PD patients experience tremor during the course of the disease. However, the distress caused by this cardinal motor feature for patients early in the course of their PD is commonly underappreciated. People living with early stage PD often experience intense embarrassment and difficulties due to their tremor that limit social interactions, and tremor frequently interferes with the ability to perform activities of daily living and simple tasks at home and work. Although tremor is primarily managed with medications, both tremor response and satisfaction with medical therapy are highly variable. This review offers an overview of reports of the patient experience of tremor in early stage PD and current management options for this cardinal motor feature.
Keywords: Parkinson's disease, deep brain stimulation, tremor, patient perspectives, tremor management
Introduction
Parkinson's disease [PD] is a movement disorder that is the second most common neurodegenerative disease. Over one million Americans currently live with PD, and ~60,000 patients are newly diagnosed each year []. Furthermore, the incidence of PD is only expected to increase in the coming decades []. Parkinson's disease is a heterogeneous condition involving both motor and non-motor features that contribute to diminishing quality of life for patients as the disease progresses. Although a myriad of signs and symptoms contribute to PD-related disability, early stage PD is largely characterized by cardinal motor symptoms, including bradykinesia, tremor, and rigidity [].
Tremor is one of the most visible features of the disease, and rest tremor is often the first PD symptom noticed by patients []. More than 75% of PD patients experience rest tremor at some point during the disease course [–], and ~60% of patients experience symptomatic tremor during action or movement [–]. Although the near-ubiquity of tremor in early PD is beyond dispute, the distress caused by this cardinal motor symptom is commonly underappreciated []. Tremor in early PD patients is currently managed pharmacologically. However, medications offer limited relief from tremor and may lead to disabling adverse effects.
The purpose of this review is to provide an overview of the patient experience and current management of tremor for patients with early stage PD. Early stage PD is frequently defined as Hoehn & Yahr Stage I [mild, unilateral motor symptoms] or II [bilateral motor symptoms without balance impairment] []. However, there are no universally-accepted criteria for defining PD stages, and definitions vary across clinical trials and studies. For clarity, we have described the criteria used to define early stage PD for each study included in this review. To conduct the review, we searched PubMed and Google Scholar using combinations of the terms “early stage Parkinson's disease,” “early Parkinson's,” “tremor,” “patient perspective,” “therapy,” “cognitive behavioral therapy,” “support group,” and “survey.”
Impact of tremor for patients with early stage parkinson's disease
Patients with early stage PD consistently rank tremor as highly important, even when asked to consider other diverse aspects of their condition. Tremor was cited as the most bothersome symptom in a survey of 75 PD patients with relatively mild symptom severity [median PDQ-39 summary index score = 20.3; estimated median modified Hoehn & Yahr stage = I to I.5] []. Twenty-eight percent [21/75] of patients mentioned tremor in their open-ended response to the question, “Which two problems related to Parkinson's disease bother you most?”
In a separate PD patient survey, nearly one-third of patients with early stage PD ranked tremor as their most troubling symptom, and tremor was the second most highly ranked symptom among all early stage patients []. In this study, early stage PD was defined as a symptom duration of