Elsevier

Revue Neurologique

Volume 171, Issue 5, May 2015, Pages 415-425
Revue Neurologique

General review
News and controversies regarding essential tremorActualités et controverses concernant le tremblement essentiel

https://doi.org/10.1016/j.neurol.2015.02.007Get rights and content

Abstract

Essential tremor is the most common movement disorder in adults. It is characterized by a postural and kinetic tremor affecting the arms, but it can also affect other body parts. It evolves gradually and can be responsible for a functional impairment in activities of daily living. Its pathophysiology remains poorly understood and effective therapeutic options are limited. There are significant semiological variations between patients, and the term “essential tremor” seems to encompass a wide range of heterogeneous clinical phenotypes. The diagnostic criteria presented in 1998 are now challenged. Furthermore, there is a current debate concerning the etiology of this affection, as to whether essential tremor is a complex degenerative disorder or a functional reversible disorder of neuronal oscillation. In this review, we summarize some aspects of clinical, etiologic and therapeutic news, to better address the questioning on unravelling the clinical presentation and examine the current pathophysiological controversy in this disorder.

Résumé

Le tremblement essentiel est le plus fréquent des mouvements anormaux de l’adulte. Il est caractérisé par un tremblement postural et d’action affectant les membres supérieurs, mais pouvant aussi atteindre d’autres parties du corps. Il évolue de façon lentement progressive et peut être responsable d’un handicap fonctionnel dans les activités de la vie quotidienne. Sa physiopathologie demeure mal connue, et les options thérapeutiques efficaces sont limitées. Il existe des variations sémiologiques importantes entre les patients, et le terme de tremblement essentiel englobe un ensemble hétérogène de phénotypes cliniques. Les critères diagnostiques décrits en 1998 sont aujourd’hui remis en cause. Par ailleurs, il existe actuellement un débat concernant l’étiologie de cette affection, qui oppose l’hypothèse neurodégénérative à celle d’une origine plutôt fonctionnelle. Cet article reprend quelques aspects des actualités cliniques, étiologiques et thérapeutiques, afin de mieux aborder le questionnement du démembrement clinique, et la controverse physiopathologique dans le tremblement essentiel.

Section snippets

Definition of essential tremor: towards new clinical criteria?

ET is characterized by a postural and kinetic tremor of the upper limbs, sometimes involving the head (30%) and more rarely the face, voice, trunk and legs. Age, family history of tremor and Caucasian ethnic background are risk factors for ET [1], [2], [3]. Age of onset has a bimodal distribution, with a first peak in the 20–40 years age range and a second higher peak after 65 years [4]. Prevalence estimates have been quite variable, mainly because of difficult diagnosis and access to care. In

New developments in the pathophysiology of essential tremor

Although many elements of the pathophysiology of ET remain unclear, research over the last decade has greatly affected our underlying approach to this disorder; some advances have been made in unraveling the different symptomatic and etiological aspects. Two opposing pathophysiological concepts can be described, one based on the hypothesis of a single-symptom disease arising from a functional disorder related to a neuronal oscillator [42] and the other considering “tremor syndrome” to be a more

What is the link between essential tremor and Parkinson's disease?

The presence of a link between ET and idiopathic Parkinson's disease (PD) remains highly controversial. The co-existence of these two commonly encountered disease states in the same patient could be incidental. There are however epidemiological, genetic and pathological data suggesting that ET could be a risk factor for developing PD [89].

It is not rare that patients with longstanding ET develop clinical manifestations of resting tremor. This tremor generally occurs alone, with no other sign of

Drug therapy

While there is no curative treatment for ET, several drug regimens are available that provide relief for about half of treated patients. First-intention drug therapy is based on two main compounds: propanolol and primidone. Both have proven efficacy demonstrated with double-blind randomized controlled trials, with a 50–60% reduction in tremor (88%). Propanolol is a non-selective beta-adrenergic blocker: symptom improvement is observed in 50–70% of patients taking a daily dose of 240–320 mg, with

Conclusion

Despite many unknowns, research advances over the last 20 years have provided us with a better understanding of the complex pathophysiology of ET. Evidence is pointing towards dysfunctional cerebello-thalamo-cortical loops, although the underlying cause remains unknown. Recent imaging, electrophysiological, and anatomopathological data have led to the emergence of two highly-debated pathophysioloical concepts: one supports a neurodegenerative origin of the disorder; the other proposes the

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.

References (131)

  • D.J. Pedrosa et al.

    Essential tremor and tremor in Parkinson's disease are associated with distinct “tremor clusters” in the ventral thalamus

    Exp Neurol

    (2012)
  • J.-S. Brittain et al.

    The many roads to tremor

    Exp Neurol

    (2013)
  • C. Vilariño-Güell et al.

    LINGO1 rs9652490 is associated with essential tremor and Parkinson disease

    Parkinsonism Relat Disord

    (2010)
  • J. Shahed et al.

    Exploring the relationship between essential tremor and Parkinson's disease

    Parkinsonism Relat Disord

    (2007)
  • E.D. Louis

    Etiology of essential tremor: should we be searching for environmental causes?

    Mov Disord

    (2001)
  • I. Rautakorpi et al.

    Essential tremor in a Finnish population

    Acta Neurol Scand

    (1982)
  • E.D. Louis et al.

    Differences in the prevalence of essential tremor among elderly African Americans, whites, and Hispanics in northern Manhattan, NY

    Arch Neurol

    (1995)
  • E.D. Louis et al.

    Does age of onset in essential tremor have a bimodal distribution? Data from a tertiary referral setting and a population-based study

    Neuroepidemiology

    (2007)
  • E.D. Louis et al.

    How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor

    Mov Disord

    (2010)
  • D. Lorenz et al.

    The psychosocial burden of essential tremor in an outpatient- and a community-based cohort

    Eur J Neurol

    (2011)
  • G. Deuschl et al.

    Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee

    Mov Disord

    (1998)
  • S. Jain et al.

    Common misdiagnosis of a common neurological disorder: how are we misdiagnosing essential tremor?

    Arch Neurol

    (2006)
  • A. Schrag et al.

    Essential tremor: an overdiagnosed condition?

    J Neurol

    (2000)
  • R.J. Elble

    Defining dystonic tremor

    Curr Neuropharmacol

    (2013)
  • M. Gasparini et al.

    Frontal lobe dysfunction in essential tremor: a preliminary study

    J Neurol

    (2001)
  • W.J. Lombardi et al.

    Cognitive deficits in patients with essential tremor

    Neurology

    (2001)
  • A.I. Tröster et al.

    Neuropsychological deficits in essential tremor: an expression of cerebello-thalamo-cortical pathophysiology?

    Eur J Neurol

    (2002)
  • H.A. Şahin et al.

    Frontal functions in young patients with essential tremor: a case comparison study

    J Neuropsychiatry Clin Neurosci

    (2006)
  • J. Schmahmann et al.

    The cerebellar cognitive affective syndrome

    Brain

    (1998)
  • F. Bermejo-Pareja et al.

    Risk of incident dementia in essential tremor: a population-based study

    Mov Disord

    (2007)
  • S.P. Thawani et al.

    Essential tremor is associated with dementia Prospective population-based study in New York

    Neurology

    (2009)
  • A. Chatterjee

    Personality in essential tremor: further evidence of non-motor manifestations of the disease

    J Neurol Neurosurg Psychiatry

    (2004)
  • F.R. Schneier et al.

    Characteristics of social phobia among persons with essential tremor

    J Clin Psychiatry

    (2001)
  • K.L. Busenbark et al.

    Olfactory function in essential tremor

    Neurology

    (1992)
  • R. Djaldetti et al.

    [123I]-FP-CIT SPECT and olfaction test in patients with combined postural and rest tremor

    J Neural Transm

    (2008)
  • N. Sobel et al.

    Odorant-induced and sniff-induced activation in the cerebellum of the human

    J Neurosci

    (1998)
  • E.D. Louis et al.

    Olfactory dysfunction in essential tremor A deficit unrelated to disease duration or severity

    Neurology

    (2002)
  • J. Benito-León et al.

    Reported hearing impairment in essential tremor: a population-based case-control study

    Neuroepidemiology

    (2007)
  • W.G. Ondo et al.

    Hearing impairment in essential tremor

    Neurology

    (2003)
  • C. Helmchen

    Eye movement abnormalities in essential tremor may indicate cerebellar dysfunction

    Brain

    (2003)
  • G.T. Gitchel et al.

    Slowed saccades and increased square wave jerks in essential tremor

    Tremor Hyperkinetic Mov

    (2013)
  • Z. Farkas et al.

    Impaired rhythm generation in essential tremor

    Mov Disord

    (2006)
  • L. Avanzino et al.

    Cerebellar involvement in timing accuracy of rhythmic finger movements in essential tremor

    Eur J Neurosci

    (2009)
  • F.J. Jimenez-Jimenez et al.

    Impairment of rapid repetitive finger movements and visual reaction time in patients with essential tremor

    Eur J Neurol

    (2010)
  • G. Deuschl et al.

    Essential tremor and cerebellar dysfunction clinical and kinematic analysis of intention tremor

    Brain

    (2000)
  • C. Singer et al.

    Gait abnormality in essential tremor

    Mov Disord

    (1994)
  • H. Stolze et al.

    The gait disorder of advanced essential tremor

    Brain

    (2001)
  • E.D. Louis et al.

    Tandem gait performance in essential tremor: clinical correlates and association with midline tremors

    Mov Disord

    (2010)
  • M. Hoskovcová et al.

    Disorders of balance and gait in essential tremor are associated with midline tremor and age

    Cerebellum

    (2013)
  • D. Arkadir et al.

    The balance and gait disorder of essential tremor: what does this mean for patients?

    Ther Adv Neurol Disord

    (2013)
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