Intention tremor in essential tremor: Prevalence and association with disease duration

Louis, Elan D.; Frucht, Steven J.; Rios, Billy

doi:10.1002/mds.22370

Cited by 114 publications

(114 citation statements)

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“…We found that there is a correlation between the extent of vermal torpedo pathology and the extent of hemispheric torpedo pathology, suggesting that these postmortem changes are not independent, but rather, that they likely reflect the presence of a common, underlying (i.e., broader) cerebellar system problem. There is a long-standing clinical literature that supports the concept that a dysfunction of the cerebellum causes ET, including the presence in ET patients of intention tremor [31,32], gait ataxia [13,33], oculomotor abnormalities [34], and problems with dysrhythmia and motor learning [35][36][37][38][39]. These findings often occur in patients with cerebellar diseases (e.g., spinocerebellar ataxia) [37,40].…”

Section: Discussionmentioning

confidence: 92%

Torpedoes in the Cerebellar Vermis in Essential Tremor Cases vs. Controls

et al. 2011

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The study of the postmortem changes in essential tremor (ET) is in its infancy, although recent evidence points to a central role of the cerebellum, where Purkinje cell axonal swellings ("torpedoes") are significantly more common in ET than control brains. Yet, all existing studies have been confined to the cerebellar hemispheres, and whether there is a more widely distributed cerebellar problem is presently unknown. Our aims were to address whether: (1) ET cases have greater numbers of torpedoes in the vermis than controls, (2) there a correlation between the extent of vermal torpedo pathology and hemispheric torpedo pathology, and (3) vermal torpedo pathology is correlated with clinical features of the disease. A parasagittal neocerebellar block and a vermal block were harvested from 24 ET and 10 control brains. Paraffin sections (7 μm) were stained with Luxol fast blue/hematoxylin and eosin, and torpedoes were quantified. All torpedo counts were corrected for Purkinje cell layer length. Vermal corrected torpedo count (VermTc) was higher in ET cases than controls (7.1±6.8 [median, 4.3] vs. 2.6±2.5 [median, 2]), p=0.002). The VermTc and the hemispheric corrected torpedo count (HemTc) were correlated with one another (Spearman's r=0.54, p=0.002). ET cases with neck, voice, and jaw tremors had the highest VermTc (p=0.046). The abundance of torpedoes in the ET brain is not confined to the ponto- or neocerebellum but is more broadly distributed, also involving the spino- or paleocerebellum. These data further confirm the central role of the cerebellum in the underlying pathophysiology of this common neurological disorder.

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Section: Discussionmentioning

confidence: 92%

Torpedoes in the Cerebellar Vermis in Essential Tremor Cases vs. Controls

et al. 2011

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“…It has been hypothesized that cognitive deficits are mediated through cerebellar, thalamic and frontal connections that are compromised in ET [Kim et al 2009;Troster et al 2002;Sahin et al 2006]. Much of the literature supports that ET is a disorder of cerebellar dysregulation, including the presence of intention tremor [Leegwater- Kim et al 2006;Louis et al 2009b], gait ataxia [Singer et al 1994;Stolze et al 2001], oculomotor abnormalities [Helmchen et al 2003] and problems with dysrhythmia and motor learning [Trillenberg et al 2006;Avanzino et al 2009;Bares et al 2010;Farkas et al 2006;Shill et al 2009;Kronenbuerger et al 2007]. In addition, postmortem studies in ET have indicated the presence of a variety of structural and degenerative changes in the cerebellum, including increased number of Purkinje cell axonal swellings ('torpedoes') [Louis et al 2007b;Axelrad et al 2008], increased number of displaced or heterotopic Purkinje cells [Kuo et al 2011], reduction in number of Purkinje cells in some studies [Axelrad et al 2008] [Bucher et al 1997], positron emission tomography [Jenkins et al 1993;Wills et al 1994;Colebatch et al 1990], 1 H magnetic resonance spectroscopic imaging [Louis et al 2002;Pagan et al 2003], diffusion tensor imaging [Shin et al 2008;Klein et al 2011;Nicoletti et al 2010], voxelbased morphometry [Benito-Leon et al 2009;Quattrone et al 2008] and studies using other automated volumetric methods [Cerasa et al 2009] which demonstrate the presence of functional, metabolic and structural abnormalities in the cerebellum of ET patients.…”

Section: Current Literature On the Relationships Between Et And Cognimentioning

confidence: 99%

The cognitive side of essential tremor: what are the therapeutic implications?

Janicki

Cosentino

Louis

2013

Ther Adv Neurol Disord

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While essential tremor (ET) has traditionally been categorized as a pure motor disease, cross-sectional and longitudinal studies of cognition in ET have demonstrated that these patients may have cognitive dysfunction. Recent epidemiological studies demonstrate an association between ET (particularly with onset after age 65) and increased risk for cognitive impairment and dementia. Although existing studies have generally conceptualized cognitive changes in ET as consistent with a 'frontosubcortical' or 'corticocerebellar' profile, results from these same studies suggest that cognitive impairment in ET may in fact be heterogeneous. Furthermore, the underlying mechanisms remain uncertain. Cognitive changes could be a byproduct of the cerebellar dysfunction of ET itself; alternately, they may be a feature of concomitant neurodegenerative diseases that have been associated in several studies with ET, including Alzheimer's disease, Parkinson's disease or progressive supranuclear palsy. While the study of cognitive dysfunction in ET has received research attention in recent years, the results of these studies have not been translated into the clinical domain and clinical practice. This review first summarizes the current literature on the potential relationships between ET and cognitive change. We then suggest areas of further clinical evaluation and treatment; these suggestions are directed at physicians caring for ET patients who may demonstrate or complain of cognitive impairment. As we discuss, clinicians should ideally screen ET patients for possible signs or symptoms of cognitive impairment in addition to assessing for psychiatric comorbidity and quality of life. These recommendations are in contrast to most current clinical practice, which does not routinely include such assessment among ET patients. To our knowledge, there have been no pharmacotherapeutic trials to date of any agent for cognitive change associated with ET. We believe that studies for this indication are now called for. Future efforts in this direction will also need to take into account the pathobiology of cognitive changes in ET, which itself is an area that is ripe for future investigations.

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“…In terms of the former, one must consider the involvement of the cerebellum and its outflow pathways [53] . There is a longstanding clinical literature that converges on the notion that ET is a disorder of cerebellar dysregulation, including the presence in ET patients of intention tremor [63,64] , gait ataxia [65,66] , oculomotor abnormalities [67] and problems with dysrhythmia and motor learning [68][69][70][71][72][73] . Deep brain stimulation surgery in ET targets the specific thalamic nucleus (i.e.…”

Section: Biological Evidencementioning

confidence: 99%

Association between Essential Tremor and Other Neurodegenerative Diseases: What Is the Epidemiological Evidence

LaRoia¹,

Louis²

2011

Neuroepidemiology

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Background: The possible links between essential tremor (ET) and Parkinson’s disease (PD) and, more recently, between ET and Alzheimer’s disease (AD) have been of great interest, particularly with the emergence of postmortem data suggesting that ET itself may be a neurodegenerative disease. Given the very high population prevalence of ET, its possible role as a risk factor for PD and AD is of special significance. At the center of this debate is the burgeoning evidence from epidemiological studies, examining whether there is an increased co-occurrence of these conditions within the same individuals or within families. Methods: We conducted a PubMed search from 1966 to March 2011 and reviewed the epidemiological evidence, restricting our analyses to studies that generated quantifiable measures of association (odds ratios or relative risks), thereby being able to assess the role of chance. Results: The most robust evidence, from case-control, prospective and familial aggregation studies, indicates that ET is associated with increased odds and increased risks of both PD and AD. Conclusions: There is reasonable epidemiological evidence to support a link between ET and these neurodegenerative diseases. Further studies are needed to corroborate the current results, provide additional estimates of effect and begin to explore the mechanistic underpinnings for these intriguing associations.

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Intention tremor in essential tremor: Prevalence and association with disease duration

Cited by 114 publications

References 9 publications

Torpedoes in the Cerebellar Vermis in Essential Tremor Cases vs. Controls

Torpedoes in the Cerebellar Vermis in Essential Tremor Cases vs. Controls

The cognitive side of essential tremor: what are the therapeutic implications?

Association between Essential Tremor and Other Neurodegenerative Diseases: What Is the Epidemiological Evidence

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