How Many People in the USA Have Essential Tremor? Deriving a Population
                        Estimate Based on Epidemiological Data

Louis, Elan D.; Ottman, Ruth

doi:10.5334/tohm.198

Cited by 117 publications

(79 citation statements)

References 21 publications

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“…remor is the most common movement disorder across the world, with more than 5 million individuals affected in the United States alone. 1,18 Many patients suffer from bilateral tremor. Over time medical therapy may fail to control tremor for these patients, and consideration of surgical intervention may ultimately be warranted.…”

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confidence: 99%

Is staged bilateral thalamic radiosurgery an option for otherwise surgically ineligible patients with medically refractory bilateral tremor?

Niranjan¹,

Raju

Monaco³

et al. 2018

Journal of Neurosurgery

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OBJECTIVE Unilateral Gamma Knife thalamotomy (GKT) is a well-established treatment for patients with medically refractory tremor who are not eligible for invasive procedures due to increased risk of compications. The purpose of this study was to evaluate whether staged bilateral GKT provides benefit with acceptable risk to patients suffering from disabling medically refractory bilateral tremor. METHODS Eleven patients underwent staged bilateral GKT during a 17-year period (1999-2016). Eight patients had essential tremor (ET), 2 had Parkinson's disease (PD)-related tremor, and 1 had multiple-sclerosis (MS)-related tremor. For the first GKT, a median maximum dose of 140 Gy was delivered to the posterior-inferior region of the nucleus ventralis intermedius (VIM) through a single isocenter with 4-mm collimators. Patients who benefitted from unilateral GKT were eligible for a contralateral GKT 1-2 years later (median 22 months). For the second GKT, a median maximum dose of 130 Gy was delivered to the opposite VIM nucleus to a single 4-mm isocenter. The Fahn-Tolosa-Marin (FTM) clinical tremor rating scale was used to score tremor, drawing, and drinking before and after each GKT. The FTM writing score was assessed only for the dominant hand before and after the first GKT. The Karnofsky Performance Status (KPS) was used to assess quality of life and activities of daily living before and after the first and second GKT. RESULTS The median time to last follow-up after the first GKT was 35 months (range 11-70 months). All patients had improvement in at least 1 FTM score after the first GKT. Three patients (27.3%) had tremor arrest and complete restoration of function (noted via FTM tremor, writing, drawing, and drinking scores equaling zero). No patient had tremor recurrence or diminished tremor relief after the first GKT. One patient experienced new temporary neurological deficit (contralateral lower-extremity hemiparesis) from the first GKT. The median time to last follow-up after the second GKT was 12 months (range 2-70 months). Nine patients had improvement in at least 1 FTM score after the second GKT. Two patients had tremor arrest and complete restoration of function. No patient experienced tremor recurrence or diminished tremor relief after the second GKT. No patient experienced new neurological or radiological adverse effect from the second GKT. Statistically significant improvements were noted in the KPS score following the first and second GKT. CONCLUSIONS Staged bilateral GKT provided effective relief for medically refractory, disabling, bilateral tremor without increased risk of neurological complications. It is an appropriate strategy for carefully selected patients with medically refractory bilateral tremor who are not eligible for deep brain stimulation.

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confidence: 99%

Is staged bilateral thalamic radiosurgery an option for otherwise surgically ineligible patients with medically refractory bilateral tremor?

Niranjan¹,

Raju

Monaco³

et al. 2018

Journal of Neurosurgery

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“…Tremor is defined as "an involuntary, rhythmic, oscillatory movement of a body part," [1] and is the most common movement disorder [2][3][4]. Essential tremor (ET) alone is estimated to affect 7 million people in the US [5,6]. Tremor makes activities of daily living (eating, clothing, writing, etc.)…”

Section: Introductionmentioning

confidence: 99%

Simulated Tremor Propagation in the Upper Limb: From Muscle Activity to Joint Displacement

Corie

Charles

2019

Journal of Biomechanical Engineering

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Although tremor is the most common movement disorder, there are few noninvasive treatment options. Creating effective tremor suppression devices requires a knowledge of where tremor originates mechanically (which muscles) and how it propagates through the limb (to which degrees-of-freedom (DOF)). To simulate tremor propagation, we created a simple model of the upper limb, with tremorogenic activity in the 15 major superficial muscles as inputs and tremulous joint displacement in the seven major DOF as outputs. The model approximated the muscle excitation–contraction dynamics, musculoskeletal geometry, and mechanical impedance of the limb. From our simulations, we determined fundamental principles for tremor propagation: (1) The distribution of tremor depends strongly on musculoskeletal dynamics. (2) The spreading of tremor is due to inertial coupling (primarily) and musculoskeletal geometry (secondarily). (3) Tremorogenic activity in a given muscle causes significant tremor in only a small subset of DOF, though these affected DOF may be distant from the muscle. (4) Assuming uniform distribution of tremorogenic activity among muscles, tremor increases proximal-distally, and the contribution from muscles increases proximal-distally. (5) Although adding inertia (e.g., with weighted utensils) is often used to suppress tremor, it is possible to increase tremor by adding inertia to the wrong DOF. (6) Similarly, adding viscoelasticity to the wrong DOF can increase tremor. Based solely on the musculoskeletal system, these principles indicate that tremor treatments targeting muscles should focus first on the distal muscles, and devices targeting DOF should focus first on the distal DOF.

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“…Tremor is considered the most common movement disorder [1,2]. It can occur in a variety of movement disorders, including Essential Tremor, Dystonia, Parkinson's disease, and Cerebellar Ataxia.…”

Section: Introductionmentioning

confidence: 99%

Frequency response of the leap motion controller and its suitability for measuring tremor

Kincaid

Vaterlaus

Stanford

et al. 2019

Medical Engineering & Physics

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Kincaid and Vaterlaus: none Stanford and Charles: NR Stanford is CEO and Co-Founder of, and holds stock in, Vykon Technologies LLC. SK Charles is a scientific advisor to, and holds stock in, Vykon Technologies LLC. This company has licensed technology invented by NR Stanford and SK Charles to develop markerless monitoring of movement disorders such as monitoring of tremor using depth sensing cameras such as the Leap Motion Controller.

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How Many People in the USA Have Essential Tremor? Deriving a Population Estimate Based on Epidemiological Data

Cited by 117 publications

References 21 publications

Is staged bilateral thalamic radiosurgery an option for otherwise surgically ineligible patients with medically refractory bilateral tremor?

Is staged bilateral thalamic radiosurgery an option for otherwise surgically ineligible patients with medically refractory bilateral tremor?

Simulated Tremor Propagation in the Upper Limb: From Muscle Activity to Joint Displacement

Frequency response of the leap motion controller and its suitability for measuring tremor

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