Epidemiology and management of essential tremor in children

Clinical and Electrophysiological Characterization of Essential Tremor in 18 Children and Adolescents

Background

Essential tremor (ET) is considered the most frequent abnormal movement in the general population, with childhood onset in 5 to 30% of the patients.

Methods

A multicenter, descriptive cross-sectional study enrolled patients ⩽18 years with a definite diagnosis of ET according to the International Parkinson and Movement Disorders Society criteria. Demographic data, clinical and electrophysiological characteristics of the tremor, neurological examination and impact on quality of life were collected.

Results

9 males and 9 females were included (mean age of 13.9 years). Tremor was characterized by : upper limb onset at a mean age of 6.5 years; at enrollment, upper limbs localization, and involvement of an additional body region in 28% of the patients; kinetic tremor in all of the patients combined with postural tremor in 17 and rest tremor in 3; tremor mean frequency of 7.6 Hz, mean burst duration of 82.7 ms; identification of mild myoclonic jerks on the polymyographic recordings in 7 patients; altered quality of life with worse emotional outcomes in girls and when a disease duration >5 years was suggested.

Discussion

Childhood-onset ET is associated with delayed diagnosis and remarkable functional impact. Electromyographic identification of additional mild myoclonus is a new finding whose significance is discussed.

Highlights

ET onset involved upper limbs and at inclusion, 28% of the patients exhibited involvement of an additional body region.ET impacted quality of life for all patients.Girls and patients affected for >5 years reported worse emotional outcomes.Mild myoclonic jerks were identified on 7/17 polymyographic recordings.

Essential tremor

Essential tremor (ET) is a chronic and progressive neurologic disease. Its central and defining clinical feature is a 4-12Hz kinetic tremor, that is, tremor that occurs during voluntary movements such as drinking from a cup or writing. Patients may also exhibit a range of other tremors-postural, rest, intention, additional motor features (e.g., mild gait ataxia, mild dystonia), as well as nonmotor features. The disease itself seems to be a risk factor for other degenerative diseases such as Alzheimer's disease and Parkinson's disease. Both genetic and toxic environmental factors have been explored as etiologic factors. In addition to a growing appreciation of the presence of clinical, etiologic, and pathologic heterogeneity, there is some support for the notion that ET itself may not be a single disease, but may be a family of diseases whose central defining feature is kinetic tremor of the arms, and which might more accurately be referred to as "the essential tremors." Recent research has increasingly placed the seat of the disease in the cerebellum and cerebellar system and identified a host of neurodegenerative changes within the cerebellum, indicating that this progressive disorder is likely degenerative.

Epidemiology of pediatric essential tremor in the United States: a systematic literature review from 2010 to 2020

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Clinical and laboratory features of children with tremor: a single-center experience

AIM

Tremor is an involuntary, rhythmic, oscillatory movement of body parts around a central point or plane which arises from contraction of antagonist muscles. Evaluation of pediatric patients with tremor can be challenging due to limited population-based studies in children. The aim of this study is to evaluate the demographic, clinical and laboratory features of childhood tremor, retrospectively.

MATERIALS AND METHODS

Patients under the age of 18 years presenting with tremor (n = 111) to the Pediatric Neurology Unit of Kecioren Research and Training Hospital between January 2014 and December 2019 were included in the study. Patients with neuromuscular disease, vertebral pathology or incomplete data in hospital records were not included. Also, benign tremor causes (jitteriness, shuddering attack, etc.) seen in the neonatal and infancy period were excluded from the study as the number of patients was insufficient. Demographic data, type and duration of tremor, accompanying symptoms, chronic diseases and medications, family history, physical and neurological examination, laboratory findings, neuroimaging findings were retrospectively analyzed and recorded.

RESULTS

A total of 111 children (59 girls and 52 boys) were included in our study and the female to male ratio was 1.1. The mean age at tremor onset and age at admission to hospital were 13.2 ± 2.8 years (range 4-17 years), and 14.8 ± 2.0 years (range 6-17 years), respectively. The most common type of tremor was essential tremor (62.2%), followed by enhanced physiologic (18.9%). None of the patients had acute metabolic disorder. Diagnostic tests revealed the etiology in 12 patients. These were vitamin B12 deficiency in 11 patients and multiple sclerosis in one patient. Drug-induced and task-specific tremors were determined in 4 patients each. It was determined that in patients with a positive family history, tremor appeared or was noticed at a younger age.

CONCLUSIONS

Most of the cases with tremor can be diagnosed accurately by a detailed medical history, physical and neurological examination. Essential tremor is the most common type of tremor in children. Laboratory tests and imaging methods have limited additional yield in elucidating the etiology. Early recognition of tremor and related signs and symptoms in childhood is important for the detection and treatment of the possible underlying cause.

Clinical approach to tremor in children

Pediatric Movement Disorders encompass a very large and complex group of diseases, among which Tremor is one of the least studied. Evaluation of tremors in kids carries significant challenges, in particular the fact that many tremor etiologies have other associated movement disorders that make tremor identification more difficult. Also, it is sometimes difficult to differentiate tremors from other shaking disorders. Yet, the correct identification of tremor leads to appropriate treatments and sometimes practical cures. Thus, in this paper we have strived to provide a succinct, clinically useful and practical review of pediatric tremors. The most useful classification of tremors in based on their predominance during rest or activity. By far, the most common tremor in children is during action. We provide a clinical algorithm on how to assess pediatric tremors at the bedside, as well as multiple useful tables. We also review common tremor etiologies.

[Diagnosis and management of essential tremor]

Essential tremor (ET) is the most common extrapyramidal disease and one of the most frequent neurological diseases. The main presentation of ET is a progressive bilateral (kinetic-postural) hand tremor. The prevalence in people over 65 years is 5%, it increases with age up to 22% in people over 95 years. About half of patients with ET have family history. The modern concepts of the pathogenesis, clinical features and differential diagnosis are considered. Possible methods of medical and surgical management are described.

Essential tremor and the cerebellum

Essential tremor (ET) is a progressive and highly prevalent neurologic disease. Along with the tremors, mild to moderate gait ataxia and other signs of cerebellar dysfunction may occur (i.e., subtle saccadic eye movement abnormalities and abnormalities of motor timing) as well as cognitive features, some of which may be due to cerebellar dysfunction. Numerous neuroimaging studies indicate the presence of functional, metabolic, and structural abnormalities in the cerebellum of a patient with ET. In tandem with these clinical and imaging studies, which were gathering increasing support for the notion that the cerebellum and/or cerebellar systems seemed to be at the root of ET, a growing postmortem literature is for the first time beginning to identify microscopic abnormalities in the ET brain, most of which are centered on the Purkinje cells and connected neuronal populations, and are likely to be degenerative. In terms of treatment, most of these pharmacotherapeutic agents serve to enhance GABAergic neurotransmission, further bolstering the notion that ET may very well be a disorder with a primary Purkinje cell dysfunction resulting in reduced cerebellar cortical inhibition. Similarly, the interruption of presumably abnormal cerebellar outflow pathways to the thalamus is the mechanism of deep-brain stimulation surgery, which is highly effective in treating ET.

Early- and late-onset essential tremor patients represent clinically distinct subgroups

OBJECTIVE

Essential tremor is a very common disease defined by sparse clinical criteria. It is unlikely that essential tremor is an etiologically homogeneous disease. Stratifying broadly defined diseases using clinical characteristics has often aided the etiopathological understanding. Most studies of essential tremor show 2 distinct age at onset peaks: early and late. This study investigates phenotypical differences between early- and late-onset essential tremor patients.

METHODS

We studied a sample of 1137 tremor patients. Of these patients, 978 suffered from definite or probable essential tremor. All of the patients underwent the same standardized examination encompassing, among other items, drawing of the Archimedes spiral and assessment of the Fahn-Tolosa-Marin scale.

RESULTS

Two subgroups of early-onset (≤ 24 years of age, n = 317) and late-onset (≥ 46 years of age, n = 356) patients were selected based on the visual and mathematical analysis of the age-at-onset distribution. Tremor severity in both groups was comparable. Tremor progression measured as Archimedes spiral score and the Fahn-Tolosa-Marin subscales divided by the disease duration in 10-year bins was significantly faster in late-onset patients when compared with early-onset patients. Early-onset patients more frequently reported a positive family history and alcohol sensitivity of the tremor.

CONCLUSIONS

The age-at-onset distribution suggests a distinction between early- and late-onset tremor. Early-onset and late-onset essential tremor differ in the progression rates and the frequencies of a positive family history and history of a positive effect of alcohol on tremor. © 2016 International Parkinson and Movement Disorder Society.

A Series of 211 Children with Probable Essential Tremor

Background

The objective of this study was to characterize the clinical features, course, and treatment of essential tremor (ET) in children.

Methods

A retrospective chart review was conducted over 25 years (1984-2011). Inclusion criteria were age <21 years and satisfying the core diagnostic criteria for ET. Primary exclusion criteria included other neurological findings, tremorogenic medications, sudden onset/stepwise progression, primary orthostatic tremor, and isolated task specificity; and secondary exclusion criteria were abnormal neuroimaging or metabolic/thyroid studies. Cases were reviewed for age, sex, family history, tremor characteristics, functional impairment, treatment, and follow-up.

Results

In total, 211 children had ET, including 130 males and 81 females. The mean ± standard deviation age was at diagnosis was 14.09 ± 5.0 years, the age of onset was 9.71 ± 5.62 years, and the age of onset was birth in 7 children. One hundred ninety-nine children had bilateral hand tremor, 34 had asymmetry, 9 had unilateral onset but later became bilateral. Twelve children had voice tremors, 13 had leg tremors, 5 had head tremors, and 7 had trunk tremors. Tremor at rest was present in 20 children. Thirty-five percent of the children had a family history of ET, including in a father (n = 21), mother (n = 13), brother (n = 6), sister (n = 3), and other family member (n = 28). Fifty-five percent of patients had functional disabilities, including writing (n = 66), eating (n = 28) drinking from a cup (n = 13), typing (n = 4), playing instruments (n = 6), buttoning (n = 6), and playing (n = 3). For treatment, 33 patients received propranolol, 1 received atenolol, 13 received primidone, 3 received metoprolol, and 1 received nadolol. In total, 99 patients were followed for a mean ± standard deviation of 1.82 ± 2.21 years.If left untreated, tremor remained unchanged in 33 patients, and 7 had an apparent short-term improvement. On propranolol, 15 of 20 patients significantly improved.

Conclusions

This is the largest series to date of ET in children. The current findings indicate that onset at birth is possible, family history is less common in children than in adults, and tremor at rest is possible. Functional disability was noted in 55% of children, and 29.4% required medication.

Movement disorders in childhood

The aim of this article is to review movement disorders in children. They are common but have etiology and phenomenology different than in adults. Tics are the most common phenomena although in most instances they are mild and have a favorable long-term prognosis. Dystonia is the second most common phenomena but when present it is usually genetic or idiopathic and causes meaningful disability. Sydenham's chorea is the most common cause of chorea in children worldwide. Systemic lupus erythematosus is a much rarer cause of chorea but it is always to be ruled out given the lack of a specific diagnostic marker for Sydenham's chorea. Tremor, usually caused by drugs or essential tremor, is regarded as rather uncommon in children. Arguably, most pediatric patients with tremor do not seek medical attention because of the lack of disability. Stereotypies are relatively uncommon but their recognition is clinically relevant since they are usually associated with severe conditions such as autism and Rett syndrome. Parkinsonism is quite rare in children and either results from encephalitis or is a side effect of medications. Wilson's disease must be ruled out in all children with movement disorders.