ABSTRACT: Orthostatic tremor (OT) remains among the most intriguing and poorly understood of movement disorders. Compared to Parkinson's disease or even essential tremor, there are very few articles addressing more basic science issues. In this review, we will discuss the findings of main case series on OT, including data on etiology, pathophysiology, diagnostic approach, treatment strategies, and outcome.Data for this review were identified by searching PUBMED (January 1966 to August 2016) for the terms "orthostatic tremor" or "shaky leg syndrome," which yielded 219 entries. We did not exclude papers on the basis of language, country, or publication date. The electronic database searches were supplemented by articles in the authors' files that pertained to this topic.Owing to its rarity, the current understanding of OT is limited and is mostly based on small case series or case reports. Despite this, a growing body of evidence indicates that OT might be a progressive condition that is clinically heterogeneous (primary vs. secondary cases) with a broader spectrum of clinical features, mainly cerebellar signs, and possible cognitive impairment and personality disturbances. Along with this, advanced neuroimaging techniques are now demonstrating distinct anatomical and functional changes, some of which are consistent with neuronal loss.OT might be a family of diseases, unified by the presence of leg tremor, but further characterized by etiological and clinical heterogeneity. More work is needed to understand the pathogenesis of this condition.
Project description:BACKGROUND:Orthostatic tremor (OT) and orthostatic myoclonus (OM) are weight-bearing hyperkinetic movement disorders most commonly affecting older people that induce "shaky legs" upon standing. OT is divided into "classical" and "slow" forms based on tremor frequency. In this paper, the first joint review of OT and OM, we review the literature and compare and contrast their demographic, clinical, electrophysiological, neuroimaging, pathophysiological, and treatment characteristics. METHODS:A PubMed search up to July 2016 using the phrases "orthostatic tremor," "orthostatic myoclonus," "shaky legs," and "shaky legs syndrome" was performed. RESULTS:OT and OM should be suspected in older patients reporting unsteadiness with prolonged standing and/or who exhibit cautious, wide-based gaits. Surface electromyography (SEMG) is necessary to verify the diagnoses. Functional neuroimaging and electrophysiology suggest the generator of classical OT lies within the cerebellothalamocortical network. For OM, and possibly slow OT, the frontal, subcortical cerebrum is the most likely origin. Clonazepam is the most useful medication for classical OT, and levetiracetam for OM, although results are often disappointing. Deep brain stimulation appears promising for classical OT. Rolling walkers reliably improve gait affected by these disorders, as both OT and OM attenuate when weight is transferred from the legs to the arms. DISCUSSION:Orthostatic hyperkinesias are likely underdiagnosed, as SEMG is often unavailable in clinical practice, and thus may be more frequent than currently recognized. The shared weight-bearing induction of OT and OM may indicate a common pathophysiology. Further research, including use of animal models, is necessary to better define the prevalence and pathophysiology of OT and OM, in order to improve their treatment, and provide additional insights into basic balance and gait mechanisms.
Project description:To review the electrophysiological and clinical characteristics of 32 patients with orthostatic myoclonus (OM), a relatively newly identified movement disorder, and compare these characteristics to those of primary orthostatic tremor (OT) patients and patients with similar gait and balance complaints without either hyperkinesia diagnosed during the same 30-month period.The database of the Mayo Clinic Florida Movement Disorders Electrophysiology Laboratory (MDEL) was searched for all patients referred for possible OM or OT from 6/2010 to 12/2012. All available clinical records and archived surface electromyographical data for these patients were reviewed and analyzed.32 patients with OM (mean age 74 years), 8 with primary OT (mean age 71), and 55 with neither orthostatic hyperkinesia (NOH) (mean age 68) were identified. All OT patients and 84% each of OM and NOH patients complained of involuntary leg movements while standing, e.g., "shaking," "trembling," or "jerking." All OM and OT patients experienced symptomatic and electrophysiological abatement or attenuation of their leg hyperkinesias by leaning forward onto an object while standing.OM has some similarities to OT, including causing "shaky legs" subjectively in standing older patients. Novel data from this work include that, as in OT, OM essentially abates when patients remove their weight from their legs. This shared isometric phenomenon may reflect that OT and OM are on a pathophysiological continuum. Further, many patients who complain of their legs "shaking" while standing may have neither OT nor OM. Surface electromyography may be a useful adjunct in extrapolating patients complaining of "shaky legs."
Project description:Background:Orthostatic tremor (OT) is a rare symmetric tremor disorder occasionally observed in association with other movement disorders. Case report:We report the presence of a fast OT in a case of Parkinson's disease (PD), and provide a comprehensive review of the literature. Discussion:A fast OT presenting as unsteadiness may be a presenting symptom of PD. This symptom may be nonresponsive to levodopa, and benzodiazepines should be prescribed to adequately control the OT and reduce disability.
Project description:Background:Orthostatic tremor (OT) is a weight-bearing hyperkinetic disorder characterized by unsteadiness while standing that is relieved when sitting or walking. Case report:A 66-year-old male presented with a 5 year-history of tremor in his abdomen, but only when he stood in a stationary position. The tremor disappeared when he stood or walked. On examination, he had palpable tremor in his rectus abdominis and gastrocnemius virtually instantaneously after standing. His electromyography findings confirmed the presence of a 12-Hz tremor in the tibialis anterior while standing, with subharmonics recorded in the external obliques and rectus abdominis. Discussion:Our case illustrates an unusual presentation of OT. The diagnosis is supported by its characteristic frequency and specific appearance only during upright stance.
Project description:Background:Orthostatic tremor (OT), a rare and complex movement disorder, is characterized by rapid tremor of both legs and the trunk while standing. These disappear while the patient is either lying down or walking. OT may be idiopathic/primary or it may coexist with several neurological conditions (secondary OT/OT plus). Primary OT remains an enigmatic movement disorder and its pathogenesis and neural correlates are not fully understood. Methods:A PubMed search was conducted in July 2017 to identify articles for this review. Results:Structural and functional neuroimaging studies of OT suggest possible alterations in the cerebello-thalamo-cortical network. As with essential tremor, the presence of a central oscillator has been postulated for OT; however, the location of the oscillator within the tremor network remains elusive. Studies have speculated a possible dopaminergic deficit in the pathogenesis of primary OT; however, the evidence in favor of this concept is not particularly robust. There is also limited evidence favoring the concept that primary OT is a neurodegenerative disorder, as a magnetic resonance spectroscopic imaging study revealed significant reduction in cerebral and cerebellar N-acetyl aspartate (NAA) levels, a marker of neuronal compromise or loss. Discussion:Based on the above, it is clear that the pathogenesis of primary OT still remains unclear. However, the available evidence most strongly favors the existence of a central oscillatory network, and involvement of the cerebellum and its connections.
Project description:Background:Orthostatic tremor (OT) is a hyperkinetic movement disorder characterized by rapid tremor in the lower extremities or trunk upon standing. Case Report:We report two patients presenting with OT, whose symptoms improved markedly following asleep bilateral thalamic deep brain stimulation (DBS) surgery. Discussion:Medically refractory OT can respond favorably to asleep bilateral DBS surgery similar to awake surgery, and may have the advantages of less psychological trauma to the patient, shorter procedure times, and less exposure to anesthesia.
Project description:Background:Orthostatic tremor (OT) is defined as tremor in the legs and trunk evoked during standing. While the classical description is tremor of ?13 Hz, slower frequencies are recognized. There is disagreement as to whether the latter represents a slow variant of classical OT, or different tremor disorder(s) given frequent coexistent neurological disease. Methods:A systematic literature search of PubMed was performed in February 2019 for "slow orthostatic tremor" and related terms which generated 573 abstracts, of which 61 were included. Results:Between 1970 and 2019, there were 70 cases of electrophysiologically confirmed slow OT. Two-thirds were female, of mean age 60 years (range 26-86), and mean disease duration 6 years (range 0-32). One-third of cases were isolated, and two-thirds had a coexistent disorder(s), including parkinsonism (30%), ataxia (12%), and dystonia (10%). Postural arm tremor was present in 34%. Median tremor frequency was 6-7 Hz (range 3-12). Tremor bursts ranged from 50 to 150 ms duration, and were alternating or synchronous in antagonistic and/or analogous muscles. Low and high coherences were reported. Five cases (7%) had coexistent classical OT. Clonazepam was the most effective medication across all frequencies, and levodopa was effective for 4-7 Hz OT with coexistent parkinsonism. Two cases resolved with the treatment of Graves' disease. Electrophysiology and imaging predominantly support a central tremor generator. Discussion:While multiple lines of evidence separate slow OT from classical OT, clinical and electrophysiological overlap may occur. Primary and secondary causes are identified, similar to classical OT. Further exploration to clarify these slow OT subtypes, clinically and neurophysiologically, is proposed.
Project description:Orthostatic tremor (OT) was first described in 1977. It is characterized by rapid tremor of 13-18 Hz and can be recorded in the lower limbs and trunk muscles. OT remains difficult to treat, although some success has been reported with deep brain stimulation (DBS).We report a 68-year-old male with OT who did not improve significantly after bilateral thalamic stimulation.Although some patients were described who improved after DBS surgery, more information is needed about the effect of these treatment modalities on OT, ideally in the form of randomized trial data.
Project description:BACKGROUND:We aimed to characterize the clinical and electrophysiological features of patients with slow orthostatic tremor. CASE REPORT:The clinical and neurophysiological data of patients referred for lower limb tremor on standing were reviewed. Patients with symptomatic or primary orthostatic tremor were excluded. Eight patients were identified with idiopathic slow 4-8 Hz orthostatic tremor, which was associated with tremor and dystonia in cervical and upper limb musculature. Coherence analysis in two patients showed findings different to those seen in primary orthostatic tremor. DISCUSSION:Slow orthostatic tremor may be associated with dystonia and dystonic tremor.
Project description:Background:Article-level citation count is a hallmark indicating scientific impact. We aimed to pinpoint and evaluate the top 50 most-cited articles in orthostatic tremor (OT). Methods:The ISI Web of Knowledge database and 2017 Journal Citation Report Science Edition were used to retrieve the 50 top-cited OT articles published from 1984 to April 2019. Information was collected by the Analyze Tool on the Web of Science, including number of citations, publication title, journal name, publication year, and country and institution of origin. Supplementary analyses were undertaken to clarify authorship, study design, level of evidence, and category. Results:Up to 66% of manuscripts were recovered from five journals: Movement Disorders (n = 18), Brain (n = 4), Journal of Clinical Neurophysiology (n = 4), Neurology (n = 4), and Clinical Neurophysiology (n = 3). Articles were published between 1984 and 2018, with expert opinion as the predominant design (n = 22) and review as category (n = 17). Most articles had level 5 evidence (n = 26). According to their countries of origin, 34% of articles belonged to the United States (n = 17) leading the list, followed by United Kingdom (n = 15). University College London yielded the greater number of articles (n = 12), followed by the University of Kiel (n = 9). Most popular authors were G. Deuschl (n = 10), C.D. Marsden (n = 6), J. Jankovic (n = 5), P.D. Thompson (n = 5), J.C. Rothwell (n = 5), L.J. Findley (n = 4), and P. Brown (n = 4), who together accounted for 48% of them. All papers were in English. Discussion:Publishing high-cited OT articles could be facilitated by source journal, study design, category, publication language, and country and institution of origin.