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Last updated: January 09, 2017
Years published: 2003, 2004, 2011, 2014, 2017
NORD gratefully acknowledges Joseph Jankovic, M.D, Professor of Neurology, Distinguished Chair in Movement Disorders, Director, Parkinsonโs Disease Center and Movement Disorders Clinic, Baylor College of Medicine, Department of Neurology, for assistance in the preparation of this report.
Summary
Primary orthostatic tremor is a rare movement disorder characterized by a rapid tremor in the legs that occurs when standing. The tremor disappears partially or completely when an affected person is walking or sitting. Individuals with primary orthostatic tremor experience feelings of unsteadiness or imbalance. The tremor is sometimes described as causing โshaky legsโ and can cause affected individuals to immediately attempt to sit or walk because of a fear of falling. In many patients, the tremors become more severe over time. Primary orthostatic tremor is a constant problem that can affect the quality of life of affected individuals. The exact cause of primary orthostatic tremor is unknown.
Introduction
Primary orthostatic tremor was first described in 1984 by Heilman. There is controversy within the medical literature regarding whether primary orthostatic tremor is a variant of essential tremor, an exaggerated physiological response to standing still or a distinct clinical entity.
The main symptom of primary orthostatic tremor is the occurrence of a rapid tremor affecting both legs while standing. A tremor is involuntary, rhythmic contractions of various muscles. Orthostatic tremor causes feelings of โvibrationโ, unsteadiness or imbalance in the legs. The tremor associated with primary orthostatic tremor has such high frequency that it may not visible to the naked eye but can be palpated by touching the thighs or calves, by listening to these muscles with a stethoscope, or by electromyography. The tremor is position-specific (standing) and disappears partially or completely when an affected individual walks, sits or lies down. In many cases, the tremor becomes progressively more severe and feelings of unsteadiness become more intense. Some affected individuals can stand for several minutes before the tremor begins; others can only stand momentarily. Eventually, affected individuals may experience stiffness, weakness and, in rare cases, pain in the legs. Orthostatic tremor, despite usually becoming progressively more pronounced, does not develop into other conditions or affect other systems of the body.
Some affected individuals may also have a tremor affecting the arms. In one case reported in the medical literature, overgrowth of the affected muscles (muscular hypertrophy) occurred in association with primary orthostatic tremor.
The exact cause of primary orthostatic tremor is unknown (idiopathic). Some researchers believe that the disorder is a variant or subtype of essential tremor. Other researchers believe the disorder is a separate entity. Some individuals with primary orthostatic tremor have had a family history of tremor suggesting that in these cases genetic factors may play a role in the development of the disorder. However, more research is necessary to determine the exact, underlying cause(s) of primary orthostatic tremor.
Primary orthostatic tremor affects females slightly more frequently than males. Because many affected individuals of primary orthostatic tremor often go unrecognized or misdiagnosed, the disorder is believed by some to be under-diagnosed, making it difficult to determine the true frequency of this disorder in the general population.
A diagnosis of primary orthostatic tremor is based upon a thorough clinical evaluation, a detailed patient history, and supported by specialized tests such as a surface electromyogram (EMG). Misdiagnosis is common. Many individuals may be initially suspected of having a psychogenic disorder (a disorder caused by a psychological cause rather than a physical one).
Clinical Testing and Work-Up
A surface EMG measures the electrical impulses of muscles at rest and during contraction. A surface electromyogram can often rapidly establish a diagnosis of primary orthostatic tremor by reproducing the characteristic tremor in the legs. With a surface electromyogram electrodes are placed on the skin overlying the muscles that are to be tested.
Treatment
Various medications may help relieve symptoms associated with primary orthostatic tremor. Most affected individuals are treated with a drug called clonazepam (Klonopin). However, some affected individuals do not respond to this first-line drug treatment.
Some affected individuals responded favorably after being treated with an anti-seizure (anticonvulsant) drug called gabapentin (Neurontin). A very small double-blind, placebo controlled study demonstrated that affected individuals experienced a sustained improvement when treated with the drug. Authors of the study suggested that gabapentin be considered a first-line therapy for individuals with primary orthostatic tremor.
Additional drug therapies that have been used to treat individuals with primary orthostatic tremor include primidone (Mysoline), chlordiazepoxide (Librium), pregabalin (Lyrica), pramipexole (Mirapex), phenobarbital and valproic acid (Depakote). Drugs commonly used to treat people with Parkinsonโs disease (levodopa or pramipexole) may also be prescribed for individuals with primary orthostatic tremor. Botulinum toxin injections into the leg muscles may be helpful. Surgical treatments such as spinal cord stimulation or deep brain stimulation should be reserved only for the most disabling cases that do not respond adequately to medical therapy. Additional treatment is symptomatic and supportive.
The medical literature details several cases of individuals with primary orthostatic tremor who have been treated by thalamic deep brain stimulation. Thalamic refers to the thalamus, a portion of the brain that relays sensory information. It is believed that some types of tremors occur due to abnormal brain activity that is processed in the thalamus. During this procedure, an electrode is placed into the thalamus and a thin wire is passed under the skin is connected to a small battery pack (which is also placed underneath the skin. The electrode is used to send electrical impulses (stimulate) to the brain and interrupt aberrant nerve signals that contribute to tremors. In some cases reported in the medical literature, tremors of individuals with primary orthostatic tremor were successfully controlled with thalamic deep brain stimulation. However, more research is necessary to determine the long-term safety and effectiveness of this potential therapy for primary orthostatic tremor.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
For information about clinical trials sponsored by private sources, contact: www.centerwatch.com
For information about clinical trials conducted in Europe, contact: https://www.clinicaltrialsregister.eu/
RareConnect offers a safe patient-hosted online community for patients and caregivers affected by this rare disease. For more information, visit www.rareconnect.org.
JOURNAL ARTICLES
Ganos C, Maugest L, Apartis E, Gasca-Salas C, Cรกceres-Redondo MT, Erro R, Navalpotro-Gรณmez I, Batla A, Antelmi E, Degos B, Roze E, Welter ML, Mestre T, Palomar FJ, Isayama R, Chen R, Cordivari C, Mir P, Lang AE, Fox SH, Bhatia KP, Vidailhet M. The long-term outcome of orthostatic tremor. J Neurol Neurosurg Psychiatry. 2016; Feb;87(2):167-72.
Benito-Leรณn J, Domingo-Santos ร. Orthostatic Tremor: An Update on a Rare Entity. Tremor Other Hyperkinet Mov (N Y). 2016 Sep 22;6:411.
Benito-Leรณn J, Domingo-Santos A, Hassan A, Ahlskog JE, Matsumoto JY, Bower JH. Orthostatic tremor: Clinical, electrophysiologic, and treatment findings in 184 patients. Neurology. 2016 Jul 19;87(3):341.
Gallea C, Popa T, Garcรญa-Lorenzo D, Valabregue R, Legrand AP, Apartis E, Marais L, Degos B, Hubsch C, Fernรกndez-Vidal S, Bardinet E, Roze E, Lehรฉricy S, Meunier S, Vidailhet M. Orthostatic tremor: a cerebellar pathology? Brain. 2016 Aug;139(Pt 8):2182-97.
Hassan A, Ahlskog JE, Matsumoto JY, Milber JM, Bower JH, Wilkinson JR. Orthostatic tremor: Clinical, electrophysiologic, and treatment findings in 184 patients. Neurology. 2016 Feb 2;86(5):458-64.
Thenganatt MA, Jankovic J. The relationship between essential tremor and Parkinsonโs disease. Parkinsonism Relat Disord. 2016 Jan;22 Suppl 1:S162-5.
Lotia M, Jankovic J. Botulinum Toxin for the Treatment of Tremor and Tics. Semin Neurol. 2016 Feb;36(1):54-63.
Gรถvert F, Witt K, Erro R, Hellriegel H, Paschen S, Martinez-Hernandez E, Wandinger KP, Deuschl G, Dalmau J, Leypoldt F. Orthostatic myoclonus associated with Caspr2 antibodies. Neurology. 2016 Apr 5;86(14):1353-5.
Feil K, Bรถttcher N, Guri F, Krafczyk S, Schรถberl F, Zwergal A, Strupp M. Long-term course of orthostatic tremor in serial posturographic measurement. Parkinsonism Relat Disord. 2015 Aug;21(8):905-10.
Rigby HB, Rigby MH, Caviness JN. Orthostatic Tremor: A Spectrum of Fast and Slow Frequencies or Distinct Entities? Tremor Other Hyperkinet Mov (N Y). 2015 Aug 25;5:324.
Contarino MF, Bour LJ, Schuurman PR, Blok ER, Odekerken VJ, van den Munckhof P, de Bie RM, van Rootselaar AF. Thalamic deep brain stimulation for orthostatic tremor: Clinical and neurophysiological correlates. Parkinsonism Relat Disord. 2015 Aug;21(8):1005-7.
Baizabal-Carvallo JF, Cardoso F, Jankovic J. Myorhythmia: phenomenology, etiology, and treatment. Mov Disord. 2015 Feb;30(2):171-9.
Thenganatt MA, Jankovic J. Psychogenic tremor: a video guide to its distinguishing features. Tremor Other Hyperkinet Mov (N Y). 2014 Aug 27;4:253.
van Gerpen JA. A retrospective study of the clinical and electrophysiological characteristics of 32 patients with orthostatic myoclonus. Parkinsonism Relat Disord. 2014 Aug;20(8):889-93.
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