title: Natural history and syndromic associations of orthostatic tremor: a review of 41 patients.
abstract: Orthostatic tremor (OT) is a rare condition characterized by unsteadiness when standing still that is relieved when sitting or walking and is thought to arise from a central generator in the cerebellum or brainstem. OT is considered to be a distinct, discrete condition, and little is known about its demographic characteristics, natural history, associated features, and treatment response. We have reviewed these aspects in 41 OT patients fulfilling current diagnostic criteria, seen at our institution between 1986 and 2001. We classified 31 (75%) as having idiopathic "primary OT" either with (n = 24) or without an associated postural arm tremor. We found that 10 of 41 (25%) cases had additional neurological features, and we defined this group as having "OT plus" syndrome. Of these 10, 6 had parkinsonism; 4 of these had typical Parkinson's disease (PD), 1 had vascular and 1 had drug-induced parkinsonism. Among the remaining 4 patients, 2 had restless legs syndrome (RLS), 1 had tardive dyskinesia, and 1 orofacial dyskinesias of uncertain etiology. One patient with PD and the patient with vascular parkinsonism also had RLS. Age at onset was significantly earlier in the "primary OT" (mean +/- SD, 50.4 +/- 15.1) than in the "OT plus" (61.8 +/- 6.4; z = 2.7; P =.006) group. In 7 of the 10 "OT plus" patients, OT leg symptoms preceded the onset of additional neurological features. OT appeared to be underdiagnosed, and on average, it took 5.7 years from the initial complaints until a diagnosis was made. In general, treatment response to a variety of drugs such as clonazepam, primidone, and levodopa was poor. In most cases, OT symptoms remain relatively unchanged over the years, but in 6 of 41 cases (15%), the condition gradually worsened over the years, and in some of these cases, symptoms spread proximally to involve the trunk and arms. OT may not be a discrete disorder as commonly believed and associated features like parkinsonism present in nearly 25% of cases. Dopaminergic dysfunction may have a role in the pathophysiology of this disorder.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.|Department of Neurology, Krankenhaus der Barmherzigen Brüder, Vienna, Austria.
authors.forename: Willibald
authors.initials: W
authors.lastname: Gerschlager
authors.affiliation: Neurology Department, Hamburg University, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Münchau
authors.affiliation: National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom.|Reta Lila Weston Institute of Neurological Studies, Royal Free and University College London Medical School, United Kingdom.
authors.forename: Regina
authors.initials: R
authors.lastname: Katzenschlager
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.
authors.forename: John C
authors.initials: JC
authors.lastname: Rothwell
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.|National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom.
authors.forename: Niall
authors.initials: N
authors.lastname: Quinn
authors.affiliation: National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom.|Reta Lila Weston Institute of Neurological Studies, Royal Free and University College London Medical School, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lees
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.|National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom.
authors.forename: Kailash P
authors.initials: KP
authors.lastname: Bhatia
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000145:classification / Q000627:therapeutic use; D001933:Brain Stem / Q000503:physiopathology; D002531:Cerebellum / Q000503:physiopathology; D004244:Dizziness / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014202:Tremor / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D016138:Walking / Q000502:physiology
chemical_list: D000978:Antiparkinson Agents; D004298:Dopamine