A Case of Slow Orthostatic Tremor, Responsive to Intravenous Immunoglobulin
Department of Neurology, University of California, San Francisco, CA, USA. .Movement Disorders (Impact Factor: 5.68). 07/2011; 26(8):1563-5. DOI: 10.1002/mds.23610
- Parkinsonism & Related Disorders 11/2011; 18(5):680-1. DOI:10.1016/j.parkreldis.2011.11.016 · 3.97 Impact Factor
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ABSTRACT: Orthostatic tremor is a rare condition, though its exact prevalence is unknown, which is clinically characterized by a feeling of unsteadiness or being about to fall on standing and which disappears on walking, sitting, or lying down. It is generally accepted that classic orthostatic tremor manifests with a high-frequency tremor (>13 Hz) of the legs when standing. However, a number of patients initially reported as orthostatic tremor did not actually have such electrophysiological features. It is our experience that there is a clinical spectrum of different conditions presenting as shaking on standing, and this highlights the importance of the electrophysiology to aid the differential diagnosis of these disorders. Here, we provide a critical review of the clinical spectrum of shaking on standing, along with demonstrative electrophysiological recordings of some of these conditions.09/2014; 1(3). DOI:10.1002/mdc3.12053
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ABSTRACT: Orthostatic tremor (OT) is defined by the presence of a high-frequency (13-18 Hz) tremor of the legs upon standing associated with a feeling of unsteadiness. However, some patients have discharge frequencies of <13 Hz, so-called "slow OT". The aim of this study was to characterize patients with unsteadiness upon standing found to have <13 Hz tremor discharges on neurophysiologic testing. A retrospective review was performed on all subjects with a diagnosis of OT who were referred to the Mayo Clinic, Scottsdale, AZ, between 1999 and 2013 for confirmation using neurophysiology. Fourteen of 28 subjects (50%) had OT discharges of <13 Hz, of whom eight had frequencies of <10 Hz and six had frequencies of 10-13 Hz. Lower frequency discharges tended to have a broader spectral peak, greater variability in discharge duration, and lower inter-muscular coherence. Subjects with <13 Hz OT had shorter mean disease duration at time of neurophysiology testing (2.00 years in <10 Hz group, 7.96 years 10-13 Hz group, and 11.43 years >13 Hz; p = 0.002). The proportion of subjects who experienced gait unsteadiness (85.7% vs. 66.6% vs. 21.4%; p = 0.016), falls (37.5% vs. 50% vs. 0%; p = 0.010), and had abnormal gait on examination (71.4% vs. 66.0% vs. 14.3%; p = 0.017) was greater in those with low and intermediate frequencies. Slow tremor electromyography frequencies (<13 Hz) may characterize a substantial proportion of patients labeled as OT. These subjects may have greater gait involvement and higher likelihood of falls leading to earlier presentation to subspecialty care.08/2015; 5:324. DOI:10.7916/D8S75FHK
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