[1] In several instances, the passing surface waves from large earthquakes have ignited nonvolcanic tremor (NVT) on major faults. Still, the mechanism of tremor and its reaction to the dynamic stressing from various body and surface waves is poorly understood. We examine tremor near Parkfield, California, beneath the San Andreas fault triggered by the Mw 9.2, 2004 Sumatra earthquake. The prolon...

The pathophysiology of essential tremor (ET), the most common movement disorder, is not fully understood. We investigated which factors determine the variability in the phase difference between neural drives to antagonist muscles, a long-standing observation yet unexplained. We used a computational model to simulate the effects of different levels of voluntary and tremulous synaptic input to an...

BACKGROUND Drawing Archimedes spirals is a popular and valid method of assessing action tremor in the upper limbs. We performed the first blinded comparison of Fahn-Tolosa-Marín (FTM) ratings and tablet measures of essential tremor to determine if a digitizing tablet is better than 0-4 ratings in detecting changes in essential tremor that exceed random variability in tremor amplitude. METHODS...

The occurrence of Parkinson's disease and of essential tremor was examined in the parents and siblings of 52 Parkinson's disease patients with onset before the age of 45 years. The expected numbers of cases with Parkinson's disease or essential tremor were calculated according to the age and sex specific incidence rates of Parkinson's disease and essential tremor in the general population. Amon...

Background: Essential tremor is characterized by several hyperkinetic movements, including arm and head tremors. We report another movement of the head in patients with essential tremor, which we term the ‘‘head snap.’’ This was observed as a jerking motion of the head in some patients while they performed the finger– nose–finger maneuver. Methods: We compared the prevalence of the head snap in...

For several years our interest has been in a postural Parkinson-like tremor at 4-6/sec. which can be produced in the monkey by lesions of the central nervous system. We have also studied the effects of harmaline, a drug which evokes or intensifies the Parkinson-like tremor in lesioned animals and which also induces a fine, generalized tremor at 7-12/sec. in normal animals. The results obtained ...

OBJECTIVES/HYPOTHESIS 1) To clarify essential voice tremor (EVT) phenomenology; 2) To report a management paradigm for essential voice tremor using botulinum toxin. STUDY DESIGN Retrospective analysis of prospectively collected data. METHODS Phenomenology from patients diagnosed with EVT between April 1996 and March 2012 was recorded, charted, and analyzed. A paradigm for treatment of EVT u...

Volcanic tremor, a continuous seismic signal, accompanies virtually all eruptions. Several published studies have examined relations between tremor reduced displacement (DR, a normalized amplitude measure) and the VEI or ash plume height. The goals of these studies are to determine the physical relationships between tremor and eruptions and to use DR values to provide real-time estimates of eru...