ABSTRACT
I. Introduction 252
II. Etiology and Classification 252
III. Epidemiology 253
A. Demographical Variables: Age, Sex and Onset Age 253
B. Family History 253
IV. Clinical and Neurophysiological Features 254
A. Relationship between Orthostatic Tremor and
Postural Arm Tremor 255
B. Relationship between Orthostatic Tremor, Parkinsonism
and Other Movement Disorders 256
V. Pathophysiology 257
A. Clinical Course 258
VI. Therapy 258
References 259
I. INTRODUCTION
Orthostatic tremor, first described by Heilman in 1984, is a rare condition charac-
terized by unsteadiness when standing that is relieved when sitting or walking,
and is accompanied by a rapid 13-18 Hz tremor of the legs (1). Orthostatic
tremor was initially classified as a variant of essential tremor (2,3), because of
the presence of a postural arm tremor resembling essential tremor in some
cases. According to the Consensus Statement of the Movement Disorder
Society on tremor (4), orthostatic tremor is defined as a subjective feeling of
unsteadiness during stance that is usually relieved during sitting or lying, associ-
ated with visible and occasionally palpable fine amplitude rippling of the leg
muscles when standing, and accompanied by a rapid 13-18 Hz tremor of the
legs. Currently, orthostatic tremor is considered a distinct tremor disorder that
it is thought to arise from a central generator in the cerebellum or brainstem.
