Case Report - Orthostatic tremor: report of a case and review of the literature

• Published in: Neurology India Vol. 51; no. 1
• Main Author: K. B. Bhattacharyya, S. Basu, A. D. Roy, S. Bhattacharya
• Format: Journal Article
• Language: English
• Published: Medknow Publications on behalf of the Neurological Society of India 05-05-2003
• Subjects: Orthostatic tremor, Electromyography, Essential tremor
• ISSN: 0028-3886

Orthostatic tremor is a rare movement disorder characterized by
tremulousness of the lower limbs on standing that disappears on
walking, sitting or on lying down and a distinctive electromyographic
burst of 14 to 16 Hz. On inspection, fine ripples can sometimes be seen
over the quadriceps on standing. The tremor has a tendency to reappear
even in the supine posture if the lower limb muscles are put to an
isometric contraction state, indicating thereby that in spite of the
fact that the tremor occurs on standing, it is essentially `orthostasis
independent' and the central factor is the contraction of the muscles.
As a matter of fact, the tremor is abolished if the subject is
suspended by harness, thus relieving him of muscle contraction. Doubts
are being cast whether it is a variant of essential tremor since a
number of families are being reported to be suffering from this disease
as well. Positron emission tomography reveals hyperactivity of
cerebellum in orthostatic tremor as it shows in essential tremor,
therefore lending credence to such a hypothesis. However, lack of
response to alcohol, propranolol and primidone in orthostatic tremor
stands out as a serious challenge to such a view. Lack of positive
family history, synchrony of contracting group of muscles and negative
'reseting' of the tremor by increasing peripheral load-phenomena
consistently observed in orthostatic tremor and not in essential
tremor, are other features that often help to distinguish between the
two conditions. We report a case of orthostatic tremor that presented
with the classical clinical and eletromyographic features. Relevant
literature in this regard is also being reviewed.