Primary Orthostatic Tremor

Timothy C. Hain, MD Last updated 12//2002 Please read our disclaimer. Return to index

Primary orthostatic tremor (OT) consists of rhythmical muscle contractions causing discomfort or unsteadiness while standing. It was first described by Heilman in 1984. The tremor is typically 12 to 18 Hz, with partial or complete cessation while walking or sitting.

It is presently controversial whether OT is a variant of essential tremor or a diagnostic entity in its own right (Gabellini, 1990). Occasionally OT is found in association with essential tremor, and it can follow head injury (Sinitate et al, 1993)

Diagnosis is usually obtained based on clinical evaluation combined with surface electromyogram (EMG). Surface EMG contains a high-frequency component -- 16 to 18 Hz. Misdiagnosis is common and many patients are initially thought to have a non-organic (psychogenic) balance disorder. Frequency domain analysis of surface EMG or sway traces can diagnose this condition (Yarrow et al, 2001).

According to Pradalier and associates(2002), clonzepam is the preferred treatment for orthostatic tremor. Other drugs that may be effective include primidone(Mysoline) as well as it's relative phenobarbital (Cabrera, 1991) and gabapentin (Neurontin) (Evidente et al, 1998; Onofrj et al, 1998). Although beta-blockers are often useful in essential tremor, they have been reported not to be effective in OT (Wee, 1986)