Primary orthostatic tremor

Alternate names

OT; Shaky leg syndrome; Orthostatic tremor, primary; POT

Definition

Primary orthostatic tremor (POT) is a rare, progressive movement disorder that causes unsteadiness when standing still, due to a rapid tremor affecting the legs and trunk. The tremor is sometimes described as having “shaky legs,” and it improves or disappears when walking, sitting, or lying down.

Cause

• The cause of POT is not completely understood, but the disorder is thought to involve dysfunction of the brain’s ability to regulate nerve signals that control muscle activity.
• Some researchers believe that POT is a type of essential tremor.

Signs and symptoms

• This condition causes unsteadiness when standing still, due to a rapid tremor affecting the legs and trunk.
• The tremor is sometimes described as having “shaky legs,” and it improves or disappears when walking, sitting, or lying down.
• This may cause people with POT to attempt to sit again or walk immediately after standing, for fear of falling.
• People with POT may also experience tiredness, physical exhaustion, muscle stiffness or weakness, and/or pain.
• Symptoms tend to gradually worsen over time and may lead to the need for a mobility aid such as a cane, scooter, or wheelchair.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• EMG abnormality
• Muscle spasm
• Tremor

30%-79% of people have these symptoms

• Myalgia(Muscle ache)

5%-29% of people have these symptoms

• Abnormality of extrapyramidal motor function

Diagnosis

The diagnosis of POT relies on a clinical exam as well as a specialized test called a surface electromyogram (EMG), which measures electrical activity in the muscles.

Treatment

• Treatment usually involves medications used to control seizures (anticonvulsants) such as clonazepam or gabapentin.
• In some cases, treatment may include medications used for Parkinson’s disease (levodopa or pramipexole), and/or botulinum toxin (Botox) injections in the leg muscles.
• More than one therapy may be tried before finding one that helps.

Prognosis

• POT does not appear to alter life expectancy.
• However, quality of life for people with POT may be severely impaired due to physical symptoms, fear of falling, and uncertainty about the course of the disorder.

NIH genetic and rare disease info

• NIH info on Primary orthostatic tremor

Primary orthostatic tremor is a rare disease.

Primary orthostatic tremor Resources
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