The information and studies that are related to OT are extremely limited. Most of the available reports and studies throughout the world are a number of years old and generally involve a very small number of patients with very few follow up reports.
The symptoms of OT are have been defined (and sometimes redefined) but the etiology is unknown. The tremor of OT is such a high frequency that it is distinct from other tremors such as Parkinson's and Essential, etc. However, there are very few new cases reported, most doctors do not identify it because they are not aware of it. I hope awareness will prevent OT from being missed as a diagnosis because if it is identified the symptoms are treatable.
** The following information contains links to the source documents, as we become aware of new information we will try to add to this list, we are only passing along this information and not making any conclusions about techniques used in diagnosis, misdiagnoses etc. - medical disclaimer - website disclaimer
A New teaching video has been posted on Neurology.org “Orthostatic Tremor: The Helicopter Sign”, this video contains the audio of the sound of the tremor, the chart of the sEMG and shows the legs of the patient under test. click to read more....
”OT is a neurologic condition manifested by tremors, mainly in the legs, but also in the cranial structures, arms, and trunk” Clinical and Neurophysiologic Spectrum of Orthostatic Tremor: Case Series of 26 Subjects , and ringing in ears (tinnitus)
Importance of electromyography studies in the diagnosis of orthostatic tremor : study includes reference EMG illustration
Surface electromyographic (EMG) recordings: This study shows that the diagnosis can be established rapidly with surface electromyographic recordings.
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). As a similar tremor can be induced in normal persons via vestibular stimulation (Sharott et al, 2003), conditions that cause imbalance should be considered in addition.
Posturography can be used to screen for primary orthostatic tremor
A dissociation between subjective and objective unsteadiness in primary orthostatic tremor ... to study the relationship between the development of subjective unsteadiness, objective unsteadiness and tremor, we recorded standing under four conditions (eyes open or closed, feet together or apart) in six patients with OT.
Orthostatic tremor can also be palpated as a kind of ‘rhythmic shivering’ of the legs, or can be heard through a stethoscope (thumping sound like a helicopter) in cases where it is not obviously visible.25 - Brown, P. New clinical sign for orthostatic tremor. Lancet 346, 306–307 (1995)
Orthostatic Tremor - A Review of 40 cases: Baylor College of Medicine, Houston, Texas
Using an Iphone to diagnose? An interesting article that may point towards future innovation: The challenge is ﬁnding a universally accessible, easily used device that can give a quick, accurate representation of tremor characteristics. Here, we present the use of the iPhone seismograph application (iSeismo by ObjectGraph LLC) in tremor detection and measurement.
( and just incase you have an iphone and are curious, here’s the link to the iphone app... it’s free )
Another new iPhone app has been developed called Lift Pulse. Using a Fourier Transform, this app can identify your tremor and calculate it's magnitude.
Click Here to read the discussion on iPhone apps in the OT Forum.
A Slow Orthostatic Tremor of Primary Origin: OT of primary origin is not necessarily a high-frequency tremor; it can also occur in a lower frequency of 10–11 Hz.
Misdiagnosis and other variations**
• Orthostatic myoclonus - this link from Mayo Clinic describes a unique clinical and physiologic phenomenon that accompanies a slowly progressive and eventually disabling gait disorder in the elderly. This phenomenon often arises in the company of more widespread CNS disease.
• Orthostatic myoclonus : this link describes the same phenomenon but the author believes Orthostatic myclonus to be the same as OT
• Orthostatic tremor induced by pharmaceuticals: ...four patients who developed orthostatic tremor after exposure to dopamine blocking drugs: metoclopramide(Reglan), sulpiride, thyethylperazine (Torecan)
• Parkinson’s disease
• Pseudo-Orthostatic Tremor : dominant frequency 6.2 to 6.9 sporadic subharmonics at 8 to 18 Hz... all patients had dopamine transporter abnormalities.
• Fast orthostatic tremor in Parkinson's disease mimicking primary orthostatic tremor.
• Multiple Sclerosis
• Cerebrospinal Fluid Leaks
Primary, OT plus, secondary OT, symptomatic OT, Slow Orthostatic Tremor, and other related terms**
The term Primary (refers to symptoms or a disease to which others are secondary) is often used interchangeably or in conjunction with idiopathic when describing Orthostatic Tremor. Idiopathic/primary is defined as “...from an obscure or unknown cause”. Primary Orthostatic Tremor often describes a condition without other neurological features whereas Orthostatic Tremor plus or OT plus is a term which is often used to describe a condition where other neurological features also exist such as: Parkinson’s disease, Parkinsonism, Ataxia, hemifacial spasm, Restless Legs Syndrome, Tardive Dyskinesia, Essential Tremors, Head trauma, Pontine lesions, Aqueduct stenosis, Peripheral neuropathy, and others. OT Plus has also been referred to as: secondary OT, and symptomatic OT. Slow Orthostatic Tremor, which exhibits tremor <12Hz is discussed in this report.
reference: 1 , 2 , 3 , 4
OT is considered to be an idiopathic disorder, as the study with cerebral neuroimaging and other examinations are generally normal. Patients suffering from OT can be divided into 2 sub-groups: “primary OT” with or without postural tremor of the upper limbs and “OT plus” in which it is associated with other movement disorders such as Parkinson’s disease, restless legs syndrome or dyskinesias.3 Some cases have also been described as associated with protuberantial lesions. Link to full PDF Neurología. 2011;26(1):53-61
Additional OT related terms can be found on the OT Glossary
There are a variety of treatments that visitors have reported in attempts to control this disorder, and the most current can be found and discussed on the user forum.