A new study suggests updated diagnosis and treatment guidelines for people with Parkinson’s disease (PD) who experience orthostatic hypotension (OH), a rapid drop in blood pressure which often occurs when changing positions into an upright position (e.g., getting out of bed or standing up after sitting). The findings were published online February 12 in Movement Disorders.
The development of OH (sometimes referred to as neurogenic orthostatic hypotension or NOH), is influenced by many factors, including PD medications and the disease itself. Some people with PD who develop OH experience symptoms such as dizziness, headache, and rarely loss of consciousness that put them at risk for falls and other injuries. Other people with PD and OH may have no symptoms, or nonspecific symptoms, such as lethargy or unsteadiness, that are difficult to distinguish from PD symptoms. This can make the condition difficult to diagnose.
Right now, doctors diagnose OH by measuring a person’s blood pressure, and observing whether it drops a certain amount a few minutes after standing up. This is called the 20/10 rule, e.g., a drop of more than 20 mm Hg in systolic pressure (the top number) or more than 10 mm Hg in diastolic pressure (the bottom number).
In the new study, researchers led by Horatio Kaufmann, M.D., at NYU Langone School of Medicine in New York City, examined the relationship between blood pressure and OH symptoms in 210 people with PD, hoping to create better guidelines for treatment and diagnosis. The average age of participants was 66 years, and nearly all were on PD medications. Blood pressure was measured in the morning after an overnight fast and before morning medications were taken, allowing the researchers to assess blood pressure and symptoms in an “off” state.
- When using the 20/10 rule, half of the 210 participants met the criterion for diagnosis of OH. When a more conservative 30/15 cut off was used for diagnosis, this number dropped to 30 percent. Consistent with earlier research, only one third of the 20/10 group and 44 percent of the 30/15 group reported OH symptoms.
- People with OH were more likely to have lived with PD for longer than those who without OH. The prevalence of both OH in general (as well as symptomatic OH more specifically) increased with age. The amount of the blood pressure drop that occurred upon standing also increased with age.
- The researchers suggest a more accurate way of diagnosing OH — is to determine the “upright mean arterial blood pressure” as calculated from a formula that takes both systolic and diastolic blood pressures into account. They report that when this number was under 75 mmHg, they correctly identified people with symptomatic OH 97 percent of the time, and correctly identified healthy individuals 98 percent of the time.
What Does It Mean?
While most of the world is battling hypertension, one of the potential complications of Parkinson's disease and its medications is low blood pressure. Low blood pressure often does not require treatment but it may, if symptomatic. Most often, symptoms occur when one changes positions from lying down or sitting to standing. Many people experienced lightheadedness when standing up quickly, especially if dehydrated or after a large meal. If blood pressure drops frequently in such circumstances physicians may diagnose orthostatic (i.e., positional) hypotension.
With the advent of new treatments to address the issue of orthostatic hypotension in people with PD and related disorders, there is a need for clinicians to define OH in a practical way so that those who need medication (and those who do not) are more easily identified.
Previous work to diagnose orthostatic hypotension in PD has relied on measuring a drop in a person’s blood pressure when standing. However, this new study suggests that treatment should be guided not by how much blood pressure falls, but rather by the level at which a person’s blood pressure eventually stabilizes (the actual blood pressure when standing).
The researchers suggest that people with an average standing blood pressure under 75 mmHg may benefit from medications to treat their OH. These people are the ones who are most likely to experience the negative symptoms of OH, like dizziness, and may warrant treatment with drugs to raise blood pressure. Others, with a standing arterial blood pressure greater than 75 mmHg, often do not have symptoms of OH. This group may be able to avoid taking medication and the risks of high blood pressure that can occur when lying down. The authors conclude that a person’s mean arterial pressure when standing for three minutes is the most effective way of defining OH in PD.
Palma, J. A., Gomez Esteban, J. C., Norcliffe Kaufmann, L., Martinez, J., Tijero, B., Berganzo, K., & Kaufmann, H. (2015). Orthostatic hypotension in Parkinson disease: How Much You Fall or How Low You Go? Movement Disorders. doi:10.1002/mds.26079 http://dx.doi.org/10.1002/mds.2607