Article In Brief
New research suggests that many patients with Parkinson's disease experience transient orthostatic hypotension, which is a brief but potentially substantial decrease in blood pressure when standing.
Patients may not mention it, and standard tilt table testing may miss it, but many patients with Parkinson's disease (PD) experience transient orthostatic hypotension, a short-lived but potentially significant drop in blood pressure upon standing, according to a new study published online September 16 in Neurology.
“A transient drop in blood pressure when changing to the upright position may be overlooked with bedside blood pressure measurements, but still contribute to orthostatic intolerance and syncope in Parkinson's disease,” said lead study author Alessandra Fanciulli, MD, PhD, a clinical researcher at the Autonomic Function Lab of the department of neurology at the Medical University of Innsbruck, Austria.
Orthostatic hypotension (OH) has long been recognized as a non-motor feature of PD, Dr. Fanciulli said, but mainly in its “classical” form (cOH), in which there is a sustained drop in blood pressure within three minutes upon standing.
In contrast, transient OH (tOH), defined as a rapid fall in blood pressure upon standing that resolves within 30 seconds, has been underappreciated, she said. It can't be captured with a blood pressure cuff because the measurement takes too long; instead, it must be detected with continuous blood pressure monitoring.
While cOH is a recognized contributor to orthostatic intolerance (characterized by lightheadedness, blurred vision, or unsteadiness upon standing), the contribution of tOH to orthostatic intolerance in PD has been less well studied.
To evaluate the frequency of tOH in people with PD, Dr. Fanciulli and colleagues drew on 13 years of data from patients undergoing cardiovascular autonomic testing at their center. They included 173 patients with PD and an equal number of age- and sex-matched controls without the disease being seen for autonomic testing.
Testing consisted of noninvasive continuous blood pressure monitoring using a finger cuff plethysmograph, a device used in autonomic function laboratories, and other medical settings such as when patients are monitored during surgery. Patients spent five minutes supine, and then stood up for five minutes.
“Forty-one percent of Parkinson's patients, and 21 percent of controls, showed a pathological blood pressure regulation upon standing,” Dr. Fanciulli said. Of the 71 patients with PD, tOH occurred in 41, and cOH in 32 (two patients exhibited both). There were no demographic or other features that distinguished patients with tOH from those with cOH.
“What was very surprising was that transient orthostatic hypotension is just as common as classic orthostatic hypotension in people with Parkinson's disease,” Dr. Fanciulli said.
Compared to controls with tOH, PD patients with tOH had a greater degree of abnormality in heart rate and blood pressure response to the Valsalva maneuver and deep breathing. Both tests were used to examine cardiovascular autonomic reflexes.
“This suggests that transient orthostatic hypotension may be due to cardiovascular dysautonomia in Parkinson's disease,” Dr. Fanciulli said. At the same time, in the general elderly population, other factors, like the more frequent prescription of antihypertensive medications, may contribute to tOH.
Forty percent of PD patients had experienced falls in the six months before and after the blood pressure measurements, in every third case that was due to syncope upon standing. The frequency of falls was not directly increased in PD patients with cOH or tOH. Still, those with a history of orthostatic intolerance and syncope had a more severe systolic BP fall and lower diastolic BP rise upon standing, which was most pronounced in the first 30 to 60 seconds.
Transient blood pressure falls within the first minute upon standing may, therefore, contribute to orthostatic intolerance and syncope-related falls in people with Parkinson's disease.
“The most important message is to ask your patients about orthostatic intolerance,” Dr. Fanciulli said, “because they may not recognize what it is when it occurs and may not tell you about it unless you ask specifically” about dizziness, numbness, and lightheadedness that develop upon standing and get better upon sitting down. If a patient reports this type of symptoms, and screening in the exam room doesn't reveal cOH, referral for supine-to-standing continuous BP measurement may be warranted to exclude tOH.
Despite the lack of clear association in this study, “it seems likely that in some Parkinson's patients, orthostatic hypotension does play a role in falls,” commented Robert A. Hauser, MD, MBA, FAAN, director of the Parkinson's and Movement Disorder Center and professor of neurology in the College of Medicine at the University of South Florida in Tampa.
“Since it is only one of the causes of falls, however, and because there are many, including balance difficulties, freezing of gait, and inattention, it may be hard to see clear associations in studies like this.”
Nonetheless, he said, “the paper highlights the fact that transient orthostatic hypotension might play an important clinical role, and it is possible to miss that if you don't take an early blood pressure on standing. But whether transient OH plays a clearly defined role in falls really remains to be determined,” he said, “as does whether treatment for transient or classic OH might reduce or prevent falls.”
“This study brings renewed attention to the impact of abnormal cardiovascular adaptation in patients with Parkinson's disease,” said Horacio C. Kaufmann, MD, FAAN, professor of dysautonomia research in the department of neurology at New York University's Grossman School of Medicine. “A big strength of the study is that they used the standing test, rather than passive tilt,” which triggers tOH more reliably and more faithfully mimics the patient's experience in daily living.
“Transient or initial orthostatic hypotension is due to a pronounced drop in vascular resistance which is quickly compensated by sympathetic vasoconstriction in the peripheral vasculature,” a response that is slower in patients with PD, as this study showed. “That is a crucial finding,” Dr. Kaufmann said.
“It is important to counsel patients about this problem, emphasizing behavioral and non-pharmacologic countermeasures to reduce this fall in pressure upon standing and prevent syncope. A patient who is lying down should first sit, and then upon standing, flex muscles such as the gluteus and abdominals, to force blood back to the heart to maintain pressure. At the end of the day, both transient and classical OH can produce impairment, and both are important to consider.”
Dr. Fanciulli reported royalties from Springer Nature Publishing Group, speaker fees from the Austrian Autonomic Society, Austrian Neurology Society, Austrian Parkinson Society, Ordensklinikum Linz, International Parkinson Disease and Movement Disorders Society and Theravance Biopharma and research grants from the Stichting ParkinsonFond and the Österreichischer Austausch Dienst, outside of the submitted work. Dr. Hauser and Kaufmann had no relevant disclosures.