ORTHO­STATIC HYPO­TENSION

Orthostatic hypotension (OH) is characterized by a drop in blood pressure upon standing, with accompanying symptoms including dizziness and lightheadedness. Usually, the autonomic nervous system regulates blood pressure (BP) and increases blood vessel constriction upon standing to keep BP constant. In MSA, disturbances in the autonomic nervous system leads to neurogenic orthostatic hypotension (nOH), defined as a drop in systolic BP ≥ 14 mmHg or in diastolic BP ≥ 6 mmHg. Lying-to-sitting drops in blood pressure can also be used to diagnose OH in patients if standing is not feasible, with drops in sitting systolic BP ≥ 14 mmHg or diastolic BP ≥ 6 mmHg indicating the presence of nOH. (Sun 2016) These drops in blood pressure can lead to dizziness, problems maintaining balance, walking and an increased risk of falls. nOH occurs in anywhere from 54%-81% of patients with MSA.

1. Non-pharmaceutical treatments for OH include correcting aggravating factors and implementing other measures to decrease symptoms and risk of fall. OH has been found to be worse in the morning, in hot weather, after eating large meals (especially carbohydrate-heavy meals) and from lifting heavy objects. Avoiding exposure to these factors can decrease the frequency and severity of OH instances. Other non-pharmaceutical interventions include:

• Expanding blood volume with salt and water supplementation may help minimize symptoms of OH, though the evidence for this is fairly weak. Patients may be encouraged to consume an additional 1-2 teaspoons of salt per day and increase their water consumption by their doctors.
• Exercise, when done in a safe environment, can improve symptoms of OH. Exercise can even be performed in a sitting or recumbent position, either on a recumbent stationary bike or rowing machine, for example. Exercise in a pool is also a safe option for those who have this option available.
• Compression stockings have been shown be an effective treatment for OH by increasing venous return. Waist-high stockings have been found to be most effective in preventing OH4.
• The Valsalva maneuver that occurs during bowel movements can be a precipitating factor for OH, so the straining that occurs during constipation must be avoided. This can be avoided through dietary changes such as increasing fiber in diet and increasing water intake. Fermented milk products with probiotics, such as kefir, have been shown to prevent constipation in patients with Parkinson’s disease and may be of use in MSA5. When dietary changes are not enough to avoid constipation, laxatives are sometimes needed.
• Supplementation with coenzyme Q10 has also shown promise to treat the symptoms of OH.
• Raising the head of the bed about 10 cm can also help decrease the symptoms of OH, especially those that occur in the morning.
• Postural maneuvers can also be used to combat the drop in blood pressure that defines OH. These include muscle tensing and swaying while standing, bending forward, leg crossing and squatting and have been found to have significant effects on blood pressure.

2. Pharmaceutical treatments for nOH try to either increase plasma volume or to increase peripheral resistance through various mechanisms of action. Drugs used to treat MSA are described in Table 1.

Table 1: Medications to Treat Orthostatic Hypotension in MSA

References