What is Neurogenic Orthostatic Hypotension?
Neurogenic orthostatic hypotension (also referred to as neurogenic OH or nOH) is a rare disorder that is defined as low blood pressure that occurs upon standing. NOH is a sub-type of orthostatic hypotension (OH). With NOH and other forms of orthostatic hypotension, patients experience the same symptoms but for different reasons.
NOHis caused by autonomic nervous system (ANS) malfunction. The ANS is the part of the nervous system that controls involuntary body activity, such as keeping blood pressure normal.
NOH only occurs in people with an existing neurologic disease, such as:
- Multiple system atrophy (MSA)
- Parkinson’s disease
- Pure autonomic failure (PAF)
- Diabetic neuropathy
- Dopamine beta hydroxylase (DBH) deficiency
In other forms of OH, symptoms can be caused by many different factors including:
- Dehydration (not enough fluid in your body)
- Heart problems
- Certain medications, such as medication for Parkinson’s disease or hypertension
Regardless of the type of orthostatic hypotension,symptoms usually occur shortly after sitting or standing up. When blood pressure drops, symptoms can include:
- Blurry vision
- Trouble concentrating
- Head and neck pain
Symptoms can be severe, especially at the start of each day and these symptoms are often associated with an increased risk for falls and injury.
Symptomatic orthostatic hypotension can make the lives of patients and the people caring for them more difficult, by:
- Causing disabling symptoms that make it harder to stand up and walk around
- Causing fear of falls and injury
- Reducing independence
Why is nOH so common in Multiple System Atrophy patients?
Multiple system atrophy is known to cause neurogenic orthostatic hypotension by damaging the autonomic nervous system. In fact, NOH is a hallmark sign of MSA, affecting approximately 80% of patients.
In MSA, the signal normally sent from the brain to tell the nerves to release norepinephrine is weak or not working.When not enough norepinephrine is released when you stand up, your blood vessels, especially in your legs do not squeeze and your blood pressure stays too low and symptoms appear. Because of the disrupted brain signaling, MSA patients are also at risk for high blood pressure when lying down (supine hypertension).