What Neurological Disorders Cause Low Blood Pressure?

Various neurological conditions cause low blood pressure. This is due to the fact that blood pressure controlled through a homeostatic mechanism which is primarily the function of the autonomic nervous system. Some neurological disorders cause damage to the neurons of the Autonomic nervous system while in some cases there is an imbalance in the neurotransmitters which are essential for the execution of the instructions generated in the brain. Both the condition causes hypotension.

Apart from hypotension cases related to peripheral diseases, one of the important neurological conditions that seriously affect the ability of the body to maintain normal blood pressure is neurogenic orthostatic hypotension or NOH. The condition is characterized by the drop of more than 20 mm Hg in the systolic pressure and more than 10mm Hg in diastolic blood pressure. Maintenance of blood pressure during a sudden change in position from lying or sitting to standing is the function primarily controlled by the autonomic nervous system. Due to various diseases, the autonomic nervous system loses the capacity to control the blood pressure during a sudden change in a position leading to a dangerous drop in the blood pressure. The initial symptoms included dizziness and vision problems. The symptoms are aggravated during early morning, prolonged sitting or eating large meals. ⁽¹⁾

Homeostasis mechanism of blood pressure is primarily regulated through the brain, although some part of it is regulated peripherally through certain organs such as the kidney. Any problem in the brain and neurons will lead to poorly controlled blood pressure. The patient may experience the dangerous rise and drop of blood pressure without any control mechanism. ^{(2) (3)}

Following are some neurological problems that may cause low blood pressure.

Multiple System Atrophy. MSA is a progressive neurodegenerative disorder. It generally affects a part of the nervous system known as the autonomic nervous system, which is responsible for regulation of autonomous activities such as blood pressure and digestion. MSA causes the progressive loss of neuronal functioning leading to low blood pressure. Some patients suffering from MSA also complain of low blood pressure and related symptoms after micturition.

Parkinson’s Disease. Both Parkinson’s disease and some of the anti-Parkinson’s drugs cause low blood pressure. Hypotension is the common symptom in Parkinson’s disease and is caused due to baroreflex failure as well as insufficient activation of norepinephrine pathways.

Pure Autonomic Failure Or Primary Autonomic Failure (PAF). Although the condition is not fatal, it disrupts the normal control of blood pressure. Previously known as Bradbury-Eggleston syndrome, the condition is characterized by the malfunctioning of various controls of the autonomic nervous system. The condition is caused due to the accumulation of synuclein in the brain at an abnormal level.

Diabetic Neuropathy. Due to the uncontrolled level of the sugar in the blood that reaches the brain, diabetes results in diabetic neuropathy. The condition is characterized by the destruction of healthy nerve cells due to the accumulation of sorbitol synthesized through an alternate pathway. Destruction of these cells results in the malfunction of the blood pressure controlling mechanism and may lead to hypotension.

Dopamine Beta-Hydroxylase (DBH) Deficiency. The condition is characterized by the complete absence of epinephrine and norepinephrine and increased levels of dopamine. This results in poor control over blood pressure and temperature regulation. The condition is caused due to deficiency of an important enzyme known as Dopamine beta-hydroxylase.

Following are the symptoms of low blood pressure.

• Fainting
• Dizziness
• Droopy eyelids
• Nasal Congestion
• Muscular weakness
• Vision problem such as blurred vision
• Chest pain
• Lack of concentration
• Nausea
• Increased thirst
• Depression

Low blood pressure caused by the neurological disorder generally comes under the category of Neurogenic Orthostatic Hypotension. Neurological conditions that cause low blood pressure are Multiple System Atrophy, parkinson’s disease, Pure Autonomic Failure, Diabetic Neuropathy, and Dopamine beta-hydroxylase (DBH) deficiency. The symptoms of low blood pressure include fainting, dizziness, headache, depression and lack of concentration.

References-

1. https://jnnp.bmj.com/content/76/2/186
2. https://www.multiplesystematrophy.org/about-msa/what-is-noh/
3. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Multiple-System-Atrophy

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