Dysautonomia is the umbrella term for a range of conditions that affect the Autonomic Nervous System (ANS). The ANS controls unconscious functions that keep us alive such as blood pressure, heart rate, digestion etc.. It is primarily responsible for our flight-or-flight response. There are around 15 types of Dysautonomia with multiple causes. The ANS is made up of the sympathetic, parasympathetic and enteric nervous system.
The most commonly reported type is Postural Orthostatic Tachycardia Syndrome (POTS). POTS is when the body becomes upright the heart rate accelerates rapidly and abnormally. This usually requires the heart rate to increase by more than 30bpm from supine (via Tilt Table test) or a heart rate above 120bpm within 10mins of being upright. This is in the absence of blood pressure dropping.
There are a few types of POTS and multiple causes such as Ehlers-Danlos, Chiari and Craniocervical Instability
Symptoms can include:
Diagnosis is via autonomic testing, mainly through a test called a Tilt Table. Where the patient is hooked up to heart rate and blood pressure monitoring. They are allowed to rest supine and are then raised up to the standing position for a period. Measurements are taken throughout to see the changes in heart rate and blood pressure. (See second picture for example results).