Neuro Disorders: POTS (Postural Orthostatic Tachycardia Syndrome)

Introduction

POTS (Postural Orthostatic Tachycardia Syndrome) is not an uncommon chronic condition. It can present with multitudinous manifestations, and sometimes of disabling in nature.

Terms explained:

Postural – position related; orthostatic - upright position; tachycardia fast heart rate, Syndrome – multiple symptoms or manifestation (symptom complex).

This condition predominantly manifests when patients assume an upright position from a recline or lying down position, although many symptoms can present irrespective of the position.

This condition is an example for orthostatic intolerance which simply implies that some people do not tolerate upright posture and become symptomatic. Orthostatic hypotension is another example for orthostatic intolerance. It is also an example of dysautonomia (dysfunctional autonomic nervous system).

What causes it?

This condition is the result of a very complex underlying Pathophysiology. It seems that an abnormal autonomic nervous system is at the core of the development of this disease however various interconnected body mechanisms are involved in mediating this condition.

How does patient manifest?

Majority of the patients are women at the reproductive age although men and children are affected too. No racial or ethnic predilections are seen.

Varieties of manifestations are seen including;

• Fatigue
• Muscle weakness
• Dizzy, light headed feeling
• Palpitations
• Headaches
• Sleep disturbances
• Various chest, abdominal symptoms etc.

See that fainting (syncope) can occur too but it is not that common with this condition in comparison to other related condition like orthostatic hypotension, vasovagal syncope etc.

Diagnosis

To diagnose this condition first patient’s BP (blood pressure) and pulse or HR (heart rate) are checked as base line in a lying down position. First patient's system should be stabilized by asking to lie down at least for 10 minutes before checking BP & pulse. Then patient is asked to stand up. BP & pulse are checked immediately (0 minutes) then repeated around 3, 5, 10, 20 minutes etc.

By definition the pulse should increase at least by 30 beats/ minute within 10 minutes after standing to consider this diagnosis. There should not be any all in BP more than 20/10 mm hg (systolic/diastolic), because if such significant drop in BP is seen then you can call this condition as orthostatic hypotension rather than Postural Orthostatic Tachycardia Syndrome. A rise of HR to above 120 /minute within 10 to 12 minutes after standing is also in favor of this diagnosis.

A tilt table is another alternative used for making this diagnosis.

Blood norephinephrine if measured at lying down & upright positions generally shows an abnormal elevation in the standing posture.

Treatment

The management of this condition is not always satisfactory and the following measures are generally considered (on case to case basis);

• Adequate hydration
• Adequate salt intake
• Leg exercises
• Compression stocking to the legs up to waist high
• Medications like;

- Beta blockers e.g. Propranolol
- SSRI e.g. Fluoxetine
- Midodrine
- Fludro cortisone (Florinef)
- Pyridostigmine etc

A neurologist is frequently involved in the care of patients with POTS.



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