Date sent:      	Fri, 15 Jun 2001 

Orthostatic Intolerance: A Review with Application to the Chronic Fatigue
Syndrome

Journal of Chronic Fatigue Syndrome, Vol. 8 (2) 2001, pp. 45-64

Julian M. Stewart, MD, PhD

Department of Pediatrics and Physiology, The Center for
Pediatric Hypotension, New York Medical College, Valhalla, NY 10595.

Address correspondence to: Julian M. Stewart, MD, PhD, Professor of
Pediatrics, Research Professor of Physiology, The Center for
Neurovascular Disease in Children, and the Division of Pediatric
Cardiology, Suite 618, Munger Pavilion, New York Medical College,
Valhalla, NY 10595 (E-mail: mailto:stewart@nymc.edu ).

Supported in part by 1R03-AI45954 from NIH/NIAID

ABSTRACT. The symptoms of the chronic fatigue syndrome closely match
those of chronic orthostatic intolerance and research suggests that
orthostatic intolerance plays a role in the symptomatology of CFS. Recent
investigations support the hypothesis that findings in CFS patients
result at least in part from impaired blood pressure and heart rate
regulation. Orthostatic intolerance has been implicated.

Effective and specific treatment for chronic orthostatic intolerance can
only be developed when a specific etiology or etiologies are discovered.


KEYWORDS. Syncope, head-up tilt test, dysautonomia, postural orthostatic
tachycardia syndrome


INTRODUCTION:

A chronically ill patient is evaluated by two different physicians. There
is a 10 month history of fatigue, neurocognitive and sleep disorders,
lightheadedness, tremulousness, nausea, abdominal pain, weakness, new
onset headache, anxiety/palpitations present on a day to day basis. She
has been extensively evaluated by previous physicians over the course of
many months. The patient appears slightly pale but vital signs are normal
although the heart rate is higher than average. Symptoms worsen when the
patient is upright. A diagnosis of chronic fatigue syndrome is made by
one physician, while a diagnosis of chronic orthostatic intolerance is
made by the other. Who is right?

Much has been stated and written about orthostatic intolerance (OI) as it
applies to the chronic fatigue syndrome (CFS) which has been confusing at
best. Some of the confusion originates from recent appreciation of the
clinical variants of orthostatic intolerance, some from our emerging
understanding that diverse pathophysiologies underlie the OI, and some
from nomenclature which seems to change from year-to-year or faster.

In order to address orthostatic intolerance in CFS, we have chosen to
adopt a scheme which includes a lot of background material:

1. A definition of Orthostatic Intolerance
2. What's syncope? (Not all syncope is orthostatic intolerance)
3. Physiology of orthostasis
4. A clinical approach using a well-known orthostatic stress test, the
tilt table, to define clinical variants of orthostatic intolerance
5. A specific discussion of OI research in CFS
6. Some suggestions concerning screening for OI in CFS patients
7. An approach to treatment.


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