Abstract
PURPOSE: Patients with idiopathic orthostatic intolerance often have debilitating
symptoms on standing that are suggestive of cerebral hypoperfusion despite the absence
of orthostatic hypotension.
SUBJECTS AND METHODS: We evaluated the effects of graded head-up tilt on cerebral
blood flow as determined by transcranial Doppler measurements in 10 patients with
idiopathic orthostatic intolerance (nine women, one man, 22 to 47 years) and nine
age- and sex-matched control subjects.
RESULTS: In patients, mean (± SD) arterial pressure at 0° head-up tilt was 90 ± 11
mm Hg and was well maintained at all tilt angles (90 ± 11 mm Hg at 75°). In controls,
mean arterial pressure was 85 ± 7 mm Hg at 0° and 82 ± 11 mm Hg at 75° head-up tilt.
There was a substantial decrease in peak velocity with increasing tilt angle in patients
(28% ± 10%) but not in controls (10% ± 10% at 75°, P <0.001). Similarly, mean velocity decreased 26% ± 13% in patients and 12% ± 11% in
controls (P = 0.01). With increasing head-up tilt, patients had a significantly greater increase
in regional cerebrovascular resistance than controls.
CONCLUSIONS: In patients with idiopathic orthostatic intolerance, peak and mean middle
cerebral artery blood flow velocity decreased in response to head-up tilt despite
well sustained arterial blood pressure. These observations indicate that in this group
of patients, regulation of cerebrovascular tone may be impaired and might therefore
be a target for therapeutic interventions.
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References
- The physiological conundrum of hyperadrenergic orthostatic intolerance.Chin J Physiol. 1997; 40: 1-8
- Effects of volume loading and pressor agents in idiopathic orthostatic tachycardia.Circulation. 1997; 96: 575-580
- Idiopathic hypovolemia.Ann Intern Med. 1986; 104: 298-303
- Hypovolemia in syncope and orthostatic intolerance.Am J Med. 1997; 103: 128-133
- Pathogenesis of hyperadrenergic orthostatic hypotension. Evidence of disordered venous innervation exclusively in the lower limbs.J Clin Invest. 1990; 86: 1582-1588
- Idiopathic postural orthostatic tachycardia syndrome.Neurology. 1993; 43: 132-137
- Sympathotonic orthostatic hypotension.Neurology. 1989; 39: 34-40
- The orthostatic tachycardia syndrome.J Clin Endocrinol Metab. 1991; 73: 132-139
- Pharmacological distinction of different orthostatic hypotension syndromes.Neurology. 1981; 31: 1-7
- Hyperdynamic beta-adrenergic circulatory state.Arch Intern Med. 1966; 117: 614-619
- Hyperdynamic beta-adrenergic circulatory state. Increased beta-receptor responsiveness.Arch Intern Med. 1969; 123: 1-7
- Pharmacology.in: Baughman K.L Greene B.M Clinical Diagnostic Manual for the House Officer. Williams & Wilkins, Baltimore1981: 86-101
- Patterns of plasma levels of catechols in neurogenic orthostatic hypotension.Ann Neurol. 1989; 26: 558-563
- Overview of cerebrovascular hemodynamics.in: Welch K.M.A Caplan L.R Reis D.J Siesjo B.K Weir B Primer on Cerebrovascular Diseases. Academic Press, New York1997: 42-44
- Cerebral autoregulation in orthostatic hypotension. A transcranial Doppler study.Stroke. 1994; 25: 1771-1775
- Cerebral vasoconstriction during head-upright tilt-induced vasovagal syncope. A paradoxic and unexpected response.Circulation. 1991; 84: 1157-1164
- Autoregulation of cerebral blood flow.in: Welch K.M.A Caplan L.R Reis D.J Siesjo B.K Weir B Primer on Cerebrovascular Diseases. Academic Press, New York1997: 51-54
- Orthostatic hypotension.in: Bardin C.W Current Therapy in Endocrinology and Metabolism. Mosby-Year Book, Baltimore1997: 197-203
- Transcranial Doppler evaluation in disorders of reduced orthostatic tolerance.in: Low P.A Clinical Autonomic Disorders. Lippincott-Raven Publishers, Philadelphia1997: 349-368
- Detection of reverse flow by duplex ultrasonography in orthostatic hypotension.Stroke. 1994; 25: 2407-2411
- The effect of orthostatic hypotension on cerebral blood flow and middle cerebral artery velocity in autonomic failure, with observations on the action of ephedrine.J Neurol Neurosurg Psychiatr. 1989; 52: 962-966
- Transcranial Doppler ultrasonography in raised intracranial pressure and in intracranial circulatory arrest.J Neurosurg. 1988; 68: 745-751
- Cerebrovascular and cardiovascular measurements during neurally mediated syncope induced by head-up tilt.Stroke. 1997; 28: 1564-1568
- Transcranial Doppler ultrasonography during head-upright tilt-table testing.Ann Intern Med. 1995; 123: 848-849
- Cerebral arterial diameters during changes in blood pressure and carbon dioxide during craniotomy.Neurosurgery. 1993; 32: 737-741
- Extrinsic innervation.in: Welch K.M.A Caplan L.R Reis D.J Siesjo B.K Weir B Primer on Cerebrovascular Diseases. Academic Press, New York1998: 60-63
- Effect of PCO2 changes induced by head-upright tilt on transcranial Doppler recordings.Stroke. 1997; 28: 1195-1197
- Cerebral autoregulation dynamics in humans.Stroke. 1989; 20: 45-52
Article info
Publication history
Published online: August 16, 2004
Accepted:
August 26,
1998
Received in revised form:
August 26,
1998
Received:
May 18,
1998
Footnotes
☆Supported in part by NIH Grants RR00095, HL56693, NS33460, NASA Grant NAS 9-19483, and a grant from the Nathan Blaser Shy-Drager Research Program. Dr. Jordan is supported by the Deutsche Forschungsgemeinschaft.
Identification
Copyright
© 1999 Excerpta Medica Inc. Published by Elsevier Inc. All rights reserved.
