Prospective Evaluation of Clinical Characteristics of Orthostatic Hypotension

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Objective

To undertake a prospective study of the clinical characteristics of orthostatic intolerant patients referred to the Mayo Autonomic Reflex Laboratory with suspected orthostatic hypotension (OH).

Design

Autonomic function tests were performed to quantify the severity of sudomotor, adrenergic, and cardiovagal failure and generate a composite autonomic symptom score (CASS). CASS was related to a symptom score, which was derived from the frequency of orthostatic intolerance and syncope and the standing time until occurrence of symptoms.

Results

Three groups were defined by their response to a tilt study: group I, 90 patients with symptomatic OH, mean age, 63.6 years; group II, 60 patients who had symptoms without OH, mean age, 48.9 years; and group III, 5 patients with asymptomatic OH, mean age, 68.0 years. Group I had a significantly higher CASS (P < 0.001 than did those without OH. Further analysis was done on the 90 patients in group I. The most common symptoms were lightheadedness, weakness, impaired cognition, visual blurring, tremulousness, and vertigo. The most common aggravating factors were prolonged standing, exercise, warming, and eating. Most patients (75%) could stand for less than 5 minutes before symptoms occurred. Symptoms regressed significantly with CASS but not with the tilt grade.

Conclusion

Patients with generalized autonomic failure have a recognizable pattern of symptoms and aggravating factors that relate, albeit imperfectly, to the severity of autonomic failure.

Section snippets

Patients and Methods

Study Subjects.—We assessed 155 consecutive patients referred to the Mayo Autonomic Reflex Laboratory with a diagnosis of suspected OH or its equivalent (for example, possible multisystem atrophy, possible idiopathic OH, autonomic neuropathy, or “rule out” OH).

Evaluation of Autonomic Function.—In all study patients, the following autonomic evaluations and analyses were done: an autonomic symptoms profile, autonomic reflex screen, determination of a composite autonomic symptom score (CASS),

Results

The demographic details are summarized in Table 2. Group I patients, who had symptomatic OH, constituted 58% of the overall study group and were approximately evenly distributed by gender. Group II, patients who did not demonstrate OH on the tilt test, were younger than those in group I (P<0.001) and had a female-to-male ratio of 3:2. Because group III consisted of only five patients, further analysis of them was not undertaken.

Causes of Orthostatic lntolerance.—The autonomic diagnoses for

Discussion

Investigators have increasingly recognized that patients with autonomic failure have a worse prognosis than do those with normal autonomic function, both in mortality5, 6, 7 and in morbidity.” Such patients have been reported to have an increase in intraoperative mortality.9, 10 During the past decade, impetus has been generated for the laboratory evaluation of autonomic failure by system, level, distribution, and severity because increased severity and extensive distribution of autonomic

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This study was supported in part by Grant NS 32352 P01 from the National Institute of Neurological and Communicative Disorders and Stroke and the Mayo Foundation.

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