[Primary orthostatic hypotension syndromes without somatic neurologic signs--idiopathic orthostatic hypotension and primary sympathicotonic orthostatic hypotension].

Idiopathic orthostatic hypotension (IOH) and primary sympathicotonic orthostatic hypotension (PSOH) are conspicuous orthostatic hypotension syndromes without overt somatic neurologic signs. IOH, also referred as pure autonomic failure, is a syndrome of chronic pandysautonomia, and its clinical features include supine hypertension, anhidrosis, impotence, neurogenic urinary and bowel disturbances. PSOH is different from IOH in which it is not accompanied with autonomic features outside of cardiovascular symptoms, and has been most commonly described in German-Scandinavian literatures. The controversy in the nosology of IOH and PSOH has prevented the both concepts from world-wide acceptance, and little has been known about IOH in Japanese population. In the present study, statistical analyses were made to elicit the cases of orthostatic hypotension syndrome without somatic neurologic signs from the pooled results of hemodynamic autonomic functional tests in our laboratory. The subjects were 287 Japanese cases comprising 253 normotensive volunteers and 34 hypertensive patients. Apart from hypertension, none of the subjects exhibited abnormal findings on physical, neurological and routine laboratory examinations. The test of 70 degrees passive head-up tilt and other hemodynamic tests were performed upon the subjects, and the results were pooled by ages. By means of the method of maximum normed residual, statistically screened out were 7 cases with extremely great orthostatic fall in systolic blood pressure (OH-I). Another OH group (OH-II) consisted of 24 cases who showed orthostatic decrease in systolic blood pressure of 30 mmHg or more, but did no fall into the extreme observation. Assuming that the orthostatic regulation mechanism of blood pressure was well maintained in the remaining 256 cases, they were used as the control.(ABSTRACT TRUNCATED AT 250 WORDS)