Clinical and neuroendocrinological characteristics of delayed orthostatic hypotension in Parkinson's disease

PURPOSE

Delayed orthostatic hypotension (DOH), a fall in blood pressure after a 3-min cutoff, is clinically meaningful. The aim of this study was to elucidate the clinical and neuroendocrinological characteristics of DOH in patients with Parkinson's disease (PD).

METHODS

A total of 132 patients with newly diagnosed PD were enrolled. Baseline clinical characteristics, including olfactory function, and changes in norepinephrine (NE) and vasopressin (ADH) concentrations during the head-up tilt test (HUT), were examined.

RESULTS

Fifty-five patients (42%) had classical orthostatic hypotension (COH), and 19 patients (14%) had DOH. Patients with COH and DOH tended to have more severe hyposmia than patients without OH. A multivariate linear regression model showed that hyposmia was associated with DOH and COH. The increase of heart rate against the fall in blood pressure was significantly lower in patients with COH and DOH than those without OH. The NE levels at supine rest and after upright tilting were lower in the COH group than in the PD without OH and DOH groups. The levels of ADH were higher in the DOH group than in the COH group at supine rest and higher than in the PD without OH group after upright tilting. There was no significant difference in the cardiac ¹²³I-MIBG scintigraphy between the COH and DOH groups.

CONCLUSION

Compared with patients without OH, patients with DOH had severe hyposmia. Relatively preserved peripheral sympathetic nervous system function in patients with DOH suggests that DOH might be an early and milder form of OH in PD.

Delayed orthostatic hypotension

Delayed orthostatic hypotension is a fall in blood pressure beyond 3 min of standing or upright tilt table testing. The prevalence, clinical features and pathophysiology are reviewed. To date, there is little data to support a standardized or recommended treatment. However, the 10-year mortality rates of individuals with delayed orthostatic hypotension are approximately 50%. Despite the fact that delayed orthostatic hypotension carries the same symptoms, risks and high mortality rate as classical orthostatic hypotension, but is under-recognized. The frequency with which delayed orthostatic hypotension develops into classical orthostatic hypotension, the high associated mortality rates and risk of development of the neurodegenerative disorders classified as alpha-synucleinopathies underscores the need for further study of this condition.

Differential diagnosis of orthostatic hypotension

Orthostatic hypotension (OH) is a common clinical manifestation characterized by a significant fall in blood pressure with postural change and is frequently accompanied by debilitating symptoms of orthostatic intolerance. The reported prevalence of OH ranges between 5 and 10% in middle-aged adults with a burden that increases concomitantly with age; in those over 60 years of age, the prevalence is estimated to be over 20%. Unfortunately, the clinical course of OH is not necessarily benign. OH patients are at an increased risk of adverse clinical outcomes including death, falls, cardiovascular and cerebrovascular events, syncope, and impaired quality of life. The differential diagnosis of OH is broad and includes acute precipitants as well as chronic underlying medical conditions, especially of neurological origin. Appropriate diagnosis relies on a systematic history and physical examination with particular attention to orthostatic vital signs, keeping in mind that ambient conditions during diagnostic testing may affect OH detection due to factors such as diurnal variation.

Cerebral Blood Oxygenation Changes in Juvenile Patients with Delayed Orthostatic Hypotension During an Active Standing Test

Delayed orthostatic hypotension (OH) is a minor subset of orthostatic dysregulation (OD). Cerebral blood oxygenation in juvenile patients with delayed OH has not been studied. We investigated the bilateral changes in cerebral oxygenation in the prefrontal cortex during an active standing test in 23 juvenile patients with delayed OH using near-infrared spectroscopy (NIRS). We measured the oxy-Hb, deoxy-Hb, and total-Hb during the active standing test. Four observations were made during the test: t1 in a resting supine position, t2 when maintaining blood pressure, and the remaining two (t3, t4) during hypotension. The concentration of oxy-Hb significantly decreased prior to satisfying the diagnostic criteria of delayed OH after standing and did not change thereafter. The concentration of deoxy-Hb increased gradually during the measurement periods. In addition, total-Hb increased from t2 to t3. There was no significant difference in the change in each Hb parameter between the left and right cerebral hemispheres. Our results indicate that NIRS parameters are more sensitive than blood pressure for the interpretation of cerebral autoregulation in juvenile patients with delayed OH.

Delayed orthostatic hypotension: Severity of clinical symptoms and response to medical treatment

INTRODUCTION

Severity of orthostatic intolerance and the benefit of medical treatment in patients with delayed OH have not been elucidated. This study aimed to compare the symptom severity between classic and delayed OH and evaluate the efficacy of midodrine or pyridostigmine in patients with delayed OH.

METHODS

This was an adjunctive study of previously reported randomized, open-label clinical trials evaluating the efficacy and safety of midodrine or pyridostigmine for classic OH. Seventeen patients with delayed OH were enrolled and also received midodrine (2.5 mg twice a day) or pyridostigmine (30 mg twice a day) alone or combined. Result of initial orthostatic vital sign and questionnaires were compared between the patients with delayed OH and previously reported 87 patients with classic OH. Delayed OH patients were followed up at 1 and 3 months post-treatment and the vital sign measurements and questionnaires were repeated during the follow-up period.

RESULTS

Questionnaire scores regarding OH-related symptoms, depression and health-related quality of life (HRQOL) were comparable between the classic and delayed OH patients at baseline. OH-related symptoms and depression were significantly improved after 3 months of medical treatment.

CONCLUSION

Patients with delayed OH exhibited orthostatic intolerance similar to that of classic OH. This study shows that these patients may benefit from medical treatment with either midodrine or pyridostigmine.