Orthostatic Cerebral Hypoperfusion Syndrome Research Articles

Immunotherapy for Recurrent orthostatic cerebral hypo-perfusion syndrome in recurrent COVID-19 infection

Orthostatic hypotension, often interpreted as a drop in blood pressure as a person moves from lying or sitting to standing, has a direct impact on the brain. It results in a decrease in brain perfusion pressure and in many cases causes symptoms of transient cerebral hypo perfusion. This report treats a case of recurrent orthostatic hypotension in a field of recurrent Covid-19 infection, with a good clinical response to early immunotherapy. Signs of lung infection retroceded until complete disappearance under treatment with chloroquine sulfate and azythromycin. However, due to persistent signs of dysautonomy and paresthesias, we had subjected the patient to intravenous immunoglobulin immunotherapy with a good therapeutic response until the patient's complete recovery 150 days after the start of treatment. The prognosis remains unknown at this time, as we do not yet have data from large-scale studies on this subject.

Tilt Test: A Review.

This review recapitulates the head-up tilt test, which is commonly used for evaluation of orthostatic syndromes and dysautonomia. Tilt test evaluates autonomic system responses to orthostatic stress. Established tilt testing includes monitoring of heart rate and blood pressure; adding capnography and cerebral blood flow monitoring expands its diagnostic yield and allows assessing cerebral blood flow regulation. Common syndromes detectable by the tilt test are neurally mediated syncope (vasodepressor, cardiovagal, or mixed), orthostatic hypotension, postural orthostatic tachycardia syndrome, hypocapnic cerebral hypoperfusion, and orthostatic cerebral hypoperfusion syndrome. This review describes relevant physiology, tilt test protocols, diagnostic criteria for orthostatic syndromes, grading test results, diagnostic accuracy, limitations of the tilt test, and safety considerations.

Orthostatic Cerebral Hypoperfusion Syndrome.

Orthostatic dizziness without orthostatic hypotension is common but underlying pathophysiology is poorly understood. This study describes orthostatic cerebral hypoperfusion syndrome (OCHOs). OCHOs is defined by (1) abnormal orthostatic drop of cerebral blood flow velocity (CBFv) during the tilt test and (2) absence of orthostatic hypotension, arrhythmia, vascular abnormalities, or other causes of abnormal orthostatic CBFv. This retrospective study included patients referred for evaluation of unexplained orthostatic dizziness. Patients underwent standardized autonomic testing, including 10 min of tilt test. The following signals were monitored: heart rate, end tidal CO2, blood pressure, and CBFv from the middle cerebral artery using transcranial Doppler. Patients were screened for OCHOs. Patients who fulfilled the OCHOs criteria were compared to age- and gender-matched controls. From 1279 screened patients, 102 patients (60/42 women/men, age 51.1 ± 14.9, range 19-84 years) fulfilled criteria of OCHOs. There was no difference in baseline supine hemodynamic variables between OCHOs and the control group. During the tilt, mean CBFv decreased 24.1 ± 8.2% in OCHOs versus 4.2 ± 5.6% in controls (p < 0.0001) without orthostatic hypotension in both groups. Supine mean blood pressure (OCHOs/controls, 90.5 ± 10.6/91.1 ± 9.4 mmHg, p = 0.62) remained unchanged during the tilt (90.4 ± 9.7/92.1 ± 9.6 mmHg, p = 0.2). End tidal CO2 and heart rate responses to the tilt were normal and equal in both groups. OCHOs is a novel syndrome of low orthostatic CBFv. Two main pathophysiological mechanisms are proposed, including active cerebral vasoconstriction and passive increase of peripheral venous compliance. OCHOs may be a common cause of orthostatic dizziness.