REN and Tinnitus: The vascular dysregulation hypothesis is one possible theory for the development of tinnitus.33 Dysregulation is often associated with a reduced cardiac output, as well as with reflex activation of vasoconstrictive systems, including the sympathetic nervous system and renin-angiotensin-aldosterone system.33 The results of the present study support the hypothesis that cardiovascular disorders may be associated with severe tinnitus.