Tinnitus hum, but it can also arise as a subjective phenomenon from an increased awareness of blood flow in the ear. Rarely, pulsatile tinnitus may be a symptom of potentially life-threatening conditions such as carotid artery aneurysm or carotid artery dissection. Pulsatile tinnitus may also indicate vasculitis, or more specifically, giant cell arteritis. Pulsatile tinnitus may also be an indication of idiopathic intracranial hypertension. Pulsatile tinnitus can be a symptom of intracranial vascular abnormalities and should be evaluated for "irregular noises of blood flow" (bruits). The mechanisms of subjective tinnitus are often obscure. While it is not surprising that direct trauma
Tinnitus retraining therapy TRT is imputed to work by interfering with the neural activity causing the tinnitus at its source, in order to prevent it from spreading to other nervous systems such as the limbic and autonomic nervous systems. Clients are classified into 5 categories. These categories are numbered 0 to 4, and based on whether or not the patient has tinnitus with hearing loss, tinnitus with no hearing loss, tinnitus with hearing loss and hyperacusis, and tinnitus with hearing loss and hyperacusis for an extended amount of time. The first component of TRT, directive counseling, may change the way tinnitus is perceived.