It is possible that the most common cause of pulsatile tinnitus is sigmoid sinus diverticulum and dehiscence, which can be collectively referred to as sinus wall abnormalities or SSWA. The sigmoid sinus is a blood carrying channel on the side of the brain that receives blood from veins within the brain. The blood eventually exits through the internal jugular vein. Sigmoid sinus diverticulum refers to the formation of small sac-like pouches (diverticula) that protrude through the wall of the sigmoid sinus into the mastoid bone behind the ear. Dehiscence refers to absence of part of the bone that surrounds the sigmoid sinus in the mastoid. It is unknown whether these conditions represent different parts of one disease process or spectrum, or whether they are two distinct conditions. These abnormalities cause pressure, blood flow, and noise changes within the sigmoid sinus, which ultimately results in pulsatile tinnitus. Narrowing of the blood vessel that leads into the sigmoid sinus, known as the transverse sinus, has also been associated with pulsatile tinnitus.
Hearing (audiological) exam. As part of the test, you'll sit in a soundproof room wearing earphones through which will be played specific sounds into one ear at a time. You'll indicate when you can hear the sound, and your results are compared with results considered normal for your age. This can help rule out or identify possible causes of tinnitus.
Tinnitus can arise anywhere along the auditory pathway, from the outer ear through the middle and inner ear to the brain's auditory cortex, where it's thought to be encoded (in a sense, imprinted). One of the most common causes of tinnitus is damage to the hair cells in the cochlea (see "Auditory pathways and tinnitus"). These cells help transform sound waves into nerve signals. If the auditory pathways or circuits in the brain don't receive the signals they're expecting from the cochlea, the brain in effect "turns up the gain" on those pathways in an effort to detect the signal — in much the same way that you turn up the volume on a car radio when you're trying to find a station's signal. The resulting electrical noise takes the form of tinnitus — a sound that is high-pitched if hearing loss is in the high-frequency range and low-pitched if it's in the low-frequency range. This kind of tinnitus resembles phantom limb pain in an amputee — the brain is producing abnormal nerve signals to compensate for missing input.
Tinnitus is characterized by ringing or buzzing in the ears. Exposure to loud noises, earwax blockages, heart or blood vessel issues, prescription medications, and thyroid disorders can all cause tinnitus. See your doctor for an accurate diagnosis, and work with them to develop a treatment plan. In many cases, tinnitus is irreversible, but there are several ways to reduce its severity. For instance, sound generators, hearing aids, and medication can help mask ringing or buzzing. Tinnitus research is a constantly evolving field, and you might be able to try experimental therapies as well.
Atherosclerosis. With age and buildup of cholesterol and other deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful, making it easier for your ear to detect the beats. You can generally hear this type of tinnitus in both ears.