Tinnitus is a medical condition defined as the perception of sound in the absence of any external sound source. The perceived sound can take the form of a whistle, hiss, hum, buzz, purr, clang, or chirp.
Tinnitus can affect one or both ears and, in some cases, may seem to originate from the middle of the head or be difficult to localize.
The sound can be continuous or intermittent. Its intensity often varies and generally worsens when there is little or no background noise, especially at night.
Some people with tinnitus often believe the sound comes from an external source and search for its origin, without ever finding it.
In some cases, older individuals passionate about music and suffering from hearing loss experience musical tinnitus, which resembles a familiar song or tune.
Tinnitus is very common and affects all ages, but it is more prevalent in people with ear problems or hearing loss.
According to statistics from the American Centers for Disease Control, approximately 50 million Americans (15%) suffer from some form of tinnitus.
Most affected individuals continue their normal activities without consequences; only a few report a significant impact on their lives.
Tinnitus Classifications
Tinnitus is divided into three different types depending on the nature of the perceived sound. These types are detailed below.
1. Subjective Tinnitus
This is the most common type of tinnitus: approximately 99% of tinnitus cases are subjective.
Subjective tinnitus is also known as non-auditory tinnitus, non-vibratory tinnitus, or tinnitus aurium.
When tinnitus is subjective, the sounds perceived by the individual cannot be detected by doctors or hearing technicians: only the patient hears them.
Subjective tinnitus is often caused by exposure to excessive noise and can be accompanied by hearing loss, especially when the hair cell nerve is damaged.
Tinnitus due to damage to the auditory nerve or inner ear is called otic. Conversely, when it is not related to an auditory nerve disorder, it is called non-otic tinnitus.
There is also a form of subjective tinnitus called somatic tinnitus. In this case, the intensity and frequency of the sound are altered by body movements, particularly those of the neck and head.
This is why somatic tinnitus is also called craniocervical tinnitus.
Actions such as applying pressure to the neck and head, moving the eyes, or clenching the jaw can alter the sound.
In some people, tinnitus disappears during sleep and intensifies upon waking, due to the absence of neck and head muscle movement during the night.
Causes of Subjective Tinnitus
Subjective tinnitus is often caused by abnormal neuronal activity in the auditory cortex.
The auditory cortex is the part of the temporal lobe responsible for processing information in humans.
When the auditory cortex begins to malfunction, signals from the auditory pathway (which includes the cochlea, auditory nerve, and auditory cortex) are altered or interrupted.
This results in the creation of new neural connections and the body's inability to inhibit intrinsic cortical activities.
Other known causes of subjective tinnitus include:
1. Hearing Loss
This is a very common cause of subjective tinnitus. Hearing loss caused by cochlear damage often leads to tinnitus.
The cochlea can be damaged by exposure to extremely loud noise, and the resulting hearing loss can be temporary or permanent.
2. Ototoxic Medications
Ototoxic medications are drugs that can cause harmful side effects to the ear.
More than 200 ototoxic drugs are sold over-the-counter or by prescription. They are used to treat health problems such as cancer, infections, heart disease, kidney disease, or to relieve pain.
The effects of ototoxic medications can be temporary or permanent depending on the extent of damage to the ear. Their impact on the ear can lead to hearing loss or make it more vulnerable to damage from loud noise exposure.
Tinnitus related to ototoxicity is usually high-pitched (above 2000 Hz).
3. Meniere's Syndrome
Meniere's syndrome or disease is an inner ear disorder that can cause loss of balance, a feeling of fullness or congestion in the ear, dizziness, and hearing loss.
Meniere's disease usually affects only one ear and is a known cause of subjective tinnitus.
Tinnitus caused by Meniere's syndrome is often low-pitched (less than 1000 Hz). It usually falls between 125 and 500 Hz.
4. Other Causes
Other factors, such as discontinuing prescribed medications like benzodiazepines or bupropion, can cause subjective tinnitus that sometimes persists for several months.
Additionally, head trauma, acoustic shock, neurological disorder, lead or mercury poisoning, vitamin B12 deficiency, depression, psychiatric disorder, Eustachian tube dysfunction, or iron deficiency anemia with vasculitis can cause subjective tinnitus.
Objective Tinnitus
Less than 1% of all tinnitus cases are objective.
Objective tinnitus, also called pseudo-tinnitus or vibratory tinnitus, is a rare type of tinnitus caused by a vascular condition or by the involuntary contraction of a muscle or group of muscles.
Muscle spasms around the middle ear can also be a cause.
Objective tinnitus can be heard by others, especially with the help of a stethoscope.
People with objective tinnitus have Eustachian tube dysfunction, a vascular anomaly, or a neurological disease, and symptoms may worsen at night.
In hypertensive patients, a soft, low-pitched venous murmur may be heard.
This murmur is often heard in the anterior neck and upper chest and is caused by turbulence in the internal jugular vein.
These turbulences cause the vessel walls to vibrate. However, the murmur can be modified by pressure on the jugular, by position, and by head movements.
When objective tinnitus is related to a patent Eustachian tube, it follows the rhythm of breathing, especially when the person is standing.
When lying down, sniffing, or inhaling deeply through the nose, the tinnitus gradually disappears.
Objective tinnitus associated with abnormal contractions of the middle ear muscles is often accompanied by a regular clicking sound, a continuous clicking sound, or a series of dry sounds.
Causes of Objective Tinnitus
Various factors can cause objective tinnitus; here are a few:
Disorders affecting the vascular and muscular systems can cause objective tinnitus.
This is why the person hears the vascular noises of the internal jugular vein. Vascular tumors, vascular stenoses, and intracranial hypertension can also cause objective tinnitus.
Neurological disorders such as idiopathic stapedius muscle spasm, or spasms associated with multiple sclerosis and brainstem tumors, can cause objective tinnitus.
A patent Eustachian tube can also cause objective tinnitus. In this case, the person hears breathing sounds in their ears, synchronized with their breathing. This situation often occurs after significant weight loss.
The advantage of objective tinnitus is that its causes are easy to identify, so it can be treated, unlike subjective tinnitus, which is often incurable.
Pulsatile Tinnitus
Pulsatile tinnitus is a form of objective tinnitus that follows the person's pulse. It is also known as vascular, rhythmic, or pulse-synchronous tinnitus.
Pulsatile tinnitus can be caused by increased blood turbulence near the ear, altered blood flow, or increased perception of blood circulation in the ear.
Affected individuals hear a rhythmic pounding or whooshing sound, often loud and disruptive.
Other symptoms also appear, such as hearing loss, visual disturbances, headaches, and dizziness, particularly in cases of idiopathic intracranial hypertension (high pressure of the fluid surrounding the brain).
Several reasons can explain pulsatile tinnitus. Here are some health problems that can lead to this type of tinnitus.
1. Hyperactive Thyroid Gland or Anemia
When the thyroid is overactive, blood flows faster and more audibly, causing pulsatile tinnitus.
2. Irregular Blood Vessels
This is one of the most common causes of pulsatile tinnitus. When blood flows through kinked or damaged vessels located in the brain near the ear, or a narrowed artery or vein, it can cause tinnitus.
3. Atherosclerosis
Atherosclerosis is the hardening of arteries caused by the accumulation of fats or cholesterol. This fatty deposit in the blood vessels makes them less flexible.
This lack of flexibility causes blood flowing through the middle and inner ear to circulate with greater force. Pulsatile tinnitus due to atherosclerosis is often heard in both ears.
4. High Blood Pressure
People with high blood pressure are often prone to pulsatile tinnitus: the increased pressure of blood flowing through the vessels can create an audible rhythm. Tinnitus worsens and becomes more noticeable with stress or consumption of caffeine or alcohol.
5. Tumors
Tumors in the head or neck can compress blood vessels and cause the perception of sounds in the head.
Similarly, a problem with the connection between arteries and veins can lead to pulsatile tinnitus.
Other Causes of Tinnitus
In addition to the various causes specific to each type of tinnitus discussed above, other factors can cause it; let's review them.
1. Inner Ear Hair Cell Damage
The delicate hair cells in the inner ear play an essential role in hearing: they move under the pressure of sound waves.
This movement causes the cells to send an electrical signal from the ear to the brain via a nerve. This signal is what the brain interprets as sound.
When the hair cells of the inner ear are damaged, they can start sending random electrical impulses to the brain, causing tinnitus.
Inner ear hair cell damage is a common cause of tinnitus but, unfortunately, it is irreversible. The person may therefore have to live with their tinnitus permanently.
2. Exposure to Extremely Loud Noises
One of the main causes of tinnitus is permanent exposure to loud noises.
Noise exposure has been identified as a major cause of inner ear hair cell damage, as discussed earlier.
Approximately 30 million workers in the United States are exposed to hazardous noise levels. Tinnitus is also the leading cause of service-related disability among veterans.
Loud noises from firearms, heavy machinery, motorcycles, or chainsaws can cause tinnitus.
Exposure to loud music from headphones, earbuds, at concerts, nightclubs, or bars can damage the ear.
This is why musicians are 57% more likely to suffer from tinnitus and 400% more likely to experience hearing loss compared to the general population.
Tinnitus caused by exposure to loud noise can be temporary or permanent, depending on the extent of ear damage.
3. TMD Disorders
The temporomandibular joint (TMJ) is the joint that connects the jaw to the skull. It acts as a hinge and facilitates jaw movements.
When the TMJ is damaged, it causes a painful localized disorder called TMJ syndrome or disorder.
This damage can be due to misalignment of the jaw or teeth, osteoarthritis, poor posture, chewing gum, teeth grinding, or trauma to the jaw or teeth.
Common symptoms of TMJ disorder include jaw clicking, ear pain, headaches, sore jaw muscles, joint locking, temple pain, and jaw pain.
TMJ disorder also causes tinnitus. It is easily treatable, and the associated tinnitus disappears once the disorder is corrected.
4. Age
Thirty percent of seniors suffer from tinnitus.
Age is a common cause of tinnitus, especially in older adults. As one ages, hearing weakens and one becomes more vulnerable to hearing disorders.
Older people with hearing loss usually suffer from tinnitus.
While some of this hearing loss is not curable, there are other solutions, such as hearing aids, to help these individuals hear better.
5. Muscle Spasms or Acoustic Shock
The muscles of the ear that control eardrum tension can sometimes contract involuntarily or stiffen.
The two main muscles involved in these spasms are the stapedius muscle and the tensor tympani muscle.
These muscles act to dampen and reduce noises from inside the body and outside the ear. Their repeated and synchronized contraction can cause tinnitus.
Ear muscle spasms can be caused by exposure to loud noise, facial nerve spasm, or extreme fatigue.
People with neurological diseases such as multiple sclerosis are also prone to ear muscle spasms.
6. Earwax Impaction
The ear canal naturally produces a greasy, waxy substance called earwax, which prevents foreign particles, water, dust, or microorganisms from entering the ear.
Naturally, earwax moves from the ear canal towards the entrance of the ear, where it can be cleaned. However, if the ear canal produces more than necessary, it can harden and block the ear.
While some people are predisposed to excessive earwax buildup, this natural accumulation cannot form a blockage unless it is interfered with.
Using objects like hairpins or cotton swabs can push earwax deeper into the ear canal and form a blockage.
An earwax blockage can irritate the eardrum and cause hearing loss or tinnitus.
Tinnitus due to earwax blockage disappears once the blockage is removed. Do not try to remove it yourself: you would only push it further in. Consult a healthcare professional.
Removing the blockage is usually very simple and painless.
7. Arteriovenous Malformation (AVM)
This is a rare condition characterized by an abnormal tangle of blood vessels that connect veins and arteries.
When these veins and arteries become entangled, they bypass normal tissues. That said, no known cause explains this abnormal entanglement.
Most people with AVM are born with it, and some never experience symptoms. These vary depending on where the tangle is located.
Symptoms include ringing in the ears, back pain, seizures, headaches, visual disturbances, and muscle weakness.
If the entanglement occurs in the head or near the ear, it can cause tinnitus, usually felt in only one ear.
8. Acoustic Neuroma
Acoustic neuroma, also called vestibular schwannoma, is a non-cancerous tumor that develops on the vestibular nerve, which connects the inner ear to the brain. The vestibular nerve plays an essential role in hearing and balance.
This tumor usually grows slowly, or not at all, but in very rare cases it can grow large enough to compress the brain.
The tumor can cause instability, ringing in the ear (tinnitus), and hearing loss. Acoustic neuroma is treated with radiation therapy and surgical removal.
Conclusion
While some of the types of tinnitus discussed in this article can be treated, others are permanent.
It is therefore essential to do your utmost to protect your ears from anything that can cause tinnitus or other hearing problems. If you notice any form of tinnitus, do not self-medicate and consult a healthcare professional immediately.
Have you ever suffered from any of these types of tinnitus? Share your experience with us.
