Endolymph

What is endolymph?

Endolymph is inner ear fluid that helps you hear and maintain your balance. Your inner ear contains structures that make up your hearing system and your vestibular (balance) system. Endolymph fills these parts. When endolymph moves or shifts, it triggers the release of nerve signals that your brain perceives as sound or information about your body’s position and stability.

Related, issues with endolymph can interfere with your hearing or your ability to stay in balance.

What does endolymph do?

Endolymph helps convert energy within your inner ear (from sound or movement) into nerve signals that reach your brain. When endolymph moves, it triggers sensory hair cells to release signals your brain can understand.

Hearing

Endolymph helps transform sound waves into auditory (sound) signals, so you can hear. Endolymph fills the cochlear duct — the innermost part of your cochlea. Also inside your cochlear duct is a structure lined with sensory hair cells called the organ of Corti.

Sound waves traveling within your inner ear create vibrations in endolymph. When the endolymph moves, so do the hair cells in the organ of Corti. The displaced hair cells release auditory signals that travel to the part of your brain that processes sound information.

Balance

Endolymph fills structures that play a role in your balance. This includes the utricle and saccule. They detect up/down and forward/back head movements. Endolymph also fills three semicircular canals, which detect rotational head movements. Like their auditory (hearing) counterparts, these structures also contain sensory hair cells.

When your head moves, the endolymph inside shifts and displaces the hair cells. The cells release signals to the part of your brain that registers information about your body’s position, so you can stay in balance.

Where is endolymph located?

Endolymph fills a network of ducts within your inner ear called the membranous labyrinth. This includes your cochlear duct (the place where sound waves get converted into auditory signals) and an intricate pathway of organs that sense movement (including the utricle, saccule and semicircular canals).

The endolymph-filled membranous labyrinth is housed inside a sturdy casing called the bony labyrinth. The bony labyrinth also contains perilymph — your other important inner ear fluid. A barrier called Reissner’s membrane separates the membranous labyrinth (and the endolymph inside) from the perilymph within the bony labyrinth.

What is endolymph made of?

The most important ingredient in endolymph fluid is potassium. When endolymph shifts, it releases potassium ions that activate the hair receptor cells to send nerve signals. These signals eventually reach your brain.

How is endolymph produced?

Endolymph gets made in the stria vascularis. This structure lines your cochlea and is made of epithelial cells. “Dark cells” inside your semicircular canals help supply endolymph with potassium.

What disorders are associated with endolymph?

Ménière’s disease is the most common disorder associated with endolymph. Some people with this condition have too much endolymph fluid in their inner ear. Excess endolymph in your inner ear is called endolymphatic hydrops.

Common symptoms of endolymph-related disorders

Symptoms of excess endolymph (endolymphatic hydrops) or problems with endolymph movement may cause:

• Bouts of hearing loss
• Vertigo (feeling as if the room is spinning)
• Ringing in your ears (tinnitus)
• Feelings of fullness or pressure in your ear
• Nausea
• Headaches

Common tests to check endolymph

Tests to check for endolymph-related conditions include the following:

• A brain MRI with contrast can show if you have too much endolymph in your inner ear.
• Hearing tests (audiometry) can check for hearing issues related to endolymph issues.
• Vestibular testing can check for balance problems that may be related to problems with endolymph.
• Electrocochleography (ECochG) can check if there are high levels of endolymph fluid in your inner ear.

What are common treatments for endolymph-related conditions?

Treatments that address excess endolymph buildup in your inner ear include:

• Changing what you eat. Cutting back on salty foods may reduce endolymph buildup in your inner ear. Salt causes your body to retain fluid.
• Medications. Medications that providers prescribe for Ménière’s disease include diuretics (water pills), corticosteroids (steroid injections) and anti-nausea medications.
• Therapies. Treatment may include vestibular rehabilitation therapy to help with balance issues. Cognitive behavioral therapy (CBT) can reduce stress related to having frequent vertigo episodes.
• Surgery. Surgical treatments include procedures that drain your endolymphatic sac. Your healthcare provider may cut into it to release excess endolymphatic fluid.

How do I take care of myself?

What’s good for your inner ear, in general, is good for all the structures and fluids inside. The best way to protect the delicate structures inside your inner ear (including endolymph) is to avoid loud noises. Over time, the loud sounds can damage your hair receptor cells. Wear proper ear protection and turn the volume down on loud music.